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                                                                    EXHIBIT 4.59



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                                TRUST INDENTURE

                             AND SECURITY AGREEMENT


                           dated as of August 1, 1996

                                    between

                  FIRST UNION NATIONAL BANK OF NORTH CAROLINA,
                  in its individual capacity only as expressly
            set forth herein and otherwise solely as Owner Trustee,

                                      and

                           WILMINGTON TRUST COMPANY,
                              as Indenture Trustee


                          ------------------------


                       One Boeing Model 737-3H4 Aircraft


                      SOUTHWEST AIRLINES 1996 TRUST N625SW


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                             Southwest Airlines Co.
                   Series SWA 1996 Trust N625SW Certificates
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                               TABLE OF CONTENTS



                                                                                                                     Page
                                                                                                                    
ARTICLE 1
         DEFINITIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
         Section 1.01.     Definitions.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
         Section 1.02      Other Definitions.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11

ARTICLE 2
         THE CERTIFICATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
         Section 2.01.     Certificates; Title and Terms.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
         Section 2.02.     Execution and Authentication.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         Section 2.03.     Registrar and Paying Agent.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
         Section 2.04.     Transfer and Exchange.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
         Section 2.05.     Holder Lists; Ownership of Certificates.   . . . . . . . . . . . . . . . . . . . . . . . .  13
         Section 2.06.     Mutilated, Destroyed, Lost or Stolen Certificates  . . . . . . . . . . . . . . . . . . . .  14
         Section 2.07.     Cancellation.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
         Section 2.08.     Payment on Certificates; Defaulted Principal and Interest.   . . . . . . . . . . . . . . .  14
         Section 2.09.     Payment from Indenture Estate Only.  . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
         Section 2.10.     Execution, Delivery and Dating of Certificates upon Issuance.  . . . . . . . . . . . . . .  16

ARTICLE 3
         RECEIPT, DISTRIBUTION AND APPLICATIONOF FUNDS IN THE INDENTURE . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 3.01.     [Reserved for Potential Future Use].   . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 3.02.     Payment in Case of Redemption of Certificates.   . . . . . . . . . . . . . . . . . . . . .  17
         Section 3.03.     Application of Rent When No Indenture Event of Default Is
                           Continuing.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 3.04.     Application of Certain Payments in Case of Requisition or Event of
                           Loss.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
         Section 3.05.     Payments During Continuance of Indenture Event of Default.   . . . . . . . . . . . . . . .  19
         Section 3.06.     Payments for Which Application Is Provided in Other Documents.   . . . . . . . . . . . . .  20
         Section 3.07.     Payments for Which No Application Is Otherwise Provided.   . . . . . . . . . . . . . . . .  20
         Section 3.08.     Application of Payments.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20

ARTICLE 4
         COVENANTS OF OWNER TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         Section 4.01.     Covenants of the Owner Trustee.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         Section 4.02.     Covenants of First Union National Bank of North Carolina.  . . . . . . . . . . . . . . . .  22






                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -i-
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ARTICLE 5
         DISPOSITION, SUBSTITUTION AND RELEASEOF PROPERTY INCLUDED IN THE INDENTURE ESTATE DURING CONTINUATION
         OF LEASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
         Section 5.01.     Disposition, Substitution and Release of Property Included in the
                           Indenture Estate During Continuation of Lease.   . . . . . . . . . . . . . . . . . . . . .  22
         Section 5.02.     Certificates in Respect of Replacement Aircraft and Engines.   . . . . . . . . . . . . . .  23

ARTICLE 6
         REDEMPTION OF CERTIFICATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         Section 6.01.     Redemption of Certificates upon Certain Events.  . . . . . . . . . . . . . . . . . . . . .  23
         Section 6.02.     Redemption or Purchase of Certificates Upon Certain Indenture Events
                           of Default.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
         Section 6.03.     Notice of Redemption to Holders.   . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
         Section 6.04.     Deposit of Redemption Price.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
         Section 6.05.     Certificates Payable on Redemption Date.   . . . . . . . . . . . . . . . . . . . . . . . .  25

ARTICLE 7
         MATTERS CONCERNING THE COMPANY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
         Section 7.01.     Repayment of Monies for Certificate Payments Held by the Indenture Trustee.                 25
         Section 7.02.     [Reserved for Potential Future Use].   . . . . . . . . . . . . . . . . . . . . . . . . . .  25
         Section 7.03.     Assumption of Obligations of Owner Trustee by the Company.   . . . . . . . . . . . . . . .  26

ARTICLE 8
         DEFAULTS AND REMEDIES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 8.01.     Indenture Events of Default.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 8.02.     Acceleration; Rescission and Annulment.  . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 8.03.     Other Remedies Available to Indenture Trustee.   . . . . . . . . . . . . . . . . . . . . .  30
         Section 8.04.     Waiver of Owner Trustee.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         Section 8.05.     Waiver of Existing Defaults.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         Section 8.06.     Control by Majority.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         Section 8.07.     Limitation on Suits by Holders.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
         Section 8.08.     Rights of Holders to Receive Payment.  . . . . . . . . . . . . . . . . . . . . . . . . . .  36
         Section 8.09.     Indenture Trustee May File Proofs of Claim.  . . . . . . . . . . . . . . . . . . . . . . .  36

ARTICLE 9
         INDENTURE TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
         Section 9.01.     Duties of Indenture Trustee.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
         Section 9.02.     Rights of Indenture Trustee.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
         Section 9.03.     Individual Rights of Indenture Trustee   . . . . . . . . . . . . . . . . . . . . . . . . .  38
         Section 9.04.     Funds May Be Held by Indenture Trustee or Paying Agent;
                           Investments.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38






                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         Section 9.05.     Notice of Defaults.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
         Section 9.06.     Compensation and Indemnity.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
         Section 9.07.     Replacement of Indenture Trustee.  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 9.08.     Successor Indenture Trustee, Agents by Merger, Etc.  . . . . . . . . . . . . . . . . . . .  41
         Section 9.09.     Eligibility; Disqualification.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  41
         Section 9.10.     Trustee's Liens.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  41
         Section 9.11.     Withholding Taxes; Information Reporting.  . . . . . . . . . . . . . . . . . . . . . . . .  42
         Section 9.12.     [Reserved for Potential Future Use]  . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
         Section 9.13.     Certain Rights of Owner Trustee and Owner Participant.   . . . . . . . . . . . . . . . . .  42

ARTICLE 10
         SATISFACTION AND DISCHARGE; DEFEASANCE;TERMINATION OF OBLIGATIONS  . . . . . . . . . . . . . . . . . . . . .  43
         Section 10.01.    Satisfaction and Discharge of Agreement; Defeasance; Termination
                           of Obligations.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         Section 10.02.    Survival of Certain Obligations.   . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
         Section 10.03.    Monies to Be Held in Trust.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
         Section 10.04.    Monies to Be Returned to Owner Trustee.  . . . . . . . . . . . . . . . . . . . . . . . . .  44
         Section 10.05.    Defeasance.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44

ARTICLE 11
         AMENDMENTS AND WAIVERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         Section 11.01.    Amendments to this Agreement Without Consent of Holders.   . . . . . . . . . . . . . . . .  46
         Section 11.02.    Amendments to this Agreement with Consent of Holders.  . . . . . . . . . . . . . . . . . .  47
         Section 11.03.    Revocation and Effect of Consents.   . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 11.04.    Notation on or Exchange of Certificates.   . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 11.05.    Indenture Trustee Protected.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 11.06.    Amendments, Waivers, Etc. of Other Operative Agreements.   . . . . . . . . . . . . . . . .  48
         Section 11.07.    Trust Supplement.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51

ARTICLE 12
         MISCELLANEOUS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
         Section 12.01.    Notices.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
         Section 12.02.    [Reserved for Potential Future Use]  . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.03.    [Reserved for Potential Future Use]  . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.04.    Rules by Indenture Trustee and Agents.   . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.05.    Non-Business Days.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.06.    GOVERNING LAW.   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.07.    No Recourse Against Others.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.08.    Execution in Counterparts.         . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
         Section 12.09.    [Reserved for Potential Future Use].52
         Section 12.10.    Severability.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53






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ARTICLE 13
         ACTIONS TO BE TAKEN UPON TERMINATION OF LEASE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53
         Section 13.01.    Actions to Be Taken upon Termination of Lease.   . . . . . . . . . . . . . . . . . . . . .  53


                                    EXHIBITS


Exhibit A-1       -        Form of Series SWA 1996 Trust N625SW Installment
                           Certificates

Exhibit A-2       -        Form of Series SWA 1996 Trust N625SW Serial
                           Certificates

Exhibit B         -        Maturity Dates, Principal Amounts and Interest Rates
                           on Series SWA 1996 Trust N625SW Certificates

Exhibit B-1       -        Installment Payment Dates and Installment Payment
                           Percentages

Exhibit B-2       -        Issuance of Series SWA 1996 Trust N625SW
                           Certificates

Exhibit C         -        [FORM OF] Trust Agreement and Trust Indenture and
                           Security Agreement Supplement





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -iv-
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                     TRUST INDENTURE AND SECURITY AGREEMENT


                 This TRUST INDENTURE AND SECURITY AGREEMENT, dated as of
August 1, 1996, is between FIRST UNION NATIONAL BANK OF NORTH CAROLINA, a
national banking association organized under the laws of the United States, in
its individual capacity only as expressly provided herein and otherwise solely
as Owner Trustee under the Trust Agreement (capitalized terms used herein
having the respective meanings specified therefor in Article 1), and WILMINGTON
TRUST COMPANY, a Delaware banking corporation, as Indenture Trustee hereunder.

                              W I T N E S S E T H:

                 WHEREAS, the Owner Participant and the Owner Trustee in its
individual capacity have entered into the Trust Agreement whereby, among other
things, (i) the Owner Trustee has established a certain trust for the use and
benefit of the Owner Participant, subject, however, to the Indenture Estate
created pursuant hereto for the use and benefit of, and with the priority of
payment to, the holders of the Certificates issued hereunder, and (ii) the
Owner Trustee has been authorized and directed to execute and deliver this
Agreement;

                 WHEREAS, the parties desire by this Agreement, among other
things, (i) to provide for the issuance by the Owner Trustee of the Series SWA
1996 Trust N625SW Certificates evidencing the loans made by the Pass Through
Trustees to finance the Owner Trustee's payment of Lessor's Cost as provided in
the Participation Agreement, and (ii) to provide for the assignment, mortgage
and pledge by the Owner Trustee to the Indenture Trustee, as part of the
Indenture Estate hereunder, among other things, of certain of the Owner
Trustee's right, title and interest in and to the Aircraft and the Operative
Agreements and certain payments and other amounts received hereunder or
thereunder in accordance with the terms hereof, as security for, among other
things, the Owner Trustee's obligations to the Indenture Trustee, for the
ratable benefit and security of the Holders; and

                 WHEREAS, all things necessary to make this Agreement the
legal, valid and binding obligation of the Owner Trustee and the Indenture
Trustee, for the uses and purposes herein set forth, in accordance with its
terms, have been done and performed and have happened;

                                GRANTING CLAUSE

                 NOW, THEREFORE, THIS TRUST INDENTURE AND SECURITY AGREEMENT
WITNESSETH, that, to secure the prompt payment of the principal of, Premium, if
any, and interest on, and all other amounts due with respect to, all
Certificates from time to time Outstanding and all other amounts due to the
Holders hereunder and under the Participation Agreement and the performance and
observance by each of the Company and the Owner Trustee of all the agreements,
covenants and provisions contained herein and in the Operative Agreements to
which it is a party, for the benefit of Indenture Trustee and the Holders, and
for the uses and purposes hereof, and in consideration of the premises and of
the covenants herein contained, and of the acceptance of the Certificates by
the Holders, and of the sum of $1 paid to the Owner Trustee by the Indenture
Trustee at or before the delivery hereof, the receipt whereof is hereby
acknowledged, the Owner Trustee has granted, bargained, sold, assigned,
transferred, conveyed, mortgaged, pledged and confirmed, and does hereby grant,
bargain, sell, assign, transfer, convey, mortgage, pledge and confirm, unto the
Indenture Trustee, its successors and assigns,





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -1-
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for the security and benefit of the Holders from time to time, a security
interest in and mortgage lien on all estate, right, title and interest of the
Owner Trustee in, to and under the following described property, rights,
interests and privileges, other than Excluded Payments (which collectively,
including all property hereafter specifically subjected to the lien of this
Agreement by any instrument supplemental hereto, but excluding the Excluded
Payments, are herein called the "Indenture Estate"):

                           (1)    the Aircraft (including the Airframe and the
         Engines originally installed thereon on the Delivery Date), and all
         replacements thereof and substitutions therefor in which the Owner
         Trustee shall from time to time acquire an interest in accordance with
         the Lease, as more particularly described in the Trust Supplement and
         the Lease Supplement executed and delivered with respect to the
         Aircraft or any such replacements or substitutions therefor, as
         provided in this Agreement, and all Records maintained with respect to
         the foregoing property;

                           (2)    the Lease and all Rent thereunder, including,
         without limitation, all amounts of Basic Rent, Supplemental Rent,
         payments of any kind required to be made by the Company thereunder
         (including the purchase price for the Aircraft pursuant to Section
         18.2 of the Lease) and any sales proceeds of the Aircraft sold
         pursuant to Section 9 of the Lease or otherwise; the Purchase
         Agreement (to the extent assigned by the Purchase Agreement
         Assignment); the Purchase Agreement Assignment; all subleases of the
         Airframe and the Engines and all rent thereunder to the extent
         assigned to the Owner Trustee by Lessee; the Bills of Sale; the
         Participation Agreement; and the Manufacturer's Consent; including,
         without limitation, in respect of each of the foregoing documents and
         instruments, all rights of the Owner Trustee to receive any payments
         or other amounts or to exercise any election or option or to make any
         decision or determination or to give or receive any notice, consent,
         waiver or approval or to take any other action under or in respect of
         any such document or to accept surrender or redelivery of the Aircraft
         or any part thereof, as well as all the rights, powers and remedies on
         the part of the Owner Trustee, whether acting under any such document
         or by statute or at law or in equity, or otherwise, arising out of any
         Lease Event of Default;

                           (3)    all rents, issues, profits, revenues and
         other income of the property subjected or required to be subjected to
         the Lien of this Agreement;

                           (4)    all requisition proceeds with respect to the
         Aircraft or any part thereof and all insurance proceeds with respect
         to the Aircraft or any part thereof;

                           (5)    all moneys and securities now or hereafter
         paid or deposited or required to be paid or deposited to or with the
         Indenture Trustee by or for the account of the Owner Trustee pursuant
         to any term of any Operative Agreement and held or required to be held
         by the Indenture Trustee hereunder; and

                           (6)    all proceeds of the foregoing.

                 On the Delivery Date the Owner Trustee shall deliver to the
Indenture Trustee an executed chattel paper original counterpart of each of the
Lease and the Lease Supplement covering the Aircraft, together with executed
copies of the Trust Agreement and each of the other Indenture Documents (other
than the Purchase Agreement, the Participation Agreement and the FAA bills of
sale).  All property referred to in this Granting Clause, whenever acquired by
the Owner Trustee, shall secure





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -2-
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all obligations under and with respect to the Certificates at any time
Outstanding.  Any and all properties referred to in this Granting Clause which
are hereafter acquired by the Owner Trustee, shall, without further conveyance,
assignment or act by the Owner Trustee or the Indenture Trustee thereby become
and be subject to the security interest hereby granted as fully and completely
as though specifically described herein.

                                HABENDUM CLAUSE

                 TO HAVE AND TO HOLD all and singular the aforesaid property
unto the Indenture Trustee, its successors and assigns, in trust for the
benefit and security of the Indenture Trustee and the Holders from time to
time, without any priority of any one Certificate over any other, and for the
uses and purposes and subject to the terms and provisions set forth in this
Agreement.

                 The Owner Trustee agrees that this Agreement is intended to
and shall create and grant a security interest in the Aircraft to the Indenture
Trustee, which security interest shall attach on the Delivery Date. The
security interest created by this Agreement and granted to the Indenture
Trustee hereunder in the Indenture Estate other than in the Aircraft shall
attach in the case of each other item of property included in the Indenture
Estate upon the delivery thereof or upon the Owner Trustee's acquiring rights
in such property.

                 It is expressly agreed that anything herein contained to the
contrary notwithstanding, the Owner Trustee shall remain liable under each of
the Operative Agreements to which it is a party, to perform all of the
obligations assumed by it thereunder, all in accordance with and pursuant to
the terms and provisions thereof, and the Indenture Trustee and the Holders
shall have no obligation or liability under any of the Operative Agreements to
which the Owner Trustee is a party by reason of or arising out of the
assignment hereunder, nor shall the Indenture Trustee or the Holders be
required or obligated in any manner to perform or fulfill any obligations of
the Owner Trustee under any of the Operative Agreements to which the Owner
Trustee is a party, or, except as herein expressly provided, to make any
payment, or to make any inquiry as to the nature or sufficiency of any payment
received by it, or present or file any claim, or take any action to collect or
enforce the payment of any amounts which may have been assigned to it or to
which it may be entitled at any time or times.

                 The Owner Trustee does hereby constitute the Indenture Trustee
the true and lawful attorney of the Owner Trustee, irrevocably, with full power
(in the name of the Owner Trustee or otherwise) to ask, require, demand,
receive and, to the extent permitted by Article 8 hereof (if an Event of
Default shall have occurred and be continuing), give acquittance for any and
all moneys and claims for moneys due and to become due to the Owner Trustee
(other than Excluded Payments) under or arising out of any Indenture Document
and all other property which now or hereafter constitutes part of the Indenture
Estate, to endorse any checks or other instruments or orders in connection
therewith and, to file any claims or take any action or institute any
proceedings which the Indenture Trustee may deem to be necessary or advisable
in the premises. The Owner Trustee has directed the Company to make all
payments of Rent (other than Excluded Payments) payable to the Owner Trustee by
the Company and all other amounts which are required to be paid to or deposited
with the Owner Trustee pursuant to the Lease directly to the Indenture Trustee
at such address as the Indenture Trustee shall specify, for application as
provided in this Agreement. The Owner Trustee agrees that promptly on receipt
thereof, it will transfer to the Indenture Trustee any and all moneys from time
to time received by it constituting part of the Indenture Estate, for
distribution by the Indenture Trustee pursuant to this Agreement, except





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -3-
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that the Owner Trustee shall accept for distribution pursuant to the Trust
Agreement any amounts distributed to it by the Indenture Trustee as expressly
provided in this Agreement and any Excluded Payments.

                 The Owner Trustee agrees that at any time and from time to
time, upon the written request of the Indenture Trustee, the Owner Trustee will
promptly and duly execute and deliver or cause to be duly executed and
delivered any and all such further instruments and documents as the Indenture
Trustee may reasonably deem desirable in obtaining the full benefits of the
assignment hereunder and of the rights and powers herein granted.

                 The Owner Trustee does hereby warrant and represent that it
has not assigned or pledged, and hereby covenants that it will not assign or
pledge, so long as the assignment hereunder shall remain in effect, any of its
right, title or interest hereby assigned, to anyone other than the Indenture
Trustee, and that it will not, except as provided in or permitted by this
Agreement, accept any payment from the Company, enter into an agreement
amending or supplementing any of the Operative Agreements, execute any waiver
or modification of, or consent under the terms of any of the Operative
Agreements, settle or compromise any claim (other than claims in respect of
Excluded Payments) against the Company arising under any of the Operative
Agreements, or submit or consent to the submission of any dispute, difference
or other matter arising under or in respect of any of the Operative Agreements,
to arbitration thereunder.

                 The Owner Trustee does hereby ratify and confirm the Indenture
Documents and does hereby agree that (except as permitted herein) it will not
take or omit to take any action, the taking or omission of which would result
in an alteration or impairment of any of the Indenture Documents or of any of
the rights created by any thereof or the assignment hereunder.

                 Notwithstanding the Granting Clause, any of the preceding
paragraphs or any other provision of this Indenture, there are hereby expressly
excluded from the foregoing grant, bargain, sale, assignment, transfer,
conveyance, mortgage, pledge and security interest all Excluded Payments.
Further, nothing in the Granting Clause or any of the preceding paragraphs
shall impair in any respect the rights of the Owner Trustee or the Owner
Participant under Section 9.13 or 11.06.

                 IT IS HEREBY COVENANTED AND AGREED by and among the parties
hereto as follows:

                                   ARTICLE 1

                                  DEFINITIONS

                 SECTION 1.01.    DEFINITIONS.     (a)      For all purposes of
this Agreement, except as otherwise expressly provided or unless the context
otherwise requires:

                          (1)     the terms defined in this Article 1 have the
         meanings assigned to them in this Article 1, and include the plural as
         well as the singular;

                          (2)     all accounting terms not otherwise defined
         herein have the meanings assigned to them in accordance with generally
         accepted accounting principles in the United States;





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -4-
   10
                          (3)     the words "herein", "hereof" and "hereunder"
         and other words of similar import refer to this Agreement as a whole
         and not to any particular Article, Section or other subdivision; and

                          (4)     unless otherwise specified, all references in
         this Agreement to Articles, Sections and Exhibits refer to Articles,
         Sections and Exhibits of this Agreement.

                 (b)      For all purposes of this Agreement, the following
capitalized terms have the following respective meanings:

                 "Affiliate" with respect to a specified Person, means any
other Person directly or indirectly controlling or controlled by or under
direct or indirect common control with such Person. For the purposes of this
definition, "control" when used with respect to any specified Person, means the
power to direct the management and policies of such Person, directly or
indirectly, whether through the ownership of voting securities, by contract or
otherwise, and the terms "controlling" and "controlled" have meanings
correlative to the foregoing.

                 "Agent" means any Paying Agent or Registrar.

                 "Bankruptcy Code" means the United States Bankruptcy Code of
1978, as amended, or any successor statute.

                 "Business Day" means any day other than a Saturday or Sunday
or a day on which commercial banks are required or authorized to close in the
City of Dallas, Texas; New York, New York; the city and state in which (i) so
long as any Certificates shall be Outstanding, each of the Indenture Trustee
and the Pass Through Trustees and (ii) thereafter, the Owner Trustee, has its
principal place of business; and the city and state in which the Indenture
Trustee, Pass Through Trustee or the Owner Trustee, as the case may be,
receives and disburses funds.

                 "Certificate" or "Certificates" means any certificate or other
debt instrument issued under this Agreement.

                 "Company" means Southwest Airlines Co., a Texas corporation,
and, subject to the provisions of the Participation Agreement, its permitted
successors and assigns.

                 "Company Request" means a written request of the Company
executed on its behalf by a Responsible Company Officer of the Company.

                 "Co-Registrar" shall have the meaning specified therefor in
Section 2.03.

                 "Debt" means any liability for borrowed money, or any
liability for the payment of money in connection with any letter of credit
transaction, or other liabilities evidenced or to be evidenced by bonds,
debentures, notes or other similar instruments.

                 "Defaulted Installment" shall have the meaning specified
therefor in Section 2.08.

                 "Defaulted Interest" shall have the meaning specified therefor
in Section 2.08.



                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -5-
   11
                 "Defeasance Trustee" shall have the meaning specified therefor
in Section 10.05.

                 "Excluded Payments" means (i) any right, title or interest of
the Owner Trustee in its individual capacity, the Owner Participant or their
respective Affiliates or of their respective, successors, permitted assigns,
directors, officers, employees, servants and agents to any indemnity payment,
including, but not limited to, any payment which by the terms of Section 7(b),
7(c), 7(f), 16 or 17 of the Participation Agreement, Section 5.03 or 7.01 of
the Trust Agreement or any section of the Tax Indemnity Agreement or any
corresponding payment under Section 3.5 of the Lease shall be payable to the
Owner Trustee in its individual capacity or to the Owner Participant, or their
respective Affiliates, as the case may be, pursuant to the terms of the
Operative Agreements, (ii) any insurance proceeds payable under insurance
maintained by the Owner Trustee in its individual or trust capacity or the
Owner Participant (whether directly or through the Owner Trustee), or to their
respective Affiliates, successors, permitted assigns, directors, officers,
employees, servants and agents, (iii) any insurance proceeds (or proceeds of
governmental indemnities in lieu thereof) payable to the Owner Trustee in its
individual capacity or to the Owner Participant or to their respective
Affiliates, successors, permitted assigns, directors, officers, employees,
servants and agents, under any liability insurance maintained by the Company
pursuant to Section 11 of the Lease or by any other Person (or proceeds of
governmental indemnities in lieu thereof), (iv) payments to the Owner
Participant by the Owner Trustee pursuant to Section 2 of the Participation
Agreement and any funds held by the Owner Trustee or payable to the Owner
Participant pursuant to any funding letter entered into in lieu of the
provisions of Section 2 of the Participation Agreement, (v) amounts paid or
payable to the Owner Trustee from Lessee pursuant to Section 18.2(c) of the
Lease, (vi) Transaction Costs or other amounts or expenses paid or payable to,
or for the benefit of, the Owner Participant pursuant to the Participation
Agreement, (vii) the respective rights of the Owner Trustee in its individual
or trust capacity or the Owner Participant to the proceeds of the foregoing,
(viii) any payment of Rent attributable to an indemnity payment under the Tax
Indemnity Agreement, (ix) any right to demand, collect, sue or otherwise
receive and enforce the payment of any amount described in clauses (i) through
(viii) above, and (x) the rights under Sections 9.13 and 11.06 hereof.

                 "Federal Aviation Act" means Subtitle VII of Title 49, U.S.C.,
as amended.

                 "Government Obligations" shall have the meaning specified
therefor in Section 10.05.

                 "Holder" or "Certificate Holder" means a Person in whose name
a Certificate is registered on the Register.

                 "Indenture Default" means any event which is, or after notice
or passage of time, or both, would be, an Indenture Event of Default.

                 "Indenture Documents" means each and every document or
instrument referred to in the Granting Clause hereof.

                 "Indenture Estate" shall have the meaning specified therefor
in the Granting Clause hereof.

                 "Indenture Event of Default" shall have the meaning specified
therefor in Section 8.01.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -6-
   12
                 "Indenture Trustee" means Wilmington Trust Company, and each
other Person which may from time to time be acting as Indenture Trustee in
accordance with the provisions of this Agreement.

                 "Independent" when used with respect to an engineer, appraiser
or other expert, means an engineer, appraiser or other expert who (i) is in
fact independent, (ii) does not have any direct financial interest or any
material indirect financial interest in the Company or any Affiliate of the
Company and (iii) is not connected with the Company or any Affiliate of the
Company as an officer, employee, promoter, underwriter, trustee, partner,
director or Person performing similar functions.

                 "Independent Investment Banker" means an Independent
investment banking institution of national standing appointed by the Company on
behalf of the Owner Trustee (and reasonably acceptable to the Owner
Participant, which acceptance shall not be unreasonably withheld after notice
to the Owner Participant); provided, that if the Indenture Trustee shall not
have received written notice of such an appointment at least 10 days prior to
the relevant Redemption Date or if a Lease Event of Default shall have occurred
and be continuing, "Independent Investment Banker" shall mean such an
institution appointed by the Indenture Trustee.

                 "Installment Certificate" means a Certificate substantially in
the form of Exhibit A-1, should any such Certificate be issued hereunder.

                 "Installment Payment Amount" means, with respect to each
Installment Certificate, the amount of the installment payment of principal due
and payable on each Installment Payment Date, which amount shall be equal to
the product of the original principal amount of such Certificate and the
Installment Payment Percentage for such Installment Payment Date.

                 "Installment Payment Date" means each date on which an
installment payment of principal is due and payable on the Certificates, as set
forth in Exhibit B-l.

                 "Installment Payment Percentage" means, with respect to each
Installment Payment Date, the percentage set forth opposite such Installment
Payment Date in Exhibit B-l.

                 "Interest Payment Date" means each July 2 and January 2
commencing on January 2, 1997.

                 "Lease" means the Sale and Lease Agreement, dated as of the
date hereof, between the Owner Trustee, as lessor, and the Company, as lessee,
relating to the Aircraft as such Sale and Lease Agreement may from time to time
be supplemented, amended or modified in accordance with the terms thereof and
this Agreement. The term "Lease" shall also include each Lease Supplement
entered into pursuant to the terms of the Lease.

                 "Lease Loss Payment Date" means the date on which Stipulated
Loss Value is payable pursuant to Section 10.1.4 of the Lease in connection
with an Event of Loss in respect of the Aircraft.

                 "Lease Termination Date" means the date the Lease terminates
pursuant to Section 9 of the Lease.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -7-
   13
                 "Maturity Date" means, with respect to the Series SWA 1996
Trust N625SW Certificates, each of the dates specified in Exhibit B as a
maturity date of such Certificates.

                 "Officers' Certificate" means a certificate signed in the case
of the Company, by (i) the Chairman of the Board of Directors, the President,
or any Executive or Senior Vice President of the Company, signing alone, or
(ii) any Vice President signing together with the Secretary, any Assistant
Secretary, the Treasurer, any Assistant Treasurer or the Controller of the
Company or, in the case of the Owner Trustee, a Responsible Officer of the
Owner Trustee.

                 "Opinion of Counsel" means a written opinion of legal counsel,
who in the case of counsel for the Company may be (i) the senior corporate
attorney employed by the Company, (ii) Vinson & Elkins L.L.P. or (iii) other
counsel designated by the Company and who shall be reasonably satisfactory to
the Indenture Trustee or, in the case of legal counsel for the Owner Trustee,
may be (x) Moore & Van Allen PLLC or (y) other counsel designated by the Owner
Trustee and who shall be reasonably satisfactory to the Indenture Trustee.

                 "Outstanding", when used with respect to Certificates, means,
as of the date of determination, all Certificates theretofore executed and
delivered under this Agreement other than:

                 (i)      Certificates theretofore cancelled by the Indenture
         Trustee or delivered to the Indenture Trustee for cancellation
         pursuant to Section 2.07 or otherwise;

                 (ii)     Certificates for whose payment or redemption money in
         the necessary amount has been theretofore deposited with the Indenture
         Trustee in trust for the Holders of such Certificates; provided, that
         if such Certificates are to be redeemed, notice of such redemption has
         been duly given pursuant to this Agreement or provision therefor
         satisfactory to the Indenture Trustee has been made; and

                 (iii)    Certificates in exchange for or in lieu of which
         other Certificates have been executed and delivered pursuant to this
         Agreement;

provided, however, that in determining whether the Holders of the requisite
aggregate principal amount of Certificates Outstanding have given any request,
demand, authorization, declaration, direction, notice, consent or waiver
hereunder, Certificates owned by or pledged to the Company or any Affiliate of
the Company or the Owner Trustee or the Owner Participant or any Affiliate
thereof, shall (unless all Certificates are then owned thereby) be disregarded
and deemed not to be Outstanding, except that, in determining whether the
Indenture Trustee shall be protected in relying upon any such request, demand,
authorization, declaration, direction, notice, consent or waiver, only
Certificates which the Indenture Trustee knows to be so owned or so pledged
shall be disregarded. Certificates owned by the Company, or the Owner Trustee
or the Owner Participant, which have been pledged in good faith may be regarded
as Outstanding if the Company, or the Owner Trustee or the Owner Participant,
as the case may be, establishes to the satisfaction of the Indenture Trustee
the pledgee's right to act with respect to such Certificates and that the
pledgee is not the Company, or the Owner Trustee or the Owner Participant or
any Affiliate thereof.

                 "Owner Trustee" means First Union National Bank of North
Carolina, not in its individual capacity, except as expressly provided herein,
but solely as trustee under the Trust Agreement,





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -8-
   14
and each other Person which may from time to time be acting as Owner Trustee in
accordance with the provisions of the Operative Agreements.

                 "Pass Through Certificates" means any of the Pass Through
Certificates issued pursuant to the Pass Through Trust Agreements.

                 "Pass Through Trust" means each pass through trust created
pursuant to the Pass Through Trust Agreements.

                 "Pass Through Trust Agreements" means the Pass Through Trust
Agreement dated as of February 1, 1993, between the Company and the Pass
Through Trustee, as supplemented by the Trust Supplements, whether one or more,
Nos.  1996-A dated as of September 1, 1996, as the same may from time to time
be further amended, supplemented or otherwise modified.

                 "Pass Through Trustee" means Wilmington Trust Company in its
capacity as trustee under each Pass Through Trust Agreement, and such other
Person that may from time to time be acting as successor trustee under any such
Pass Through Trust Agreement.

                 "Past Due Rate" means, in respect of any Certificate, the rate
of interest applicable pursuant to the provisions of such Certificate to any
amount of principal or interest payable thereunder not paid when due.

                 "Paying Agent" means any person acting as Paying Agent
hereunder pursuant to Section 2.03.

                 "Payment Date" means any Installment Payment Date, Interest
Payment Date or Maturity Date.

                 "Permitted Investment" means any of the investments permitted
by Section 22.1 of the Lease.

                 "Premium" means, with respect to each Series SWA 1996 Trust
N625SW Certificate to be redeemed, purchased or otherwise prepaid pursuant to
Article 6, an amount determined as of the Business Day next preceding the
applicable Redemption Date which an Independent Investment Banker determines to
be equal to an excess, if any, of (i) the present values of all remaining
scheduled payments of such principal amount or portion thereof and interest
thereon (excluding interest accrued from the immediately preceding Interest
Payment Date to such Redemption Date) to the Maturity Date of such Certificate
in accordance with generally accepted financial practices assuming a 360-day
year consisting of twelve 30-day months at a discount rate equal to the
Treasury Yield, all as determined by the Independent Investment Banker over
(ii) the unpaid principal amount of such Certificate.  Premium shall never be
below zero.

                 "Premium Termination Date" means, with respect to each Series
SWA 1996 Trust N625SW Certificate, the date set forth as the "Premium
Termination Date" in Exhibit B hereto.

                 "Record Date" for the interest or Installment Payment Amount
payable on any Interest Payment Date or Installment Payment Date (other than
the Maturity Date of the Certificates), as the case





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -9-
   15
may be, means the calendar day (whether or not a Business Day) which is 15
calendar days prior to the related Interest Payment Date or the related
Installment Payment Date.

                 "Redemption Date" means the date on which the Certificates are
to be redeemed or purchased pursuant to Section 6.01 or 6.02.

                 "Redemption Price" means the price at which any or all of the
Certificates (as the context may require) are to be redeemed or purchased,
determined as of the applicable Redemption Date, pursuant to Section 6.01, 6.02
or 15.03, as the case may be.

                 "Refinancing Date" means the date designated by the Company as
the date for a refinancing of the Certificates in accordance with Section 17 of
the Participation Agreement.

                 "Register" shall have the meaning specified therefor in
Section 2.03.
                 "Registrar" means any person acting as Registrar hereunder
pursuant to Section 2.03.

                 "Remaining Weighted Average Life" means, for any Installment
Certificate, at the Redemption Date of such Certificate, the number of days
equal to the quotient obtained by dividing (a) the sum of the products obtained
by multiplying (i) the amount of each then remaining scheduled payment of
principal, including the payment due on the Maturity Date of such Certificate,
by (ii) the number of days from and including the Redemption Date to but
excluding the regularly scheduled date of such scheduled payment of principal;
by (b) the then unpaid principal amount of such Certificate.

                 "Responsible Company Officer" means, with respect to the
Company or Owner Participant, its Chairman of the Board, its President, the
Chief Financial Officer, any Vice President, the Treasurer or any other
management employee (a) working under the direct supervision of such Chairman
of the Board, President, Chief Financial Officer, Vice President or Treasurer
and (b) whose responsibilities include the administration of the transactions
and agreements, including the Lease, contemplated by the Participation
Agreement.

                 "Responsible Officer", with respect to First Union National
Bank of North Carolina, the Owner Trustee or the Indenture Trustee, means any
officer in its Corporate Trust Administration Department or any officer of the
Owner Trustee or the Indenture Trustee, as the case may be, customarily
performing functions similar to those performed by the persons who at the time
shall be such officers, respectively, or to whom any corporate trust matter is
referred because of his knowledge of and familiarity with a particular subject,
and in each case whose responsibilities include the administration of the
transactions and agreements, including the Lease, contemplated by the
Participation Agreement.

                 "SEC" means the Securities and Exchange Commission.

                 "Series SWA 1996 Trust N625SW Certificate" means any
certificate of such designation issued by the Owner Trustee under this
Agreement substantially in the form of Exhibit A-1 or A-2, should any of such
certificates be issued hereunder, and any such certificate issued in
replacement or exchange thereof in accordance with the provisions hereof.

                 "Treasury Yield" means (i) In the case of a Certificate having
a Maturity Date within one year after the Redemption Date the average yield to
maturity on a government bond equivalent basis of





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -10-
   16
the applicable United States Treasury Bill due the week of the Maturity of such
Certificate and (ii) in the case of a Certificate having a Maturity Date one
year or more after the Redemption Date, the average yield of the most actively
traded United States Treasury Notes (as reported by Cantor Fitzgerald
Securities Corp. on page 5 of Telerate Systems, Inc., a financial news service,
or if such report is not available, a source deemed comparable by the
Independent Investment Banker selected to determine the Premium and reasonably
acceptable to the Company and the Owner Participant) corresponding in maturity
(x) for any Certificate issued in serial form, the Maturity Date or (y) for any
Certificate issued in installment form, to the Average Life Date, in each case,
of such Certificate (or, if there is no corresponding maturity, an
interpolation of maturities by the Independent Investment Banker), in each case
determined by the Independent Investment Banker selected to determine the
Premium based on the average of the yields to stated maturity determined from
the bid prices as of 10:00 A.M. and 2:00 P.M. New York time, on the second
Business Day preceding the Redemption Date.  "Average Life Date" means, with
respect to the redemption of an Installment Certificate, the date which follows
the Redemption Date by a period equal to the Remaining Weighted Average Life of
such Certificate.

                 "Trust Estate" shall have the meaning specified therefor in
the Trust Agreement.

                 "Trust Indenture Act" means the Trust Indenture Act of 1939,
as amended.

                 "Trust Indenture and Security Agreement", "this Indenture" or
"this Agreement" means this Trust Indenture and Security Agreement, as the same
may from time to time be supplemented, amended or modified, including by any
Trust Supplement.

                 "Trust Office" means the principal corporate trust office of
the Owner Trustee located at 230 South Tryon Street, 9th Floor, Charlotte,
North Carolina 28288-1179, Attention: Bond Administration, or at such other
office at which the Owner Trustee's corporate trust business shall be
administered which the Owner Trustee shall have specified by notice in writing
to the Company, the Indenture Trustee and each Holder.

                 "Trust Supplement" means a supplement to the Trust Agreement
and this Agreement substantially in the form of Exhibit C.

                 "Trustee's Liens" shall have the meaning specified therefor in
Section 9.10.

                 SECTION 1.02     OTHER DEFINITIONS.        For all purposes of
this Agreement, terms defined in the heading and recitals of this Agreement are
used as so defined and capitalized terms used but not defined herein are used
as defined in the Lease.

                                   ARTICLE 2

                                THE CERTIFICATES

                 SECTION 2.01.    CERTIFICATES; TITLE AND TERMS.    The
Certificates issued hereunder shall be designated as Series SWA 1996 Trust
N625SW Certificates. The Series SWA 1996 Trust N625SW Certificates shall be
substantially in the form set forth in Exhibit A-l or A-2. The Series SWA 1996
Trust N625SW Certificates shall be dated the Delivery Date, shall be issued in
the maturities and principal amounts, and shall bear the interest rates per
annum (subject to Section 2.10 hereof), in each case as specified in Exhibits
B, B-1 and B-2, as the case may be.  The principal of each Certificate, other





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -11-
   17
than Installment Certificates, shall be payable in full on the Maturity Date
for such Certificate. The principal of each Installment Certificate shall be
payable in installments, on each Installment Payment Date, in amounts equal to
the Installment Payment Amount for such Installment Payment Date.

                 The Series SWA 1996 Trust N625SW Certificates shall be issued
in denominations of $1,000 and integral multiples thereof, except that one of
such Certificates may be issued in any denomination.

                 The Certificates shall be issued in registered form only. The
Certificates are not redeemable prior to maturity except as provided in this
Agreement. Interest accrued on the Certificates shall be calculated on the
basis set forth therein.

                 The principal of, Premium, if any, and interest on the
Certificates shall be payable at the principal corporate trust office of the
Indenture Trustee or at any office or agency maintained for such purpose
pursuant to Section 2.03, provided, that all such amounts (other than those
payable on the Maturity Date of the Installment Certificates) may be payable at
the option of the Indenture Trustee or the Paying Agent by check mailed on or
before the due date by the Indenture Trustee or the Paying Agent to the address
of the Holder entitled thereto as such address shall appear in the Register.

                 All payments in respect of the Certificates shall be made in
Dollars.  Any payment due on any Certificate on a day that is not a Business
Day shall be made on the next succeeding day which is a Business Day and
(provided such payment is made on such next succeeding Business Day) no
interest shall accrue on the amount of such payment from and after such
scheduled date.

                 SECTION 2.02.    EXECUTION AND AUTHENTICATION.     (a)
Certificates shall be executed on behalf of the Owner Trustee by the manual or
facsimile signature of its president, a senior vice president, a vice
president, an assistant vice president, its treasurer, its secretary, an
assistant secretary or an assistant treasurer.

                 (b)      If any officer of the Owner Trustee executing the
Certificates by facsimile signature no longer holds that office at the time the
Certificate is executed on behalf of the Owner Trustee, the Certificate shall
be valid nevertheless.

                 (c)      At any time and from time to time after the execution
of the Certificates, the Owner Trustee may deliver such Certificates to the
Indenture Trustee for authentication and, subject to the provisions of Section
2.10, the Indenture Trustee shall authenticate the Certificates by manual
signature upon written orders of the Owner Trustee. Certificates shall be
authenticated on behalf of the Indenture Trustee by any authorized officer or
signatory of the Indenture Trustee.

                 (d)      A Certificate shall not be valid or obligatory for
any purpose or entitled to any security or benefit hereunder until executed on
behalf of the Owner Trustee by the manual or facsimile signature of the officer
of the Owner Trustee specified in the first sentence of Section 2.02(a) and
until authenticated on behalf of the Indenture Trustee by the manual signature
of the officer or signatory of the Indenture Trustee specified in the second
sentence of Section 2.02(c). Such signatures shall be conclusive evidence that
such Certificate has been duly executed, authenticated and issued under this
Agreement.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -12-
   18
                 SECTION 2.03.    REGISTRAR AND PAYING AGENT.       The
Indenture Trustee shall maintain an office or agency where the Certificates may
be presented for registration of transfer or for exchange (the "Registrar") and
an office or agency where (subject to Sections 2.04 and 2.08) the Certificates
may be presented for payment or for exchange (the "Paying Agent"). The
Registrar shall keep a register (the "Register") with respect to the
Certificates and to their transfer and exchange and the payments of Installment
Payment Amounts thereon, if any. The Indenture Trustee may appoint one or more
co-registrars (the "Co-Registrars") and one or more additional Paying Agents
for the Certificates and the Indenture Trustee may terminate the appointment of
any Co-Registrar or Paying Agent at any time upon written notice. The term
"Registrar" includes any Co-Registrar. The term "Paying Agent" includes any
additional Paying Agent.

                 The Indenture Trustee shall initially act as Registrar and
Paying Agent.

                 SECTION 2.04.    TRANSFER AND EXCHANGE.    At the option of
the Holder thereof, Certificates may be exchanged for an equal aggregate
initial principal amount of other Certificates of the same maturity and type,
dated the Delivery Date, and of any authorized denominations or transferred
upon surrender of the Certificates to be exchanged or transferred at the
principal corporate trust office of the Indenture Trustee, or at any office or
agency maintained for such purpose pursuant to Section 2.03.  Whenever any
Certificate is so surrendered for exchange, the Owner Trustee shall execute,
and the Indenture Trustee shall authenticate and deliver, the replacement
Certificate which the Holder making the exchange is entitled to receive.

                 All Certificates issued upon any registration of transfer or
exchange of Certificates shall be the valid obligations of the Owner Trustee,
evidencing the same obligations, and entitled to the same security and benefits
under this Agreement, as the Certificates surrendered upon such registration of
transfer or exchange.

                 Every Certificate presented or surrendered for registration of
transfer or exchange shall (if so required by the Registrar) be duly endorsed
by, or be accompanied by a written instrument of transfer in form satisfactory
to the Registrar duly executed by, the Holder thereof or its attorney duly
authorized in writing.

                 No service charge shall be made to a Holder or any transferee
for any registration of transfer or exchange of Certificates, but the Registrar
may, as a condition to any transfer or exchange hereunder require payment of a
sum sufficient to cover any tax or other governmental charge that may be
imposed in connection with any registration of such transfer or exchange of
Certificates.

                 The Registrar shall not be required to register the transfer
of or to exchange any Certificate called for redemption or purchase pursuant to
Section 6.01 or 6.02.

                 SECTION 2.05.    HOLDER LISTS; OWNERSHIP OF CERTIFICATES.
(a) The Indenture Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
the Holders, which list shall be available to the Owner Trustee or its
representative (which may be the Owner Participant) and the Company for
inspection. If the Indenture Trustee is not the Registrar, the Registrar shall
be required to furnish to the Indenture Trustee semiannually on or before each
Interest Payment Date, and at such other times as the Indenture Trustee may
request in writing, a list, in such form and as of such date as the Indenture
Trustee may reasonably





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -13-
   19
require, containing all the information in the possession or control of the
Registrar as to the names and addresses of the Holders.

                 (b)      Ownership of the Certificates shall be proved by the
Register kept by the Registrar. Prior to due presentment for registration of
transfer of any Certificate, the Owner Trustee, the Owner Participant, the
Company, the Indenture Trustee, the Paying Agent and the Registrar shall deem
and treat the Person in whose name any Certificate is registered as the
absolute owner of such Certificate for the purpose of receiving payment of
principal (including, subject to the provisions herein regarding the applicable
record dates, Installment Payment Amounts) of, Premium, if any, and (subject to
the provisions herein regarding the applicable record dates), interest on such
Certificate and for all other purposes whatsoever, whether or not such
Certificate is overdue, and none of the Owner Trustee, the Owner Participant,
the Company, the Indenture Trustee, the Paying Agent or the Registrar shall be
affected by notice to the contrary.

                 SECTION 2.06.    MUTILATED, DESTROYED, LOST OR STOLEN
CERTIFICATES.          If any Certificate shall become mutilated, destroyed,
lost or stolen, the Owner Trustee shall, upon the written request of the Holder
of such Certificate, issue and execute, and the Indenture Trustee shall
authenticate and deliver, in replacement thereof, as applicable, a new
Certificate of the same type and having the same maturity, payable to the same
Holder in the same principal amount and dated the same date as the Certificate
so mutilated, destroyed, lost or stolen. If the Certificate being replaced has
become mutilated, such Certificate shall be surrendered to the Indenture
Trustee. If the Certificate being replaced has been destroyed, lost or stolen,
the Holder of such Certificate shall furnish to the Owner Trustee and the
Indenture Trustee such security or indemnity as may be required by it to save
the Owner Trustee and the Indenture Trustee harmless and evidence satisfactory
to the Owner Trustee and the Indenture Trustee of the destruction, loss or
theft of such Certificate and of the ownership thereof; provided, however, that
if the affected Holder is the Original Holder, the written notice of such
destruction, loss or theft and such ownership and the written undertaking of
such Holder delivered to the Owner Trustee and the Indenture Trustee to hold
harmless the Owner Trustee and the Indenture Trustee in respect of the
execution, authentication and delivery of such new Certificate shall be
sufficient evidence, security and indemnity.

                 SECTION 2.07.    CANCELLATION.    The Registrar and any Paying
Agent shall forward to the Indenture Trustee all Certificates surrendered to
them for replacement, redemption, registration of transfer, exchange or
payment.  The Indenture Trustee shall cancel all Certificates surrendered for
replacement, redemption, registration of transfer, exchange, payment or
cancellation and shall destroy all cancelled Certificates.

                 SECTION 2.08.    PAYMENT ON CERTIFICATES; DEFAULTED PRINCIPAL
AND INTEREST.  (a) The Indenture Trustee will arrange directly with any Paying
Agent for the payment, or the Indenture Trustee will make payment, all pursuant
to Section 2.09, of the principal of, Premium, if any, and interest on, and any
other amounts payable on or in respect of each Certificate or to the Holder
thereof hereunder. Payment on Series SWA 1996 Trust N625SW Certificates in
respect of interest and Installment Payment Amounts, if any, payable on an
Interest Payment Date or Installment Payment Date, respectively (other than the
Maturity Date of the Series SWA 1996 Trust N625SW Certificates) shall be paid
in Dollars on each Interest Payment Date or Installment Payment Date (other
than the Maturity Date of such Series SWA 1996 Trust N625SW Certificates), as
the case may be, to the Holder thereof at the close of business on the relevant
Record Date; provided, however, that the Paying Agent will, at the request of
the Indenture Trustee and may, at its option, pay such interest and Installment
Payment Amounts (other than those payable on the Maturity Date of the
Installment Certificate) by check mailed on or before the





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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due date to such Holder's address as it appears on the Register.  Otherwise,
principal of Series SWA 1996 Trust N625SW Certificates and Premium, if any,
with respect thereto, shall be payable only against presentation and surrender
thereof at the principal corporate trust office of the Indenture Trustee or at
the office of the Paying Agent maintained for such purpose pursuant to Section
2.03.

                 A Holder shall have no further interest in, or other right
with respect to, the Indenture Estate when and if the principal amount of,
Premium and interest on all Certificates held by such Holder and all other sums
payable to such Holder hereunder, under such Certificates and under the
Participation Agreement shall have been paid in full.

                 (b)      Any Installment Payment Amount payable on an
Installment Payment Date (other than the Maturity Date with respect to a
Certificate) or any interest payable on an Interest Payment Date on any Series
SWA 1996 Trust N625SW Certificate which is not punctually paid on such
Installment Payment Date or such Interest Payment Date, as the case may be
(herein called, respectively, a "Defaulted Installment" and "Defaulted
Interest") shall forthwith cease to be payable to the Holder on the relevant
Record Date by virtue of his having been such Holder; and such Defaulted
Installment or Defaulted Interest may be paid by the Indenture Trustee, at its
election in each case, as provided in clause (1) or (2) below:

                          (1)     The Indenture Trustee may elect to make
         payment of any Defaulted Installment or Defaulted Interest, as the
         case may be, to the Person in whose name any Series SWA 1996 Trust
         N625SW Certificate is registered at the close of business on a special
         record date for the payment of such Defaulted Installment or Defaulted
         Interest, as the case may be, which shall be fixed in the following
         manner. The Indenture Trustee shall notify the Paying Agent in writing
         of the amount of Defaulted Installment or Defaulted Interest, as the
         case may be, proposed to be paid on each such Certificate and the date
         of the proposed payment, and at the same time the Indenture Trustee
         shall make arrangements to set aside an amount of money equal to the
         aggregate amount proposed to be paid in respect of such Defaulted
         Installment or Defaulted Interest, as the case may be, prior to the
         date of the proposed payment, to be held in trust for the benefit of
         the Persons entitled to such Defaulted Installment or Defaulted
         Interest, as the case may be, as this clause provides and shall fix a
         special record date for the payment of such Defaulted Installment or
         Defaulted Interest, as the case may be, which shall be not more than
         15 days and not less than 10 days prior to the date of the proposed
         payment. The Indenture Trustee shall promptly notify the Owner
         Trustee, the Company and the Registrar of such special record date and
         shall cause notice of the proposed payment of such Defaulted
         Installment or Defaulted Interest, as the case may be, and the special
         record date therefor to be mailed, first class postage prepaid, to
         each Holder of a Series SWA 1996 Trust N625SW Certificate at its
         address as it appears in the Register, not less than 10 days prior to
         such special record date. Notice of the proposed payment of such
         Defaulted Installment or Defaulted Interest, as the case may be, and
         the special record date therefor having been mailed, as aforesaid,
         such Defaulted Installment or Defaulted Interest, as the case may be,
         shall be paid to the Persons in whose names the applicable Series SWA
         1996 Trust N625SW Certificates are registered on such special record
         date and shall no longer be payable pursuant to the following clause
         (2).

                          (2)     The Indenture Trustee may make, or cause to
         be made, payment of any Defaulted Installment or Defaulted Interest,
         as the case may be, in any other lawful manner not inconsistent with
         the requirements of any securities exchange on which Series SWA 1996
         Trust





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -15-
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         N625SW Certificates may be listed, and upon such notice as may be
         required by such exchange, if such payment shall be deemed practicable
         by the Indenture Trustee.

                 (c)      The Indenture Trustee shall require each Paying Agent
to agree in writing that such Paying Agent will hold in trust, for the benefit
of the Holders and the Indenture Trustee, all money held by such Paying Agent
for the payment of the principal of, Premium, if any, or interest or any other
amounts payable to any Holder hereunder or under the Participation Agreement
and shall give to the Indenture Trustee notice of any default in the making of
any such payment upon the Certificates. The Indenture Trustee at any time may
require a Paying Agent to repay to the Indenture Trustee all money held by it.
Upon so doing the Paying Agent shall have no further liability for the money so
paid.

                 SECTION 2.09.    PAYMENT FROM INDENTURE ESTATE ONLY.
All amounts payable by the Indenture Trustee and the Owner Trustee under the
Certificates and this Agreement shall be made only from the income and proceeds
of the Indenture Estate and from the other amounts specified in Section 3.03.
Each Holder of a Certificate, by its acceptance of such Certificate, agrees
that (a) it will look solely to the income and proceeds of the Indenture Estate
and from the other amounts specified in Section 3.03 for the payment of such
amounts, to the extent available for distribution to it as herein provided, and
(b) none of the Owner Trustee, the Owner Participant or the Indenture Trustee
is or shall be personally liable to any Holder of any Certificate for any
amount payable under such Certificate or this Agreement or, except as expressly
provided in this Agreement in the case of the Owner Trustee and the Indenture
Trustee, for any liability thereunder.

                 First Union National Bank of North Carolina, is entering into
this Agreement solely as Owner Trustee under the Trust Agreement and not in its
individual capacity, and in no case whatsoever shall First Union National Bank
of North Carolina, (or any entity acting as successor trustee under the Trust
Agreement) be personally liable for, or for any loss in respect of, any
statements, representations, warranties, agreements or obligations hereunder or
thereunder; provided, that First Union National Bank of North Carolina, shall
be liable hereunder in its individual capacity, (i) for the performance of its
agreements in its individual capacity hereunder and under Section 8 of the
Participation Agreement, (ii) for its own willful misconduct or gross
negligence and (iii) failure to use ordinary care in the handling and
disbursing of funds. If a successor Owner Trustee is appointed in accordance
with the terms of the Trust Agreement and the Participation Agreement, such
successor Owner Trustee shall, without any further act, succeed to all of the
rights, duties, immunities and obligations hereunder, and its predecessor Owner
Trustee and First Union National Bank of North Carolina, shall be released from
all further duties and obligations hereunder, without prejudice to any claims
against First Union National Bank of North Carolina, or such predecessor Owner
Trustee for any default by First Union National Bank of North Carolina, or such
predecessor Owner Trustee, respectively, in the performance of its obligations
hereunder prior to such appointment.

                 SECTION 2.10.    EXECUTION, DELIVERY AND DATING OF
CERTIFICATES UPON ISSUANCE.  The Owner Trustee shall issue and execute, and the
Indenture Trustee shall authenticate and deliver, the Certificates for original
issuance upon payment of an amount equal to the aggregate original principal
amount thereof. Each Certificate issued hereunder shall be dated the Delivery
Date, and the Indenture Trustee shall note thereon, if issued after the
Delivery Date, the date through which has been paid interest thereon.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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                                   ARTICLE 3

                     RECEIPT, DISTRIBUTION AND APPLICATION
                        OF FUNDS IN THE INDENTURE ESTATE

                 SECTION 3.01.    [RESERVED FOR POTENTIAL FUTURE USE].

                 SECTION 3.02.    PAYMENT IN CASE OF REDEMPTION OF
CERTIFICATES.     (a) Except as otherwise provided in Section 3.05, in the
event the Certificates are redeemed in accordance with the provisions of
Section 6.01(a) or (b), the Indenture Trustee will apply on the Redemption Date
any amounts then held by it in the Indenture Estate and received by it from or
on behalf of the Owner Trustee or, as assignee of the Owner Trustee, from the
Company, including, without limitation, pursuant to Section 9, 10, 11 or
(subject to Section 7.03) 18.2 of the Lease in the following order of priority:

                 first, so much thereof as was received by the Indenture
         Trustee with respect to the amounts due to it pursuant to Section 9.06
         shall be applied to pay the Indenture Trustee such amounts;

                 second, so much thereof remaining as shall be required to pay
         an amount equal to the Redemption Price on the Outstanding
         Certificates pursuant to Section 6.01(a) or (b), as the case may be,
         on the Redemption Date shall be applied to the redemption of the
         Certificates on the Redemption Date; and

                 third, the balance, if any, thereof remaining thereafter shall
         be distributed to the Owner Trustee to be held or distributed to the
         Owner Participant in accordance with the terms of the Trust Agreement.

                 (b)      In the case of any refinancing or purchase of the
Certificates pursuant to Section 6.01(c) or 6.02, the Indenture Trustee will
apply on the Redemption Date the amounts received by it from or on behalf of
the Owner Trustee, or as assignee of the Owner Trustee, from the Company, to
the payment of the Redemption Price of the Outstanding Certificates pursuant to
Section 6.01(c) or 6.02, as the case may be, on the Redemption Date; it being
understood that any such payment shall be a refinancing or purchase of the
indebtedness represented by the Outstanding Certificates and is not, and shall
not be construed so as to be, a redemption thereof or payment or prepayment
thereon.

                 SECTION 3.03.    APPLICATION OF RENT WHEN NO INDENTURE EVENT
OF DEFAULT IS CONTINUING.        Except as otherwise provided in Section 3.02,
3.04, 3.05 or 3.06, each amount of Basic Rent received by the Indenture Trustee
from the Owner Trustee or, as assignee of the Owner Trustee, from the Company,
any payment of interest on overdue installments of Basic Rent, together with
any amount received by the Indenture Trustee pursuant to Section 8.03(e)(i),
shall be distributed by the Indenture Trustee in the following order of
priority:

                 first, so much of such aggregate amount as shall be required
         to pay in full the interest, principal of, Premium, if any, and any
         other amounts then due on, all Outstanding Certificates shall be
         distributed to the Persons entitled thereto; and in case such payments
         or amounts shall be insufficient to pay in full the whole amount so
         due and unpaid, then to the payment of such interest, principal,
         Premium, if any, such other amounts payable to the Holders, and
         without any preference or priority of one Certificate over another,
         ratably according to the aggregate amount





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         so due for interest, principal, Premium, if any and such other amounts
         at the date fixed by the Indenture Trustee for the distribution of
         such payments or amounts;

                 second, so much of such aggregate amount remaining as shall be
         required to pay any amount due the Indenture Trustee pursuant to
         Section 9.06 shall be applied to pay the Indenture Trustee such
         amounts; and

                 third, the balance, if any, of such aggregate amount remaining
         thereafter shall be distributed to the Owner Trustee to be held or
         distributed in accordance with the terms of the Lease, the
         Participation Agreement and the Trust Agreement; provided, however,
         that if an Indenture Default shall have occurred and be continuing,
         then such balance shall not be distributed as provided in this clause
         "third" but shall be held by the Indenture Trustee as part of the
         Indenture Estate until whichever of the following shall first occur:
         (i) all Indenture Events of Default shall have been cured, in which
         event such balance shall, to the extent not theretofore distributed as
         provided herein, be distributed as provided in this clause "third", or
         (ii) Section 3.04 or Section 3.05 shall be applicable, in which event
         such balance shall be distributed in accordance with the provisions of
         said Section 3.04 or Section 3.05, as the case may be, or (iii) such
         installment or payment shall have been held for a period in excess of
         183 days (during which no Indenture Event of Default which is not a
         Lease Event of Default shall have occurred and be continuing and
         during which period the Indenture Trustee and the Holders shall not
         have been stayed or otherwise precluded by operation of law from
         taking action to accelerate the Certificates or to exercise remedies
         hereunder or under the Lease), in which event such balance shall, to
         the extent not theretofore applied as provided herein, be distributed
         as provided in this clause "third".

                 SECTION 3.04.    APPLICATION OF CERTAIN PAYMENTS IN CASE OF
REQUISITION OR EVENT OF LOSS.     Except as otherwise provided in Section 3.05,
any amounts received directly or otherwise pursuant to the Lease from any
governmental authority or other Person pursuant to Section 10 of the Lease with
respect to the Airframe or the Airframe and the Engines or engines then
installed on the Airframe as the result of an Event of Loss, to the extent that
such amounts are not required to be paid to the Company pursuant to said
Section 10, and any amounts of insurance proceeds for damage to the Indenture
Estate received directly or otherwise pursuant to the Lease (and not
constituting Excluded Payments) from any insurer pursuant to Section 11 of the
Lease with respect thereto as the result of an Event of Loss, to the extent
such amounts are not required to be paid to the Company pursuant to said
Section 11, shall, except as otherwise provided in the next sentence, be
applied by the Indenture Trustee on behalf of, and as assignee of, the Owner
Trustee in reduction of the Company's obligations to pay Stipulated Loss Value
and the other amounts payable by the Company pursuant to Section 10 of the
Lease and the remainder, if any, shall, except as provided in the next
sentence, be distributed to the Owner Trustee to be held or distributed in
accordance with the terms of the Lease and the Trust Agreement.  Any portion of
any such amount referred to in the preceding sentence which is not required to
be so paid to the Company pursuant to the Lease, solely because a Lease Default
of the type referred to in Section 14.1 or 14.5 of the Lease or Lease Event of
Default shall have occurred and be continuing, shall, subject to Section 10.04
hereof, be held by the Indenture Trustee on behalf of the Owner Trustee as
security for the obligations of the Company under the Lease and at such time as
there shall not be continuing any Lease Default of the type referred to in
Section 14.1 or 14.5 of the Lease or Lease Event of Default or such earlier
time as shall be provided for in the Lease, or upon satisfaction and discharge
of this Indenture as provided herein, such portion shall be paid to the Owner
Trustee to be held or distributed in accordance with the terms of the Lease,
unless the Indenture Trustee (as assignee from the





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -18-
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Owner Trustee of the Lease) shall have theretofore commenced to exercise
remedies pursuant to Section 15 thereof, in which event such portion shall be
distributed in accordance with the provisions of Section 3.05 hereof.

                 SECTION 3.05.    PAYMENTS DURING CONTINUANCE OF INDENTURE
EVENT OF DEFAULT.  All payments (except Excluded Payments) received and amounts
held or realized by the Indenture Trustee after an Indenture Event of Default
shall have occurred and so long as such an Indenture Event of Default shall be
continuing, and after the Indenture Trustee shall foreclose or enforce this
Indenture or after the Certificates shall have become due and payable as
provided in Section 8.02 (including any amounts realized by the Indenture
Trustee from the exercise of any remedies pursuant to Article 8), as well as
all payments or amounts then held or thereafter received by the Indenture
Trustee as part of the Indenture Estate while such Indenture Event of Default
shall be continuing, shall be distributed by the Indenture Trustee in the
following order of priority:

                 first, so much of such payments or amounts as shall be
         required to pay the Indenture Trustee all amounts then due it pursuant
         to Section 9.06 shall be applied to pay the Indenture Trustee such
         amounts;

                 second, so much of such payments or amounts remaining as shall
         be required to (i) pay the expenses incurred (including unbilled
         expenses in respect of property delivered or contracted for or
         services rendered or contracted for if the amount of such expenses is
         liquidated) in using, operating, storing, leasing, controlling or
         managing the Indenture Estate, and of all maintenance, insurance,
         repairs, replacements, alterations, additions and improvements of and
         to the Indenture Estate and to make all payments which the Indenture
         Trustee may be required or may elect to make, if any, for taxes,
         assessments, insurance or other proper charges upon the Indenture
         Estate or any part thereof (including the employment of engineers and
         accountants to examine and make reports upon the properties, books and
         records of the Owner Trustee and, to the extent permitted under the
         Lease, the Company), all in accordance with Section 8.03(c), shall be
         applied for such purposes and (ii) reimburse the Holders in full for
         payments made pursuant to Section 9.01(c) (to the extent not
         previously reimbursed) shall be distributed to such Holders, and if
         the aggregate amount remaining shall be insufficient to reimburse all
         such payments in full, it shall be distributed ratably, without
         priority of any Certificate over any other, in the proportion that the
         aggregate amount of the unreimbursed payments made by each such Holder
         pursuant to Section 9.01(c) bears to the aggregate amount of the
         unreimbursed payments made by all Holders pursuant to Section 9.01(c);

                 third, so much of such payments or amounts remaining as shall
         be required to pay the principal of, and accrued interest on all
         Certificates Outstanding and all other amounts payable to the Holders
         hereunder or under the Participation Agreement and then due and
         payable, whether by declaration of acceleration pursuant to Section
         8.02 or otherwise, shall be applied to the payment of such interest,
         principal, and such other amounts; and in case such payments or
         amounts shall be insufficient to pay in full the whole amount so due
         and unpaid, then to the payment of such interest, principal, such
         other amounts and interest, without any preference or priority of one
         Certificate over another, ratably according to the aggregate amount so
         due for interest, principal, and such other amounts at the date fixed
         by the Indenture Trustee for the distribution of such payments or
         amounts; and





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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                 fourth, the balance, if any, of such payments or amounts
         remaining thereafter shall be distributed to the Owner Trustee to be
         held or distributed in accordance with the terms of the Lease, the
         Participation Agreement and the Trust Agreement.

                 SECTION 3.06.    PAYMENTS FOR WHICH APPLICATION IS PROVIDED IN
OTHER DOCUMENTS. Except as otherwise provided in this Agreement, any payment
received by the Indenture Trustee for which provision as to the application
thereof is made in the Lease or the Participation Agreement shall be
distributed to the Person for whose benefit such payments were made in
accordance with, and subject to the terms, thereof and hereof.  The Indenture
Trustee shall be obligated to distribute any Excluded Payments received by the
Indenture Trustee promptly upon receipt thereof by the Indenture Trustee to the
Person entitled thereto.

                 SECTION 3.07.    PAYMENTS FOR WHICH NO APPLICATION IS
OTHERWISE PROVIDED.   Except as otherwise provided in Section 3.05:

                 (a)      any payment received by the Indenture Trustee for
         which no provision as to the application thereof is made elsewhere in
         this Agreement, and

                 (b)      any payment received and amounts realized by the
         Indenture Trustee with respect to the Aircraft to the extent received
         or realized at any time after the conditions set forth in Article 10
         for the satisfaction and discharge of this Agreement or for the
         defeasance of the Certificates shall have been duly satisfied, as well
         as any other amounts remaining as part of the Indenture Estate after
         such satisfaction shall be distributed by the Indenture Trustee in the
         following order of priority:

                          first, so much of such aggregate amount as shall be
                 required to pay the Indenture Trustee all amounts then due it
                 pursuant to Section 9.06 shall be applied to pay the Indenture
                 Trustee such amounts; and

                          second, the balance, if any, of such aggregate amount
                 remaining thereafter shall be distributed to the Owner Trustee
                 to be held or distributed in accordance with the terms of the
                 Trust Agreement.

                 SECTION 3.08.    APPLICATION OF PAYMENTS.  Each payment of
principal and interest or other amounts due hereunder to the Indenture Trustee
or any Holder or in respect of each Certificate shall, except as otherwise
expressly provided herein, be applied, first, to the payment of any amount
(other than the principal of or Premium, or interest on such Certificate) due
hereunder or in respect of such Certificate, second, to the payment of Premium
or, if any, and interest on such Certificate (as well as any interest on
overdue principal and, to the extent permitted by law, interest and other
amounts payable hereunder and thereunder) due thereunder, third, to the payment
of the principal of such Certificate then due and fourth, the balance, if any,
remaining thereafter, to the payment of the principal of such Certificate
remaining unpaid (provided, that such Certificate shall not be subject to
prepayment or purchase without the consent of the affected Holder except as
expressly permitted hereby).  The amounts paid pursuant to clause fourth above
shall be applied to the installments of principal of such Certificate in
inverse order of maturity.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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   26
                                   ARTICLE 4

                           COVENANTS OF OWNER TRUSTEE

                 SECTION 4.01.    COVENANTS OF THE OWNER TRUSTEE.   The Owner
Trustee hereby covenants and agrees that:

                          (i)     the Owner Trustee will duly and punctually
         perform its obligations under the Lease and will duly and punctually
         pay the principal of, Premium, if any, and interest on and other
         amounts due hereunder and under the Certificates and all other amounts
         payable by it to the Holders under the Participation Agreement and the
         other Operative Agreements;

                          (ii)    the Owner Trustee will not directly or
         indirectly create, incur, assume or suffer to exist any Lessor Lien
         attributable to it with respect to any of the properties or assets of
         the Indenture Estate and shall, at its own cost and expense, promptly
         take such action as may be necessary to discharge duly any such Lessor
         Lien, and the Owner Trustee will cause restitution to be made to the
         Indenture Estate in the amount of any diminution of the value thereof
         as the result of any Lessor Liens attributable to it;

                          (iii)   in the event a Responsible Officer of the
         Owner Trustee shall have actual knowledge of an Indenture Event of
         Default or Indenture Default or an Event of Loss, the Owner Trustee
         will give prompt written notice of such Indenture Event of Default or
         Indenture Default or Event of Loss to the Indenture Trustee, the Owner
         Participant, the Company;

                          (iv)    except as contemplated by the Operative
         Agreements, the Owner Trustee will not contract for, create, incur,
         assume or permit to exist any Debt, and will not guarantee (directly
         or indirectly or by an instrument having the effect of assuring
         another's payment or performance on any obligation or capability of so
         doing, or otherwise), endorse or otherwise be or become contingently
         liable, directly or indirectly, in connection with the Debt of any
         other Person;

                          (v)     the Owner Trustee will not enter into any
         activity other than owning the Aircraft, the leasing thereof to the
         Company and the carrying out of the transactions contemplated hereby
         and by the Participation Agreement, the Trust Agreement and the other
         Operative Agreements;

                          (vi)    the Owner Trustee will furnish to the
         Indenture Trustee, and the Indenture Trustee will furnish to each
         Holder at the time outstanding, promptly upon receipt thereof,
         duplicates or copies of all reports, notices, requests, demands,
         certificates, financial statements and other instruments furnished to
         the Owner Trustee under the Lease, including, without limitation, a
         copy of each report or notice received pursuant to Section 11 of the
         Lease, to the extent that the same shall not be required to have been
         furnished directly to the Indenture Trustee pursuant to the Lease; and

                          (vii)   the Owner Trustee will not (except as
         permitted herein) assign or pledge or otherwise dispose of, so long as
         this Indenture shall remain in effect and shall not have been
         terminated pursuant to Section 10.01, any of its right, title or
         interest hereby  assigned to anyone other than the Indenture Trustee,
         and, with respect to such right, title and interest hereby





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -21-
   27
         assigned, will not, except as provided in this Indenture, (1) accept
         any payment that is subjected to the Lien of this Indenture from the
         Lessee or any sublessee, enter into any agreement amending or
         supplementing any of the Indenture Documents, execute any waiver or
         modification of, or consent under, the terms of any of the Indenture
         Documents, (2) exercise any rights with respect to the Indenture
         Estate, (3) settle or compromise any claim arising under any of the
         Indenture Documents, or (4) submit or consent to the submission of any
         dispute, difference or other matter arising under or in respect of any
         of the Indenture Documents to arbitration thereunder.

                 SECTION 4.02.    COVENANTS OF FIRST UNION NATIONAL BANK OF
NORTH CAROLINA.  First Union National Bank of North Carolina, hereby covenants
and agrees that it will not directly or indirectly create, incur, assume or
suffer to exist any Lessor Liens attributable to it with respect to any of the
properties or assets of the Indenture Estate and it shall, at its own cost and
expense, promptly take such action as may be necessary to discharge duly any
such Lessor Lien.  First Union National Bank of North Carolina, will cause
restitution to be made to the Indenture Estate in the amount of any diminution
of the value thereof as the result of any Lessor Liens thereon attributable to
it.

                                   ARTICLE 5

                     DISPOSITION, SUBSTITUTION AND RELEASE
              OF PROPERTY INCLUDED IN THE INDENTURE ESTATE DURING
                             CONTINUATION OF LEASE

                 SECTION 5.01.    DISPOSITION, SUBSTITUTION AND RELEASE OF
PROPERTY INCLUDED IN THE INDENTURE ESTATE DURING CONTINUATION OF LEASE.     So
long as the Lease is in effect:

                 (a)      Parts.  Any Parts and alterations, improvements and
         modifications in and additions to the Aircraft shall, to the extent
         required or specified by the Lease, become subject to the lien of this
         Agreement and be leased to the Company under the Lease; provided, that
         to the extent permitted by and as provided in the Lease, the Company
         shall have the right, at any time and from time to time, without any
         release from or consent by the Owner Trustee or the Indenture Trustee,
         to remove, replace and pool Parts and to make alterations,
         improvements and modifications in, and additions to, the Aircraft. The
         Indenture Trustee agrees that, to the extent permitted by and as
         provided in the Lease, title to any such Part shall vest in the
         Company.  The Indenture Trustee shall from time to time execute an
         appropriate written instrument or instruments to confirm the release
         of the security interest of the Indenture Trustee in any Part as
         provided in this Section 5.01, in each case upon receipt by the
         Indenture Trustee of a Company Request stating that said action was
         duly taken by the Company in conformity with this Section 5.01 and
         that the execution of such written instrument or instruments is
         appropriate to evidence such release of a security interest under this
         Section 5.01.

                 (b)      Substitution Under the Lease upon an Event of Loss
         Occurring to Airframe or Engines or upon Voluntary Termination of
         Lease with Respect to Engines.  Upon (i) the occurrence of an Event of
         Loss occurring to the Airframe or an Engine, or (ii) a voluntary
         termination of the Lease with respect to an Engine, the Company, in
         accordance with the Lease, may, in the case of an Event of Loss which
         has occurred to the Airframe, or shall, except as provided in Section
         10.2 of the Lease, in the case of an Event of Loss which has occurred
         to or termination of the Lease with respect to an Engine, substitute
         an airframe or engine, as the case





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         may be, in which case, upon due satisfaction of all conditions to such
         substitution specified in Section 10 of the Lease, the Indenture
         Trustee shall release all of its right, interest and lien in and to
         the Airframe or such Engine in accordance with the provisions of the
         following sentence. The Indenture Trustee shall execute and deliver to
         the Owner Trustee an instrument releasing its lien in and to the
         Airframe or such Engine and shall execute for recording in public
         offices, at the expense of the Owner Trustee (if requested by the
         Owner Trustee) or the Company (if requested by the Company), such
         instruments in writing as the Owner Trustee or the Company shall
         reasonably request and as shall be reasonably acceptable to the
         Indenture Trustee in order to make clear upon public records that such
         lien has been released under the laws of the applicable jurisdiction.

Each of the Owner Trustee and the Company hereby waives and releases any and
all rights existing or that may be acquired to any penalties, forfeit or
damages from or against the Indenture Trustee for failure to execute and
deliver any document in connection with the release of a lien or to file any
certificate in compliance with any law or statute requiring the filing of the
same in connection with the release of a lien, except for failure by the
Indenture Trustee to execute and deliver any document or to file any
certificate as may be specifically requested in writing by the Owner Trustee or
the Company and with respect to which the Owner Trustee or the Company shall be
duly entitled.

                 SECTION 5.02.    CERTIFICATES IN RESPECT OF REPLACEMENT
AIRCRAFT AND ENGINES.  Upon the execution and delivery of a Trust Supplement
covering a Replacement Airframe and/or Replacement Engine, as provided in
Section 5.01(b), each Certificate shall be deemed to have been issued in
connection with such Replacement Airframe and/or Replacement Engine and each
Certificate issued thereafter upon a transfer or exchange of, or as a
replacement for, a Certificate, shall be designated as having been issued in
connection with such Replacement Airframe and/or Replacement Engine, but
without any other change therein.

                                   ARTICLE 6

                           REDEMPTION OF CERTIFICATES

                 SECTION 6.01.    REDEMPTION OF CERTIFICATES UPON CERTAIN
EVENTS.    (a) If there shall be an Event of Loss to the Aircraft and the
Aircraft is not replaced pursuant to Section 10.1.2 of the Lease, each
Outstanding Certificate shall be redeemed in whole at a Redemption Price equal
to 100% of the outstanding principal amount of such Certificate plus accrued
and unpaid interest thereon to but excluding the applicable Redemption Date and
all other amounts payable to the Holders hereunder or under the Participation
Agreement.  The Redemption Date for Certificates to be redeemed pursuant to
this Section 6.01(a) shall be the Lease Loss Payment Date. No Premium shall be
paid in the case of a redemption pursuant to any provision of this Section
6.01(a).

                 (b)      The Certificates shall be redeemed on the Lease
Termination Date or upon the purchase of the Aircraft by the Company at its
option on the Special Purchase Option Date pursuant to Section 18.2(b) of the
Lease (unless the Company shall have elected to assume the rights and
obligations of the Owner Trustee hereunder to the extent and as provided for in
Section 7.03).  In the case of any Series SWA 1996 Trust N625SW Certificate,
such Redemption Price therefor shall be equal to the unpaid principal amount of
such Certificate as at such Redemption Date together with an amount equal to
the accrued but unpaid interest thereon and, in the case of each Certificate
redeemed prior to the Premium Termination Date applicable to such Certificate,
the Premium, if any.  The Redemption Date for





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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Certificates to be redeemed shall be (A) in the case of a termination of the
Lease pursuant to Section 9 thereof, on the Lease Termination Date or (B) in
the case of purchase of the Aircraft by the Company pursuant to Section 18.2(b)
of the Lease, on the Special Purchase Option Date.

                 (c)      The Series SWA 1996 Trust N625SW Certificates may be
refinanced if all the conditions to such refunding or refinancing set forth in
Section 17 of the Participation Agreement shall have been satisfied.  In any
such event, each Outstanding Certificate may be so refinanced at a Redemption
Price determined in accordance with the procedures described above in Section
6.01(b); and the applicable Redemption Date for Certificates to be redeemed
shall be the applicable Refinancing Date under Section 17 of the Participation
Agreement.

                 SECTION 6.02.    REDEMPTION OR PURCHASE OF CERTIFICATES UPON
CERTAIN INDENTURE EVENTS OF DEFAULT.     If the Owner Trustee shall have given
notice of redemption or purchase to the Indenture Trustee pursuant to its
rights under Section 8.03(e)(ii) at any time (x) after the Certificates shall
have been accelerated pursuant to section 8.02 or (y) after one or more Lease
Events of Default shall have occurred and be continuing for 180 days or more,
each Outstanding Certificate shall be redeemed or purchased in whole at a
Redemption Price equal to 100% of its principal amount plus accrued and unpaid
interest thereon (including, without limitation, interest on overdue interest)
but excluding the applicable Redemption Date as determined below and all other
amounts payable to the Holders hereunder or under the Participation Agreement,
and, if to be purchased or redeemed pursuant to clause (y) above prior to the
one year anniversary of the first occurrence of the relevant Lease Event of
Default, the Premium, if any.  The Redemption Date for Certificates to be
redeemed or purchased pursuant to this Section 6.02 shall be the date specified
in the notice given by the Owner Trustee to the Indenture Trustee pursuant to
Section 8.03(e)(ii). If the Owner Trustee elects to purchase the Certificates
under Section 8.03(e)(ii), nothing herein, including use of the terms
"Redemption Date" and "Redemption Price", shall be deemed to result in a
redemption of the Certificates.

                 SECTION 6.03.    NOTICE OF REDEMPTION TO HOLDERS.  Notice of
redemption or purchase with respect to the Series SWA 1996 Trust N625SW
Certificates shall be given by the Indenture Trustee by first-class mail,
postage prepaid, mailed not less than 30 nor more than 60 days prior to the
Redemption Date, to each Holder of such Certificates to be redeemed or
purchased, at such Holder's address appearing in the Register; provided, that
in the case of a redemption pursuant to Section 6.01(b) related to Lessee's
exercise of its option pursuant to Section 9 of the Lease, such notice shall be
revocable and shall be deemed revoked in the event the Lease does not in fact
terminate on the related Lease Termination Date.

                 All notices of redemption or purchase shall state:

                 (1)      the Redemption Date,

                 (2)      the applicable basis for determining the Redemption
                          Price,

                 (3)      that on the Redemption Date, the Redemption Price
         will become due and payable upon each such Certificate, and that
         interest on Certificates shall cease to accrue on and after such
         Redemption Date, and

                 (4)      the place or places where such Certificates are to be
         surrendered for payment of the Redemption Price.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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Notice of redemption or purchase of Certificates to be redeemed or purchased
shall be given by the Indenture Trustee.

                 SECTION 6.04.    DEPOSIT OF REDEMPTION PRICE.      On or
before the Redemption Date, the Owner Trustee (or any Person on behalf of the
Owner Trustee) shall, to the extent an amount equal to the Redemption Price for
the Certificates to be redeemed or purchased on the Redemption Date shall not
then be held in the Indenture Estate, deposit or cause to be deposited with the
Indenture Trustee or the Paying Agent by 12:00 Noon in immediately available
funds (i) the Redemption Price of the Certificates to be redeemed, refinanced
or purchased, as the case may be, on the Redemption Date and (ii) all other
amounts due and payable hereunder, including any amounts payable to the
Indenture Trustee pursuant to Section 9.06.

                 SECTION 6.05.    CERTIFICATES PAYABLE ON REDEMPTION DATE.
Notice of redemption, refinancing or purchase having been given as aforesaid
(and not deemed revoked as contemplated in the proviso to Section 6.03(a)), the
Certificates (or the purchase or refinancing price therefor) shall, on the
applicable Redemption Date, become due and payable at the Redemption Price
therefor at the principal corporate trust office of the Indenture Trustee or at
any office or agency maintained for such purposes pursuant to Section 2.03, and
from and after such Redemption Date (unless there shall be a default in the
payment of the Redemption Price) any Certificates then Outstanding shall cease
to bear interest. Unless payment prior to surrender is expressly provided for
herein or in the Participation Agreement, upon surrender of any such
Certificate for redemption or purchase in accordance with said notice such
Certificate shall be paid at the Redemption Price.  The Certificates shall not
be subject to prepayment, redemption, refunding or refinancing except as
provided in this Article 6 and in Section 8.02 hereof.

                 If any Certificate called for redemption or purchase shall not
be so paid upon surrender thereof for redemption or purchase, the principal
amount thereof shall, until paid, continue to bear interest from the applicable
Redemption Date at the interest rate applicable to such Certificate.

                                   ARTICLE 7

                         MATTERS CONCERNING THE COMPANY

                 SECTION 7.01.    REPAYMENT OF MONIES FOR CERTIFICATE PAYMENTS
HELD BY THE INDENTURE TRUSTEE.  Any money held by the Indenture Trustee or any
Paying Agent in trust for any payment of the principal of, Premium, if any, or
interest on any Series SWA 1996 Trust N625SW Certificate, including without
limitation any money deposited pursuant to Article 10 and remaining unclaimed
for two years and eleven months after the due date for such payment, shall be
paid to the Owner Trustee; and the Holders of any Outstanding Certificates
shall thereafter, as unsecured general creditors, look only to the Owner
Participant (to the extent the Owner Trustee distributed any such trust money
to the Owner Participant) and to the Company on behalf of the Owner Trustee for
payment thereof, and all liability of the Indenture Trustee or any such Paying
Agent with respect to such trust money shall thereupon cease; provided, that
the Indenture Trustee or such Paying Agent, before being required to make any
such repayment, may at the expense of the Company cause to be mailed to each
such Holder notice that such money remains unclaimed and that, after a date
specified therein, which shall not be less than 30 days from the date of
mailing, any unclaimed balance of such money then remaining will be repaid to
the Owner Trustee as provided herein.

                 SECTION 7.02.    [RESERVED FOR POTENTIAL FUTURE USE].





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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                 SECTION 7.03.    ASSUMPTION OF OBLIGATIONS OF OWNER TRUSTEE BY
THE COMPANY.   In the event that the Company shall have elected to assume all
of the rights and obligations of the Owner Trustee under this Agreement in
respect of the Certificates pursuant to Section 8(r) of the Participation
Agreement in connection with the purchase by the Company of the Aircraft, and
if on or prior to the Special Purchase Option Date (the "Assumption Date") the
Indenture Trustee shall have received:

                 (a)      an instrument of assumption (the "Assumption
Agreement") pursuant to which the Company irrevocably and unconditionally
assumes and undertakes, with full recourse to the Company, the Owner Trustee's
obligations with respect to principal, interest, Premium and all other amounts
payable to the Holders or the Indenture Trustee under the Certificates then
Outstanding, this Agreement, and the Participation Agreement and which
incorporates therein events of default substantially similar in scope and
effect to those set forth in the Lease and covenants substantially similar to
the covenants of the Company under the Lease and the Participation Agreement;

                 (b)      a supplement to this Agreement and/or such other
instruments and documents (including, without limitation, Uniform Commercial
Code financing statement(s)) covering all of the security interests created by
or pursuant to this Indenture that are not covered by the recording system
established by the Federal Aviation Act as may be necessary (or reasonably
requested by the Indenture Trustee) for the security interest of the Indenture
Trustee in the Aircraft and in the other rights, property and interests
included in the Indenture Estate (other than those rights, property and
interests that depend on the existence of the Trust Estate and the
participation of the Owner Trustee and Owner Participant in the transactions
contemplated by the Participation Agreement and this Indenture) to continue to
be perfected and duly recorded with the Federal Aviation Administration and in
all other places necessary or, in the reasonable opinion of the Indenture
Trustee, advisable under the Uniform Commercial Code;

                 (c)      an insurance report dated the Assumption Date of the
independent insurance broker referred to in Section 11.5 of the Lease and the
certificates of insurance, each in form and substance reasonably satisfactory
to the Indenture Trustee as to the due compliance as of the Assumption Date
with the terms of Section 11 of the Lease (as it relates to the Holders and the
Indenture Trustee) relating to the insurance with respect to the Aircraft;

                 (d)      evidence that as of the Assumption Date, and after
giving effect to the transactions contemplated hereby, the Company has good
title to the Aircraft free and clear of all Liens other than the Lien of, and
the security interest created by, this Indenture and other Permitted Liens
(other than Lessor Liens) and Section 18.2 of the Lease, if applicable;

                 (e)      a copy of the application that was filed with the FAA
on the Assumption Date regarding the registration of the Aircraft in the name
of the Company;

                 (f)      a certificate from a Responsible Company Officer of
the Company that no Lease Default of the type referred to in Section 14.1 or
14.5 of the Lease or Lease Event of Default shall have occurred and be
continuing as of the Assumption Date;

                 (g)      an opinion of the General Counsel of the Company (or
other counsel reasonably satisfactory to the Indenture Trustee) in form and
substance reasonably satisfactory to the Indenture Trustee, addressed to the
Indenture Trustee and dated the Assumption Date, to the effect that (i) the
execution, delivery and performance of the Assumption Agreement and the
supplement to this Indenture referred to in paragraph (b) of this Section 7.03
(and all other instruments and documents the execution





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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of which are necessary for and directly related to the assumption of the
obligations contemplated by this Section 7.03 or the continued perfection of
the security interests referred to in paragraph (b) of this Section 7.03) have
been duly authorized by the Company by all necessary action; (ii) the
Assumption Agreement, such supplement to this Indenture, all such other
documents and instruments referred to above and the security interests arising
therefrom are legal, valid and binding obligations of the Company enforceable
in accordance with their terms, except as the same may be limited by applicable
bankruptcy, insolvency, reorganization, moratorium or similar laws affecting
the rights of creditors generally and by general principles of equity, and
except as limited by applicable laws which may affect the remedies provided for
in this Indenture, which laws, however, do not in the opinion of such counsel
make the remedies provided for in this Indenture inadequate for the practical
realization of the rights and benefits purported to be provided thereby; (iii)
the Assumption Agreement, such supplement and all such other documents and
instruments referred to above do not and will not contravene any provision of
the Company's articles of incorporation or by-laws or any law or regulation
applicable to the Company or any agreement, mortgage or instrument to which the
Company is a party or by which the Company is bound; and (iv) the Indenture
Trustee (on behalf of the Certificate Holders) should continue to be entitled
to the benefits of Section 1110 of the Bankruptcy Code with respect to the
Aircraft upon and after the assumption of the obligations by the Company,
provided, that the opinion referred to in this clause (iv) need not be
delivered to the extent that the benefits of Section 1110 of the Bankruptcy
Code were not, by reason of a change of law or governmental interpretation
thereof, available to the Indenture Trustee with respect to the Aircraft
immediately prior to such assumption and provided, further, that such opinion
may contain qualifications of the tenor contained in the opinion relating to
said Section 1110 delivered pursuant to Section 4(a)(xi) of the Participation
Agreement on the Delivery Date;

                 (h)      an opinion of Daugherty, Fowler & Peregrin, special
counsel in Oklahoma City (or other counsel reasonably satisfactory to the
Indenture Trustee), in form and substance reasonably satisfactory to the
Indenture Trustee, addressed to the Indenture Trustee and dated the Assumption
Date, (i) to the effect that all documents executed in connection with the
assumption of the obligations contemplated by this Section 7.03 and required to
be filed with the Federal Aviation Administration are in proper form, and all
steps necessary have been taken, for the Aircraft to be duly registered in the
name of the Company and for the Lien of this Agreement with respect to the
Aircraft and Engines to continue to be duly perfected and of first priority;

                 (i)      an opinion of Vinson & Elkins, LLP (or other tax
counsel reasonably acceptable to the Indenture Trustee) in form and substance
reasonably satisfactory to the Indenture Trustee, to the effect that no
Certificate Holder will be required to recognize gain or loss for tax purposes
in connection with the assumption of the debt by Lessee; and

                 (j)      such other documentation reasonably requested by the
Indenture Trustee (in form and substance reasonably satisfactory to the
Indenture Trustee) to amend the Operative Agreements to give effect to the
foregoing;

then, automatically and without the requirement of further action by any
Person, effective as of the Assumption Date, the Owner Trustee shall be
released from all of its obligations under this Agreement in respect of the
Certificates or otherwise (other than any obligations or liabilities of the
Owner Trustee in its individual capacity incurred on or prior to the Assumption
Date or arising out of or based upon events occurring on or prior to the
Assumption Date, which obligations and liabilities shall remain the sole
responsibility of the Owner Trustee in such capacity).  Promptly upon the
filing and recording of the documents referred to in the opinion of counsel
specified in Section (h) above with the FAA, the





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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Company shall cause such counsel to deliver to the Indenture Trustee an opinion
addressed to the Indenture Trustee, in form and substance reasonably
satisfactory to the Indenture Trustee, as to due recording of said documents
with the FAA.

                                   ARTICLE 8

                             DEFAULTS AND REMEDIES

                 SECTION 8.01.    INDENTURE EVENTS OF DEFAULT.      The
following events shall constitute "Indenture Events of Default" under this
Agreement (whether any such event shall be voluntary or involuntary or come
about or be effected by operation of law or pursuant to or in compliance with
any judgment, decree or order of any court or any order, rule or regulation of
any administrative or governmental body) and each such Indenture Event of
Default shall be deemed to exist so long as, but only so long as, it shall not
be waived or remedied:

                 (a)      the failure (other than by reason of a Lease Event of
         Default) of the Owner Trustee to pay when due any payment of principal
         of or Premium or interest on any Certificate and such failure shall
         have continued unremedied for seven Business Days, or the failure
         (other than by reason of a Lease Event of Default) of the Owner
         Trustee to pay when due any other amount due and payable hereunder, or
         under any Certificate, and such failure shall have continued
         unremedied for 10 Business Days after notice thereof to the Owner
         Trustee; or

                 (b)      any Lessor Lien required to be discharged by First
         Union National Bank of North Carolina, pursuant to Section 4.02 or
         required to be discharged by the Owner Trustee pursuant to Section
         4.01(ii) or required to be discharged or bonded (in a manner
         reasonably satisfactory to the Indenture Trustee) by the Owner
         Participant pursuant to Section 8(g) of the Participation Agreement
         shall remain undischarged for a period of 30 calendar days after a
         Responsible Officer or Responsible Company Officer, as the case may
         be, of First Union National Bank of North Carolina, the Owner Trustee
         or the Owner Participant, as the case may be, shall have actual
         knowledge of such Lessor Lien; or

                 (c)      any representation or warranty made by the Owner
         Trustee or the Owner Participant or First Union National Bank of North
         Carolina, herein or in the Participation Agreement, or made by any
         Person guaranteeing or supporting the obligations of the Owner
         Participant under the Operative Agreements in its guarantee or support
         agreement, shall prove to have been false or incorrect when made in
         any material respect to the Certificate Holders, is material at the
         time of discovery and, if curable, is not cured within 30 days of
         notice thereof to the Owner Participant and the Owner Trustee from the
         Indenture Trustee; or

                 (d)      [Intentionally reserved]

                 (e)      any failure by the Owner Trustee or First Union
         National Bank of North Carolina, to observe or perform any other
         covenant or obligation of the Owner Trustee or First Union National
         Bank of North Carolina, as the case may be, contained in this
         Indenture or in the Participation Agreement or any failure by the
         Owner Participant to observe or perform any other covenant or
         obligation of the Owner Participant contained in the Participation
         Agreement or any failure by any Person guaranteeing or supporting the
         obligations of the Owner Participant under the Operative Agreements to
         perform any covenant or obligation of such Person under its





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         guarantee or support agreement which, in any case, is not remedied
         within a period of 30 calendar days after notice thereof has been
         given to the Owner Trustee and the Owner Participant or such Person,
         as the case may be; or

                 (f)      there shall be a Lease Event of Default other than,
         without the consent of the Owner Trustee in its sole discretion, a
         Lease Event of Default arising by reason of nonpayment when due of any
         Excluded Payments; or

                 (g)      either the Trust Estate or the Owner Trustee with
         respect thereto (and not in its individual capacity) or the Owner
         Participant or any Person guaranteeing or supporting the obligations
         of the Owner Participant under the Operative Agreements shall (i)
         file, or consent by answer or otherwise to the filing against it of a
         petition for relief or reorganization or arrangement or any other
         petition in bankruptcy, for liquidation or to take advantage of any
         bankruptcy or insolvency law of any jurisdiction, (ii) make an
         assignment for the benefit of its creditors, or (iii) consent to the
         appointment of a custodian, receiver, trustee or other officer with
         similar powers of itself or any substantial part of its property;
         provided, that an event referred to in this Section 8.01(g) with
         respect to the Owner Participant shall not constitute an Indenture
         Event of Default if (A) an order, judgment or decree shall be entered
         in a proceeding by a court or a trustee, custodian, receiver or
         liquidator which is either final and non-appealable or has not been
         stayed pending any appeal, or (B) an opinion of counsel satisfactory
         to the Indenture Trustee shall be provided by the Owner Participant,
         in each case to the effect that no part of the Trust Estate created by
         the Trust Agreement (except for the Owner Participant's beneficial
         interest in such Trust Estate) and no right, title or interest under
         the Indenture Estate shall be included in, or be subject to, any
         declaration or adjudication of, or proceedings with respect to, the
         bankruptcy, insolvency or liquidation of the Owner Participant
         referred to in this Section 8.01(g); or

                 (h)      a court or governmental authority of competent
         jurisdiction shall enter an order appointing, without consent by the
         Trust Estate or the Owner Trustee with respect thereto (and not in its
         individual capacity) or the Owner Participant or any Person
         guaranteeing or supporting the obligations of the Owner Participant
         under the Operative Agreements, a custodian, receiver, trustee or
         other officer with similar powers with respect to it or with respect
         to any substantial part of its property, or constituting an order for
         relief or approving a petition for relief or reorganization or any
         other petition in bankruptcy or for liquidation or to take advantage
         of any bankruptcy or insolvency law of any jurisdiction, or ordering
         the dissolution, winding-up or liquidation of the Trust Estate or the
         Owner Trustee with respect thereto (and not in its individual
         capacity) or the Owner Participant or any Person guaranteeing or
         supporting the obligations of the Owner Participant under the
         Operative Agreements and any such order or petition is not dismissed
         or stayed within 90 days after the earlier of the entering of any such
         order or the approval of any such petition; provided, that an event
         referred to in this Section 8.01(h) with respect to the Owner
         Participant shall not constitute an Event of Default if (A) an order,
         judgment or decree shall be entered in a proceeding by a court or a
         trustee, custodian, receiver or liquidator which is either final and
         non-appealable or has not been stayed pending any appeal, or (B) an
         opinion of counsel satisfactory to the Indenture Trustee shall be
         provided by the Owner Participant, in each case to the effect that no
         part of the Trust Estate created by the Trust Agreement (except for
         the Owner Participant's beneficial interest in such Trust Estate) and
         no right, title or interest under the Indenture Estate shall be
         included in, or be subject to, any





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         declaration or adjudication of, or proceedings with respect to, the
         bankruptcy, insolvency or liquidation of the Owner Participant
         referred to in this Section 8.01(h).

                 SECTION 8.02.    ACCELERATION; RESCISSION AND ANNULMENT.    If
an Indenture Event of Default occurs and is continuing, either the Indenture
Trustee, by notice to the Company and the Owner Trustee, or the Holders of at
least 25% in aggregate principal amount of Outstanding Certificates, by notice
to the Company, the Indenture Trustee and the Owner Trustee may declare the
principal of all the Certificates to be due and payable, whereupon the same
shall be accelerated and be and become due and payable; provided, that if an
Indenture Event of Default referred to in clause (g) or (h) of Section 8.01
shall have occurred or a Lease Event of Default of the type referred to in
clause (g) or (h) of said Section 8.01 shall have occurred with respect to the
Company, then and in every such case the unpaid principal of all Certificates
then Outstanding shall, unless the Indenture Trustee acting upon instructions
of at least 25% in aggregate principal amount of Outstanding Certificates shall
otherwise direct, immediately and without further act become due and payable,
without presentment, demand, protest or notice, all of which are hereby waived.
Upon such declaration (or automatic acceleration, as the case may be), the
principal of all Certificates together with accrued interest thereon from the
date in respect of which interest was last paid hereunder to the date payment
of such principal has been made or duly provided for, and all other amounts
payable to the Holders hereunder as at such date of payment shall be
immediately due and payable (but not including any Premium).  At any time after
such declaration and prior to the sale or disposition of the Indenture Estate,
the Holders of a majority in aggregate principal amount of all of the
Outstanding Certificates, by notice to the Indenture Trustee, the Company and
the Owner Trustee, may rescind such a declaration and thereby annul its
consequences if (i) an amount sufficient to pay all principal of any
Certificates which have become due otherwise than by such declaration and any
interest thereon and interest due or past due, if any, and all sums due and
payable to the Indenture Trustee have been deposited with the Indenture
Trustee, (ii) the rescission would not conflict with any judgment or decree and
(iii) all existing Indenture Defaults and Indenture Events of Default under
this Agreement have been cured or waived except nonpayment of principal of, or
interest on, the Certificates that has become due solely because of such
acceleration.

                 SECTION 8.03.    OTHER REMEDIES AVAILABLE TO INDENTURE
TRUSTEE.     (a)  After an Indenture Event of Default shall have occurred and
so long as such Indenture Event of Default shall be continuing, then and in
every such case the Indenture Trustee, as trustee of an express trust and as
assignee hereunder of the Lease or as holder of a security interest in the
Aircraft or Engines or otherwise, may, and when required pursuant to the
provisions of Article 9 shall, exercise, subject to Sections 8.03(b) and
8.03(e), any or all of the rights and powers and pursue any and all of the
remedies accorded to the Owner Trustee pursuant to Section 15 of the Lease and
this Article 8, may recover judgment in its own name as Indenture Trustee
against the Indenture Estate and may take possession of all or any part of the
Indenture Estate and may exclude the Owner Trustee and the Owner Participant
and all Persons claiming under any of them wholly or partly therefrom.  The
Indenture Trustee shall have and may exercise all of the rights and remedies of
a secured party under the Uniform Commercial Code as in effect in any
applicable jurisdiction.

                 (b)      After an Indenture Event of Default, subject to
Section 8.03(e), the Indenture Trustee may, if at the time such action may be
lawful and always subject to compliance with any mandatory legal requirements,
either with or without taking possession, and either before or after taking
possession, and without instituting any legal proceedings whatsoever, and
having first given notice of such sale to the Owner Trustee, the Owner
Participant and the Company at least 10 days prior to the date of such sale,
sell and dispose of the Indenture Estate, or any part thereof, or interest
therein, at public





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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or private auction, in one lot as an entirety or in separate lots, and either
for cash or on credit and on such terms as the Indenture Trustee may determine,
and at any place (whether or not it be the location of the Indenture Estate or
any part thereof) and time designated in the notice above referred to;
provided, however, that notwithstanding any provision herein to the contrary,
the Indenture Trustee may not provide the notice provided for above of its
intention to sell any of the Indenture Estate or exercise other remedies
against the Indenture Estate seeking to deprive the Owner Trustee or the Owner
Participant of its rights therein unless a declaration of acceleration has been
made pursuant to Section 8.02 or the Certificates have otherwise theretofore
become due and payable through redemption or otherwise. Any such sale or sales
may be adjourned from time to time by announcement at the time and place
appointed for such sale or sales, or for any such adjourned sale or sales,
without further notice, and the Indenture Trustee and the Holder or Holders of
any Certificates, or any interest therein, may bid and become the purchaser at
any such sale, and each Holder shall be entitled, at any such sale, to credit
against the purchase price bid thereby all or any part of the unpaid
obligations owing to such Holder and secured by the Lien of this Agreement. The
Indenture Trustee may exercise such right without possession or production of
the Certificates or proof of ownership thereof, and as representative of the
Holders may exercise such right without notice to the Holders or including the
Holders as parties to any suit or proceeding relating to foreclosure of any
property in the Indenture Estate. The Owner Trustee hereby irrevocably
constitutes the Indenture Trustee the true and lawful attorney-in-fact of the
Owner Trustee (in the name of the Owner Trustee or otherwise) for the purpose
of effectuating any sale, assignment, transfer or delivery for enforcement of
the Lien created under this Agreement, whether pursuant to foreclosure or power
of sale or otherwise, to execute and deliver all such bills of sale,
assignments and other instruments as the Indenture Trustee may consider
necessary or appropriate, with full power of substitution, the Owner Trustee
hereby ratifying and confirming all that such attorney or any substitute shall
lawfully do by virtue hereof. Nevertheless, if so requested by the Indenture
Trustee or any purchaser, the Owner Trustee shall ratify and confirm any such
sale, assignment, transfer or delivery, by executing and delivering to the
Indenture Trustee or such purchaser all bills of sale, assignments, releases
and other proper instruments to effect such ratification and confirmation as
may be designated in any such request.

                 (c)      Subject to Sections 8.03(b) and 8.03(e), if an
Indenture Event of Default has occurred and is continuing, the Owner Trustee
shall, at the request of the Indenture Trustee, promptly execute and deliver to
the Indenture Trustee such instruments of title or other documents as the
Indenture Trustee may deem necessary or advisable to enable the Indenture
Trustee or an agent or representative designated by the Indenture Trustee, at
such time or times and place or places as the Indenture Trustee may specify, to
obtain possession of all or any part of the Indenture Estate. If the Owner
Trustee shall for any reason fail to execute and deliver such instruments and
documents after such request by the Indenture Trustee, the Indenture Trustee
shall be entitled to a judgment for specific performance of the covenants
contained in the foregoing sentence, conferring upon the Indenture Trustee the
right to immediate possession and requiring the Owner Trustee to execute and
deliver such instruments and documents to the Indenture Trustee. The Indenture
Trustee shall also be entitled to pursue all or any part of the Indenture
Estate wherever it may be found and may enter any of the premises of the Owner
Trustee or any other Person wherever the Indenture Estate may be or be supposed
to be and search for the Indenture Estate and take possession of any item of
the Indenture Estate pursuant to this Section 8.03(c). The Indenture Trustee
may, from time to time, at the expense of the Indenture Estate, make all such
expenditures for maintenance, insurance, repairs, replacements, alterations,
additions and improvements to and of the Indenture Estate, as it may deem
proper. In each such case, the Indenture Trustee shall have the right to use,
operate, store, lease, control or manage the Indenture Estate, and to exercise
all rights and powers of the Owner Trustee relating to the Indenture Estate as
the Indenture





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Trustee shall deem appropriate, including the right to enter into any and all
such agreements with respect to the use, operation, storage, leasing, control
or management of the Indenture Estate or any part thereof; and the Indenture
Trustee shall be entitled to collect and receive directly all tolls, rents
(including Rent), issues, profits, products, revenues and other income of the
Indenture Estate and every part thereof, without prejudice, however, to the
right of the Indenture Trustee under any provision of this Agreement to collect
and receive all cash held by, or required to be deposited with, the Indenture
Trustee hereunder. In accordance with the terms of this Section 8.03(c), such
tolls, rents (including Rent), issues, profits, products, revenues and other
income shall be applied to pay the expenses of using, operating, storing,
leasing, controlling or managing the Indenture Estate, and of all maintenance,
insurance, repairs, replacements, alterations, additions and improvements, and
to make all payments which the Indenture Trustee may be required or may elect
to make, if any, for taxes, assessments, insurance or other proper charges upon
the Indenture Estate or any part thereof (including the employment of engineers
and accountants to examine, inspect and make reports upon the properties and
books and records of the Owner Trustee and, to the extent permitted by the
Lease, the Company), and all other payments which the Indenture Trustee may be
required or authorized to make under any provision of this Agreement, including
this Section 8.03(c), as well as just and reasonable compensation for the
services of the Indenture Trustee, and of all persons properly engaged and
employed by the Indenture Trustee.

                 If an Indenture Event of Default occurs and is continuing and
the Indenture Trustee shall have obtained possession of or title to the
Aircraft, the Indenture Trustee shall not be obligated to use or operate the
Aircraft or cause the Aircraft to be used or operated directly or indirectly by
itself or through agents or other representatives or to lease, license or
otherwise permit or provide for the use or operation of the Aircraft by any
other Person unless (i) the Indenture Trustee shall have been able to obtain
insurance in kinds, at rates and in amounts satisfactory to it in its
discretion to protect the Indenture Estate and the Indenture Trustee, as
trustee and individually, against any and all liability for loss or damage to
the Aircraft and for public liability and property damage resulting from use or
operation of the Aircraft and (ii) funds are available in the Indenture Estate
to pay for all such insurance or, in lieu of such insurance, the Indenture
Trustee is furnished with indemnification from the Holders or any other Person
upon terms and in amounts satisfactory to the Indenture Trustee in its
discretion to protect the Indenture Estate and the Indenture Trustee, as
trustee and individually, against any and all such liabilities.

                 (d)      Subject to Sections 8.03(b) and 8.03(e), the
Indenture Trustee may proceed to protect and enforce this Agreement and the
Certificates by suit or suits or proceedings in equity, at law or in
bankruptcy, and whether for the specific performance of any covenant or
agreement herein contained or in execution or aid of any power herein granted
or for foreclosure hereunder, or for the appointment of a receiver or receivers
for the Indenture Estate or any part thereof, or for the recovery of judgment
for the indebtedness secured by the Lien created under this Agreement or for
the enforcement of any other power, legal or equitable remedy available under
applicable law.

                 (e)      (i)     If the Company shall fail to make any payment
of Basic Rent under the Lease and such failure shall have become a Lease Event
of Default then as long as no other Indenture Event of Default shall have
occurred and be continuing (other than those arising from a Lease Event of
Default), the Owner Participant or the Owner Trustee may (but need not) pay to
the Indenture Trustee, at any time prior to the expiration of a period of ten
Business Days (the "10-Day Period") after such failure shall have become a
Lease Event of Default (prior to the expiration of which 10-Day Period the
Indenture Trustee shall not (without the prior written consent of the Owner
Trustee) exercise any of the rights, powers or remedies pursuant to Section 15
of the Lease or this Article 8), an amount equal to the





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full amount of such payment of Basic Rent, together with any interest due
thereon under the Lease on account of the delayed payment thereof to the date
of such payment, and such payment by the Owner Participant or the Owner Trustee
shall be deemed to cure any Indenture Event of Default which arose from such
failure of the Company as of such date of payment (but such cure shall not
relieve the Company of any of its obligations). If the Company shall fail to
perform or observe any covenant, condition or agreement to be performed or
observed by it under the Lease (other than its obligation to pay Basic Rent),
and if (but only if) the performance or observance thereof can be effected by
the payment of money alone (it being understood that actions such as the
obtaining of insurance and the procurement of maintenance services can be so
effected), then as long as no other Indenture Event of Default (other than
those arising from a Lease Event of Default) shall have occurred and be
continuing, the Owner Participant or the Owner Trustee may (but need not) pay
to the Indenture Trustee (or to such other Person as may be entitled to receive
the same), at any time prior to the expiration of a period of ten Business Days
after the expiration of the grace period, if any, provided with respect to such
failure on the part of the Company in Section 14 of the Lease (prior to the
expiration of which 10-Day Period the Indenture Trustee shall not (without the
prior written consent of the Owner Trustee) exercise any of the rights, powers
or remedies pursuant to Section 15 of the Lease or this Article 8), all sums
necessary to effect the performance or observance of such covenant or agreement
of the Company, together with any interest due thereon under the Lease on
account of the delayed payment thereof to the date of such payment, and such
payment by the Owner Participant or the Owner Trustee shall be deemed to cure
any Indenture Event of Default which arose from such failure of the Company as
of such date of payment (but such cure shall not relieve the Company of any of
its obligations).  If, on the basis specified in the preceding sentences, any
Lease Events of Default shall have been remedied, then any declaration pursuant
to this Indenture that the Certificates are due and payable or that an
Indenture Event of Default exists hereunder, based solely upon such Lease
Events of Default, shall be deemed to be rescinded, and, in the case of the
first and second sentences of this Section 8.03(e)(i), the Owner Participant or
the Owner Trustee shall (to the extent of any such payments made by it) be
subrogated to the rights of the Holders of the Certificates under Section 3.03,
to receive from the Indenture Trustee such payment of overdue Basic Rent or
other amount (and the payment of interest on account of such Basic Rent or
other amount being overdue) and shall be entitled, so long as no other
Indenture Event of Default or Indenture Default shall have occurred and be
continuing or would result therefrom, to receive, subject to the provisions of
this Indenture, such payment upon receipt thereof by the Indenture Trustee;
provided, that the Owner Participant shall not otherwise attempt to recover any
such amount paid by it on behalf of the Company pursuant to this Section
8.03(e)(i) except by demanding payment of such amount or by commencing an
action at law against the Company for the payment of such amount; and provided,
further, that:

                 (x)      this Section 8.03(e)(i) shall not apply with respect
         to any default in the payment of Basic Rent due under the Lease if the
         Lessee itself shall have theretofore failed to pay Basic Rent in the
         manner required under the Lease (after giving effect to any applicable
         grace period) (i) due on each of the two Rent Payment Dates
         immediately preceding the date of such default, or (ii) due on a total
         of four Rent Payment Dates; and

                 (y)      neither the Owner Trustee nor the Owner Participant
         shall have the right to cure any Lease Event of Default except as
         specified in this Section 8.03(e)(i).

                          (ii)    In the event that (A) at any time one or more
Lease Events of Default shall have occurred and be continuing for a period of
180 days during which the Holders or the Indenture Trustee shall not have been
stayed or otherwise precluded by operation of law from taking action to





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accelerate the Certificates or to exercise remedies hereunder or under the
Lease or (B) the Certificates shall have been accelerated pursuant to Section
8.02, the Owner Trustee or the Owner Participant may, at its option, give at
least 30 days' prior irrevocable notice to the Indenture Trustee that the Owner
Trustee or the Owner Participant will redeem (except subsequent to the
establishment of the Redemption Date in respect of the Certificates) or
purchase all Certificates then Outstanding on a date determined consistently
with the applicable provisions of Article 6 and, concurrently with such notice,
the Owner Trustee or the Owner Participant will deposit with the Indenture
Trustee an amount sufficient to redeem (except subsequent to the establishment
of the Redemption Date in respect of the Certificates) or purchase at the
applicable Redemption Price determined in accordance with Article 6 all
Certificates then Outstanding (including, when applicable, an estimate of the
Premium to be paid on the Redemption Date computed using the Treasury Yield
determined as if the Redemption Date were the date of such notice) and to pay
the Indenture Trustee all amounts then due it hereunder, which funds shall be
held by the Indenture Trustee as provided in Section 9.04.  Subject to the
subsequent satisfaction by the Owner Trustee of its obligations pursuant to the
next following sentence, upon the giving of such notice and the receipt by the
Indenture Trustee of such deposit, the Indenture Trustee shall deem all
instructions received from the Owner Trustee as having been given by the
Holders of 100% of the Outstanding principal amount of Certificates for all
purposes of this Indenture. If such notice is given, the Owner Trustee further
agrees that it will deposit or cause to be deposited with the Indenture
Trustee, on or prior to the applicable Redemption Date, whether or not an
Indenture Event of Default is then continuing, funds sufficient, when added to
the funds already held by the Indenture Trustee for such purpose, to redeem or
purchase at the applicable Redemption Price (including the Premium (if the
Redemption Price includes Premium) actually payable in respect thereof, if any,
and all other amounts payable to the Holders hereunder or under any other
Operative Agreement on such Redemption Date) all Certificates then Outstanding
and to pay the Indenture Trustee all amounts then due it hereunder.

                          (iii)   Anything in this Agreement to the contrary
notwithstanding, the Indenture Trustee shall not be entitled to exercise any
remedy hereunder as a result of an Indenture Event of Default which arises
solely by reason of one or more events or circumstances which constitute a
Lease Event of Default unless the Indenture Trustee as security assignee of the
Owner Trustee shall have exercised or concurrently be exercising one or more of
the remedies provided for in Section 15 of the Lease with respect to the
Aircraft, provided, that the requirement to exercise such remedies under the
Lease shall not apply in circumstances where the Indenture Trustee is
involuntarily stayed or otherwise prohibited by applicable law or court order
from exercising such remedies under the Lease after the Section 1110 Period;
provided, further that if any Indenture Event of Default is as a result of the
Lessee being subject to bankruptcy proceedings under the Bankruptcy Code and
the Lease has been assumed by the Lessee pursuant to Section 365 of the
Bankruptcy Code (or any comparable successor provision), then the Indenture
Trustee shall not exercise any remedies against the Owner Trustee, so long as
no other Indenture Event of Default occurs and is continuing.  The "Section
1110 Period" shall mean the period commencing on the date of such stay or
prohibition and ending on the earlier of (x) the 60th day thereafter (or such
longer period (A) as may be specified in Section 1110(a)(1) of the Bankruptcy
Code, (B) equal to the period of an extension with the consent of the Indenture
Trustee of the 60-day period specified therein pursuant to Section 1110(b) of
the Bankruptcy Code, or (C) resulting from the Indenture Trustee's own failure
to give any requisite notice to any Person) and (y) the date of repossession of
the Aircraft.  References in this sentence to particular sections of the
Bankruptcy Code as in effect on the date hereof shall include any substantially
similar successor provisions.

                 (f)      Notwithstanding any provision of this Agreement to
the contrary, including, without limitation, Sections 8.03(b), 8.03(c) and
8.03(d), as long as no Lease Event of Default shall have





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occurred and be continuing, neither the Indenture Trustee nor the Owner Trustee
shall take any action in violation of the Company's rights under the Lease,
including, without limitation, (x) the right to receive all monies due and
payable to it in accordance with the provisions of the Lease and (y) the
Company's rights to possession and use of, and of quiet enjoyment of, the
Aircraft.

                 (g)      Each and every right, power and remedy herein given
to the Indenture Trustee specifically or otherwise in this Agreement shall be
cumulative and shall be in addition to every other right, power and remedy
herein specifically given or now or hereafter existing at law, in equity or by
statute, and each and every right, power and remedy whether specifically herein
given or otherwise existing may be exercised from time to time and as often in
such order as may be deemed expedient by the Indenture Trustee, and the
exercise or the beginning of the exercise of any power or remedy shall not be
construed to be a waiver of the right to exercise at the same time or
thereafter any other right, power or remedy.  No delay or omission by the
Indenture Trustee in the exercise of any right, remedy or power or in pursuing
any remedy shall impair any such right, power or remedy or be construed to be a
waiver of any default on the part of the Owner Trustee or the Company or to be
an acquiescence therein.

                 SECTION 8.04.    WAIVER OF OWNER TRUSTEE.  To the extent now
or at any time hereafter enforceable under applicable law, the Owner Trustee
covenants that it will not at any time insist upon or plead, or in any manner
whatsoever claim or take any benefit or advantage of or from any law now or
hereafter in force providing for the valuation or appraisement of the Indenture
Estate or any part thereof, prior to any sale or sales thereof to be made
pursuant to any provision herein contained, or prior to any applicable decree,
judgment or order of any court of competent jurisdiction; nor, after such sale
or sales, claim or exercise any right under any statute now or hereafter made
or enacted by any state or otherwise to redeem the property so sold or any part
thereof, and hereby expressly waives for itself and on behalf of each and every
Person, except decree or judgment creditors of the Owner Trustee acquiring any
interest in or title to the Indenture Estate or any part thereof subsequent to
the date of this Agreement, all benefit and advantage of any such law or laws,
and covenants that it will not invoke or utilize any such law or laws, but will
suffer and permit the execution of every such power as though no such law or
laws had been made or enacted. Nothing in this Section 8.04 shall be deemed to
be a waiver by the Owner Trustee of its rights under Section 8.03(e).

                 The Indenture Trustee may maintain such a pleading, or in any
manner whatsoever claim or take any benefit or advantage of or from any law now
or hereafter in force even if it does not possess any of the Certificates or
does not produce any of them in the proceeding. A delay or omission by the
Indenture Trustee or any Holder in exercising any right or remedy accruing upon
an Indenture Event of Default under this Agreement shall not impair the right
or remedy or constitute a waiver of or acquiescence in such Indenture Event of
Default.

                 SECTION 8.05.    WAIVER OF EXISTING DEFAULTS.      The Holders
of a majority in aggregate principal amount of the Outstanding Certificates by
notice to the Indenture Trustee may waive on behalf of the Holders an existing
Indenture Default or Indenture Event of Default and its consequences except (i)
an Indenture Default or Indenture Event of Default in the payment of the
principal of or interest on any Certificate or (ii) in respect of a covenant or
provision hereof which pursuant to Section 11.02 cannot be amended or modified
without the consent of the Holder affected.

                 SECTION 8.06.    CONTROL BY MAJORITY.       The Holders of a
majority in aggregate principal amount of the Outstanding Certificates may
direct the time, method and place of conducting any





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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proceeding for any remedy available to the Indenture Trustee or exercising any
trust or power conferred on it by this Agreement. However, the Indenture
Trustee may refuse to follow any direction that conflicts with law or this
Agreement, that is unduly prejudicial to the rights of the Holders so affected,
or that would, without satisfactory indemnity from the Holders, subject the
Indenture Trustee to personal liability.

                 SECTION 8.07.    LIMITATION ON SUITS BY HOLDERS.   A Holder of
a Certificate may pursue a remedy under this Agreement or thereunder only if:

                 (1)      the Holder gives to the Indenture Trustee written
         notice of a continuing Indenture Event of Default under this
         Agreement;

                 (2)      the Holders of at least 25% in aggregate principal
         amount of the Outstanding Certificates make a written request to the
         Indenture Trustee to pursue the remedy;

                 (3)      such Holder or Holders offer to the Indenture Trustee
         indemnity satisfactory to the Indenture Trustee against any loss,
         liability or expense to be, or which may be, incurred by the Indenture
         Trustee in pursuing the remedy;

                 (4)      the Indenture Trustee does not comply with the
         request within 60 days after receipt of the request and the offer of
         indemnity; and

                 (5)      during such 60-day period the Holders of a majority
         in aggregate principal amount of the Outstanding Certificates do not
         give the Indenture Trustee a direction inconsistent with the request.

                 A Holder may not use this Agreement to prejudice the rights of
another Holder or to obtain a preference or priority over another Holder.

                 SECTION 8.08.    RIGHTS OF HOLDERS TO RECEIVE PAYMENT.
Notwithstanding any other provision of this Agreement the right of any Holder
to receive payment of principal of, Premium and interest on such Holder's
Certificate on or after the respective due dates expressed in such Certificate,
or to bring suit for the enforcement of any such payment on or after such
respective dates, shall not be impaired or affected without the consent of such
Holder.

                 SECTION 8.09.    INDENTURE TRUSTEE MAY FILE PROOFS OF CLAIM.
The Indenture Trustee may file such proofs of claim and other papers or
documents as may be necessary or advisable in order to have the claims of the
Indenture Trustee and of the Holders allowed in any judicial proceedings
relating to any obligor on the Certificates, its creditors, or its property.

                                   ARTICLE 9

                               INDENTURE TRUSTEE

                 SECTION 9.01.    DUTIES OF INDENTURE TRUSTEE.

                 (a)      The Indenture Trustee will furnish to each
Certificate Holder promptly upon receipt thereof, duplicates or copies of all
reports, notices, requests, demands, certificates, financial





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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statements and other instruments furnished to the Indenture Trustee under any
Operative Agreement or received from the Owner Trustee pursuant to Section
4.01(vi) to the extent the same shall not have been otherwise directly
distributed to the Holders pursuant to the express provision of any other
Operative Agreement.

                 (b)      Subject to the terms of Sections 8.03(e), 8.05, 8.06,
9.01(c), 11.02 and 11.06, upon the written instructions at any time and from
time to time of Holders of a majority in aggregate principal amount of the
Outstanding Certificates, the Indenture Trustee shall take such of the
following actions as may be specified in such instructions:  (i) exercise such
election or option, or make such decision or determination, or give such
notice, consent, waiver or approval or exercise such right, remedy or power or
take such other action hereunder or under any other Operative Agreement or in
respect of any part or all of the Indenture Estate as shall be specified in
such instructions; (ii) take such action with respect to, or to preserve or
protect, the Indenture Estate (including the discharge of Liens) as shall be
specified in such instructions and as are consistent with this Indenture; and
(iii) take such other action in respect of the subject matter of this Indenture
as is consistent with the terms hereof and the other Indenture Documents.  The
Indenture Trustee will execute and the Owner Trustee will file or cause to be
filed such continuation statements with respect to financing statements
relating to the security interest created hereunder in the Indenture Estate as
may be specified from time to time in written instructions of Holders of a
majority in aggregate principal amount of the Outstanding Certificates (which
instructions may, by their terms, be operative only at a future date and which
shall be accompanied by the execution form of such continuation statement so to
be filed).

                 (c)      The Indenture Trustee shall not be required to take
any action or refrain from taking any action under Section 8.06 or 9.01(b)
unless the Indenture Trustee shall have been indemnified by the Holders against
any liability, cost or expense (including counsel fees) which may be incurred
in connection therewith.  The Indenture Trustee shall not be under any
obligation to take any action under this Agreement and nothing in this
Agreement contained shall require the Indenture Trustee to expend or risk its
own funds or otherwise incur any financial liability in the performance of any
of its duties hereunder or in the exercise of any of its rights or powers if it
shall have reasonable grounds for believing that repayment of such funds or
adequate indemnity against such risk or liability is not reasonably assured to
it.  The Indenture Trustee shall not be required to take any action under
Section 8.06 or 9.01(b), nor shall any other provision of this Indenture be
deemed to impose a duty on the Indenture Trustee to take any action, if the
Indenture Trustee shall have been advised by counsel that such action is
contrary to the terms hereof or is otherwise contrary to law.

                 (d)      The Indenture Trustee shall not have any duty or
obligation to use, operate, store, lease, control, manage, sell, dispose of or
otherwise deal with the Aircraft or any other part of the Indenture Estate, or
to otherwise take or refrain from taking any action under, or in connection
with, this Indenture or any part of the Indenture Estate, except as expressly
provided by the terms of this Indenture or as expressly provided in written
instructions from Holders as provided in this Indenture; and no implied duties
or obligations shall be read into this Indenture against the Indenture Trustee.

                 (e)      The Owner Trustee and the Indenture Trustee agree
that they will not use, operate, store, lease, control, manage, sell, dispose
of or otherwise deal with the Aircraft or any other part of the Indenture
Estate except (i) in accordance with the terms of the Lease or the
Participation Agreement, or (ii) in accordance with the powers granted or
reserved to, or the authority conferred upon, the Owner Trustee and the
Indenture Trustee pursuant to this Indenture and in accordance with the express
terms hereof.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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                 (f)      Subject to the provisions of Section 9.04, the
Indenture Trustee shall not be liable for interest on any money received except
as otherwise provided in any other Operative Agreement.  Money held in trust by
the Indenture Trustee need not be segregated from other funds except to be
extent required by law.

                 SECTION 9.02.    RIGHTS OF INDENTURE TRUSTEE.      (a)  The
Indenture Trustee may rely on any document believed by it to be genuine and to
have been signed or presented by the proper person.  The Indenture Trustee need
not investigate any fact or matter stated in the document.

                 (b)      Before the Indenture Trustee acts or refrains from
acting, it may consult with counsel or require an Officer's Certificate or an
Opinion of Counsel from the Company or the Owner Trustee after which it will
take such action or refrain from acting as it deems appropriate. The Indenture
Trustee shall not be liable for any action it takes or omits to take in good
faith and in accordance herewith in reliance on a resolution of the Board of
Directors of the Company, the written advice of counsel acceptable to the Owner
Trustee, the Company and the Indenture Trustee, officer's certificates or
opinions of counsel provided by the Company or the Owner Trustee.

                 (c)      The Indenture Trustee may act through agents and
shall not be responsible for the misconduct or negligence of any such agent
appointed with due care; provided, that so long as no Indenture Event of
Default shall have occurred and be continuing no such agents shall be appointed
by the Indenture Trustee without the consent of the Company and the Owner
Trustee, which consent shall, in each case, not be unreasonably withheld.

                 (d)      The Indenture Trustee shall not be liable for any
action it takes or omits to take in good faith which it believes to be
authorized or within its rights or powers.

                 (e)      If an Indenture Event of Default under this Agreement
has occurred and is continuing, the Indenture Trustee shall exercise its rights
and powers under this Agreement, and shall use the same degree of care and
skill in their exercise, as a prudent man would exercise or use under the
circumstances in the conduct of his own affairs.

                 SECTION 9.03.    INDIVIDUAL RIGHTS OF INDENTURE TRUSTEE
The Indenture Trustee in its individual or any other capacity may become the
owner or pledgee of Certificates and may otherwise deal with the Owner Trustee,
the Company or an Affiliate of the Owner Trustee or the Company or a subsidiary
of the Owner Trustee or the Company with the same rights it would have if it
were not the Indenture Trustee. Any Agent may do the same with like rights.

                 SECTION 9.04.    FUNDS MAY BE HELD BY INDENTURE TRUSTEE OR
PAYING AGENT; INVESTMENTS.         Any monies (including without limitation for
purposes of this Section 9.04 Permitted Investments constituting the proceeds
of the maturity, sale or other disposition of any Permitted Investment) held by
the Indenture Trustee or the Paying Agent hereunder as part of the Indenture
Estate, until paid out by the Indenture Trustee or the Paying Agent as herein
provided, (i) subject to clause (ii) below, may be carried by the Indenture
Trustee or the Paying Agent on deposit with itself or on deposit to its account
with any bank, trust company or national banking association incorporated or
doing business under the laws of the United States of America or one of the
States thereof having combined capital and surplus and retained earnings of at
least $100,000,000, and neither the Indenture Trustee nor the Paying Agent
shall have any liability for interest upon any such monies except as otherwise
agreed in writing or (ii) at any time and from time to time, so long as no
Lease Default (of the type described





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -38-
   44
in Section 14.1 or 14.5 of the Lease) or Lease Event of Default shall have
occurred and be continuing, at the request (given directly by the Company to
the Indenture Trustee) of the Company acting as the agent of the Owner Trustee,
shall be invested and reinvested in Permitted Investments as specified in such
request (if such investments are reasonably available for purchase) and sold,
in any case at such prices, including accrued interest or its equivalent, as
are set forth in such request, and such Permitted Investments shall be held by
the Indenture Trustee in trust as part of the Indenture Estate until so sold;
provided, that the Company, on behalf of the Owner Trustee, as agent of the
Owner Trustee, shall upon demand pay to the Indenture Trustee the amount of any
loss realized upon maturity, sale or other disposition of any such Permitted
Investment and, so long as no Lease Default (of the type referred to in Section
14.1 or 14.5 of the Lease) or Lease Event of Default shall have occurred and be
continuing, be entitled to receive from the Indenture Trustee, and the
Indenture Trustee on behalf of the Owner Trustee, shall promptly pay to the
Company pursuant to Section 22.1 of the Lease, any profit, income, interest,
dividend or gain realized upon maturity, sale or other disposition of any
Permitted Investment.  If any Lease Default (of the type referred to in Section
14.1 or 14.5 of the Lease) or Lease Event of Default shall have occurred and be
continuing, any net income, profit, interest, dividend or gain realized upon
maturity, sale or other disposition of any Permitted Investment shall be held
as part of the Indenture Estate and shall be applied by the Indenture Trustee
at the same time, on the same conditions and in the same manner as the amounts
in respect of which such income, profit, interest, dividend or gain was
realized are required to be distributed in accordance with the provisions
hereof or of the Lease pursuant to which such amounts were required to be held.
The Indenture Trustee shall not be responsible for any losses on any
investments or sales of Permitted Investments made pursuant to the procedure
specified in this Section 9.04.

                 SECTION 9.05.    NOTICE OF DEFAULTS.       If an Indenture
Event of Default under this Agreement occurs and is continuing and the
Indenture Trustee has actual knowledge of same, the Indenture Trustee shall (i)
promptly send written notice thereof to the Company, the Owner Trustee and the
Owner Participant and (ii) within 90 days after it occurs, mail to each other
Holder notice of all uncured Indenture Events of Default under this Agreement.
Except in the case of a default in the payment of the principal of, Premium, if
any, or interest on any Certificates, the Indenture Trustee shall be protected
in withholding the notice required under clause (ii) above if and so long as
the executive committee or trust committee of directors of the Indenture
Trustee and/or Responsible Officers thereof in good faith determines that
withholding such notice is in the interest of the Holders. In addition, if an
Indenture Default under this Agreement occurs and is continuing and if the
Indenture Trustee has actual knowledge of same, the Indenture Trustee shall
promptly send written notice thereof to the Company, the Owner Trustee and the
Owner Participant.

                 SECTION 9.06.    COMPENSATION AND INDEMNITY.        (a)  The
Owner Trustee shall pay to the Indenture Trustee from time to time (i)
reasonable compensation for its services, which compensation shall not be
limited by any law on compensation of a trustee of an express trust, (ii)
reimbursement for all reasonable out-of-pocket expenses incurred by the
Indenture Trustee in connection with the performance of its duties under this
Agreement (including the reasonable compensation and expenses of the Indenture
Trustee's counsel and any agent appointed in accordance with Section 9.02(c)),
and (iii) indemnification against any loss or liability incurred by it arising
out of or in connection with its acceptance or administration of the trust or
trusts hereunder except (A) as such expenses or loss or liability might result
from the gross negligence or willful misconduct of the Indenture Trustee or the
inaccuracy of any representation or warranty of the Indenture Trustee in its
individual capacity in Section 8 of the Participation Agreement or failure by
the Indenture Trustee to perform its payment and investment obligations
hereunder, (B) as otherwise provided in Section 9.10 and (C) as





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otherwise excluded by the terms of Sections 7(b) and 7(c) of the Participation
Agreement from the Company's indemnities under said Sections; provided, that
the Indenture Trustee shall not make any claim under this Section 9.06(a) for
any claim or expense indemnified against by the Company under the Participation
Agreement without first making demand on, and pursuing such demand on a
reasonable basis for a reasonable length of time, the Company for payment of
such claim or expense. The Indenture Trustee shall notify the Owner Trustee and
the Company promptly of any claim for which it is entitled to be indemnified
hereunder. Subject to the conditions and procedures equivalent to those set
forth in Sections 7(b) and 7(c) of the Participation Agreement, the Owner
Trustee shall defend the claim and the Indenture Trustee shall cooperate in the
defense.  The Indenture Trustee may have separate counsel and the Owner Trustee
shall pay the reasonable fees and expenses of such counsel.  The Owner Trustee
need not pay for any settlement made without its and the Company's consent.

                 (b)      To secure the payment obligations of the Owner
Trustee pursuant to this Section 9.06, the Indenture Trustee shall have a lien
prior to that of the Holders of the Certificates on all money or property
constituting a part of the Indenture Estate held or collected by the Indenture
Trustee, except that held in trust to pay the principal of, and interest on,
the Certificates.

                 SECTION 9.07.    REPLACEMENT OF INDENTURE TRUSTEE.
(a)  The resignation or removal of the Indenture Trustee and the appointment of
a successor Indenture Trustee shall become effective only upon the successor
Indenture Trustee's acceptance of appointment as provided in this Section.

                 (b)      The Indenture Trustee may resign by giving at least
30 days' prior written notice to the Company, the Owner Trustee and the Holders
of a majority in aggregate principal amount of the Outstanding Certificates.
The Holders of a majority in aggregate principal amount of the Outstanding
Certificates may remove the Indenture Trustee by giving at least 30 days' prior
written notice to the Indenture Trustee, the Owner Trustee and the Company and
may appoint a successor Indenture Trustee with the Owner Trustee's and the
Company's consent.  At such time as Series SWA 1996 Trust N625SW Certificates
are Outstanding, the Owner Trustee may remove the Indenture Trustee if:

                          (1)     the Indenture Trustee fails to comply with
         Section 9.09, fails to perform its payment obligations hereunder or
         otherwise fails to perform any of its material obligations hereunder;

                          (2)     the Indenture Trustee is adjudged a bankrupt
         or an insolvent;
                          (3)     a receiver or public officer takes charge of
         the Indenture Trustee or its property; or

                          (4)     the Indenture Trustee becomes incapable of
         acting.
                 (c)      If the Indenture Trustee resigns or is removed, or if
a vacancy exists in the office of Indenture Trustee for any reason, Holders of
a majority in aggregate principal amount of the Certificates or, at such time
as Series SWA 1996 Trust N625SW Certificates are Outstanding, the Owner
Trustee, shall promptly appoint a successor Indenture Trustee.

                 (d)      If a successor Indenture Trustee does not take office
within 30 days after the retiring Indenture Trustee resigns or is removed, the
retiring Indenture Trustee, the Company, the Owner





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Trustee or the Holders of a majority in aggregate principal amount of the
Outstanding Certificates may petition any court of competent jurisdiction for
the appointment of a successor Indenture Trustee.

                 (e)      If the Indenture Trustee fails to comply with Section
9.09, any Holder may petition any court of competent jurisdiction for the
removal of such Indenture Trustee and the appointment of a successor Indenture
Trustee.

                 (f)      A successor Indenture Trustee shall deliver a written
acceptance of its appointment to the retiring Indenture Trustee, to the Company
and to the Owner Trustee. Thereupon, the resignation or removal of the retiring
Indenture Trustee shall become effective, and the successor Indenture Trustee
shall have all the rights, powers and duties of the retiring Indenture Trustee
for which the successor Indenture Trustee is to be acting as Indenture Trustee
under this Agreement. The retiring Indenture Trustee shall promptly transfer
all property and all books and records relating to the administration of the
Indenture Estate held by it as Indenture Trustee to the successor Indenture
Trustee subject to the lien provided for in Section 9.06. The successor
Indenture Trustee shall give notice of each appointment of a successor
Indenture Trustee if there are Certificates Outstanding, by mailing written
notice of such event by first-class mail to the Holders.

                 (g)      All provisions of this Section 9.07 except
subparagraphs (b)(l) and (e) and the words "subject to the lien provided for in
Section 9.06" in subparagraph (f) shall apply also to any Paying Agent.

                 SECTION 9.08.    SUCCESSOR INDENTURE TRUSTEE, AGENTS BY
MERGER, ETC.  If the Indenture Trustee or any Agent consolidates with, merges
or converts into, or transfers all or substantially all of its corporate trust
business assets to, another corporation, the successor corporation, without any
further act, shall be the successor Indenture Trustee or Agent, as the case may
be.

                 SECTION 9.09.    ELIGIBILITY; DISQUALIFICATION.    This
Agreement shall at all times have an Indenture Trustee which shall have a
combined capital and surplus of at least $100,000,000 and shall be a "citizen
of the United States" as defined in the Federal Aviation Act.  If such
corporation publishes reports of conditions at least annually, pursuant to law
or to the requirements of Federal, State, Territorial, or District of Columbia
supervising or examining authority, then for the purposes of this Section 9.09,
the combined capital and surplus of such corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of
conditions so published.

                 In case at any time the Indenture Trustee shall cease to be
eligible in accordance with the provisions of this Section 9.09, the Indenture
Trustee shall resign immediately in the manner and with the effect specified in
Section 9.07.

                 SECTION 9.10.    TRUSTEE'S LIENS.          The Indenture
Trustee in its individual capacity agrees that it will at its own cost and
expense promptly take such action as may be necessary to duly discharge and
satisfy in full all Liens ("Trustee's Liens") on the Indenture Estate which are
either (i) attributable to the Indenture Trustee in its individual capacity and
which are unrelated to the transactions contemplated by the Operative
Agreements, or (ii) which are attributable to the Indenture Trustee as trustee
hereunder or in its individual capacity and which arise out of acts or
omissions which are not expressly contemplated by this Agreement.





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                 SECTION 9.11.    WITHHOLDING TAXES; INFORMATION REPORTING.
The Indenture Trustee shall exclude and withhold from each distribution of
principal, Premium, if any, and interest and other amounts due hereunder or
under the Certificates any and all withholding taxes applicable thereto as
required by law. The Indenture Trustee agrees to act as such withholding agent
and, in connection therewith, whenever any present or future taxes or similar
charges are required to be withheld with respect to any amounts payable in
respect to the Certificates, to withhold such amounts and timely pay the same
to the appropriate authority in the name of and on behalf of the Holders, that
it will file any necessary withholding tax returns or statements when due, and
that, as promptly as possible after the payment thereof, it will deliver to
each Holder appropriate documentation showing the payment thereof, together
with such additional documentary evidence as such Holders may reasonably
request from time to time. The Indenture Trustee agrees to file any other
information reports as it may be required to file under United States law. Such
withholding by the Indenture Trustee shall in no event give rise to an
Indenture Event of Default.

                 SECTION 9.12.    [RESERVED FOR POTENTIAL FUTURE USE]

                 SECTION 9.13.    CERTAIN RIGHTS OF OWNER TRUSTEE AND OWNER
PARTICIPANT.  Notwithstanding any other provisions of this Indenture, including
the Granting Clause, the following rights shall be reserved to the Owner
Trustee or the Owner Participant, as the case may be (as separate and
independent rights) to the extent described herein:

                 (a)      at all times the Owner Trustee and the Owner
         Participant shall have the right, together with the Indenture Trustee,
         to receive from the Lessee all notices, certificates, reports,
         filings, opinions of counsel and other documents and all information
         which the Company is permitted or required to give or furnish to the
         Owner Trustee or the Lessor pursuant to any Indenture Document;

                 (b)      at all times (unless otherwise specified in the
         Lease) the Owner Trustee shall have the right (1) to the exclusion of
         the Indenture Trustee but subject to and without affecting the
         provisions of Section 11.06, (i) to exercise the rights, elections and
         options of the Lessor to make any decision or determination to
         exercise rights and to give any notice, consent, waiver or approval
         under Section 3.7 or (with respect to liability insurance for the
         Owner Participant and Owner Trustee) 11, of the Lease and Section 17
         of the Participation Agreement, (ii) to exercise the rights, elections
         and options of the Lessor with respect to the termination of the Lease
         and solicitations of bids and appraisals pursuant to Section 9 of the
         Lease, or with respect to renewals or purchase options and
         terminations to take effect upon or after the payment in full (or
         assumption by the Company) of the obligations secured hereby, (iii) to
         effect cures pursuant to Section 20 of the Lease; provided that this
         will not be deemed to cure the related Event of Default unless
         permitted by the terms of Section 8.03(e)(i), and (iv) to maintain and
         exercise all rights regarding separate insurance with respect to the
         Aircraft for its own account pursuant to Section 11.7 of the Lease
         (provided, that no such insurance impairs or reduces coverage under
         any insurance required to be maintained by the Company under Section
         11 of the Lease) and (2) so long as no Indenture Event of Default
         shall have occurred and be continuing, to the exclusion of the
         Indenture Trustee (i) to approve as satisfactory any other
         accountants, inspectors, engineers or counsel to render services for
         or issue opinions to the Owner Trustee, together with the contents of
         any certificates and opinions to be delivered by such Persons, in each
         case pursuant to express provisions of the Operative Agreements and
         (ii) to grant such consents, approvals and waivers as may be requested
         under the Indenture Documents and (3) together with





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         the Indenture Trustee (each acting separately), to request all
         certificates and documents of Lessee, to request assignment of any
         sublease of the Aircraft and to exercise inspection rights pursuant to
         Section 12 of the Lease;

                 (c)      at all times, the Owner Trustee shall have the
         non-exclusive right, as Lessor, to seek specific performance of the
         covenants of the Company under the Lease relating to the protection,
         insurance, maintenance, possession and use of the Aircraft and to
         obtain performance by Lessee under Sections 11(a) and (b) of the
         Participation Agreement; and

                 (d)      at all times each of the Owner Trustee (as Owner
         Trustee, individually and as Lessor) and the Owner Participant shall
         have the right, to the exclusion of the Indenture Trustee, to demand,
         collect, sue for or receive the payment of, and waive, modify or
         otherwise deal with Excluded Payments due and payable to it, and, in
         the case of the Owner Participant, to give the written notice referred
         to in the proviso to Section 14.1 of the Lease.

                                   ARTICLE 10

                    SATISFACTION AND DISCHARGE; DEFEASANCE;
                           TERMINATION OF OBLIGATIONS

                 SECTION 10.01.   SATISFACTION AND DISCHARGE OF AGREEMENT;
DEFEASANCE; TERMINATION OF OBLIGATIONS.  Subject to Section 10.02, this
Agreement shall cease to be of further effect, and the Owner Trustee and the
Indenture Trustee shall, except as herein provided, be deemed to have been
discharged from their respective obligations with respect to the Certificates
(and the Indenture Trustee, on demand and at the expense of the Owner Trustee,
shall execute proper instruments acknowledging satisfaction and discharge of
this Agreement in respect of the Certificates), when

                 (a)      (i)     all Certificates theretofore executed and
delivered (other than (A) Certificates which have been mutilated, destroyed,
lost or stolen and which have been replaced or exchanged as provided in Section
2.06 and (B) Certificates for the payment of which money held in trust
hereunder has been paid and discharged from such trust, as provided in Section
7.01) have been delivered to the Indenture Trustee for cancellation; or

                          (ii)    all Certificates not theretofore delivered to
the Indenture Trustee for cancellation have become due and payable (whether
upon stated maturity or as a result of redemption or upon acceleration), or
will become due and payable (including as a result of redemption in respect of
which irrevocable notice has been given to the Indenture Trustee on or prior to
the date of such deposit) at maturity within one year, and there has been
deposited with the Indenture Trustee in trust for the purpose of paying and
discharging the entire indebtedness on the Certificates not theretofore
canceled by the Indenture Trustee or delivered to the Indenture Trustee for
cancellation, an amount of cash and/or Government Obligations sufficient to
discharge such indebtedness, including the principal of, Premium, if any, and
interest on the Certificates to the date of such deposit (in the case of
Certificates which have become due and payable), or to the maturity thereof, as
the case may be; or

                          (iii)   the Certificates shall have been defeased as
provided in Section 10.05; provided, however, that upon the making of the
deposit referred to in subsection A of Section 10.05, the right of the Owner
Trustee or the Company to cause the redemption of Certificates (except a
redemption in respect of which irrevocable notice has theretofore been given)
shall terminate;





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                 (b)      all other amounts then due and payable hereunder have
been paid; and

                 (c)      the Company on behalf of the Owner Trustee has
delivered to the Indenture Trustee an Officers' Certificate and an Opinion of
Counsel, each stating that all conditions precedent provided for or relating to
the satisfaction and discharge of this Agreement contemplated by this Section
10.01 have been complied with.

                 SECTION 10.02.   SURVIVAL OF CERTAIN OBLIGATIONS.
Notwithstanding the provisions of Section 10.01, the obligations of the
Indenture Trustee contained in Sections 2.01 through 2.08, 2.10, Section 7.01,
Section 9.11, Section 10.03 and Section 10.04, and the rights, duties,
immunities and privileges hereunder of the Indenture Trustee shall survive.

                 SECTION 10.03.   MONIES TO BE HELD IN TRUST.       All money
and Government Obligations deposited with the Indenture Trustee pursuant to
Section 10.01 shall be held in trust and applied by it, in accordance with the
provisions of the Certificates and this Agreement, either directly or through
any Paying Agent as the Indenture Trustee may determine, to the Holders, of all
sums due and to become due thereon for principal, Premium, if any, interest,
and all other amounts payable to the Holders hereunder or under any other
Operative Agreement, but such money need not be segregated from other funds
except to the extent required by law.

                 SECTION 10.04.   MONIES TO BE RETURNED TO OWNER TRUSTEE.
The Indenture Trustee and any Paying Agent shall promptly pay or return to the
Owner Trustee upon request of the Owner Trustee any money or Government
Obligations held by them at any time that are not required for the payment of
the amounts described above in Section 10.03 on the Certificates for which
money or Government Obligations have been deposited pursuant to Section 10.01.

                 SECTION 10.05.   DEFEASANCE.       The Owner Trustee may, at
any time, defease the interest of the Indenture Trustee in the Indenture Estate
in whole, but not in part, through the deposit with the Defeasance Trustee, in
accordance with the provisions of this Section 10.05, of cash and/or Government
Obligations.  Such deposit shall be made pursuant to a declaration or other
appropriate instrument of trust satisfactory in form and substance to the
Defeasance Trustee and the Indenture Trustee; such deposit shall be absolute
and irrevocable and the instrument of trust shall expressly provide that the
Owner Trustee shall have no further title to or interest in or power to direct
the use or application of the cash and/or Government Obligations so deposited
or any of the proceeds arising therefrom; such instrument shall state that the
trust created thereby and the cash and/or Government Obligations deposited
pursuant thereto are for the sole and exclusive benefit of the Holders and
shall expressly provide that the Defeasance Trustee shall apply such cash and
payments of principal and/or interest on such Government Obligations to, and
only to, the punctual payment of the principal and interest on the Certificates
as and when such payments become due (such declaration or instrument to contain
appropriate provisions for the recording of transfers of Certificates and the
names and addresses of the Holders); and the Owner Trustee shall agree to pay,
as the same shall become due and payable, all fees, costs and charges of the
Defeasance Trustee under such instrument of trust, including those which may
become payable after the date the conditions hereinbelow specified have been
met.  Upon compliance with the following conditions, and provided, that no
Indenture Event of Default or Indenture Default shall have occurred and be
continuing on a date 91 days after the date of the deposit of Government
Obligations and/or cash with the Defeasance Trustee as provided in Subsection A
below, the Owner Trustee's obligations with respect to the Certificates will be
discharged and this Indenture shall terminate as provided in Section 10.01:





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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                 A.       the Owner Trustee shall have deposited with the
         Defeasance Trustee absolutely and irrevocably (irrespective of whether
         the conditions in Subsections B, C, D and E of this Section 10.05 have
         been satisfied) (1) cash and/or (2) Government Obligations which
         through the payment of principal and interest in respect thereof in
         accordance with their terms, without any reinvestment or further
         investment of the principal of or interest earned on such Government
         Obligations, will absolutely and unconditionally provide in any and
         all circumstances not later than one day before each Payment Date an
         amount sufficient to pay and discharge the payment of principal and
         interest to be due and payable on such Payment Date;

                 B.       no Indenture Event of Default or Indenture Default
         shall have occurred and be continuing on the date of the deposit of
         cash and/or Government Obligations as contemplated hereby;

                 C.       the Owner Trustee shall have delivered to the
         Defeasance Trustee and to the Certificate Holders written confirmation
         by a nationally recognized firm of independent public accountants
         (other than the accounting firm then serving as First Union National
         Bank of North Carolina's or the Owner Participant's regular auditors)
         selected by the Owner Trustee, the form and substance of which
         confirmation and the identity of such accounting firm shall be
         satisfactory to the Indenture Trustee, that the Government Obligations
         deposited for payment of the Certificates, together with any cash
         deposited by the Owner Trustee, are sufficient to satisfy the
         requirements of Subsection A hereof;

                 D.       the Owner Trustee shall have delivered to the
         Defeasance Trustee, the Indenture Trustee and the Certificate Holders
         an opinion of counsel in form and substance satisfactory to the
         Indenture Trustee to the effect that (1) the trust declaration or
         other instrument, as the case may be, is legal, valid, binding and
         enforceable in accordance with its terms for the sole benefit and use
         of the Holders, is irrevocable and the Government Obligations and/or
         cash deposited thereunder and the proceeds thereof and therefrom are
         held by the Defeasance Trustee thereunder in trust solely for the
         benefit of the Holders and will not be subject to any valid interest,
         lien, claim or encumbrance of any other Person, including the Owner
         Trustee or the Owner Participant or any Person claiming by, through,
         under or in the name or on behalf of the Owner Trustee or the Owner
         Participant or any creditor or beneficiary of the Owner Trustee or the
         Owner Participant, or by any court or trustee in bankruptcy and (2)
         such deposit will not constitute a preferential transfer or a
         fraudulent conveyance under any bankruptcy or other similar law and
         shall cover such other matters as the Indenture Trustee may reasonably
         require in connection with such final deposit and matters relating
         thereto;

                 E.  the Owner Trustee shall have delivered to the Defeasance
         Trustee, the Indenture Trustee and the Certificate Holders an
         Officers' Certificate and an Opinion of Counsel (1) to the effect that
         there has been published by the Internal Revenue Service a ruling, or
         (2) since the date of this Agreement that there has been a change in
         or clarification of the applicable Federal income tax law, in either
         case to the effect that Holders will not recognize income, gain or
         loss for Federal income tax purposes as a result of the exercise by
         the Owner Trustee of its option under Section 10.01(a)(iii) and will
         be subject to Federal income tax on the same amounts and in the same
         manner and at the same times, as would have been the case if such
         option had not been exercised; and





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                 F.  the Owner Trustee shall have (1) taken such further action
         and executed such further documents as may be reasonably required by
         any Holder, the Indenture Trustee or the Defeasance Trustee and (2)
         delivered to the Defeasance Trustee, the Indenture Trustee and to the
         Holders a certificate of a Responsible Officer of the Owner Trustee
         stating that all conditions precedent herein to the defeasance of the
         Certificates contemplated by this Section 10.05 have been satisfied.

                 The Owner Participant will pay all expenses (including,
without limitation, reasonable legal fees) incident to the implementation of
the transactions contemplated by this Section 10.05.

                 For the purpose of this Article 10, the following terms have
the following definitions:

                 "Defeasance Trustee" shall mean an institution that is
         authorized to transact in the State of New York the business of a
         trust company and is selected by the Owner Trustee and approved by the
         Indenture Trustee; provided, that at the time of the delivery of cash
         and/or Government Obligations pursuant to this Section 10.05, the
         institution selected shall have a combined capital and surplus of at
         least $500,000,000 and shall not be an Affiliate of the Company, the
         Owner Participant or First Union National Bank of North Carolina.

                 "Government Obligations" shall mean direct U.S. Dollar
         obligations of the United States of America which are not callable,
         redeemable or prepayable, directly or indirectly, by any Person.

                                   ARTICLE 11

                             AMENDMENTS AND WAIVERS

                 SECTION 11.01.   AMENDMENTS TO THIS AGREEMENT WITHOUT CONSENT
OF HOLDERS.  The Owner Trustee and the Indenture Trustee may enter into one or
more agreements supplemental hereto without the consent of any Holder for any
of the following purposes:

                          (1)     to correct any mistake or cure any ambiguity,
         defect or inconsistency herein or in the Certificates or to make any
         change not inconsistent with the provisions hereof; provided, that
         such change does not adversely affect the interests of any Holder;

                          (2)     to evidence the succession of another party
         as the Owner Trustee in accordance with the terms of the Trust
         Agreement or to evidence (in accordance with Article 9) the succession
         of a new trustee hereunder, the removal of the trustee hereunder or
         the appointment of any co-trustee or co-trustees or any separate or
         additional trustee or trustees;

                          (3)     to convey, transfer, assign, mortgage or
         pledge any property to or with the Indenture Trustee or to make any
         other provisions with respect to matters or questions arising
         hereunder so long as such action shall not adversely affect the
         interests of the Holders;

                          (4)     to correct or amplify the description of any
         property at any time subject to the Lien of this Agreement or better
         to assure, convey and confirm unto the Indenture Trustee any property
         subject or required to be subject to the Lien of this Agreement or to
         subject to the Lien of this Agreement the Airframe or Engines or
         airframe or engines substituted for the





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
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         Airframe or Engines in accordance herewith or with the Lease;
         provided, that Trust Supplements entered into for the purpose of
         subjecting to the Lien of this Agreement the Airframe or Engines (or
         the Replacement Airframe or any Replacement Engines) in accordance
         with the Lease need only be executed by the Owner Trustee;

                          (5)     to add to the covenants of the Owner Trustee,
         for the benefit of the Holders, or to surrender any rights or power
         herein conferred upon the Owner Trustee or the Owner Participant;

                          (6)     to add to the rights of the Holders;

                          (7)     to provide for the assumption by the Company
         of the obligations of the Owner Trustee hereunder in accordance with
         the terms and conditions applicable thereto specified in Section 7.03;
         or

                          (8)     to include on the Certificates any legend as
         may be required by applicable law.

                 SECTION 11.02.   AMENDMENTS TO THIS AGREEMENT WITH CONSENT OF
HOLDERS.         (a) With the written consent of the Holders of a majority of
the aggregate principal amount of the Outstanding Certificates, the Owner
Trustee and the Indenture Trustee may enter into such supplemental agreements
to add any provisions to or to change or eliminate any provisions of this
Agreement or of any such supplemental agreements or to modify the rights of the
Holders; provided, however, that without the consent of each Holder affected
thereby, an amendment under this Section 11.02 may not:

                          (1)     reduce the principal amount of, Premium if
         any, or any installment of interest on, any Certificate; or

                          (2)     change the date on which any principal amount
         of, any Installment Payment Amount payable with respect to, Premium,
         if any, or interest on any Certificate, is due or payable; or

                          (3)     create any Lien on the Indenture Estate prior
         to or pari passu with the Lien thereon under this Agreement except
         such as are permitted by this Agreement, or deprive any Holder of the
         benefit of the Lien on the Indenture Estate created by this Agreement;
         or

                          (4)     reduce the percentage in principal amount of
         the Outstanding Certificates, the consent of whose holders is required
         for any such supplemental agreement, or the consent of whose holders
         is required for any waiver (of compliance with certain provisions of
         this Agreement or of certain defaults hereunder or their consequences)
         provided for in this Agreement; or

                          (5)     make any change in Section 8.05, 8.08, or
         this Section 11.02(a).

                 (b)      It is not necessary under this Section 11.02 for the
Holders to consent to the particular form of any proposed supplemental
agreement, but it is sufficient if they consent to the substance thereof.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -47-
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                 (c)      Promptly after the execution by the Owner Trustee and
the Indenture Trustee of any supplemental agreement pursuant to the provisions
of this Section 11.02, the Indenture Trustee shall transmit by first-class mail
a notice, setting forth in general terms the substance of such supplemental
agreement, to all Holders, as the names and addresses of such Holders appear on
the Register. Any failure of the Indenture Trustee to mail such notice, or any
defect therein, shall not, however, in any way impair or affect the validity of
any such supplemental agreement.

                 SECTION 11.03.   REVOCATION AND EFFECT OF CONSENTS.
Until an amendment or waiver becomes effective, a consent to it by a Holder is
a continuing consent by the Holder and every subsequent Holder, even if
notation of the consent is not made on any Certificate. However, any such
Holder or subsequent Holder may revoke the consent as to his Certificate if the
Indenture Trustee receives the notice of revocation before the date the
amendment or waiver becomes effective. After an amendment or waiver becomes
effective, it shall bind every Holder affected by such amendment or waiver.

                 SECTION 11.04.   NOTATION ON OR EXCHANGE OF CERTIFICATES.
The Indenture Trustee may place an appropriate notation about an amendment or
waiver on any Certificate thereafter executed. The Indenture Trustee in
exchange for such Certificates may execute new Certificates that reflect the
amendment or waiver.

                 SECTION 11.05.   INDENTURE TRUSTEE PROTECTED.  The Indenture
Trustee need not sign any supplemental agreement that adversely affects its
rights.

                 SECTION 11.06.   AMENDMENTS, WAIVERS, ETC. OF OTHER OPERATIVE
AGREEMENTS.  (a)  Subject to Sections 9.13 and 11.01, without the consent of
the Holders of a majority in principal amount of Outstanding Certificates, the
respective parties to the Participation Agreement, the Lease and the Trust
Agreement may not modify, amend or supplement any of said agreements, or give
any consent, waiver, authorization or approval thereunder, for any purpose,
including adding any provisions to or changing in any manner or eliminating any
of the provisions thereof or modifying in any manner the rights of the
respective parties thereunder; provided, however, that the actions specified in
subsection (b) of this Section 11.06 may be taken without the consent of the
Indenture Trustee or any Holder.

                 (b)      Subject to the provisions of subsection (c) of this
Section 11.06, the respective parties to the Participation Agreement, the Lease
and the Trust Agreement, at any time and from time to time without the consent
of the Indenture Trustee or of any Holder may:

                          (1)     so long as no Indenture Event of Default
         shall have occurred and be continuing, modify, amend or supplement the
         Lease, or give any consent, waiver, authorization or approval with
         respect thereto, except that without compliance with subsection (a) of
         this Section 11.06 (except as specifically provided below) the parties
         to the Lease shall not modify, amend or supplement, or give any
         consent, waiver, authorization or approval for the purpose of adding
         any provisions to or changing in any manner or eliminating any of the
         provisions thereof or of modifying in any manner the rights of the
         respective parties thereunder, with respect to the following
         provisions of the Lease as originally executed:  Sections 2, 3.1, 3.2
         (if the result thereof would be to shorten the Term of the Lease to a
         period shorter than the period ending with the final Principal Payment
         Date, Installment Date or Maturity Date of the Certificates), 3.3,
         3.4, 3.5 (except to the extent such Section relates to Excluded
         Payments and amounts payable to the Indenture Trustee in its
         individual capacity), 3.6 (except insofar as it relates to the address
         or account information of the Owner Trustee or the Indenture Trustee),
         4, 5 (but only insofar as





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -48-
   54
         it relates to return condition upon termination of the Lease pursuant
         to Section 15), 6, 7 (except that further restrictions may be imposed
         on the Company), 9, 10 (except that additional requirements may be
         imposed on the Company), 11 (except for Section 11.6 insofar as such
         Section relates to the Owner Participant and the Lessor and except
         that additional insurance requirements may be imposed on the Company),
         12 (except in order to increase the Company's liabilities or enhance
         the Lessor's rights thereunder), 13 (except in the case of an
         assignment by the Lessor in circumstances where the Aircraft shall
         remain registrable under the Federal Aviation Act), 14 (except to
         impose additional or more stringent Lease Events of Default), 15
         (except to impose additional remedies), 16, 17, 18.2(b) (except to
         impose additional requirements on the Company), 19, 20, 21 and 22, and
         (i) any definition of terms used in the Lease, to the extent that any
         modification of such definition would result in a modification of the
         Lease not permitted pursuant to this subsection (b) and (ii) any other
         provision of the Lease not hereinabove referred to if the
         modification, amendment or supplement thereto, or consent, waiver,
         authorization or approval in respect thereof would adversely affect
         the Indenture Trustee's interest in the Trust Estate, reduce Lessee's
         obligations in respect of maintaining the Aircraft or otherwise impair
         the value of the Trust Estate; provided, that in the event an
         Indenture Event of Default shall have occurred and be continuing, the
         Indenture Trustee shall have all rights of the Owner Trustee as Lessor
         under the Lease to modify, amend or supplement the Lease or give any
         consent, waiver, authorization or approval thereunder, for any
         purpose, including, adding any provisions to or changing in any manner
         or eliminating any of the provisions thereof or of modifying in any
         manner the rights of the Lessor thereunder; provided, further, that
         without the prior consent of the Owner Trustee, and whether or not an
         Indenture Event of Default shall have occurred and be continuing, no
         such action shall be taken with respect to any of the provisions of
         Sections 1 (to the extent any modification of a definition contained
         therein would result in a modification of the Lease not permitted by
         this proviso), 3.7, 4, 5 (to the extent not related to return upon
         termination of the Lease pursuant to Section 15 of the Lease), 6 (to
         the extent such action would reduce the Company's obligations), 7, 8,
         9, 10, 11, 12, 13, 14, 15, 16 (insofar as it relates to the Lessor),
         18, 19, 20, 21 and 22 of the Lease, or any other Section of the Lease
         to the extent such action shall affect the amount or timing of any
         amounts payable by the Company under the Lease as originally executed
         (or as subsequently modified with the consent of the Owner Trustee)
         which, absent the occurrence and continuance of an Indenture Event of
         Default, will be distributable to the Owner Trustee under Article 3;
         and provided, further, that the parties to the Lease may take any such
         action without the consent of the Indenture Trustee or any Holder to
         the extent such action relates to the payment of amounts constituting,
         or the Owner Trustee's, the Owner Participant's or the Company's
         rights or obligations with respect to, Excluded Payments;

                          (2)     modify, amend or supplement the Trust
         Agreement, or give any consent, waiver, authorization or approval with
         respect thereto, in each case only to the extent any such action shall
         not adversely affect the interests of the Holders;

                          (3)     modify, amend or supplement the Participation
         Agreement, or give any consent, waiver authorization or approval with
         respect thereto, except that without compliance with subsection (a) of
         this Section 11.06 the parties to the Participation Agreement shall
         not modify, amend or supplement, or give any consent, waiver,
         authorization or approval for the purpose of adding any provisions to
         or changing in any manner or eliminating any of the provisions thereof
         or of modifying in any manner the rights of the respective parties
         thereunder, with respect to the following provisions of the
         Participation Agreement as originally executed:





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -49-
   55
         Sections 1(b), 7 (insofar as such Section 7 relates to the Indenture
         Trustee and the Holders), 8, 11, 13, 17, and 19 and (i) any definition
         of terms used in the Participation Agreement, to the extent that any
         modification of such definition would result in a modification of the
         Participation Agreement not permitted pursuant to this subsection (b)
         and (ii) any other provision of the Participation Agreement not
         hereinabove referred to if the modification, amendment or supplement
         thereto, or consent, authorization or approval in respect thereof
         would adversely affect the Indenture Trustee's interest in the Trust
         Estate or otherwise impair the value of the Trust Estate; and

                          (4)     modify, amend or supplement any of said
         agreements in order to cure any ambiguity, to correct or supplement
         any provisions thereof which may be defective or inconsistent with any
         other provision thereof or of any provision of this Indenture, or to
         make any other provision with respect to matters or questions arising
         thereunder or under this Agreement which shall not be inconsistent
         with the provisions of this Agreement, provided the making of any such
         other provision shall not adversely affect the interests of the
         Holders.

                 (c)      No modification, amendment, supplement, consent,
waiver, authorization or approval with respect to the Lease or the
Participation Agreement, whether effected pursuant to subsection (a) or
pursuant to subsection (b) of this Section 11.06 and anything in such
subsections or elsewhere in this Agreement to the contrary notwithstanding,
shall, without the consent of the holder of each Outstanding Certificate
affected thereby,

                          (1)     modify, amend or supplement the Lease in such
         a way as to extend the time of, or the manner of making any, payment
         of any Basic Rent, or Stipulated Loss Value or any other amounts
         payable to the Indenture Trustee for its own account or for the
         account of the Holders (subject in any event to the last paragraph of
         Section 3.3 of the Lease) upon the occurrence of an Event of Loss or
         Termination Value and any other amounts payable to the Indenture
         Trustee for its own account or for the account of the Holders (subject
         in any event to the last paragraph of Section 3.3 of the Lease) upon
         termination of the Lease with respect to the Aircraft, payable under,
         or as provided in, the Lease as originally executed, or reduce the
         amount of any installment of any Basic Rent or Supplemental Rent so
         that the same is less than the payment of principal of, Premium, if
         any, and interest on the Certificates, as the case may be, to be made
         from such installment of any Basic Rent or Supplemental Rent, or
         reduce the aggregate amount of Stipulated Loss Value, or any other
         amounts payable under, or as provided in, the Lease as originally
         executed upon the occurrence of an Event of Loss so that the same is
         less than the accrued interest on and the principal as of the Lease
         Loss Payment Date, of the Certificates at the time Outstanding or
         reduce the amount of Termination Value or Special Purchase Price and
         any other amounts payable under, or as provided in, the Lease as
         originally executed upon termination of the Lease so that the same is
         less than the accrued interest on and principal as of the date of any
         such termination and Premium, if any, of Certificates at the time
         Outstanding, or

                          (2)     modify, amend or supplement the Lease in such
         a way as to, or consent to any assignment of the Lease or give any
         consent, waiver, authorization or approval which would, release the
         Company from its obligations in respect of payment of Basic Rent or
         Supplemental Rent, or Stipulated Loss Value and any other amounts
         payable to the Indenture Trustee for its own account or the account of
         the Holders (subject in any event to the last paragraph of Section 3.3
         of the Lease) upon the occurrence of any Event of Loss, or Termination





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -50-
   56
         Value or Special Purchase Price and any other amounts payable to the
         Indenture Trustee for its own account or the account of the Holders
         (subject in any event to the last paragraph of Section 3.3 of the
         Lease), payable under, or as provided in, the Lease as originally
         executed, and except as provided in the Lease as originally executed.

                 SECTION 11.07.   TRUST SUPPLEMENT.         The Owner Trustee
and the Indenture Trustee hereby confirm and agree that upon execution and
delivery of any Trust Supplement covering the Aircraft by the Owner Trustee
substantially in the form attached hereto as Exhibit C or any trust supplement
covering a sublease of the Aircraft, this Agreement shall be supplemented by
such Trust Supplement or such trust supplement without further action by the
Owner Trustee or Indenture Trustee.

                                   ARTICLE 12

                                 MISCELLANEOUS

                 SECTION 12.01.   NOTICES.         (a) Unless otherwise
specifically provided herein, all notices required under the terms and
provisions of this Agreement shall be in English and in writing, and any such
notice may be given by courier service, telegram, telex, telemessage, telecopy,
telefax, cable or facsimile (confirmed by telephone or in writing in the case
of notice by telegram, telex, telemessage, telecopy, telefax, cable or
facsimile) or any other customary means of written communication, and any such
notice shall be effective when delivered,

                 if to the Indenture Trustee, to:

                          Wilmington Trust Company
                          Rodney Square North
                          1100 North Market Street
                          Wilmington, Delaware 19890-0001

                          Attention:  Corporate Trust Administration

                          Telex:  835437 WILM TR
                          Facsimile:  (302) 651-8882
                          Telephone:  (302) 651-1000

                 if to the Owner Trustee, to:

                          First Union National Bank of North Carolina
                          230 South Tryon Street, 9th Floor
                          Charlotte, North Carolina 28288-1179

                          Attention:  Bond Administration

                          Telex: 684-3115 CHA FUN
                          Facsimile:  (704) 383-7316
                          Telephone:  (704) 383-5272

or if to any other Person, addressed to such Person as provided in the
Participation Agreement.





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -51-
   57
                 (b)      The Company, the Owner Trustee, the Indenture
Trustee, or the Owner Participant by notice to the others may designate
additional or different addresses for subsequent notices or communications.

                 (c)      Any notice or communication to Holders of the Series
SWA 1996 Trust N625SW Certificates shall be mailed by first-class mail to the
addresses for Holders shown on the Register kept by the Registrar and to
addresses filed with the Indenture Trustee for other Holders.  Failure so to
mail a notice or communication or any defect in such notice or communication
shall not affect its sufficiency with respect to other Holders of such
Certificates of that or any other series entitled to receive notice.

                 (d)      If a notice or communication is mailed in the manner
provided above within the time prescribed, it is conclusively presumed to have
been duly given, whether or not the addressee receives it.

                 (e)      Notwithstanding the foregoing, all communications or
notices to the Indenture Trustee shall be deemed to be given only when received
by a Responsible Officer of the Indenture Trustee.

                 SECTION 12.02.   [RESERVED FOR POTENTIAL FUTURE USE]

                 SECTION 12.03.   [RESERVED FOR POTENTIAL FUTURE USE]

                 SECTION 12.04.   RULES BY INDENTURE TRUSTEE AND AGENTS.
The Indenture Trustee may make reasonable rules for action by or a meeting of
the Holders.  The Paying Agent or Registrar may make reasonable rules and set
reasonable requirements for its functions.

                 SECTION 12.05.   NON-BUSINESS DAYS.        If a payment date
is not a Business Day at a place of payment, payment may be made at such place
on the next succeeding day that is a Business Day, and no interest shall accrue
for the intervening period.

                 SECTION 12.06.   GOVERNING LAW.    THIS AGREEMENT AND THE
CERTIFICATES SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF
THE STATE OF NEW YORK.

                 SECTION 12.07.   NO RECOURSE AGAINST OTHERS.       No
director, officer, employee or stockholder, as such, of the Company, the Owner
Trustee or the Owner Participant, as the case may be, shall have any liability
for any obligations of the Company, the Owner Trustee or the Owner Participant,
as the case may be, under this Agreement or for any claim based on, in respect
of or by reason of such obligations or their creation.  Each Holder by
accepting a Certificate waives and releases all such liability.  The waiver and
release are part of the consideration for the issue of the Certificates.

                 SECTION 12.08.   EXECUTION IN COUNTERPARTS.        This
Agreement may be executed in any number of counterparts, each of which shall be
an original, but such counterparts shall together constitute but one
instrument.

                 SECTION 12.09.   [RESERVED FOR POTENTIAL FUTURE USE].





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -52-
   58
                 SECTION 12.10.   SEVERABILITY.    Any provision of this
Indenture which is prohibited or unenforceable in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining provisions hereof, and any
such prohibition or unenforceability in any jurisdiction shall not invalidate
or render unenforceable such provision in any other jurisdiction.

                                   ARTICLE 13

                 ACTIONS TO BE TAKEN UPON TERMINATION OF LEASE

                 SECTION 13.01.   ACTIONS TO BE TAKEN UPON TERMINATION OF
LEASE. Upon any of:

                 (a)      the voluntary termination of the Lease by the Company
pursuant to Section 9 thereof on the Lease Termination Date, and upon payment
to the Indenture Trustee of an amount equal to the Redemption Price of all
Outstanding Certificates, or

                 (b)      the purchase of the Aircraft by the Company at its
option pursuant to Section 18.2 of the Lease on the Special Purchase Option
Date (unless the Company shall have elected to assume all of the rights and
obligations of the Owner Trustee hereunder as provided for in Section 8(r) of
the Participation Agreement), and upon payment to the Indenture Trustee of an
amount equal to the Redemption Price as at the applicable Redemption Date of
all Outstanding Certificates, or

                 (c)      the termination of the Lease, on the Lease Loss
Payment Date, following an Event of Loss suffered by the Airframe under
circumstances where the Company does not exercise its option to substitute a
Replacement Airframe therefor pursuant to Section 10.1.2 of the Lease, and upon
payment to the Indenture Trustee of an amount equal to the Redemption Price as
at the Redemption Date of all Outstanding Certificates, or

                 (d)      the satisfaction, discharge, defeasance and
termination of obligations under this Agreement in accordance with Section
10.01, the Lien of this Agreement on the Indenture Estate shall terminate
(except for the Lien on funds held by the Indenture Trustee to pay the
Certificates and the Lien on amounts due from the Company under the Lease
necessary to pay the Certificates or the Indenture Trustee) and the Indenture
Trustee shall execute such instruments as may be requested by the Company or
the Owner Trustee to evidence such termination (at the Company's or the Owner
Trustee's expense).





                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -53-
   59
                 IN WITNESS WHEREOF, the Owner Trustee and the Indenture
Trustee have caused this Indenture to be duly executed by their respective
officers thereunto duly authorized, as of the day and year first above written.

                                        FIRST UNION NATIONAL BANK OF NORTH
                                        CAROLINA, in its individual capacity
                                        only as expressly provided herein 
                                        and otherwise solely as Owner Trustee


                                        By:
                                           -------------------------------------
                                           Corporate Trust Officer


                                        WILMINGTON TRUST COMPANY, not in its
                                        individual capacity, except as
                                        otherwise expressly provided herein, 
                                        but solely as Indenture Trustee




                                        By:
                                           -------------------------------------
                                        Title:
                                              ----------------------------------


                TRUST INDENTURE AND SECURITY AGREEMENT [N625SW]
                                      -54-
   60


                                              Exhibit A-1 to Trust Indenture and
                                                              Security Agreement

         Form of Series SWA 1996 Trust N625SW Installment Certificates

$                                                               No.
 ------------------                                                -------------

                                             Dated as of ______________ __, 199_


                    SERIES SWA 1996 TRUST N625SW CERTIFICATE

                  FIRST UNION NATIONAL BANK OF NORTH CAROLINA,
                        Not in its Individual Capacity,
                          but Solely as Owner Trustee
                           Under the Trust Agreement
                           Dated as of August 1, 1996

                   Issued in connection with Aircraft N625SW
                                   Leased to
                             SOUTHWEST AIRLINES CO.

INTEREST RATE                                                      MATURITY DATE
                                                                        
- ---------------------                                                     , 2
                                                             -------------   ---


         FIRST UNION NATIONAL BANK OF NORTH CAROLINA, not in its individual
capacity, but solely as owner trustee (the "Owner Trustee") under that certain
Trust Agreement dated as of August 1, 1996, between the Owner Trustee in its
individual capacity and the institution referred to therein as the "Owner
Participant" relating to the Aircraft (herein as such Trust Agreement may be
amended or supplemented from time to time called the "Trust Agreement"), for
value received, hereby promises to pay to ________________ or registered
assigns the principal sum of ________________ Dollars in installments on each
Installment Payment Date as set forth herein with the final installment due and
payable on the Maturity Date specified above and to pay interest on the
principal amount remaining unpaid from time to time at the rate per annum
specified above from ________________, 1996 or from the most recent date to
which interest has been paid or duly provided for, semiannually, on
_____________ and _______ in each year, commencing ____________________, 1996,
until the principal hereof is paid or made available for payment in full. All
amounts payable by the Owner Trustee hereunder and under the Trust Indenture
and Security Agreement dated as of August 1, 1996, as supplemented (as amended
or supplemented from time to time referred to herein as the "Indenture", the
defined terms therein not otherwise defined herein being used herein with the
same meanings), by and among the Owner Trustee and Wilmington Trust Company, as
Indenture Trustee thereunder, shall be made only from the income and proceeds
of the Indenture Estate and the other amounts referred to in Section 3.03 of
the Indenture.  Each Holder hereof, by its acceptance of this Certificate,
agrees that (a) it will look solely to the income and proceeds of the Indenture
Estate and the other amounts referred to in Section 3.03 of the Indenture for
payment of such amounts, to the extent available for distribution to the Holder
hereof as provided in the Indenture and (b) neither the Owner Trustee, the
Owner Participant nor the Indenture Trustee is or shall be personally





   61
liable to the Holder hereof for any amount payable hereunder or under the
Indenture or, except as provided in the Indenture, for any liability under the
Indenture.

         Any amount of interest or principal (including any Installment Payment
Amount) payable hereunder which is not paid when due shall, to the maximum
extent permitted by law, bear interest from the due date thereof until the date
of payment at an interest rate equal to the interest rate specified above plus
2% per annum.  Any other amounts payable to the Holder hereof hereunder
(including, without limitation, Premium) or under the Indenture which is not
paid when due shall bear interest from the due date thereof, until the date of
payment at an interest rate equal to the Overdue Rate.  All computations of
interest hereunder shall be calculated on the basis of a year of twelve 30-day
months.

         The interest or Installment Payment Amount (other than that payable on
the Maturity Date hereof) so payable, and punctually paid or duly provided for,
on the applicable Interest Payment Date or Installment Payment Date, as the
case may be, will, as provided in the Indenture, be paid to the Person in whose
name this Certificate (or one or more predecessor Certificates) is registered
at the close of business on the Record Date for payment of such interest or
Installment Payment Amount, which shall be the fifteenth day (whether or not a
Business Day) next preceding such Interest Payment Date or Installment Payment
Date, as the case may be.  Any such interest or Installment Payment Amount not
so punctually paid or duly provided for shall forthwith cease to be payable to
the registered Holder hereof on such Record Date (or to the Person in whose
name this Certificate is registered upon issuance) and may be paid to the
Person in whose name this Certificate (or one or more predecessor Certificates)
is registered at the close of business on a Special Record Date for the payment
of such Defaulted Installment or Defaulted Interest to be fixed by the
Indenture Trustee, notice whereof shall be given to Holders of Certificates
entitled thereto not less than 10 days prior to such Special Record Date, or
may be paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Certificates may be
listed, and upon such notice as may be required by such exchange, all as more
fully provided in the Indenture.

         Payment of the principal of, Premium, if any, and interest on this
Certificate will be made at the principal corporate trust office of the
Indenture Trustee, or the office or agency maintained by the Indenture Trustee
for such purpose, in such coin or currency of the United States of America as
at the time of payment is legal tender for payment of public and private debts;
provided, however, that payment of interest and Installment Payments Amounts
(other than that payable on the Maturity Date hereof) may be made at the option
of the Indenture Trustee or the Paying Agent by check mailed on or before the
due date to the address of the Holder entitled thereto as such address shall
appear on the Register.

         This Certificate shall not be entitled to any benefit under the
Indenture or be valid or obligatory for any purpose unless this Certificate has
been executed on behalf of the Owner Trustee by the manual or facsimile
signature of an authorized officer of the Owner Trustee, and authenticated by
the Indenture Trustee by the manual signature of an authorized officer or
signatory of the Indenture Trustee, in each case as specified in Section 2.02
of the Indenture.

         Reference is made to the Indenture and all supplements and amendments
thereto (a copy of which is on file with the Indenture Trustee at its principal
corporate trust office) for a more complete statement of the terms and
provisions thereof, including a statement of the properties thereby conveyed,
pledged and assigned, the nature and extent of the security, the respective
rights thereunder of the Owner Trustee, the Indenture Trustee and the Holders
of the Certificates, the terms upon which the Certificates are, and are to be,
executed and delivered, the terms upon which the Certificates may be redeemed,
as well as





                                    A-1-2
   62
for a statement of the terms and conditions of the trust created by the
Indenture, to all of which terms and conditions in the Indenture each Holder
hereof agrees by its acceptance of this Certificate.

         On each Installment Payment Date, the Holder hereof will receive a
payment of principal equal to the Installment Payment Percentage for such
Installment Payment Date multiplied by the initial principal amount of this
Certificate which is set forth herein.



                 Installment                          Installment           
                   Payment                              Payment             
                     Date                              Percentage            
                 -----------                          -----------           
                                                                    
             ___________, _____                           ______%            
                                                                             
             ___________, _____                           ______%            
                                                                             
             ___________, _____                           ______%            
                                                                             
             ___________, _____                           ______%            


         As more fully provided in the Indenture, the Certificates are subject
to redemption on not less than 30 nor more than 60 days' notice by mail, under
the circumstances set forth in the Indenture, at a Redemption Price equal to
the unpaid principal amount thereof, Premium, if any, plus accrued interest
thereon to the Redemption Date.

         If an Indenture Event of Default shall occur and be continuing, the
principal amount remaining unpaid of the Certificates may be declared due and
payable in the manner and with the effect provided in the Indenture. If, and
only if, such an Indenture Event of Default constitutes a Lease Event of
Default by the Company under the Lease, the Indenture Trustee may, to the
exclusion of the Owner Trustee, exercise one or more of the remedies of the
Owner Trustee provided in the Lease. Such remedies include (but are not limited
to) the right to repossess and use or operate the Aircraft, to sell or relet
the Aircraft free and clear of the Company's rights and retain the proceeds and
to require the Company to pay as liquidated damages (i) any unpaid Basic Rent
plus an amount equal to the excess of the Stipulated Loss Value of the Aircraft
over the aggregate fair market rental value thereof for the remainder of the
term for the Aircraft, (ii) any unpaid Basic Rent plus the excess of the
Stipulated Loss Value of the Aircraft over the fair market sales value thereof
or (iii) if the Aircraft has been sold, any unpaid Basic Rent plus the excess
of the Stipulated Loss Value thereof over the net sales proceeds.

         By acceptance of this Certificate, the Holder hereof agrees to be
bound by the provisions of the Participation Agreement applicable to Holders.

         The Owner Trustee or the Owner Participant may cure any default by the
Company under the Lease arising from the failure of the Company to make any
payment of Basic Rent under the Lease, provided, that such failure of the
Company is not the third consecutive such failure, or the fifth or subsequent
cumulative such failure. The Owner Trustee or the Owner Participant may (but
need not) cure any other default by the Company in the performance of its
obligations under the Lease which can be cured by the payment of money, by
making such payment on behalf of the Company, subject, however, to certain
limitations.





                                     A-1-3
   63
         The right of the Holder of this Certificate to institute action for
any remedy under the Indenture, including the enforcement of payment of any
amount due hereon, is subject to certain restrictions specified in the
Indenture.

         The Owner Trustee and the Indenture Trustee will be discharged from
their respective obligations in respect of the Certificates (except for certain
matters, including obligations to register the transfer or exchange of
Certificates, replace stolen, lost or mutilated Certificates, maintain paying
agencies and hold money for payment in trust), and the Indenture Trustee may
thereupon cause the release of the Indenture Estate from the lien of the
Indenture, if (a) the Owner Trustee deposits or causes to be deposited
irrevocably with the Indenture Trustee, in trust, money or Government
Obligations which through the payment of interest and principal in respect
thereof in accordance with their terms will provide money in an amount
sufficient to pay principal of, Premium, if any, and interest on the
Outstanding Certificates on the dates such payments are due in accordance with
the terms of such Certificates and (b) certain other conditions are satisfied,
including the publication by the United States Internal Revenue Service of a
ruling to the effect that the deposit and related defeasance would not cause
the Holders of the Certificates to recognize income, gain or loss for Federal
income tax purposes.

         As provided in the Indenture and subject to certain limitations
therein set forth, this Certificate is transferable, and upon surrender of this
Certificate for registration of transfer at the principal corporate trust
office of the Registrar, or at the office or agency maintained for such
purpose, duly endorsed by, or accompanied by a written instrument of transfer
in form satisfactory to the Registrar duly executed by, the Holder or his
attorney duly authorized in writing, one or more new Certificates of the same
maturity and type and of authorized denominations and for the same aggregate
principal amount will be issued to the designated transferee or transferees.

         The Certificates are issuable only as registered Certificates.  The
Certificates are issuable in denominations of $1,000 and integral multiples
thereof.  As provided in the Indenture and subject to certain limitations
therein set forth, Certificates are exchangeable for a like aggregate principal
amount of Certificates of the same maturity and type and of authorized
denominations, as requested by the Holder surrendering the same, upon
presentation thereof for such purpose at the principal corporate trust office
of the Registrar, or at an office or agency maintained for such purpose.

         No service charge shall be made for any such registration of transfer
or exchange, but the Registrar may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment for registration of transfer of this
Certificate, the Owner Trustee, the Indenture Trustee, the Paying Agent, the
Registrar, the Owner Participant and the Company may deem and treat the Person
in whose name this Certificate is registered as the absolute owner hereof for
the purpose of receiving payment of the principal of and interest on this
Certificate and for all other purposes whatsoever whether or not this
Certificate be overdue, and neither the Owner Trustee, the Indenture Trustee,
the Paying Agent, the Registrar, the Owner Participant nor the Company shall be
affected by notice to the contrary.

         AS PROVIDED IN THE INDENTURE, THE INDENTURE AND THIS CERTIFICATE SHALL
BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW
YORK.

                                   *   *   *





                                     A-1-4
   64
         IN WITNESS WHEREOF, the Owner Trustee has caused this instrument to be
duly executed under its corporate seal.


                                        FIRST UNION NATIONAL
                                        BANK OF NORTH CAROLINA,
                                        not in its individual capacity, but
                                        solely as Owner Trustee


                                        By:
                                           -------------------------------------
                                        Title:
                                              ----------------------------------

Issue Date:





                                     A-1-5
   65
               INDENTURE TRUSTEE'S CERTIFICATE OF AUTHENTICATION


 This is one of the Certificates referred to in the within-mentioned Indenture.


                                        WILMINGTON TRUST COMPANY,
                                        not in its individual capacity, but
                                        solely as Indenture Trustee


                                        By:
                                           -------------------------------------
                                           Authorized officer or signatory





                                     A-1-6
   66
                                                                  Exhibit A-2 to
                                                             Trust Indenture and
                                                              Security Agreement

            Form of Series SWA 1996 Trust N625SW Serial Certificates

$                                                               No.
 ------------------                                                -------------


                                         Dated as of __________________ __, 199_


                    SERIES SWA 1996 TRUST N625SW CERTIFICATE

                  FIRST UNION NATIONAL BANK OF NORTH CAROLINA,
                        Not in its Individual Capacity,
                          but Solely as Owner Trustee
                           Under the Trust Agreement
                           Dated as of August 1, 1996

                   Issued in connection with Aircraft N625SW
                                   Leased to
                             SOUTHWEST AIRLINES CO.

INTEREST RATE                                                      MATURITY DATE
                                                                        
- ---------------------                                                     , 2
                                                             -------------   ---

                 FIRST UNION NATIONAL BANK OF NORTH CAROLINA, not in its
individual capacity, but solely as owner trustee (the "Owner Trustee") under
that certain Trust Agreement dated as of August 1, 1996 between the Owner
Trustee in its individual capacity and the institution referred to therein as
the "Owner Participant" relating to the Aircraft (herein as such Trust
Agreement may be amended or supplemented from time to time called the "Trust
Agreement"), for value received, hereby promises to pay to ________________ or
registered assigns the principal sum of ________________ Dollars on the
Maturity Date specified above and to pay interest thereon at the rate per annum
specified above from ________________, 1996 or from the most recent date to
which interest has been paid or duly provided for, semiannually, on
_______________________ and ___________________ in each year, commencing
______________________, 1996, until the principal hereof is paid or made
available for payment. All amounts payable by the Owner Trustee hereunder and
under the Trust Indenture and Security Agreement dated as of August 1, 1996, as
supplemented (as amended or supplemented from time to time referred to herein
as the "Indenture", the defined terms therein not otherwise defined herein
being used herein with the same meanings), by and among the Owner Trustee and
Wilmington Trust Company, as Indenture Trustee thereunder, shall be made only
from the income and proceeds of the Indenture Estate and the other amounts
referred to in Section 3.03 of the Indenture.  Each Holder hereof, by its
acceptance of this Certificate, agrees that (a) it will look solely to the
income and proceeds of the Indenture Estate and the other amounts referred to
in Section 3.03 of the Indenture for payment of such amounts, to the extent
available for distribution to the Holder hereof as provided in the Indenture
and (b) neither the Owner Trustee, the Owner Participant nor the Indenture
Trustee is or shall be personally liable to the Holder hereof for any amount
payable hereunder or under the Indenture or, except as provided in the
Indenture, for any liability under the Indenture.
   67
                 Any amount of interest or principal payable hereunder which is
not paid when due shall, to the maximum extent permitted by law, bear interest
from the due date thereof until the date of payment at an interest rate equal
to the interest rate specified above plus 2% per annum.  Any other amounts
payable to the Holder hereof hereunder (including, without limitation, Premium)
or under the Indenture which is not paid when due shall bear interest from the
due date thereof, until the date of payment at an interest rate equal to the
Overdue Rate.  All computations of interest hereunder shall be calculated on
the basis of a year of twelve 30-day months.

                 The interest so payable, and punctually paid or duly provided
for, on the applicable Interest Payment Date will, as provided in the
Indenture, be paid to the Person in whose name this Certificate (or one or more
predecessor Certificates) is registered at the close of business on the Record
Date for payment of such interest, which shall be the fifteenth day (whether or
not a Business Day) next preceding such Interest Payment Date. Any such
interest not so punctually paid or duly provided for shall forthwith cease to
be payable to the registered Holder hereof on the such Record Date (or to the
Person in whose name this Certificate is registered upon issuance) and may be
paid to the Person in whose name this Certificate (or one or more predecessor
Certificates) is registered at the close of business on a Special Record Date
for the payment of such Defaulted Interest to be fixed by the Indenture
Trustee, notice whereof shall be given to Holders of Certificates entitled
thereto not less than 10 days prior to such Special Record Date, or may be paid
at any time in any other lawful manner not inconsistent with the requirements
of any securities exchange on which the Certificates may be listed, and upon
such notice as may be required by such exchange, all as more fully provided in
the Indenture.

                 Payment of the principal of, Premium, if any, and interest on
this Certificate will be made at the principal corporate trust office of the
Indenture Trustee, or the office or agency maintained by the Indenture Trustee
for such purpose, in such coin or currency of the United States of America as
at the time of payment is legal tender for payment of public and private debts;
provided, however, that payment of interest may be made at the option of the
Indenture Trustee or the Paying Agent by check mailed on or before the due date
to the address of the Holder entitled thereto as such address shall appear on
the Register.

                 This Certificate shall not be entitled to any benefit under
the Indenture or be valid or obligatory for any purpose unless this Certificate
has been executed on behalf of the Owner Trustee by the manual or facsimile
signature of an authorized officer of the Owner Trustee, and authenticated by
the Indenture Trustee by the manual signature of an authorized officer or
signatory of the Indenture Trustee, in each case as specified in Section 2.02
of the Indenture.

                 Reference is made to the Indenture and all supplements and
amendments thereto (a copy of which is on file with the Indenture Trustee at
its principal corporate trust office) for a more complete statement of the
terms and provisions thereof, including a statement of the properties thereby
conveyed, pledged and assigned, the nature and extent of the security, the
respective rights thereunder of the Owner Trustee, the Indenture Trustee and
the Holders of the Certificates, the terms upon which the Certificates are, and
are to be, executed and delivered, the terms upon which the Certificates may be
redeemed, as well as for a statement of the terms and conditions of the trust
created by the Indenture, to all of which terms and conditions in the Indenture
each Holder hereof agrees by its acceptance of this Certificate.

                 As more fully provided in the Indenture, the Certificates are
subject to redemption on not less than 30 nor more than 60 days' notice by
mail, under the circumstances set forth in the Indenture, at a Redemption Price
equal to the unpaid principal amount thereof, Premium, if any, plus accrued
interest thereon to the Redemption Date.





                                     A-2-2
   68
                 If an Indenture Event of Default shall occur and be
continuing, the principal of the Certificates may be declared due and payable
in the manner and with the effect provided in the Indenture. If, and only if,
such an Indenture Event of Default constitutes a Lease Event of Default by the
Company under the Lease, the Indenture Trustee may, to the exclusion of the
Owner Trustee, exercise one or more of the remedies of the Owner Trustee
provided in the Lease. Such remedies include (but are not limited to) the right
to repossess and use or operate the Aircraft, to sell or relet the Aircraft
free and clear of the Company's rights and retain the proceeds and to require
the Company to pay as liquidated damages (i) any unpaid Basic Rent plus an
amount equal to the excess of the Stipulated Loss Value of the Aircraft over
the aggregate fair market rental value thereof for the remainder of the term
for the Aircraft, (ii) any unpaid Basic Rent plus the excess of the Stipulated
Loss Value of the Aircraft over the fair market sales value thereof or (iii) if
the Aircraft has been sold, any unpaid Basic Rent plus the excess of the
Stipulated Loss Value thereof over the net sales proceeds.

                 The Owner Trustee or the Owner Participant may cure any
default by the Company under the Lease arising from the failure of the Company
to make any payment of Basic Rent under the Lease, provided, that such failure
of the Company is not the third consecutive such failure, or the fifth or
subsequent cumulative such failure. The Owner Trustee or the Owner Participant
may (but need not) cure any other default by the Company in the performance of
its obligations under the Lease which can be cured by the payment of money, by
making such payment on behalf of the Company, subject, however, to certain
limitations.

                 The right of the Holder of this Certificate to institute
action for any remedy under the Indenture, including the enforcement of payment
of any amount due hereon, is subject to certain restrictions specified in the
Indenture.

                 By acceptance of this Certificate, the Holder hereof agrees to
be bound by the provisions of the Participation Agreement applicable to
Holders.

                 The Owner Trustee and the Indenture Trustee will be discharged
from their respective obligations in respect of the Certificates (except for
certain matters, including obligations to register the transfer or exchange of
Certificates, replace stolen, lost or mutilated Certificates, maintain paying
agencies and hold money for payment in trust), and the Indenture Trustee may
thereupon cause the release of the Indenture Estate from the lien of the
Indenture, if (a) the Owner Trustee deposits or causes to be deposited
irrevocably with the Indenture Trustee, in trust, money or Government
Obligations which through the payment of interest and principal in respect
thereof in accordance with their terms will provide money in an amount
sufficient to pay principal of, Premium, if any, and interest on the
Outstanding Certificates on the dates such payments are due in accordance with
the terms of such Certificates and (b) certain other conditions are satisfied,
including the publication by the United States Internal Revenue Service of a
ruling to the effect that the deposit and related defeasance would not cause
the Holders of the Certificates to recognize income, gain or loss for Federal
income tax purposes.

                 As provided in the Indenture and subject to certain
limitations therein set forth, this Certificate is transferable, and upon
surrender of this Certificate for registration of transfer at the principal
corporate trust office of the Registrar, or at the office or agency maintained
for such purpose, duly endorsed by, or accompanied by a written instrument of
transfer in form satisfactory to the Registrar duly executed by, the Holder or
his attorney duly authorized in writing, one or more new Certificates of the
same maturity and type and of authorized denominations and for the same
aggregate principal amount will be issued to the designated transferee or
transferees.





                                     A-2-3
   69
                 The Certificates are issuable only as registered Certificates.
The Certificates are issuable in denominations of $1,000 and integral multiples
thereof.  As provided in the Indenture and subject to certain limitations
therein set forth, Certificates are exchangeable for a like aggregate principal
amount of Certificates of the same maturity and type and of authorized
denominations, as requested by the Holder surrendering the same, upon
presentation thereof for such purpose at the principal corporate trust office
of the Registrar, or at an office or agency maintained for such purpose.

                 No service charge shall be made for any such registration of
transfer or exchange, but the Registrar may require payment of a sum sufficient
to cover any tax or other governmental charge payable in connection therewith.

                 Prior to due presentment for registration of transfer of this
Certificate, the Owner Trustee, the Indenture Trustee, the Paying Agent, the
Registrar, the Owner Participant and the Company may deem and treat the Person
in whose name this Certificate is registered as the absolute owner hereof for
the purpose of receiving payment of the principal of and interest on this
Certificate and for all other purposes whatsoever whether or not this
Certificate be overdue, and neither the Owner Trustee, the Indenture Trustee,
the Paying Agent, the Registrar, the Owner Participant nor the Company shall be
affected by notice to the contrary.

                 AS PROVIDED IN THE INDENTURE, THE INDENTURE AND THIS
CERTIFICATE SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF
THE STATE OF NEW YORK.


                                   *   *   *





                                     A-2-4
   70
                 IN WITNESS WHEREOF, the Owner Trustee has caused this
instrument to be duly executed under its corporate seal.


                                        FIRST UNION NATIONAL BANK
                                        OF NORTH CAROLINA,
                                        not in its individual capacity, but
                                        solely as Owner Trustee


                                        By:
                                           -------------------------------------
                                        Title:
                                              ----------------------------------
Issue Date:





                                     A-2-5
   71
               INDENTURE TRUSTEE'S CERTIFICATE OF AUTHENTICATION


 This is one of the Certificates referred to in the within-mentioned Indenture.


                                        WILMINGTON TRUST COMPANY,
                                        not in its individual capacity, but
                                        solely as Indenture Trustee


                                        By: 
                                           -------------------------------------
                                           Authorized officer or signatory





                                     A-2-6
   72
                                                                    Exhibit B to
                                                             Trust Indenture and
                                                              Security Agreement


Maturity Dates, Principal Amounts and
Interest Rates of Series SWA 1996 Trust N625SW Certificates



                                                                                                  Premium
                                   Principal                                                    Termination
Maturity Date                       Amount                    Interest Rate                         Date    
- -------------                      --------                   -------------                     ------------
                                                                                       







[To be completed at time of issuance of Series SWA 1996 Trust N625SW
Certificates, if any shall be issued hereunder.]
   73
                                                                  Exhibit B-1 to
                                                             Trust Indenture and
                                                              Security Agreement


         Installment Payment Dates and Installment Payment Percentages


Installment Certificates shall be those
Certificates with the following Maturity Dates:

Installment Certificate No. 1 - Maturity Date:
                                              ------------------



      Installment Payment                   Installment Payment                   Aggregate Installment
      -------------------                   -------------------                   ---------------------
              Date                              Percentage                           Payment Amount
              ----                              ----------                           --------------
                                                                                




[To be completed at time of issuance of Series SWA 1996 Trust N625SW
Certificates, if any shall be issued hereunder.]


                                                                              
             TOTAL                             100.00000000                         ________________



Installment Certificate No. 2 - Maturity Date: 
                                              ----------------------------




      Installment Payment                   Installment Payment                   Aggregate Installment
      -------------------                   -------------------                   ---------------------
              Date                              Percentage                           Payment Amount
              ----                              ----------                           --------------
                                                                               




[To be completed at time of issuance of Series SWA 1996 Trust N625SW
Certificates, if any shall be issued hereunder.]



                                                                              
             TOTAL                             100.00000000                         ________________

   74
                                                                  Exhibit B-2 to
                                                             Trust Indenture and
                                                              Security Agreement



             Issuance of Series SWA 1996 Trust N625SW Certificates


                 The Series SWA 1996 Trust N625SW Certificates issued hereunder
shall be issued to and shall be payable to the Pass Through Trustee under each
Pass Through Trust Agreement with respect to the grantor trust created thereby,
in each case as set forth below:

                                 1996-A1 Trust:
                     7.67% Certificate due January 2, 2014

                                 1996-A2 Trust:
                       8.00% Certificate due July 2, 2019





                                      B-2
   75
                                                                    Exhibit C to
                                                             Trust Indenture and
                                                              Security Agreement

                                   [FORM OF]
                    TRUST AGREEMENT AND TRUST INDENTURE AND
                         SECURITY AGREEMENT SUPPLEMENT


                 This TRUST AGREEMENT AND TRUST INDENTURE AND SECURITY
AGREEMENT SUPPLEMENT, is dated ____________, 1996 (herein called the
"Supplement") of FIRST UNION NATIONAL BANK OF NORTH CAROLINA, not in its
individual capacity, but solely as Owner Trustee (herein called the "Owner
Trustee"), under the Trust Agreement, dated as of August 1, 1996 (herein called
the "Trust Agreement"), between the Owner Trustee and the Owner Participant
named therein,

                                  WITNESSETH:

                 WHEREAS, the Trust Agreement provides for the execution and
delivery of one or more supplements thereto substantially in the form hereof,
which shall particularly describe the Aircraft (such term and other terms
defined in the Trust Indenture referred to below, or in the Lease therein
referred to, being used herein as therein defined) included in the property
covered by the Trust Agreement;

                 WHEREAS, the Trust Indenture and Security Agreement, dated as
of August 1, 1996 (herein called the "Trust Indenture"), between the Owner
Trustee and Wilmington Trust Company, as Indenture Trustee (herein called the
"Indenture Trustee"), provides for the execution and delivery of a supplement
thereto substantially in the form hereof, which shall particularly describe the
Aircraft, and shall specifically mortgage such Aircraft to the Indenture
Trustee; and

                 WHEREAS, each of the Trust Agreement and Trust Indenture
relates to the Airframe and Engines described below, and a counterpart of the
Trust Indenture is attached hereto and made a part hereof and this Supplement,
together with such counterpart of the Trust Indenture, is being filed for
recordation on the date hereof with the Federal Aviation Administration as one
document;

                 NOW, THEREFORE, This Supplement Witnesseth, that, to secure
the prompt payment of the principal of, Premium, if any, and interest on, and
all other amounts due with respect to, all Certificates from time to time
Outstanding and all other amounts due to the Holders under the Trust Indenture
and the Participation Agreement and the performance and observance by each of
the Company and the Owner Trustee of all the agreements, covenants and
provisions in the Trust Indenture and in the other Operative Agreements for the
benefit of the Indenture Trustee and the Holders of the Certificates and in the
Certificates contained, and the prompt payment of all amounts from time to time
owing under the Operative Agreements to the Holders of the Certificates, and
for the uses and purposes of the Trust Indenture, and in consideration of the
premises and of the covenants contained in the Trust Indenture, and of the
acceptance of the Certificates by the Holders thereof, and of the sum of $1.00
paid to the Owner Trustee by the Indenture Trustee at or before the delivery
hereof, the receipt whereof is hereby acknowledged, the Owner Trustee has
granted, bargained, sold, assigned, transferred, conveyed, mortgaged, pledged
and confirmed, and does hereby grant, bargain, sell, assign, transfer, convey,
mortgage, pledge and confirm unto the Indenture Trustee, its successors and
assigns, for the security and benefit of the Holders from time to time of the
Certificates, upon the trusts created by the Trust
   76
Indenture, all right, title and interest of the Owner Trustee in, to and under
the following described property:

                                    AIRFRAME

                      One Airframe Identified as follows:



                                                                    FAA
                                                               Registration                Manufacturer's
         Manufacturer                    Model                    Number                    Serial Number 
         ------------                    -----                 ------------                ---------------
                                                                                       
The Boeing Company                      737-3H4                   N625SW                        27701


together with all Parts relating to such airframe.

                                AIRCRAFT ENGINES

                 Two aircraft engines, each such engine having 750 or more
rated take-off horsepower or the equivalent thereof, whether or not such
engines shall be installed in or attached to the Airframe or any other
airframe, identified as follows:



                                                                                           Manufacturer's
    Manufacturer                                    Model                                   Serial Number 
    ------------                                    -----                                  ---------------
                                                                                         
CFM International                                CFM56-3-B1                                    858329
CFM International                                CFM56-3-B1                                    859337


together with all Parts relating to such engines.

                 Together with all substitutions or replacements of and
additions, improvements, accessories and accumulations to the property above
described for which title vests in the Owner Trustee under the Operative
Agreements and all property which shall hereafter become physically attached to
or incorporated in the property above described, whether the same are now owned
by the Owner Trustee or shall hereafter be acquired by it for which title vests
in the Owner Trustee under the Operative Agreements.

                 As further security for the obligations referred to above and
secured by the Trust Indenture and hereby, the Owner Trustee has granted,
bargained, sold, assigned, transferred, conveyed, mortgaged, pledged and
confirmed, and does hereby grant, bargain, sell, assign, transfer, convey,
mortgage, pledge and confirm, unto the Indenture Trustee, its successors and
assigns, for the security and benefit of the Holders from time to time of the
Certificates, in the trust created by the Trust Indenture, all of the right,
title and interest of the Owner Trustee in, to and under the Lease Supplement
of even date herewith covering the property described above.

                 Notwithstanding any provision hereof, no Excluded Payment
shall constitute security for any of the aforementioned obligations.

                 TO HAVE AND TO HOLD all and singular the aforesaid property
unto the Indenture Trustee, its successors and assigns, in trust for the
benefit and security of the Holders from time to time




                                     C-2
   77
of the Certificates for the uses and purposes and subject to the terms and
provisions set forth in the Trust Indenture.

                 This Supplement shall be construed as supplemental to the
Trust Indenture and to the Trust Agreement and shall form a part of each, and
the Trust Agreement and the Trust Indenture are each hereby incorporated by
reference herein and each is hereby ratified, approved and confirmed.

                 AND, FURTHER, the Owner Trustee hereby acknowledges that the
Aircraft referred to in this Supplement and the aforesaid Lease Supplement has
been delivered to the Owner Trustee and is included in the property of the
Owner Trustee covered by all the terms and conditions of the Trust Agreement,
subject to the pledge and mortgage thereof under the Trust Indenture.

         THIS SUPPLEMENT IS BEING DELIVERED IN THE STATE OF NEW YORK AND SHALL
IN ALL RESPECTS BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF
THE STATE OF NEW YORK.





                                      C-3
   78
                 IN WITNESS WHEREOF, the Owner Trustee has caused this
Supplement to be duly executed by one of its officers, thereunto duly
authorized, on the day and year first above written.


                                        FIRST UNION NATIONAL
                                        BANK OF NORTH CAROLINA,
                                        not in its individual capacity, but
                                        solely as Owner Trustee


                                        By: 
                                           ------------------------------------

                                        Title:
                                              ---------------------------------




                                      C-4