Exhibit 4.13
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                        NEW NEXTLINK COMMUNICATIONS, INC.
                 (to be known as NEXTLINK Communications, Inc.)

                                       and

                     UNITED STATES TRUST COMPANY OF NEW YORK
                                     Trustee

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                                      FIRST
                             SUPPLEMENTAL INDENTURE
                            Dated as of June 3, 1998

                                    Amending

                                    INDENTURE
                            Dated as of April 1, 1998

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


                                  $636,974,000

                           9.45% Senior Discount Notes
                                    Due 2008

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          THIS FIRST SUPPLEMENTAL INDENTURE, dated as of June 3, 1998 (herein
called the "Supplement"), is between NEW NEXTLINK COMMUNICATIONS, INC., a
corporation organized and existing under the laws of the State of Delaware
(herein called the "Company"), having its principal office at 155 108th Avenue
N.E., 8th Floor, Bellevue, Washington 98004, and UNITED STATES TRUST COMPANY OF
NEW YORK, duly organized and existing under the laws of the State of New York,
as Trustee (herein called the "Trustee").

                             RECITALS OF THE COMPANY

          WHEREAS, pursuant to the terms of the Indenture, dated as of April 1,
1998 (the "Original Indenture"), between NEXTLINK Communications, Inc., a
corporation organized under the laws of the State of Washington, and the
Trustee, $636,974,000 principal amount of 9.45% Senior Discount Notes due 2008
(herein called the "Securities") were issued; and

          WHEREAS, pursuant to the terms of that certain Agreement and Plan of
Merger, dated as of May 29, 1998, by and among the Company and NEXTLINK-WA,
NEXTLINK-WA will be merged with and into the Company, with the Company as the
surviving corporation (the "Merger"); and

          WHEREAS, as a result of the Merger, the Company will change its name
to NEXTLINK Communications, Inc.; and

          WHEREAS, Section 901 of the Original Indenture provides for the
execution and delivery by the Company and, subject to the provisions of Section
903 of the Original Indenture, by the Trustee of one or more supplemental
indentures, without the consent of the Holders of the Securities, for the
purposes specified therein; and

          WHEREAS, pursuant to the provisions of Section 801 and assuming the
requirements of such Section are satisfied, NEXTLINK-WA is permitted to become a
Delaware corporation through a merger transaction in which NEXTLINK-WA is not
the surviving corporation, and under the Original Indenture, the Company and the
Trustee may enter into a supplemental indenture, "to evidence the succession of
another Person to the Company and the assumption by such successor of the
covenants of the Company contained in the Securities," which supplement,
pursuant to Section 901 of the Original Indenture, does not require the consent
of the Holders of the Securities; and

          WHEREAS, pursuant to the provisions of Section 801(b) the Company
wishes by this Supplemental Indenture to evidence its succession to NEXTLINK-WA
and its assumption of the covenants of NEXTLINK-WA contained in the Original
Indenture and the Securities and pursuant to the provisions of Section 802 the
Company shall succeed to, and be substituted for, and may exercise every right
and power of, NEXTLINK-WA under the Original Indenture; and

          WHEREAS, all things necessary to make this Supplement, when executed
and delivered by the Trustee, the valid agreement of the Company in accordance
with its terms have been done.

          NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:





          SECTION 101. Definitions. Except as otherwise expressly provided
herein, all capitalized words and terms used herein shall have the respective
meanings ascribed thereto in Article One of the Original Indenture.

          SECTION 102. Representations of the Company. The Company hereby
represents and warrants to the Trustee that as of the date hereof:

          (a) The Company is a corporation validly existing and in good standing
under the laws of the State of Delaware; and

          (b) no Default or Event of Default will result from the Merger or the
execution and delivery of this Supplement.

          SECTION 103. Assumption of Obligations. The Company hereby assumes all
of the obligations of NEXTLINK-WA in its capacity as the Company under the
Original Indenture.

          SECTION 104. Construction with Original Indenture. All of the
covenants, agreements and provisions of this Supplement shall be deemed to be
and construed as part of the Original Indenture and VICE VERSA to the same
extent as if fully set forth verbatim therein and herein and shall be fully
enforceable in the manner provided in the Original Indenture. Except as provided
in this Supplement, the Original Indenture shall remain in full force and effect
and the terms and conditions thereof are hereby confirmed.

          SECTION 105. Conflict with Trust Indenture Act. If any provision
hereof limits, qualifies or conflicts with a provision of the Trust Indenture
Act that is required under such Act to be part of and govern the Original
Indenture or this Supplement, the latter provision shall control. If any
provision hereof modifies or excludes any provision of the Trust Indenture Act
that may be so modified or excluded, the latter provision shall be deemed to
apply to this Supplement as so modified or to be excluded, as the case may be.

          SECTION 106. Effect of Headings. The Section headings herein are for
convenience only and shall not affect the construction hereof.

          SECTION 107. Separability Clause. In case any provision in this
Supplement shall be invalid, illegal or unenforceable, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby, it being intended that all of the provisions hereof shall
be enforceable to the full extent permitted by law.

          SECTION 108. Benefits of Supplement and Original Indenture. Nothing in
this Supplement or the Original Indenture or in the Securities, express or
implied, shall give to any Person other than the parties hereto and thereto and
their successors hereunder and thereunder and the Holders of Securities, any
benefit or any legal or equitable right, remedy or claim under this Supplement
or the Original Indenture. Neither this Supplement nor the Original Indenture
may be used to interpret another indenture, loan agreement or debt agreement of
the Company or 




any of their respective Subsidiaries. No such other indenture or loan or debt
agreement may be utilized to interpret this Supplement or the Original
Indenture.

          SECTION 109. GOVERNING LAW. THIS SUPPLEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

          SECTION 110. No Recourse Against Others. A director, member, managing
member officer, employee, stockholder or incorporator, as such, of the Company
shall not have any liability for any obligations of the Company under this
Supplement or for any claim based on, in respect or by reason of such
obligations or their creation.

          SECTION 111. Duplicate Originals. All parties may sign any number of
copies or counterparts of this Supplement. Each signed copy or counterpart shall
be an original, but all of them together shall represent the same agreement.

          SECTION 112. Effectiveness. This Supplement shall become effective in
accordance with the provisions of Article Nine of the Original Indenture.

          IN WITNESS WHEREOF, the parties hereto have caused this Supplement to
be duly executed as of the day and year first above written.

                                         NEW NEXTLINK COMMUNICATIONS, INC.

                                         By /s/ R. Bruce Easter, Jr.
                                            ------------------------
                                            Title: President

Attest:

/s/ Richard A. Montfort, Jr.
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Name: Richard A. Montfort, Jr.
Title: counsel






                                         UNITED STATES TRUST COMPANY
                                         OF NEW YORK, Trustee

                                         By /s/ Patricia Stermer
                                            --------------------
                                            Title: Asst. Vice President

Attest:

/s/ Sirojni Dihdial
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Name: Sirojni Dihdial
Title: Asst. Secretary



STATE OF WASHINGTON        )
                           )ss.:
COUNTY OF KING             )

          On the 2nd day of June, 1998, before me personally came R. BRUCE
EASTER, JR., to me known, who, being by me duly sworn, did depose and say that
he is the President of NEW NEXTLINK COMMUNICATIONS, INC., a Delaware
corporation, one of the corporations described in and which executed the
foregoing instrument, and duly acknowledged to me that he executed the same by
authority of the Board of Directors of said corporation.

          IN WITNESS WHEREOF, I have hereunto set my hand and official seal the
day and year first above written.

                                          /s/ Julia A. Aviles
                                          -------------------
                                          NOTARY PUBLIC in and for the State of 
                                          Washington, residing at Bellvue, WA
                                          My appointment expires 1-19-02
                                          Print Name Julia A. Aviles




STATE OF NEW YORK   )
                    ) ss.:
COUNTY OF NEW YORK  )

          On the 3rd day of June, 1998, before me personally came Patricia
Stermer, to me known, who, being by me duly sworn, did depose and say that
he/she is Asst. Vice President of UNITED STATES TRUST COMPANY OF NEW YORK, one
of the corporations described in and which executed the foregoing instrument,
and duly acknowledged to me that he/she signed his/her name thereto by authority
of the By-Laws of said corporation.

          IN WITNESS WHEREOF, I have hereunto set my hand and official seal the
day and year first above written.

                                         /s/ Christine C. Collins
                                         ------------------------
                                         NOTARY PUBLIC in and for the State of 
                                         New York, residing at
                                                                ---------------
                                         My appointment expires 
                                                                ---------------
                                         Print Name
                                                    ---------------------------

                                         Christine C. Collins
                                         Notary Public, State of New York
                                         No. 03-4624735
                                         Qualified in Bronx County
                                         Certificate Filed in New York County
                                         Commission Expires March 30, 2000