EXHIBIT 10.6.8


            AMENDMENT NO. 4 TO SECURITY AGREEMENT AND CHATTEL MORTGAGE
                            (AIRCRAFT NO. N5O5MC)(1)

            THIS FOURTH AMENDMENT TO THE SECURITY AGREEMENT AND CHATTEL MORTGAGE
is dated as of May 31, 2005, (this "AMENDMENT"), and entered into by and between
Atlas  Freighter  Leasing III, Inc., a Delaware  corporation  ("BORROWER"),  and
Deutsche  Bank  Trust  Company  Americas,  as agent  for and  representative  of
("ADMINISTRATIVE  AGENT") the financial  institutions  ("LENDERS")  party to the
Amended and Restated Credit Agreement referred to below.

                              W I T N E S S E T H;

            WHEREAS,  Borrower is party to that certain Credit Agreement,  dated
as of April 25,  2000,  among  Borrower,  the  Lenders  from time to time  party
thereto and the Administrative  Agent (as amended,  modified and/or supplemented
to, but not including, the date hereof, the "CREDIT AGREEMENT").

            WHEREAS,  pursuant  to that  certain  Amended  and  Restated  Credit
Agreement,  dated as of July 27, 2004, among Borrower,  the Lenders from time to
time party thereto and the  Administrative  Agent (as amended,  modified  and/or
supplemented  from time to time, the "AMENDED AND RESTATED  CREDIT  AGREEMENT"),
Borrower has agreed to further amend and restate the Credit Agreement.

            WHEREAS,  Borrower and the Administrative  Agent are parties to that
certain  Security  Agreement  and Chattel  Mortgage  with  respect to one Boeing
747-2D3B,  U.S.  Registration  No. N5O5MC,  Manufacturer's  Serial Number 21251,
dated as of April 25, 2000, between the Borrower and the Agent,  recorded by the
Federal  Aviation  Administration  on May 24, 2000, as Conveyance No.  DD018943,
supplemented  by  Supplemental  Chattel  Mortgage No. 1 dated as of November 13,
2000,  recorded on December 20, 2000, as  Conveyance  No.  SS016138,  amended by
Amendment No. 1 to Security  Agreement and Chattel  Mortgage dated as of October
30r20(0)l,  recorded  January 9, 2002, as Conveyance  No.  SS018002,  amended by
Amendment No. 2 to Aircraft Chattel Mortgage dated as of June 14, 2002, recorded
August 21, 2002,  as  Conveyance  No.  YY034496,  amended by Amendment  No. 3 to
Security  Agreement  and Chattel  Mortgage  dated as of July 27, 2004,  recorded
August 24, 2004 as Conveyance No. NN027686 (the "AIRCRAFT CHATTEL MORTGAGE").

- ----------
(1) This  Amendment  to the  Security  Agreement  and Chattel  Mortgage has been
executed in several counterparts.  To the extent, if any, that this Amendment to
the Security Agreement and Chattel Mortgage  constitutes  chattel paper (as such
term is defined in the Uniform  Commercial  Code as in effect in any  applicable
jurisdiction),  no security interest in this Amendment to the Security Agreement
and Chattel  Mortgage may be created  through the transfer or  possession of any
counterpart  other than the original.  The counterpart to be deemed the original
shall be the counterpart that contains the receipt therefor executed by Deutsche
Bank Trust Company  Americas,  as  Administrative  Agent,  on the signature page
thereof and no security interest in this Amendment to the Security Agreement and
Chattel  Mortgage may be created through the transfer of any  counterpart  other
than said original counterpart.



            WHEREAS,  subject to the terms and conditions  set forth below,  the
parties hereto wish to amend certain provisions of the Aircraft Chattel Mortgage
as provided herein.

            NOW THEREFORE, it is agreed:

A. AMENDMENT TO AIRCRAFT CHATTEL MORTGAGE

      1. The proviso to Section  4(g)(ii) of the  Aircraft  Chattel  Mortgage is
hereby amended by (x) deleting the text "$50,000,000" appearing therein, and (y)
inserting the text "$15,000,000" in lieu thereof.

B. MISCELLANEOUS PROVISIONS

      1. This Amendment may be executed in any number of counterparts and by the
different parties hereto on separate  counterparts,  each of which  counterparts
when  executed  and  delivered  (including  by way of  facsimile  or  electronic
transmission)  shall be an original,  but all of which shall together constitute
one and the same instrument. A complete set of counterparts shall be lodged with
Borrower and the Administrative Agent.

      2. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES  HEREUNDER
SHALL BE  CONSTRUED IN  ACCORDANCE  WITH AND GOVERNED BY THE LAW OF THE STATE OF
NEW YORK.

      3. This  Amendment  is limited as  specified  and shall not  constitute  a
modification,  acceptance  or  waiver  of any other  provision  of the  Aircraft
Chattel Mortgage.

      4. From and after the date hereof,  all references in the Aircraft Chattel
Mortgage to the Aircraft  Chattel  Mortgage  shall be deemed to be references to
the Aircraft Chattel Mortgage as modified hereby.

                                      * * *


                                       -2-


            IN WITNESS WHEREOF, the undersigned have caused this Amendment to be
duly executed and delivered as of the date first above written.

                                              ATLAS FREIGHTER LEASING III, INC.


                                              By: /s/ William C. Bradley
                                                  ------------------------------
                                                  Name:  William C. Bradley
                                                  Title: Treasurer & Secretary

                                                              Mortgage Amendment
                                                                        (N505MC)



                                              DEUTSCHE BANK TRUST COMPANY
                                              AMERICAS, as Agent

                                              By: /s/ Mark B. Cohen
                                                  ------------------------------
                                                  Name:  Mark B. Cohen
                                                  Title: Managing Director


                                              By: /s/ Steven A. Cohen
                                                  ------------------------------
                                                  Name:  Steven A. Cohen
                                                  Title: Director

                                                              Mortgage Amendment
                                                                        (N505MC)



                           Schedule to Exhibit 10.6.8

The agreements listed below are substantially identical to this exhibit and are
not being filed separately as exhibits pursuant to instruction 2 to Regulation
S-K, Item 601.



- -------------------- ------------------------ ---------------- ------------------------- -----------------------------
REGISTRATION         MANUFACTURER'S SERIAL    AGENT            BORROWER                  AGREEMENT
NUMBER               NUMBER(S)
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------
                                                                             
N509MC               21221                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N509MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N512MC               21220                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N512MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N517MC               23300                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N517MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N522MC               21783                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N522MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N523MC               21782                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N523MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N524MC               21784                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N524MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N526MC               22337                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N526MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N527MC               22471                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N527MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N528MC               22472                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N528MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N534MC               21832                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N534MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N808MC               21048                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N808MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

N809MC               20887                    Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
                                              Trust Company    III                       Agreement (N809MC) dated as
                                              Americas                                   of May 31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

CF6-50E2 Spare       530168; 517530;          Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
Engines              517790; 517602;          Trust Company    III                       Agreement (CF6-50E2 Spare
                     517547; 517,538;         Americas                                   Engines) dated as of May
                     517,539; 455167; 530255                                             31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------

CF6-80C2 BSF Spare   704,699; 704860; 704918  Deutsche Bank    Atlas Freighter Leasing   Amendment No. 4 to Security
Engines                                       Trust Company    III                       Agreement (CF6-50E2 Spare
                                              Americas                                   Engines) dated as of May
                                                                                         31, 2005
- -------------------- ------------------------ ---------------- ------------------------- -----------------------------