<PAGE>
                                                                   Exhibit 4.2



                          PASS THROUGH TRUST AGREEMENT

                          Dated as of October 10, 2001


                                     between


                            SOUTHWEST AIRLINES CO.

                                       and

                          WILMINGTON TRUST COMPANY,

                                   as Trustee


<PAGE>
                                TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                            Page
                             ARTICLE I - DEFINITIONS
<S>                                                                         <C>
      Section 1.01. Definitions.........................................     2
      Section 1.02. Compliance Certificates and Opinions................    11
      Section 1.03. Form of Documents Delivered to Trustee..............    12
      Section 1.04. Directions of Certificateholders....................    12

                 ARTICLE II - ORIGINAL ISSUANCE OF CERTIFICATES:
                          ACQUISITION OF TRUST PROPERTY

      Section 2.01. Amount Unlimited; Issuable in Series................    13
      Section 2.02. Acquisition of Equipment Notes......................    15
      Section 2.03. Acceptance by Trustee...............................    17
      Section 2.04. Limitation of Powers................................    17

                         ARTICLE III - THE CERTIFICATES

      Section 3.01. Form, Denomination and Execution of
                    Certificates........................................    17
      Section 3.02. Authentication of Certificates......................    18
      Section 3.03. Temporary Certificates..............................    18
      Section 3.04. Transfer and Exchange...............................    19
      Section 3.05. Book-Entry and Definitive Certificates..............    19
      Section 3.06. Mutilated, Destroyed, Lost or Stolen
                    Certificates........................................    21
      Section 3.07. Persons Deemed Owners...............................    22
      Section 3.08. Cancellation........................................    22
      Section 3.09. Limitation of Liability for Payments................    22

         ARTICLE IV - DISTRIBUTIONS; STATEMENTS TO CERTIFICATEHOLDERS

      Section 4.01. Certificate Account and Special Payments
                    Account.............................................    23
      Section 4.02. Distributions from Certificate Account and
                    Special Payments Account............................    23
      Section 4.03. Statements to Certificateholders....................    25
      Section 4.04. Investment of Special Payment Moneys................    26

                             ARTICLE V - THE COMPANY

      Section 5.01. Maintenance of Corporate Existence..................    26
      Section 5.02. Consolidation, Merger, Etc..........................    26

                              ARTICLE VI - DEFAULT

      Section 6.01. Events of Default...................................    27
</TABLE>

                                        i
<PAGE>

<TABLE>
<CAPTION>
                                TABLE OF CONTENTS
                                  (Continued)
                                                                            Page

<S>                                                                         <C>
      Section 6.02. Incidents of Sale of Equipment Notes................    28
      Section 6.03. Judicial Proceedings Instituted by Trustee;
                    Trustee May Bring Suit..............................    29
      Section 6.04. Control by Certificateholders.......................    29
      Section 6.05. Waiver of Past Defaults.............................    30
      Section 6.06. Right of Certificateholders to Receive
                    Payments Not to Be Impaired.........................    30
      Section 6.07. Certificateholders May Not Bring Suit Except
                    Under Certain Conditions............................    31
      Section 6.08. Remedies Cumulative.................................    31
      Section 6.09. Undertaking for Costs...............................    31

                            ARTICLE VII - THE TRUSTEE

      Section 7.01. Certain Duties and Responsibilities.................    32

      Section 7.02. Notice of Defaults..................................    32

      Section 7.03. Certain Rights of Trustee...........................    32

      Section 7.04. Not Responsible for Recitals or Issuance of
                    Certificates........................................    34
      Section 7.05. May Hold Certificates...............................    34

      Section 7.06. Money Held in Trust.................................    34

      Section 7.07. Compensation and Reimbursement......................    34

      Section 7.08. Corporate Trustee Required; Eligibility.............    35

      Section 7.09. Resignation and Removal; Appointment of
                    Successor...........................................    37

      Section 7.10. Acceptance of Appointment by Successor..............    37

      Section 7.11. Merger, Conversion, Consolidation or
                    Succession to Business..............................    38

      Section 7.12. Maintenance of Agencies.............................    38

      Section 7.13. Money for Certificate Payments to Be Held in
                    Trust...............................................    39

      Section 7.14. Registration of Equipment Notes in Trustee's
                    Name................................................    39

      Section 7.15. Representations and Warranties of Trustee...........    40

      Section 7.16. Withholding Taxes; Information Reporting............    40

      Section 7.17. Trustee's Liens.....................................    41

      Section 7.18. Preferential Collection of Claims...................    41


       ARTICLE VIII - CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE


      Section 8.01. The Company to Furnish Trustee with Names and
                    Addresses of Certificateholders.....................    41

      Section 8.02. Preservation of Information; Communications
                    to Certificateholders...............................    41

      Section 8.03. Reports by Trustee..................................    42

      Section 8.04. Reports by the Company..............................    42
</TABLE>


                                       ii
<PAGE>

                                TABLE OF CONTENTS
                                  (Continued)
<TABLE>
<CAPTION>
                                                                            Page
                      ARTICLE IX - SUPPLEMENTAL AGREEMENTS
<S>                                                                         <C>
      Section 9.01. Supplemental Agreements Without Consent of
                    Certificateholders..................................    43

      Section 9.02. Supplemental Agreements with Consent of
                    Certificateholders..................................    44

      Section 9.03. Documents Affecting Immunity or Indemnity...........    45

      Section 9.04. Execution of Supplemental Agreements................    45

      Section 9.05. Effect of Supplemental Agreements...................    45

      Section 9.06. Conformity with Trust Indenture Act.................    46
      Section 9.07. Reference in Certificates to Supplemental
                    Agreements..........................................    46

             ARTICLE X - AMENDMENTS TO INDENTURE AND NOTE DOCUMENTS

      Section 10.01. Amendments and Supplements to Indenture and
                     Other Note Documents ..............................    46

                       ARTICLE XI - TERMINATION OF TRUSTS

      Section 11.01 Termination of the Trusts ..........................    47

                    ARTICLE XII - MISCELLANEOUS PROVISIONS

      Section 12.01 Limitation on Rights of Certificateholders .........    48

      Section 12.02 Liabilities of Certificateholders ..................    48

      Section 12.03. Registration of Equipment Notes in
                      Name of Subordination Agent ......................    48

      Section 12.04 Notices ............................................    48

      Section 12.05 Governing Law ......................................    50

      Section 12.06 Severability of Provisions .........................    50

      Section 12.07 Trust Indenture Act Controls .......................    50

      Section 12.08 Effect of Headings and Table of Contents ...........    50

      Section 12.09 Successors and Assigns .............................    50

      Section 12.10 Benefits of Agreement ..............................    50

      Section 12.11 Legal Holidays .....................................    50

      Section 12.12 Counterparts .......................................    50

      Section 12.13. Communication by Certificateholders with
                     Other Certificateholders ..........................    51

      Section 12.14 Intention of Parties ...............................    51

</TABLE>

                                    EXHIBITS

Exhibit A         Form of Certificate

                                       iii
<PAGE>
Reconciliation and tie between Southwest Airlines Co. Pass Through Trust
Agreement, dated as of October 10, 2001 and the Trust Indenture Act of 1939.
This reconciliation does not constitute part of the Pass Through Trust
Agreement.

<TABLE>
<CAPTION>
      Trust Indenture Act             Pass Through Trust
        of 1939 Section                Agreement Section
        ---------------               ------------------
<S>                                   <C>
        310(a)(1)                           7.07
           (a)(2)                           7.07
        312(a)                              3.05; 8.01; 8.02
        313(a)                              7.07
        314(a)                              8.04(a) - (c)
           (a)(4)                           8.04(d)
           (c)(1)                           1.02
           (c)(2)                           1.02
           (d)(1)                           7.13; 11.01
           (d)(2)                           7.13; 11.01
           (d)(3)                           2.01
           (e)                              1.02
        315(b)                              7.02
        316(a)(last sentence)               1.01(c)
           (a)(1)(A)                        6.04
           (a)(1)(B)                        6.05
           (b)                              6.06
           (c)                              1.04(d)
        317(a)(1)                           6.03
           (b)                              7.13
        318(a)                              12.05
</TABLE>
<PAGE>


                                                                               1
                          PASS THROUGH TRUST AGREEMENT

            This PASS THROUGH TRUST AGREEMENT, dated as of October 10, 2001 (the
"Basic Agreement"), between SOUTHWEST AIRLINES CO., a Texas corporation (the
"Company"), and WILMINGTON TRUST COMPANY, a Delaware trust company, as Trustee,
is made with respect to the formation from time to time of separate Southwest
Airlines Co. Pass Through Trusts, and the issuance from time to time of separate
series of Pass Through Certificates representing fractional undivided interests
in the respective Trusts.

                                   WITNESSETH:

            WHEREAS, from time to time, the Company and the Trustee may enter
into a Trust Supplement (this and certain other defined terms used herein are
defined in Section 1.01) pursuant to which the Trustee shall declare the
creation of a separate Trust for the benefit of the Holders of the series of
Certificates to be issued in respect of such Trust, and the initial Holders of
the Certificates of such series, as the grantors of such Trust, by their
respective acceptances of the Certificates of such series, shall join in the
creation of such Trust with the Trustee;

            WHEREAS, all Certificates to be issued in respect of each separate
Trust will be issued as a separate series pursuant to this Agreement, will
evidence fractional undivided interests in such Trust and will have no rights,
benefits or interests in respect of any other separate Trust or the property
held therein, subject, however, to the provisions of any Intercreditor Agreement
to which one or more Trusts may be a party;

            WHEREAS, from time to time, pursuant to the terms and conditions of
this Agreement with respect to each separate Trust formed hereunder, the Trustee
on behalf of such Trust shall purchase one or more issues of Equipment Notes
having the same interest rate as, and final maturity dates not later than the
final Regular Distribution Date of, the series of Certificates issued in respect
of such Trust and, subject to the terms of any related Intercreditor Agreement,
shall hold such Equipment Notes in trust for the benefit of the
Certificateholders of such Trust;

            WHEREAS, to facilitate the sale of Equipment Notes to, and the
purchase of Equipment Notes by, the Trustee on behalf of each Trust created from
time to time pursuant to this Agreement, the Company as the "issuer", as such
term is defined in and solely for purposes of the Securities Act of 1933, as
amended, of the Certificates to be issued in respect of each Trust and as the
"obligor", as such term is defined in and solely for purposes of the Trust
Indenture Act of 1939, as amended, has duly authorized the execution and
delivery of this Basic Agreement and each Trust Supplement with respect to all
such Certificates and is undertaking to perform certain administrative and
ministerial duties hereunder and is also undertaking to pay the fees and
expenses of the Trustee; and

            WHEREAS, this Basic Agreement, as supplemented from time to time, is
subject to the provisions of the Trust Indenture Act of 1939, as amended, and
shall, to the extent applicable, be governed by such provisions;
<PAGE>
                                                                               2
            NOW, THEREFORE, in consideration of the mutual agreements herein
contained, and of other good and valuable consideration the receipt and adequacy
of which are hereby acknowledged, the parties hereto agree as follows:


                                    ARTICLE I
                                   DEFINITIONS

            Section 1.01.  Definitions.  For all purposes of this Basic
Agreement, except as otherwise expressly provided or unless the context
otherwise requires:

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

            (2) all other terms used herein which are defined in the Trust
      Indenture Act, either directly or by reference therein, or by the rules
      promulgated under the Trust Indenture Act, have the meanings assigned to
      them therein;

            (3) all references in this Basic Agreement to designated "Articles",
      "Sections", "Subsections" and other subdivisions are to the designated
      Articles, Sections, Subsections and other subdivisions of this Basic
      Agreement;

            (4) the words "herein", "hereof" and "hereunder" and other words of
      similar import refer to this Basic Agreement as a whole and not to any
      particular Article, Section, Subsection or other subdivision;

            (5) unless the context otherwise requires, whenever the words
      "including", "include" or "includes" are used herein, it shall be deemed
      to be followed by the phrase "without limitation"; and

            (6) the term "this Agreement" (as distinguished from "this Basic
      Agreement") refers, unless the context otherwise requires, to this Basic
      Agreement as supplemented by the Trust Supplement creating a particular
      Trust and establishing the series of Certificates issued or to be issued
      in respect thereof, with reference to such Trust and such series of
      Certificates, as this Basic Agreement as so supplemented may be further
      supplemented with respect to such Trust and such series of Certificates.

            Act:  Has the meaning, with respect to any Certificateholder,
      specified in Section 1.04(a).

            Affiliate: Means, with respect to any specified Person, 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, directly or indirectly, to direct the management and
      policies of such Person, whether through the ownership of voting
      securities or by contract
<PAGE>
                                                                               3

      or otherwise, and the terms "controlling" and "controlled" have meanings
      correlative to the foregoing.

            Aircraft:  Means one or more aircraft, including engines
      therefor, owned by or leased to the Company and securing one or more
      Equipment Notes.

            Authorized Agent:  Means, with respect to the Certificates of any
      series, any Paying Agent or Registrar for the Certificates of such
      series.

            Basic Agreement: Means this Pass Through Trust Agreement, as the
      same may from time to time be supplemented, amended or modified, but does
      not include any Trust Supplement.

            Book-Entry Certificates: Means, with respect to the Certificates of
      any series, a beneficial interest in the Certificates of such series,
      ownership and transfers of which shall be made through book entries as
      described in Section 3.05.

            Business Day: Means, with respect to the Certificates of any series,
      any day other than a Saturday, a Sunday or a day on which commercial banks
      are required or authorized to close in Dallas, Texas, New York, New York,
      or, so long as any Certificate of such series is outstanding, the city and
      state in which the Trustee or any related Loan Trustee maintains its
      Corporate Trust Office or receives and disburses funds.

            Certificate:  Means any one of the certificates executed and
      authenticated by the Trustee, substantially in the form of Exhibit A
      hereto.

            Certificate Account: Means, with respect to the Certificates of any
      series, the account or accounts created and maintained for such series
      pursuant to Section 4.01(a) and the related Trust Supplement.

            Certificateholder or Holder: Means, with respect to the Certificates
      of any series, the Person in whose name a Certificate of such series is
      registered in the Register for Certificates of such series.

            Certificate Owner:  Means, with respect to the Certificates of
      any series, for purposes of Section 3.05, the Person who owns a
      Book-Entry Certificate of such series.

            Clearing Agency:  Means an organization registered as a "clearing
      agency" pursuant to Section 17A of the Securities Exchange Act of 1934,
      as amended.

            Clearing Agency Participant: Means a broker, dealer, bank, other
      financial institution or other Person for whom from time to time a
      Clearing Agency effects, directly or indirectly, book-entry transfers and
      pledges of securities deposited with the Clearing Agency.

            Company: Has the meaning set forth in the introductory paragraph
      hereof, or its successor in interest pursuant to Section 5.02, or (only in
      the context of provisions hereof,
<PAGE>
                                                                               4

      if any, when such reference is required for purposes of compliance with
      the Trust Indenture Act) any other "obligor" (within the meaning of the
      Trust Indenture Act) with respect to the Certificates of any series.

            Controlling Party:  Means the Person entitled to act as such
      pursuant to the terms of any Intercreditor Agreement.

            Corporate Trust Office: Means, with respect to the Trustee or any
      Loan Trustee, the office of such trustee in the city at which at any
      particular time its corporate trust business shall be principally
      administered.

            Cut-off Date:  Means, with respect to the Certificates of any
      series, the date designated as such in the Trust Supplement
      establishing such series.

            Definitive Certificates:  Has the meaning, with respect to the
      Certificates of any series, specified in Section 3.05.

            Direction:  Has the meaning specified in Section 1.04(a).

            Equipment Notes:  Means, with respect to the Certificates of any
      series, all of the equipment notes issued under the Indentures related
      to such series of Certificates.

            ERISA:  Means the Employee Retirement Income Security Act of
      1974, as amended from time to time, or any successor federal statute.

            Escrow Account:  Has the meaning, with respect to the
      Certificates of any series, specified in Section 2.02(b).

            Escrowed Funds:  Has the meaning, with respect to any Trust,
      specified in Section 2.02(b).

            Event of Default: Means, in respect of any Trust, an Indenture Event
      of Default under any Indenture pursuant to which Equipment Notes held by
      such Trust were issued.

            Fractional Undivided Interest: Means the fractional undivided
      interest in a Trust that is evidenced by a Certificate relating to such
      Trust.

            Indenture: Means, with respect to any Trust, each of the one or more
      separate trust indenture and security agreements or trust indenture and
      mortgages or similar documents described in, or on a schedule attached to,
      the Trust Supplement and an indenture having substantially the same terms
      and conditions which relates to a Substitute Aircraft, as each such
      indenture may be amended or supplemented in accordance with its respective
      terms; and "Indentures" means all of such agreements.

            Indenture Event of Default: Means, with respect to any Indenture,
      any Indenture Event of Default (as such term is defined in such
      Indenture).
<PAGE>
                                                                               5

            Initial Regular Distribution Date:  Means, with respect to the
      Certificates of any series, the first Regular Distribution Date on
      which a Scheduled Payment is to be made.

            Intercreditor Agreement: Means any agreement by and among the
      Trustee, as trustee hereunder with respect to one or more Trusts, one or
      more Liquidity Providers and a Subordination Agent providing, among other
      things, for the distribution of payments made in respect of Equipment
      Notes held by such Trusts.

            Issuance Date:  Means, with respect to the Certificates of any
      series, the date of the issuance of such Certificates.

            Lease: Means any lease between an Owner Trustee, as the lessor, and
      the Company, as the lessee, referred to in the related Indenture, as such
      lease may be amended, supplemented or otherwise modified in accordance
      with its terms; and "Leases" means all such Leases.

            Letter of Representations:  Means, with respect to the
      Certificates of any series, an agreement among the Company, the Trustee
      and the initial Clearing Agency.

            Liquidity Facility: Means, with respect to the Certificates of any
      series, any revolving credit agreement, letter of credit or similar
      facility relating to the Certificates of such series between a bank or
      other financial institution and a Subordination Agent, as amended,
      replaced, supplemented or otherwise modified from time to time in
      accordance with its terms and the terms of any Intercreditor Agreement.

            Liquidity Provider: Means, with respect to the Certificates of any
      series, a bank or other financial institution that agrees to provide a
      Liquidity Facility for the benefit of the holders of Certificates of such
      series.

            Loan Trustee: Means, with respect to any Equipment Note or the
      Indenture applicable thereto, the bank or trust company designated as loan
      or indenture trustee under such Indenture, and any successor to such Loan
      Trustee as such trustee; and "Loan Trustees" means all of the Loan
      Trustees under the Indentures.

            Note Documents: Means, with respect to the Certificates of any
      series, the Equipment Notes with respect to such Certificates and, with
      respect to such Equipment Notes, the related Indenture, Note Purchase
      Agreement and, if the related Aircraft is leased to the Company, the
      related Lease and the related Owner Trustee's Purchase Agreement.

            Note Purchase Agreement: Means, with respect to the Certificates of
      any series, any note purchase, refunding, participation or similar
      agreement providing for, among other things, the purchase of Equipment
      Notes by the Trustee on behalf of the relevant Trust; and "Note Purchase
      Agreements" means all such agreements.
<PAGE>
                                                                               6

            Officer's Certificate: Means a certificate signed, (a) in the case
      of the Company, by the Chairman or Vice Chairman of the Board of
      Directors, the President, the Chief Executive Officer, any Vice President
      or the Treasurer of the Company, signing alone, or (b) in the case of the
      Trustee or an Owner Trustee or a Loan Trustee, a Responsible Officer of
      the Trustee or such Owner Trustee or such Loan Trustee, as the case may
      be.

            Opinion of Counsel: Means a written opinion of legal counsel who (a)
      in the case of counsel for the Company may be (i) a senior attorney of the
      Company one of whose principal duties is furnishing advice as to legal
      matters, (ii) Vinson & Elkins L.L.P. or (iii) such other counsel
      designated by the Company and reasonably acceptable to the Trustee and (b)
      in the case of any Owner Trustee or any Loan Trustee, may be such counsel
      as may be designated by any of them whether or not such counsel is an
      employee of any of them, and who shall be reasonably acceptable to the
      Trustee.

            Other Agreements:  Has the meaning specified in Section 6.01(b).

            Outstanding: When used with respect to Certificates of any series,
      means, as of the date of determination, all Certificates of such series
      theretofore authenticated and delivered under this Agreement, except:

                  (i)   Certificates of such series theretofore cancelled by
            the Registrar or delivered to the Trustee or the Registrar for
            cancellation;

                  (ii) All of the Certificates of such series if money in the
            full amount required to make the final distribution with respect to
            such series pursuant to Section 11.01 hereof has been theretofore
            deposited with the Trustee in trust for the Holders of the
            Certificates of such series as provided in Section 4.01 pending
            distribution of such money to such Certificateholders pursuant to
            payment of such final distribution payment; and

                  (iii) Certificates of such series in exchange for or in lieu
            of which other Certificates of such series have been authenticated
            and delivered pursuant to this Agreement.

            Owner Participant: Means, with respect to any Equipment Note, the
      "Owner Participant", if any, as referred to in the Indenture pursuant to
      which such Equipment Note is issued and any permitted successor or assign
      of such Owner Participant; and "Owner Participants" at any time of
      determination means all of the Owner Participants thus referred to in the
      Indentures.

            Owner Trustee: Means, with respect to any Equipment Note, the "Owner
      Trustee", if any, as referred to in the Indenture pursuant to which such
      Equipment Note is issued, not in its individual capacity but solely as
      trustee; and "Owner Trustees" means all of the Owner Trustees party to any
      of the related Indentures.
<PAGE>
                                                                               7


            Owner Trustee's Purchase Agreement: Has the meaning, with respect to
      the Certificates of any series if the related Aircraft is leased to the
      Company, specified therefor in the related Lease.

            Paying Agent:  Means, with respect to the Certificates of any
      series, the paying agent maintained and appointed for the Certificates
      of such series pursuant to Section 7.12.

            Permitted Investments: Means obligations of the United States of
      America or agencies or instrumentalities thereof for the payment of which
      the full faith and credit of the United States of America is pledged,
      maturing in not more than 60 days after the date of acquisition thereof or
      such lesser time as is required for the distribution of any Special
      Payments on a Special Distribution Date.

            Person: Means any person, including any individual, corporation,
      limited liability company, partnership, joint venture, association,
      joint-stock company, trust, trustee, unincorporated organization, or
      government or any agency or political subdivision thereof.

            Pool Balance: Means, with respect to the Certificates of any series
      as of any date, (i) the original aggregate face amount of the Certificates
      of any series less (ii) the aggregate amount of all payments made in
      respect of such Certificates other than payments made in respect of
      interest or premium thereon or reimbursement of any costs or expenses
      incurred in connection therewith. The Pool Balance as of any Distribution
      Date shall be computed after giving effect to the payment of principal, if
      any, on the Equipment Notes or other Trust Property held in the Trust and
      the distribution thereof to be made on such Distribution Date.

            Pool Factor: Means, with respect to any series of Certificates as of
      any date, the quotient (rounded to the seventh decimal place) computed by
      dividing (i) the Pool Balance of such series as at such date by (ii) the
      original aggregate face amount of the Certificates of such series. The
      Pool Factor as of any Distribution Date shall be computed after giving
      effect to the payment of principal, if any, on the Equipment Notes or
      other Trust Property held in the Trust and the distribution thereof to be
      made on such Distribution Date.

            Postponed Notes: Means, with respect to any Trust or the related
      series of Certificates, the Equipment Notes to be held in such Trust as to
      which a Postponement Notice shall have been delivered pursuant to Section
      2.02(b).

            Postponement Notice: Means, with respect to any Trust or the related
      series of Certificates, an Officer's Certificate of the Company signed by
      an officer of the Company (1) requesting that the Trustee temporarily
      postpone purchase of the related Equipment Notes to a date later than the
      Issuance Date of such series of Certificates, (2) identifying the amount
      of the purchase price of each such Equipment Note and the aggregate
      purchase price for all such Equipment Notes, (3) setting forth the reasons
      for such
<PAGE>
                                                                               8


      postponement and (4) with respect to each such Equipment Note, either (a)
      setting or resetting a new Transfer Date (which shall be on or prior to
      the applicable Cut-off Date) for payment by the Trustee of such purchase
      price and issuance of the related Equipment Note (subject to subsequent
      change from time to time in accordance with the relevant Note Purchase
      Agreement), or (b) indicating that such new Transfer Date (which shall be
      on or prior to the applicable Cut-off Date) will be set by subsequent
      written notice not less than one Business Day prior to such new Transfer
      Date (subject to subsequent change from time to time in accordance with
      the relevant Note Purchase Agreement).

            Potential Purchaser:  Has the meaning, with respect to any
      Certificateholder, specified in Section 6.01(b).

            PTC Event of Default: Means, with respect to the Certificates of any
      series, any failure to pay within ten Business Days of the due date
      thereof: (i) the outstanding Pool Balance of such series of Certificates
      on the date specified in any Trust Supplement for such payment or (ii)
      interest due on the Certificates of such series on any Distribution Date
      (unless the related Subordination Agent shall have made an Interest
      Drawing or Drawings (as defined in the related Intercreditor Agreement),
      or a withdrawal or withdrawals pursuant to a cash collateral account under
      such Intercreditor Agreement, with respect thereto in an aggregate amount
      sufficient to pay such interest and shall have distributed such amount to
      the Trustee).

            Purchasing Certificateholder:  Has the meaning, with respect to
      any Certificateholder, specified in Section 6.01(b).

            Record Date: Means, with respect to any Trust or the related series
      of Certificates, (i) for Scheduled Payments to be distributed on any
      Regular Distribution Date, other than the final distribution with respect
      to such series, the 15th day (whether or not a Business Day) preceding
      such Regular Distribution Date, and (ii) for Special Payments to be
      distributed on any Special Distribution Date, other than the final
      distribution with respect to such series, the 15th day (whether or not a
      Business Day) preceding such Special Distribution Date.

            Register and Registrar: Means, each with respect to the Certificates
      of any series, the register maintained and the registrar appointed
      pursuant to Sections 3.04 and 7.12.

            Regular Distribution Date: Means, with respect to distributions of
      Scheduled Payments in respect of any series of Certificates, each date
      designated as such in this Agreement, until payment of all the Scheduled
      Payments to be made under the Equipment Notes held in the Trust have been
      made.

            Request: Means a request by the Company setting forth the subject
      matter of the request accompanied by an Officer's Certificate and an
      Opinion of Counsel as provided in Section 1.02 of this Basic Agreement.
<PAGE>
                                                                               9


            Responsible Officer: Means, with respect to any Trustee, any Loan
      Trustee and any Owner Trustee, any officer in the Corporate Trust
      Department of the Trustee, Loan Trustee or Owner Trustee or any other
      officer 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.

            Responsible Party:  Means, with respect to the Certificates of
      any series, the person designated as such in the related Trust
      Supplement.

            Scheduled Payment: Means, with respect to any Equipment Note, (i)
      any payment of principal or interest on such Equipment Note (other than
      any such payment which is not in fact received by the Trustee or any
      Subordination Agent within five days of the date on which such payment is
      scheduled to be made) or (ii) any payment of interest on the Certificates
      of any series with funds drawn under the Liquidity Facility for such
      series, which payment represents the installment of principal on such
      Equipment Note at the stated maturity of such installment, the payment of
      regularly scheduled interest accrued on the unpaid principal amount of
      such Equipment Note, or both; provided, however, that any payment of
      principal, premium, if any, or interest resulting from the redemption or
      purchase of any Equipment Note shall not constitute a Scheduled Payment.

            SEC: Means the Securities and Exchange Commission, as from time to
      time constituted or created under the Securities Exchange Act of 1934, as
      amended, or, if at any time after the execution of this instrument such
      Commission is not existing and performing the duties now assigned to it
      under the Trust Indenture Act, then the body performing such duties on
      such date.

            Selling Certificateholder:  Has the meaning, with respect to any
      Certificateholder, specified in Section 6.01(b).

            Special Distribution Date:  Means, with respect to the
      Certificates of any series, each date on which a Special Payment is to
      be distributed as specified in this Agreement.

            Special Payment: Means (i) any payment (other than a Scheduled
      Payment) in respect of, or any proceeds of, any Equipment Note or Trust
      Indenture Estate (as defined in each Indenture), (ii) the amounts required
      to be distributed pursuant to the last paragraph of Section 2.02(b) or
      (iii) the amounts required to be distributed pursuant to the penultimate
      paragraph of Section 2.02(b).

            Special Payments Account: Means, with respect to the Certificates of
      any series, the account or accounts created and maintained for such series
      pursuant to Section 4.01(b) and the related Trust Supplement.

            Specified Investments: Means, with respect to any Trust, unless
      otherwise specified in the related Trust Supplement, (i) obligations of,
      or guaranteed by, the United
<PAGE>
                                                                              10

      States Government or agencies thereof, (ii) open market commercial paper
      of any corporation incorporated under the laws of the United States of
      America or any state thereof rated at least P-2 or its equivalent by
      Moody's Investors Service, Inc. or at least A-2 or its equivalent by
      Standard & Poor's Ratings Services, a division of The McGraw-Hill
      Companies, Inc., (iii) certificates of deposit issued by commercial banks
      organized under the laws of the United States or of any political
      subdivision thereof having a combined capital and surplus in excess of
      $100,000,000 which banks or their holding companies have a rating of A or
      its equivalent by Moody's Investors Service, Inc. or Standard & Poor's
      Ratings Services, a division of The McGraw-Hill Companies, Inc.; provided,
      however, that the aggregate amount at any one time so invested in
      certificates of deposit issued by any one bank shall not exceed 5% of such
      bank's capital and surplus, (iv) U.S. dollar-denominated offshore
      certificates of deposit issued by, or offshore time deposits with, any
      commercial bank described in clause (iii) above or any subsidiary thereof
      and (v) repurchase agreements with any financial institution having
      combined capital and surplus of at least $100,000,000 with any of the
      obligations described in clauses (i) through (iv) above as collateral;
      provided further that if all of the above investments are unavailable, the
      entire amounts to be invested may be used to purchase federal funds from
      an entity described in clause (iii) above.

            Subordination Agent:  Has the meaning specified therefor in any
      Intercreditor Agreement.

            Substitute Aircraft: Means, with respect to any Trust, any Aircraft
      of a type specified in this Agreement and, at the election of the Company,
      substituted prior to the applicable Cut-off Date, if any, pursuant to the
      terms of this Agreement.

            Transfer Date: Has the meaning assigned to that term or any of the
      terms "Delivery Date", "Funding Date" or "Closing Date" in a Note Purchase
      Agreement, and in any event refers to any such date as it may be changed
      from time to time in accordance with the terms of such Note Purchase
      Agreement.

            Triggering Event:  Has the meaning specified therefor in any
      Intercreditor Agreement.

            Trust:  Means, with respect to the Certificates of any series,
      the trust under this Agreement.

            Trustee:  Means Wilmington Trust Company, or its successor in
      interest, and any successor or other trustee appointed as provided
      herein.

            Trust Indenture Act: Except as otherwise provided in Section 9.06,
      means, with respect to any particular Trust, the United States Trust
      Indenture Act of 1939, as in force at the date as of which the related
      Trust Supplement was executed.

            Trust Property: Means, with respect to any Trust, (i) subject to any
      related Intercreditor Agreement, the Equipment Notes held as the property
      of such Trust, all
<PAGE>
                                                                              11

      monies at any time paid thereon and all monies due and to become due
      thereunder, (ii) funds from time to time deposited in the related Escrow
      Account, the related Certificate Account and the related Special Payments
      Account and, subject to the related Intercreditor Agreement, any proceeds
      from the sale by the Trustee pursuant to Article VI hereof of any such
      Equipment Note, (iii) all rights of such Trust and the Trustee, on behalf
      of the Trust, under any Intercreditor Agreement, including, without
      limitation, all monies receivable in respect of such rights, and (iv) all
      monies receivable under any Liquidity Facility for such Trust.

            Trust Supplement: Means an agreement supplemental hereto pursuant to
      which (i) a separate Trust is created for the benefit of the Holders of
      the Certificates of a series, (ii) the issuance of the Certificates of
      such series representing fractional undivided interests in such Trust is
      authorized and (iii) the terms of the Certificates of such series are
      established.

            Section 1.02. Compliance Certificates and Opinions. Upon any
application or request by the Company, any Owner Trustee or any Loan Trustee to
the Trustee to take any action under any provision of this Basic Agreement or,
in respect of the Certificates of any series, this Agreement, the Company, such
Owner Trustee or such Loan Trustee, as the case may be, shall furnish to the
Trustee (i) an Officer's Certificate stating that, in the opinion of the
signers, all conditions precedent, if any, provided for in this Basic Agreement
or this Agreement relating to the proposed action have been complied with and
(ii) an Opinion of Counsel stating that in the opinion of such counsel all such
conditions precedent, if any, have been complied with, except that in the case
of any such application or request as to which the furnishing of such documents
is specifically required by any provision of this Basic Agreement or this
Agreement relating to such particular application or request, no additional
certificate or opinion need be furnished.

            Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Basic Agreement or, in respect of the
Certificates of any series, this Agreement (other than a certificate provided
pursuant to Section 8.04(d)) or any Trust Supplement shall include:

            (1) a statement that each individual signing such certificate or
      opinion has read such covenant or condition and the definitions in this
      Basic Agreement or this Agreement relating thereto;

            (2) a brief statement as to the nature and scope of the examination
      or investigation upon which the statements or opinions contained in such
      certificate or opinion are based;

            (3) a statement that, in the opinion of each such individual, he has
      made such examination or investigation as is necessary to enable him to
      express an informed opinion as to whether or not such covenant or
      condition has been complied with; and

            (4) a statement as to whether, in the opinion of each such
      individual, such condition or covenant has been complied with.
<PAGE>
                                                                              12

            Section 1.03. Form of Documents Delivered to Trustee. In any case
where several matters are required to be certified by, or covered by an opinion
of, any specified Person, it is not necessary that all such matters be certified
by, or covered by the opinion of, only one such Person, or that they be so
certified or covered by only one document, but one such Person may certify or
give an opinion with respect to some matters and one or more other such Persons
as to other matters and any such Person may certify or give an opinion as to
such matters in one or several documents.

            Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Basic Agreement or, in respect of the Certificates of any
series, this Agreement, they may, but need not, be consolidated and form one
instrument.

            Section 1.04. Directions of Certificateholders. (a) Any direction,
consent, request, demand, authorization, notice, waiver or other action provided
by this Agreement in respect of the Certificates of any series to be given or
taken by Certificateholders (a "Direction") may be embodied in and evidenced by
one or more instruments of substantially similar tenor signed by such
Certificateholders in person or by an agent or proxy duly appointed in writing;
and, except as herein otherwise expressly provided, such action shall become
effective when such instrument or instruments are delivered to the Trustee and,
when it is hereby expressly required pursuant to this Agreement, to the Company
or any Loan Trustee. Such instrument or instruments (and the action embodied
therein and evidenced thereby) are herein sometimes referred to as the "Act" of
the Certificateholders signing such instrument or instruments. Proof of
execution of any such instrument or of a writing appointing any such agent or
proxy shall be sufficient for any purpose of this Trust Agreement and conclusive
in favor of the Trustee, the Company and the related Loan Trustee, if made in
the manner provided in this Section 1.04.

            (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the certificate of any notary public or
other officer of any jurisdiction authorized to take acknowledgments of deeds or
administer oaths that the Person executing such instrument acknowledged to him
the execution thereof, or by an affidavit of a witness to such execution sworn
to before any such notary or such other officer, and where such execution is by
an officer of a corporation or association or a member of a partnership, on
behalf of such corporation, association or partnership, such certificate or
affidavit shall also constitute sufficient proof of his authority. The fact and
date of the execution of any such instrument or writing, or the authority of the
Person executing the same, may also be proved in any other reasonable manner
which the Trustee deems sufficient.

            (c) In determining whether the Certificateholders of the requisite
Fractional Undivided Interests of Certificates of any series Outstanding have
given any Direction under this Agreement, Certificates owned by the Company or
any Affiliate thereof shall be disregarded and deemed not to be Outstanding for
purposes of any such determination. In determining whether the Trustee shall be
protected in relying upon any such Direction, only Certificates which the
Trustee knows to be so owned shall be so disregarded. Notwithstanding the
foregoing, (i) if any such Person owns 100% of the Certificates of any series
Outstanding, such Certificates shall not
<PAGE>
                                                                              13

be so disregarded, and (ii) if any amount of Certificates of any series so owned
by any such Person have been pledged in good faith, such Certificates shall not
be disregarded if the pledgee establishes to the satisfaction of the Trustee the
pledgee's right so to act with respect to such Certificates and that the pledgee
is not the Company or any Affiliate thereof.

            (d) The Company may, at its option, by delivery of an Officer's
Certificate to the Trustee, set a record date to determine the
Certificateholders in respect of the Certificates of any series, entitled to
give any Direction. Notwithstanding Section 316(c) of the Trust Indenture Act,
such record date shall be the record date specified in such Officer's
Certificate, which shall be a date not more than 30 days prior to the first
solicitation of Certificateholders of the applicable series in connection
therewith. If such a record date is fixed, such Direction may be given before or
after such record date, but only the Certificateholders of record of the
applicable series at the close of business on such record date shall be deemed
to be Certificateholders for the purposes of determining whether
Certificateholders of the requisite proportion of Outstanding Certificates of
such series have authorized or agreed or consented to such Direction, and for
that purpose the Outstanding Certificates shall be computed as of such record
date; provided, however, that no such Direction by the Certificateholders on
such record date shall be deemed effective unless it shall become effective
pursuant to the provisions of this Agreement not later than one year after such
record date.

            (e) Any Direction by the Holder of any Certificate shall bind the
Holder of every Certificate issued upon the transfer thereof or in exchange
therefor or in lieu thereof, whether or not notation of such Direction is made
upon such Certificate.

            (f) Except as otherwise provided in Section 1.04(c), Certificates of
any series owned by or pledged to any Person shall have an equal and
proportionate benefit under the provisions of this Agreement, without
preference, priority or distinction as among all of the Certificates of such
series.


                                   ARTICLE II

                       ORIGINAL ISSUANCE OF CERTIFICATES:
                          ACQUISITION OF TRUST PROPERTY

            Section 2.01. Amount Unlimited; Issuable in Series. (a) The
aggregate principal amount of Certificates which may be authenticated and
delivered under this Basic Agreement is unlimited. The Certificates may be
issued from time to time in one or more series and shall be designated generally
as the "Pass Through Certificates", with such further designations added or
incorporated in such title for the Certificates of each series as specified in
the related Trust Supplement. Each Certificate shall bear upon its face the
designation so selected for the series to which it belongs. All Certificates of
the same series shall be substantially identical except that the Certificates of
a series may differ as to denomination and as may otherwise be provided in the
Trust Supplement establishing the Certificates of such series. Each series of
Certificates issued pursuant to this Agreement will evidence fractional
undivided interests in the related Trust and, except as may be contained in any
Intercreditor Agreement, will have no rights, benefits or

<PAGE>
                                                                              14

interests in respect of any other Trust or the Trust Property held therein. All
Certificates of the same series shall be in all respects equally and ratably
entitled to the benefits of this Agreement without preference, priority or
distinction on account of the actual time or times of authentication and
delivery, all in accordance with the terms and provisions of this Agreement.

            (b) The following matters shall be established with respect to the
Certificates of each series issued hereunder by a Trust Supplement executed and
delivered by and among the Company and the Trustee:

            (1) the formation of the Trust as to which the Certificates of such
      series represent fractional undivided interests and its designation (which
      designation shall distinguish such Trust from each other Trust created
      under this Basic Agreement and a Trust Supplement);

            (2) the specific title of the Certificates of such series (which
      title shall distinguish the Certificates of such series from each other
      series of Certificates created under this Basic Agreement and a Trust
      Supplement);

            (3) any limit upon the aggregate principal amount of the
      Certificates of such series which may be authenticated and delivered
      (which limit shall not pertain to Certificates authenticated and delivered
      upon registration of transfer of, or in exchange for, or in lieu of, other
      Certificates of the series pursuant to Sections 3.03, 3.04 and 3.06);

            (4)   the Cut-off Date with respect to the Certificates of such
      series;

            (5)   the Regular Distribution Dates applicable to the
      Certificates of such series;

            (6)   the Special Distribution Dates applicable to the
      Certificates of such series;

            (7) if other than as provided in Section 7.12(b), the Registrar or
      the Paying Agent for the Certificates of such series, including any
      Co-Registrar or additional Paying Agent;

            (8)   if other than as provided in Section 3.02, the
      denominations in which the Certificates of such series shall be
      issuable;

            (9) the specific form of the Certificates of such series (including
      the interest rate applicable thereto) and whether or not Certificates of
      such series are to be issued as Book-Entry Certificates and, if such
      Certificates are to be Book-Entry Certificates, the form of Letter of
      Representations, if any or if other than as provided in Section 3.05,
      whether and the circumstances under which the beneficial owners of
      interests in such Certificates in permanent global form may exchange such
      interests for Certificates of such series and of like tenor of any
      authorized form and denomination);
<PAGE>
                                                                              15

            (10)  a description of the Equipment Notes to be acquired and
      held in the related Trust and of the related Aircraft and Note
      Documents;

            (11) provisions with respect to the terms for which the definitions
      set forth in Article I hereof or the terms of Section 11.01 hereof require
      further specification in the related Trust Supplement;

            (12)  any restrictions (including legends) in respect of ERISA;

            (13) whether such series will be subject to an Intercreditor
      Agreement and, if so, the specific designation of such Intercreditor
      Agreement;

            (14) whether such series will have the benefit of a Liquidity
      Facility and, if so, the specific designation of such Liquidity Facility;

             (15) whether there will be a deposit agreement or other comparable
      arrangement prior to the delivery of one or more Aircraft and, if so, any
      terms appropriate thereto; and

            (16) any other terms of the Certificates of such series (which terms
      shall not be inconsistent with the provisions of the Trust Indenture Act),
      including any terms of the Certificates of such series which may be
      required or advisable under United States laws or regulations or advisable
      in connection with the marketing of Certificates of the series.

            (c) At any time and from time to time after the execution and
delivery of this Basic Agreement and a Trust Supplement forming a Trust and
establishing the terms of Certificates of a series, Certificates of such series
shall be executed, authenticated and delivered by the Trustee to the Person or
Persons specified by the Company upon request of the Company and upon
satisfaction or waiver of any conditions precedent set forth in such Trust
Supplement.

            Section 2.02. Acquisition of Equipment Notes. (a) Unless otherwise
specified in the related Trust Supplement, on or prior to the Issuance Date of
the Certificates of a series, the Trustee shall execute and deliver the related
Note Purchase Agreements in the form delivered to the Trustee by the Company and
shall, subject to the respective terms thereof, perform its obligations under
such Note Purchase Agreements. The Trustee shall issue and sell such
Certificates, in authorized denominations and in such Fractional Undivided
Interests, so as to result in the receipt of consideration in an amount equal to
the aggregate purchase price of the Equipment Notes contemplated to be purchased
by the Trustee under the related Note Purchase Agreements and, concurrently
therewith, the Trustee shall purchase, pursuant to the terms and conditions of
the Note Purchase Agreements, such Equipment Notes at a purchase price equal to
the amount of such consideration so received. Except as provided in Sections
3.03, 3.04 and 3.06 hereof, the Trustee shall not execute, authenticate or
deliver Certificates of such series in excess of the aggregate amount specified
in this paragraph. The provisions of this Subsection (a) are subject to the
provisions of Subsection (b) below.
<PAGE>
                                                                              16

            (b) If on or prior to the Issuance Date with respect to a series of
Certificates the Company shall deliver to the Trustee a Postponement Notice
relating to one or more Postponed Notes, the Trustee shall postpone the purchase
of such Postponed Notes and shall deposit into an escrow account (as to such
Trust, the "Escrow Account") to be maintained as part of the related Trust an
amount equal to the purchase price of such Postponed Notes (the "Escrowed
Funds"). The portion of the Escrowed Funds so deposited with respect to any
particular Postponed Notes shall be invested by the Trustee at the written
direction and risk of, and for the benefit of, the Responsible Party in
Specified Investments (i) maturing no later than any scheduled Transfer Date
relating to such Postponed Notes or (ii) if no such Transfer Date has been
scheduled, maturing on the next Business Day, or (iii) if the Company has given
notice to the Trustee that such Postponed Notes will not be issued, maturing on
the next applicable Special Distribution Date, if such investments are
reasonably available for purchase. The Trustee shall make withdrawals from the
Escrow Account only as provided in this Agreement. Upon request of the Company
on one or more occasions and the satisfaction or waiver of the closing
conditions specified in the applicable Note Purchase Agreements on or prior to
the related Cut-off Date, the Trustee shall purchase the applicable Postponed
Notes with the Escrowed Funds withdrawn from the Escrow Account. The purchase
price shall equal the principal amount of such Postponed Notes.

            The Trustee shall hold all Specified Investments until the maturity
thereof and will not sell or otherwise transfer Specified Investments. If
Specified Investments held in an Escrow Account mature prior to any applicable
Transfer Date, any proceeds received on the maturity of such Specified
Investments (other than any earnings thereon) shall be reinvested by the Trustee
at the written direction and risk of, and for the benefit of, the Responsible
Party in Specified Investments maturing as provided in the preceding paragraph.

            Any earnings on Specified Investments received from time to time by
the Trustee shall be promptly distributed to the Responsible Party. The
Responsible Party shall pay to the Trustee for deposit to the relevant Escrow
Account an amount equal to any losses on such Specified Investments as incurred.
On the Initial Regular Distribution Date in respect of the Certificates of any
series, the Responsible Party will pay (in immediately available funds) to the
Trustee an amount equal to the interest that would have accrued on any Postponed
Notes with respect to such Certificates, if any, purchased after the Issuance
Date if such Postponed Notes had been purchased on the Issuance Date, from the
Issuance Date to, but not including, the date of the purchase of such Postponed
Notes by the Trustee.

      If, in respect of the Certificates of any series, the Company notifies the
Trustee prior to the Cut-off Date that any Postponed Notes will not be issued on
or prior to the Cut-off Date for any reason, on the next Special Distribution
Date for such Certificates occurring not less than 15 days following the date of
such notice, (i) the Responsible Party shall pay to the Trustee for deposit in
the related Special Payments Account, in immediately available funds, an amount
equal to the interest that would have accrued on the Postponed Notes designated
in such notice at a rate equal to the interest rate applicable to such
Certificates from the Issuance Date to, but not including, such Special
Distribution Date and (ii) the Trustee shall transfer an amount equal to that
amount of Escrowed Funds that would have been used to purchase the Postponed
Notes
<PAGE>
                                                                              17

designated in such notice and the amount paid by the Responsible Party pursuant
to the immediately preceding clause (i) to the related Special Payments Account
for distribution as a Special Payment in accordance with the provisions hereof.

            If, on such Cut-off Date, an amount equal to less than all of the
Escrowed Funds (other than Escrowed Funds referred to in the immediately
preceding paragraph) has been used to purchase Postponed Notes, on the next such
Special Distribution Date occurring not less than 15 days following such Cut-off
Date (i) the Responsible Party shall pay to the Trustee for deposit in such
Special Payments Account, in immediately available funds, an amount equal to the
interest that would have accrued on such Postponed Notes contemplated to be
purchased with such unused Escrowed Funds (other than Escrowed Funds referred to
in the immediately preceding paragraph) but not so purchased at a rate equal to
the interest rate applicable to such Certificates from the Issuance Date to, but
not including, such Special Distribution Date and (ii) the Trustee shall
transfer such unused Escrowed Funds and the amount paid by the Responsible Party
pursuant to the immediately preceding clause (i) to such Special Payments
Account for distribution as a Special Payment in accordance with the provisions
hereof.

            Section 2.03. Acceptance by Trustee. The Trustee, upon the execution
and delivery of a Trust Supplement creating a Trust and establishing a series of
Certificates, shall acknowledge its acceptance of all right, title and interest
in and to the Trust Property to be acquired pursuant to Section 2.02 hereof and
the related Note Purchase Agreements and shall declare that the Trustee holds
and will hold such right, title and interest for the benefit of all then present
and future Certificateholders of such series, upon the trusts herein and in such
Trust Supplement set forth. By the acceptance of each Certificate of such series
issued to it under this Agreement, each initial Holder of such series as grantor
of such Trust shall thereby join in the creation and declaration of such Trust.

            Section 2.04. Limitation of Powers. Each Trust shall be constituted
solely for the purpose of making the investment in the Equipment Notes provided
for in the related Trust Supplement, and, except as set forth herein, the
Trustee shall not be authorized or empowered to acquire any other investments or
engage in any other activities and, in particular, the Trustee shall not be
authorized or empowered to do anything that would cause such Trust to fail to
qualify as a "grantor trust" for federal income tax purposes (including, as
subject to this restriction, acquiring any Aircraft (as defined in the
respective Indentures) by bidding such Equipment Notes or otherwise, or taking
any action with respect to any such Aircraft once acquired).


                                   ARTICLE III

                                THE CERTIFICATES

            Section 3.01. Form, Denomination and Execution of Certificates. The
Certificates of each series shall be issued in fully registered form without
coupons and shall be substantially in the form attached hereto as Exhibit A,
with such omissions, variations and insertions as are permitted by this
Agreement, and may have such letters, numbers or other marks
<PAGE>
                                                                              18


of identification and such legends or endorsements placed thereon as may be
required to comply with the rules of any securities exchange on which such
Certificates may be listed or to conform to any usage in respect thereof, or as
may, consistently herewith, be determined by the Trustee or the officers
executing such Certificates, as evidenced by the Trustee's or respective
officers' execution of the Certificates.

            Except as provided in Section 3.05, the definitive Certificates of
such series shall be typed, printed, lithographed or engraved or produced by any
combination of these methods or may be produced in any other manner permitted by
the rules of any securities exchange on which the Certificates may be listed,
all as determined by the officers executing such Certificates, as evidenced by
their execution of such Certificates.

            Except as otherwise provided in the related Trust Supplement, the
Certificates of each series shall be issued in minimum denominations of $1,000
or integral multiples thereof except that one Certificate of such series may be
issued in a different denomination.

            The Certificates of such series shall be executed on behalf of the
Trustee by manual or facsimile signature of a Responsible Officer of the
Trustee. Certificates of any series bearing the manual or facsimile signature of
an individual who was, at the time when such signature was affixed, authorized
to sign on behalf of the Trustee shall be valid and binding obligations of the
Trustee, notwithstanding that such individual has ceased to be so authorized
prior to the authentication and delivery of such Certificates or did not hold
such office at the date of such Certificates.

            Section 3.02. Authentication of Certificates. (a) On the Issuance
Date, the Trustee shall duly execute, authenticate and deliver Certificates of
each series in authorized denominations equalling in the aggregate the aggregate
principal amount of the Equipment Notes that may be purchased by the Trustee
pursuant to the related Note Purchase Agreements, and evidencing the entire
ownership of the related Trust. Thereafter, the Trustee shall duly execute,
authenticate and deliver the Certificates of such series as herein provided.

            (b) No Certificate of any series shall be entitled to any benefit
under this Agreement, or be valid for any purpose, unless there appears on such
Certificate a certificate of authentication substantially in the form set forth
in Exhibit A hereto executed by the Trustee by manual signature, and such
certificate of authentication upon any Certificate shall be conclusive evidence,
and the only evidence, that such Certificate has been duly authenticated and
delivered hereunder. All Certificates of any series shall be dated the date of
their authentication.

            Section 3.03. Temporary Certificates. Until definitive Certificates
are ready for delivery, the Trustee shall execute, authenticate and deliver
temporary Certificates of each series. Temporary Certificates of each series
shall be substantially in the form of definitive Certificates of such series but
may have insertions, substitutions, omissions and other variations determined to
be appropriate by the officers executing the temporary Certificates of such
series, as evidenced by their execution of such temporary Certificates. If
temporary Certificates of any series are issued, the Trustee will cause
definitive Certificates of such series to be prepared without unreasonable
delay. After the preparation of definitive Certificates of such series, the
temporary
<PAGE>
                                                                              19

Certificates shall be exchangeable for definitive Certificates upon surrender of
such temporary Certificates at the office or agency of the Trustee designated
for such purpose pursuant to Section 7.12, without charge to the
Certificateholder. Upon surrender for cancellation of any one or more temporary
Certificates, the Trustee shall execute, authenticate and deliver in exchange
therefor a like face amount of definitive Certificates of like series, in
authorized denominations and of a like Fractional Undivided Interest. Until so
exchanged, such temporary Certificates shall be entitled to the same benefits
under this Agreement as definitive Certificates.

            Section 3.04. Transfer and Exchange. The Trustee shall cause to be
kept at the office or agency to be maintained by it in accordance with the
provisions of Section 7.12 a register (the "Register") for each series of
Certificates in which, subject to such reasonable regulations as it may
prescribe, the Trustee shall provide for the registration of Certificates of
such series and of transfers and exchanges of such Certificates as herein
provided. The Trustee shall initially be the registrar (the "Registrar") for the
purpose of registering such Certificates of each series and transfers and
exchanges of such Certificates as herein provided.

            All Certificates issued upon any registration of transfer or
exchange of Certificates of any series shall be valid obligations of the
applicable Trust, evidencing the same interest therein, and entitled to the same
benefits under this Agreement, as the Certificates of such series surrendered
upon such registration of transfer or exchange.

            Upon surrender for registration of transfer of any Certificate at
the Corporate Trust Office or such other office or agency, the Trustee shall
execute, authenticate and deliver, in the name of the designated transferee or
transferees, one or more new Certificates of like series, in authorized
denominations of a like aggregate Fractional Undivided Interest.

            At the option of a Certificateholder, Certificates may be exchanged
for other Certificates of like series, in authorized denominations and of a like
aggregate Fractional Undivided Interest, upon surrender of the Certificates to
be exchanged at any such office or agency. Whenever any Certificates are so
surrendered for exchange, the Trustee shall execute, authenticate and deliver
the Certificates that the Certificateholder making the exchange is entitled to
receive. Every Certificate presented or surrendered for registration of transfer
or exchange shall be duly endorsed or accompanied by a written instrument of
transfer in form satisfactory to the Trustee and the Registrar duly executed by
the Certificateholder thereof or its attorney duly authorized in writing.

            No service charge shall be made to a Certificateholder for any
registration of transfer or exchange of Certificates, but the Trustee shall
require payment of a sum sufficient to cover any tax or governmental charge that
may be imposed in connection with any transfer or exchange of Certificates. All
Certificates surrendered for registration of transfer or exchange shall be
cancelled and subsequently destroyed by the Trustee.

            Section 3.05. Book-Entry and Definitive Certificates. (a) The
Certificates of any series may be issued in the form of one or more typewritten
Certificates representing the Book-Entry Certificates of such series, to be
delivered to The Depository Trust Company, the initial Clearing Agency, by, or
on behalf of, the Company. In such case, the Certificates of such series


<PAGE>
                                                                              20
delivered to The Depository Trust Company shall initially be registered on the
Register in the name of CEDE & Co., the nominee of the initial Clearing Agency,
and no Certificate Owner will receive a definitive certificate representing such
Certificate Owner's interest in the Certificates of such series, except as
provided above and in Subsection (d) below. As to the Certificates of any
series, unless and until definitive, fully registered Certificates (the
"Definitive Certificates") have been issued pursuant to Subsection (d) below:

            (i)   the provisions of this Section 3.05 shall be in full force
      and effect;

            (ii) the Company, the Paying Agent, the Registrar and the Trustee
      may deal with the Clearing Agency Participants for all purposes (including
      the making of distributions on the Certificates) as the authorized
      representatives of the Certificate Owners;

            (iii) to the extent that the provisions of this Section 3.05
      conflict with any other provisions of this Agreement (other than the
      provisions of any Trust Supplement expressly amending this Section 3.05 as
      permitted by this Basic Agreement), the provisions of this Section 3.05
      shall control;

            (iv) the rights of Certificate Owners shall be exercised only
      through the Clearing Agency and shall be limited to those established by
      law and agreements between such Certificate Owners and the Clearing Agency
      Participants; and until Definitive Certificates are issued pursuant to
      Subsection (d) below, the Clearing Agency will make book-entry transfers
      among the Clearing Agency Participants and receive and transmit
      distributions of principal, interest and premium, if any, on the
      Certificates to such Clearing Agency Participants; and

            (v) whenever this Agreement requires or permits actions to be taken
      based upon instructions or directions of Certificateholders of such series
      holding Certificates of such series evidencing a specified percentage of
      the Fractional Undivided Interests in the related Trust, the Clearing
      Agency shall be deemed to represent such percentage only to the extent
      that it has received instructions to such effect from Clearing Agency
      Participants owning or representing, respectively, such required
      percentage of the beneficial interest in Certificates of such series and
      has delivered such instructions to the Trustee. The Trustee shall have no
      obligation to determine whether the Clearing Agency has in fact received
      any such instructions.

            (b) Whenever notice or other communication to the Certificateholders
of such series is required under this Agreement, unless and until Definitive
Certificates shall have been issued pursuant to Subsection (d) below, the
Trustee shall give all such notices and communications specified herein to be
given to Certificateholders of such series to the Clearing Agency.

            (c) Unless and until Definitive Certificates of a series are issued
pursuant to Subsection (d) below, on the Record Date prior to each applicable
Regular Distribution Date and Special Distribution Date, the Trustee will
request from the Clearing Agency a securities position
<PAGE>
                                                                              21

listing setting forth the names of all Clearing Agency Participants reflected on
the Clearing Agency's books as holding interests in the Certificates on such
Record Date.

            (d) If with respect to the Certificates of any series (i) the
Company advises the Trustee in writing that the Clearing Agency is no longer
willing or able to discharge properly its responsibilities and the Trustee or
the Company is unable to locate a qualified successor, (ii) the Company, at its
option, advises the Trustee in writing that it elects to terminate the
book-entry system through the Clearing Agency or (iii) after the occurrence of
an Event of Default, Certificate Owners of Book-Entry Certificates of such
series evidencing Fractional Undivided Interests aggregating not less than a
majority in interest in the related Trust, by Act of such Certificate Owners
delivered to the Company and the Trustee, advise the Company, the Trustee and
the Clearing Agency through the Clearing Agency Participants in writing that the
continuation of a book-entry system through the Clearing Agency Participants is
no longer in the best interests of the Certificate Owners of such series, then
the Trustee shall notify all Certificate Owners of such series, through the
Clearing Agency, of the occurrence of any such event and of the availability of
Definitive Certificates. Upon surrender to the Trustee of all the Certificates
of such series held by the Clearing Agency, accompanied by registration
instructions from the Clearing Agency Participants for registration of
Definitive Certificates in the names of Certificate Owners of such series, the
Trustee shall issue and deliver the Definitive Certificates of such series in
accordance with the instructions of the Clearing Agency. Neither the Company,
the Registrar, the Paying Agent nor the Trustee shall be liable for any delay in
delivery of such instructions and may conclusively rely on, and shall be
protected in relying on, such registration instructions. Upon the issuance of
Definitive Certificates of such series, the Trustee shall recognize the Person
in whose name the Definitive Certificates are registered in the Register as
Certificateholders hereunder. Neither the Company nor the Trustee shall be
liable if the Trustee or the Company is unable to locate a qualified successor
Clearing Agency.

            (e) Except as otherwise provided in the related Trust Supplement,
the Trustee shall enter into the applicable Letter of Representations with
respect to such series of Certificates and fulfill its responsibilities
thereunder.

            (f) The provisions of this Section 3.05 may be made inapplicable to
any series or may be amended with respect to any series in the related Trust
Supplement.

            Section 3.06. Mutilated, Destroyed, Lost or Stolen Certificates. If
(a) any mutilated Certificate is surrendered to the Registrar, or the Registrar
receives evidence to its satisfaction of the destruction, loss or theft of any
Certificate, and (b) there is delivered to the Registrar and the Trustee such
security, indemnity or bond, as may be required by them to save each of them
harmless, then, in the absence of notice to the Registrar or the Trustee that
such destroyed, lost or stolen Certificate has been acquired by a bona fide
purchaser, and provided, however, that the requirements of Section 8-405 of the
Uniform Commercial Code in effect in any applicable jurisdiction are met, the
Trustee shall execute, authenticate and deliver, in exchange for or in lieu of
any such mutilated, destroyed, lost or stolen Certificate, a new Certificate or
Certificates of like series, in authorized denominations and of like Fractional
Undivided Interest and bearing a number not contemporaneously outstanding.
<PAGE>
                                                                              22

            In connection with the issuance of any new Certificate under this
Section 3.06, the Trustee shall require the payment of a sum sufficient to cover
any tax or other governmental charge that may be imposed in relation thereto and
any other expenses (including the fees and expenses of the Trustee and the
Registrar) connected therewith.

            Any duplicate Certificate issued pursuant to this Section 3.06 shall
constitute conclusive evidence of the appropriate Fractional Undivided Interest
in the related Trust, as if originally issued, whether or not the lost, stolen
or destroyed Certificate shall be found at any time.

            The provisions of this Section 3.06 are exclusive and shall preclude
(to the extent lawful) all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Certificates.

            Section 3.07. Persons Deemed Owners. Prior to due presentment of a
Certificate for registration of transfer, the Trustee, the Registrar and any
Paying Agent may treat the Person in whose name any Certificate is registered
(as of the day of determination) as the owner of such Certificate for the
purpose of receiving distributions pursuant to Article IV and for all other
purposes whatsoever, and none of the Trustee, the Registrar or any Paying Agent
shall be affected by any notice to the contrary.

            Section 3.08. Cancellation. All Certificates surrendered for payment
or transfer or exchange shall, if surrendered to the Trustee or any agent of the
Trustee other than the Registrar, be delivered to the Registrar for cancellation
and shall promptly be cancelled by it. No Certificates shall be authenticated in
lieu of or in exchange for any Certificates cancelled as provided in this
Section 3.08, except as expressly permitted by this Agreement. All cancelled
Certificates held by the Registrar shall be destroyed and a certification of
their destruction delivered to the Trustee.

            Section 3.09. Limitation of Liability for Payments. All payments and
distributions made to Certificateholders of any series in respect of the
Certificates of such series shall be made only from the Trust Property of the
related Trust and only to the extent that the Trustee shall have sufficient
income or proceeds from such Trust Property to make such payments in accordance
with the terms of Article IV of this Agreement. Each Certificateholder, by its
acceptance of a Certificate, agrees that it will look solely to the income and
proceeds from the Trust Property of the related Trust for any payment or
distribution due to such Certificateholder pursuant to the terms of this
Agreement and that it will not have any recourse to the Company, the Trustee,
the Loan Trustees, the Owner Trustees or the Owner Participants, except as
otherwise expressly provided herein or in the related Intercreditor Agreement.

            The Company is a party to this Agreement solely for purposes of
meeting the requirements of the Trust Indenture Act, and therefore shall not
have any right, obligation or liability hereunder (except as otherwise expressly
provided herein).
<PAGE>
                                                                              23
                                   ARTICLE IV

                          DISTRIBUTIONS; STATEMENTS TO
                               CERTIFICATEHOLDERS

            Section 4.01. Certificate Account and Special Payments Account. (a)
The Trustee shall establish and maintain on behalf of the Certificateholders of
each series a Certificate Account as one or more non-interest-bearing accounts.
The Trustee shall hold such Certificate Account in trust for the benefit of the
Certificateholders of such series, and shall make or permit withdrawals
therefrom only as provided in this Agreement. On each day when a Scheduled
Payment is made to the Trustee (under an Intercreditor Agreement, if applicable)
with respect to the Certificates of such series, the Trustee, upon receipt
thereof, shall immediately deposit the aggregate amount of such Scheduled
Payment in such Certificate Account.

            (b) The Trustee shall establish and maintain on behalf of the
Certificateholders of each series a Special Payments Account as one or more
accounts, which shall be non-interest bearing except as provided in Section
4.04. The Trustee shall hold the Special Payments Account in trust for the
benefit of the Certificateholders of such series and shall make or permit
withdrawals therefrom only as provided in this Agreement. On each day when one
or more Special Payments are made to the Trustee (under an Intercreditor
Agreement, if applicable) with respect to the Certificates of such series, the
Trustee, upon receipt thereof, shall immediately deposit the aggregate amount of
such Special Payments in such Special Payments Account.

            (c) The Trustee shall present (or, if applicable, cause the
Subordination Agent to present) to the related Loan Trustee of each Equipment
Note such Equipment Note on the date of its stated final maturity or, in the
case of any Equipment Note which is to be redeemed in whole pursuant to the
related Indenture, on the applicable redemption date under such Indenture.

            Section 4.02. Distributions from Certificate Account and Special
Payments Account. (a) On each Regular Distribution Date with respect to a series
of Certificates or as soon thereafter as the Trustee has confirmed receipt of
the payment of all or any part of the Scheduled Payments due on the Equipment
Notes held (subject to the Intercreditor Agreement) in the related Trust on such
date, the Trustee shall distribute out of the applicable Certificate Account the
entire amount deposited therein pursuant to Section 4.01(a). There shall be so
distributed to each Certificateholder of record of such series on the Record
Date with respect to such Regular Distribution Date (other than as provided in
Section 11.01 concerning the final distribution) by check mailed to such
Certificateholder, at the address appearing in the Register, such
Certificateholder's pro rata share (based on the Fractional Undivided Interest
in the Trust held by such Certificateholder) of the total amount in the
applicable Certificate Account, except that, with respect to Certificates
registered on the Record Date in the name of a Clearing Agency (or its nominee),
such distribution shall be made by wire transfer in immediately available funds
to the account designated by such Clearing Agency (or such nominee).

            (b) On each Special Distribution Date with respect to any Special
Payment with respect to a series of Certificates or as soon thereafter as the
Trustee has confirmed receipt
<PAGE>
                                                                              24

of any Special Payments due on the Equipment Notes held (subject to the
Intercreditor Agreement) in the related Trust or realized upon the sale of such
Equipment Notes, the Trustee shall distribute out of the applicable Special
Payments Account the entire amount of such applicable Special Payment deposited
therein pursuant to Section 4.01(b). There shall be so distributed to each
Certificateholder of record of such series on the Record Date with respect to
such Special Distribution Date (other than as provided in Section 11.01
concerning the final distribution) by check mailed to such Certificateholder, at
the address appearing in the Register, such Certificateholder's pro rata share
(based on the Fractional Undivided Interest in the related Trust held by such
Certificateholder) of the total amount in the applicable Special Payments
Account on account of such Special Payment, except that, with respect to
Certificates registered on the Record Date in the name of a Clearing Agency (or
its nominee), such distribution shall be made by wire transfer in immediately
available funds to the account designated by such Clearing Agency (or such
nominee).

            (c) The Trustee shall, at the expense of the Company, cause notice
of each Special Payment with respect to a series of Certificates to be mailed to
each Certificateholder of such series at his address as it appears in the
Register. In the event of redemption or purchase of Equipment Notes held in the
related Trust, such notice shall be mailed not less than 15 days prior to the
Special Distribution Date for the Special Payment resulting from such redemption
or purchase, which Special Distribution Date shall be the date of such
redemption or purchase. In the event that the Trustee receives a notice from the
Company that Postponed Notes will not be purchased by the Trustee pursuant to
Section 2.02, such notice of Special Payment shall be mailed as soon as
practicable after receipt of such notice from the Company and shall state the
Special Distribution Date for such Special Payment, which shall occur 15 days
after the date of such notice of Special Payment or (if such 15th day is not
practicable) as soon as practicable thereafter. In the event that any Special
Payment is to be made pursuant to the last paragraph of Section 2.02(b) hereof,
there shall be mailed on the Cut-off Date (or, if such mailing on the Cut-off
Date is not practicable, as soon as practicable after the Cut-off Date), notice
of such Special Payment stating the Special Distribution Date for such Special
Payment, which shall occur 15 days after the date of such notice of such Special
Payment (or, if such 15th day is not practicable, as soon as practicable
thereafter). In the case of any other Special Payments, such notice shall be
mailed as soon as practicable after the Trustee has confirmed that it has
received funds for such Special Payment, stating the Special Distribution Date
for such Special Payment which shall occur not less than 15 days after the date
of such notice and as soon as practicable thereafter. Notices mailed by the
Trustee shall set forth:

            (i)   the Special Distribution Date and the Record Date therefor
      (except as otherwise provided in Section 11.01),

            (ii) the amount of the Special Payment (taking into account any
      payment to be made by the Company pursuant to Section 2.02(b)) for each
      $1,000 face amount Certificate and the amount thereof constituting
      principal, premium, if any, and interest,

            (iii) the reason for the Special Payment, and
<PAGE>
                                                                              25


            (iv) if the Special Distribution Date is the same date as a Regular
      Distribution Date for the Certificates of such series, the total amount to
      be received on such date for each $1,000 face amount Certificate.

If the amount of premium, if any, payable upon the redemption or purchase of an
Equipment Note has not been calculated at the time that the Trustee mails notice
of a Special Payment, it shall be sufficient if the notice sets forth the other
amounts to be distributed and states that any premium received will also be
distributed.

            If any redemption of the Equipment Notes held in any Trust is
cancelled, the Trustee, as soon as possible after learning thereof, shall cause
notice thereof to be mailed to each Certificateholder of the related series at
its address as it appears on the Register.

            Section 4.03. Statements to Certificateholders. (a) On each Regular
Distribution Date and Special Distribution Date, the Trustee will include with
each distribution of a Scheduled Payment or Special Payment, as the case may be,
to Certificateholders of the related series a statement setting forth the
information provided below. Such statement shall set forth (per $1,000 aggregate
principal amount of Certificate as to (i) and (ii) below) the following
information:

            (i)   the amount of such distribution hereunder allocable to
      principal and the amount allocable to premium, if any;

            (ii)  the amount of such distribution hereunder allocable to
      interest; and

            (iii) the Pool Balance and the Pool Factor of the related Trust.

            With respect to the Certificates registered in the name of a
Clearing Agency or its nominee, on the Record Date prior to each Distribution
Date, the Trustee will request from the Clearing Agency a securities position
listing setting forth the names of all the Clearing Agency Participants
reflected on the Clearing Agency's books as holding interests in the
Certificates on such Record Date. On each Distribution Date, the applicable
Trustee will mail to each such Clearing Agency Participant the statement
described above and will make available additional copies as requested by such
Clearing Agency Participant for forwarding to holders of interests in the
Certificates.

            (b) Within a reasonable period of time after the end of each
calendar year but not later than the latest date permitted by law, the Trustee
shall furnish to each Person who at any time during such calendar year was a
Certificateholder of record a statement containing the sum of the amounts
determined pursuant to clauses (a)(i) and (a)(ii) above with respect to the
related Trust for such calendar year or, in the event such Person was a
Certificateholder of record during a portion of such calendar year, for the
applicable portion of such year, and such other items as are readily available
to the Trustee and which a Certificateholder shall reasonably request as
necessary for the purpose of such Certificateholder's preparation of its federal
income tax returns. With respect to Certificates registered in the name of a
Clearing Agency or its nominee, such statement and such other items shall be
prepared on the basis of information supplied to the
<PAGE>
                                                                              26

Trustee by the Clearing Agency Participants and shall be delivered by the
Trustee to such Clearing Agency Participants to be available for forwarding by
such Clearing Agency Participants to the holders of interests in the
Certificates in the manner described in Section 4.03(a).

            Section 4.04. Investment of Special Payment Moneys. Any money
received by the Trustee pursuant to Section 4.01(b) representing a Special
Payment which is not distributed on the date received shall, to the extent
practicable, be invested in Permitted Investments by the Trustee pending
distribution of such Special Payment pursuant to Section 4.02. Any investment
made pursuant to this Section 4.04 shall be in such Permitted Investments having
maturities not later than the date that such moneys are required to be used to
make the payment required under Section 4.02 on the applicable Special
Distribution Date and the Trustee shall hold any such Permitted Investments
until maturity. The Trustee shall have no liability with respect to any
investment made pursuant to this Section 4.04, other than by reason of the
willful misconduct or negligence of the Trustee. All income and earnings from
such investments shall be distributed on such Special Distribution Date as part
of such Special Payment.


                                    ARTICLE V

                                   THE COMPANY

            Section 5.01. Maintenance of Corporate Existence. The Company, at
its own cost and expense, will do or cause to be done all things necessary to
preserve and keep in full force and effect its corporate existence, rights and
franchises, except as otherwise specifically permitted in Section 5.02;
provided, however, that the Company shall not be required to preserve any right
or franchise if the Company shall determine that the preservation thereof is no
longer desirable in the conduct of the business of the Company.

            Section 5.02. Consolidation, Merger, Etc. The Company shall not
consolidate with or merge into any other corporation or convey, transfer or
lease substantially all of its assets as an entirety to any Person unless:

            (a) the corporation formed by such consolidation or into which the
      Company is merged or the Person that acquires by conveyance, transfer or
      lease substantially all of the assets of the Company as an entirety shall
      be (i) organized and validly existing under the laws of the United States
      of America or any state thereof or the District of Columbia, (ii) a
      "citizen of the United States" as defined in 49 U.S.C. Section
      40102(a)(15), as amended, and (iii) a United States certificated air
      carrier, if and so long as such status is a condition of entitlement to
      the benefits of Section 1110 of the Bankruptcy Reform Act of 1978, as
      amended (11 U.S.C. Section 1110), with respect to the Leases or the
      Aircraft owned by the Company;

            (b) the corporation formed by such consolidation or into which the
      Company is merged or the Person which acquires by conveyance, transfer or
      lease substantially all of the assets of the Company as an entirety shall
      execute and deliver to the Trustee
<PAGE>
                                                                              27

      applicable to the Certificates of each series a duly authorized, valid,
      binding and enforceable agreement in form and substance reasonably
      satisfactory to the Trustee containing an assumption by such successor
      corporation or Person of the due and punctual performance and observance
      of each covenant and condition of the Note Documents and of this Agreement
      applicable to the Certificates of each series to be performed or observed
      by the Company; and

            (c) the Company shall have delivered to the Trustee an Officer's
      Certificate of the Company and an Opinion of Counsel of the Company
      reasonably satisfactory to the Trustee, each stating that such
      consolidation, merger, conveyance, transfer or lease and the assumption
      agreement mentioned in clause (b) above comply with this Section 5.02 and
      that all conditions precedent herein provided for relating to such
      transaction have been complied with.

            Upon any consolidation or merger, or any conveyance, transfer or
lease of substantially all of the assets of the Company as an entirety in
accordance with this Section 5.02, the successor corporation or Person formed by
such consolidation or into which the Company is merged or to which such
conveyance, transfer or lease is made shall succeed to, and be substituted for,
and may exercise every right and power of, the Company under this Agreement
applicable to the Certificates of each series with the same effect as if such
successor corporation or Person had been named as the Company herein. No such
conveyance, transfer or lease of substantially all of the assets of the Company
as an entirety shall have the effect of releasing any successor corporation or
Person which shall have become such in the manner prescribed in this Section
5.02 from its liability in respect of this Agreement and any Note Document
applicable to the Certificates of such series to which it is a party.


                                   ARTICLE VI

                                     DEFAULT

            Section 6.01. Events of Default. (a) Exercise of Remedies. Upon the
occurrence and during the continuation of any Indenture Event of Default under
any Indenture, the Trustee may (i) to the extent it is the Controlling Party at
such time (as determined pursuant to the related Intercreditor Agreement),
direct the exercise of remedies as provided in such related Intercreditor
Agreement and (ii) if there is no related Intercreditor Agreement, direct the
exercise of remedies or take other action as provided in the relevant Indenture
to the extent that it may do so as the holder of the Equipment Notes issued
under such Indenture and held in the related Trust.

            (b) Purchase Rights of Certificateholders. At any time after the
occurrence and during the continuation of a Triggering Event, each
Certificateholder of Certificates of certain series (each, a "Potential
Purchaser" and, collectively, the "Potential Purchasers") will have certain
rights to purchase the Certificates of one or more other series, all as set
forth in the Trust Supplement applicable to the Certificates held by such
Potential Purchaser. The purchase price with respect to the Certificates of any
series shall be equal to the Pool Balance of the Certificates of such series,
together with accrued and unpaid interest thereon to the date of such
<PAGE>
                                                                              28

      purchase, without premium, but including any other amounts then due and
      payable to the Certificateholders of such series under this Agreement, any
      related Intercreditor Agreement or any other Note Document or on or in
      respect of the Certificates of such series; provided, however, that if
      such purchase occurs after a Record Date, such purchase price shall be
      reduced by the amount to be distributed hereunder on the related
      Distribution Date (which deducted amounts shall remain distributable to,
      and may be retained by, the Certificateholder as of such Record Date);
      provided, further, that no such purchase of Certificates of such series
      shall be effective unless the purchasing Certificateholder (each, a
      "Purchasing Certificateholder" and, collectively, the "Purchasing
      Certificateholders") shall certify to the Trustee that contemporaneously
      with such purchase, one or more Purchasing Certificateholders are
      purchasing, pursuant to the terms of this Agreement and the other
      Agreements, if any, relating to the Certificates of a series that are
      subject to the same Intercreditor Agreement (such other Agreements, the
      "Other Agreements"), the Certificates of each such series that the Trust
      Supplement applicable to the Certificates held by the Purchasing
      Certificateholder specifies may be purchased by such Purchasing
      Certificateholder. Each payment of the purchase price of the Certificates
      of any series shall be made to an account or accounts designated by the
      Trustee and each such purchase shall be subject to the terms of this
      Section 6.01. By acceptance of its Certificate, each Certificateholder
      (each, a "Selling Certificateholder" and, collectively, the "Selling
      Certificateholders") of a series that is subject to purchase by Potential
      Purchasers, all as set forth in the Trust Supplement applicable to the
      Certificates held by the Selling Certificateholders, agrees that, at any
      time after the occurrence and during the continuance of a Triggering
      Event, it will, upon payment of the purchase price specified herein by one
      or more Purchasing Certificateholders, forthwith sell, assign, transfer
      and convey to such Purchasing Certificateholder (without recourse,
      representation or warranty of any kind except for its own acts), all of
      the right, title, interest and obligation of such Selling
      Certificateholder in this Agreement, any related Intercreditor Agreement,
      the related Liquidity Facility, the related Note Documents and all
      Certificates of such series held by such Selling Certificateholder
      (excluding all right, title and interest under any of the foregoing to the
      extent such right, title or interest is with respect to an obligation not
      then due and payable as respects any action or inaction or state of
      affairs occurring prior to such sale) and the Purchasing Certificateholder
      shall assume all of such Selling Certificateholder's obligations under
      this Agreement, any related Intercreditor Agreement, the related Liquidity
      Facility and the related Note Documents. The Certificates of such series
      will be deemed to be purchased on the date payment of the purchase price
      is made notwithstanding the failure of any Selling Certificateholder to
      deliver any Certificates of such series and, upon such a purchase, (i) the
      only rights of the Selling Certificateholders will be to deliver the
      Certificates to the Purchasing Certificateholder and receive the purchase
      price for such Certificates of such series and (ii) if the Purchasing
      Certificateholder shall so request, such Selling Certificateholder will
      comply with all of the provisions of Section 3.04 hereof to enable new
      Certificates of such series to be issued to the Purchasing
      Certificateholder in such denominations as it shall request. All charges
      and expenses in connection with the issuance of any such new Certificates
      shall be borne by the Purchasing Certificateholder.

            Section 6.02. Incidents of Sale of Equipment Notes. Upon any sale of
all or any part of the Equipment Notes held in the Trust made either under the
power of sale given under
<PAGE>
                                                                              29

      this Agreement or otherwise for the enforcement of this Agreement, the
      following shall be applicable:

            (1) Certificateholders and Trustee May Purchase Equipment Notes. Any
      Certificateholder, the Trustee in its individual or any other capacity or
      any other Person may bid for and purchase any of the Equipment Notes held
      in the Trust, and upon compliance with the terms of sale, may hold,
      retain, possess and dispose of such Equipment Notes in their own absolute
      right without further accountability.

            (2) Receipt of Trustee Shall Discharge Purchaser. The receipt of the
      Trustee making such sale shall be a sufficient discharge to any purchaser
      for his purchase money, and, after paying such purchase money and
      receiving such receipt, such purchaser or its personal representative or
      assigns shall not be obliged to see to the application of such purchase
      money, or be in any way answerable for any loss, misapplication or
      non-application thereof.

            (3) Application of Moneys Received upon Sale. Any moneys collected
      by the Trustee upon any sale made either under the power of sale given by
      this Agreement or otherwise for the enforcement of this Agreement shall be
      applied as provided in Section 4.02.

            Section 6.03. Judicial Proceedings Instituted by Trustee; Trustee
May Bring Suit. If there shall be a failure to make payment of the principal of,
premium, if any, or interest on any Equipment Note held in the related Trust, or
if there shall be any failure to pay Rent (as defined in the relevant Lease)
under any Lease when due and payable, then the Trustee, in its own name and as
trustee of an express trust, as holder of such Equipment Notes, to the extent
permitted by and in accordance with the terms of any related Intercreditor
Agreement and any related Note Documents (subject to rights of the applicable
Owner Trustee or Owner Participant to cure any such failure to pay principal of,
premium, if any, or interest on any Equipment Note or to pay Rent under any
Lease in accordance with the applicable Indenture), shall be entitled and
empowered to institute any suits, actions or proceedings at law, in equity or
otherwise, for the collection of the sums so due and unpaid on such Equipment
Notes or under such Lease and may prosecute any such claim or proceeding to
judgment or final decree with respect to the whole amount of any such sums so
due and unpaid.

            Section 6.04. Control by Certificateholders. Subject to Section 6.03
and any related Intercreditor Agreement, the Certificateholders holding
Certificates of a series evidencing Fractional Undivided Interests aggregating
not less than a majority in interest in the related Trust shall have the right
to direct the time, method and place of conducting any proceeding for any remedy
available to the Trustee with respect to such Trust or pursuant to the terms of
such Intercreditor Agreement, or exercising any trust or power conferred on the
Trustee under this Agreement or such Intercreditor Agreement, including any
right of the Trustee as Controlling Party under such Intercreditor Agreement or
as holder of the Equipment Notes held in the related Trust; provided, however,
that
<PAGE>
                                                                              30

            (1) such Direction shall not in the opinion of the Trustee be in
      conflict with any rule of law or with this Agreement and would not involve
      the Trustee in personal liability or expense,

            (2) the Trustee shall not determine that the action so directed
      would be unjustly prejudicial to the Certificateholders of such series not
      taking part in such Direction, and

            (3) the Trustee may take any other action deemed proper by the
      Trustee which is not inconsistent with such Direction.

            Section 6.05. Waiver of Past Defaults. Subject to any related
Intercreditor Agreement, the Certificateholders holding Certificates of a series
evidencing Fractional Undivided Interests aggregating not less than a majority
in interest in the Trust (i) may on behalf of all of the Certificateholders
waive any past Event of Default hereunder and its consequences or (ii) if the
Trustee is the Controlling Party, may direct the Trustee to instruct the
applicable Loan Trustee to waive any past Indenture Event of Default under any
related Indenture and its consequences, and thereby annul any Direction given by
such Certificateholders or the Trustee to such Loan Trustee with respect
thereto, except a default:

            (1) in the deposit of any Scheduled Payment or Special Payment under
      Section 4.01 or in the distribution of any payment under Section 4.02 on
      the Certificates of a series, or

            (2)   in the payment of the principal of (premium, if any) or
      interest on the Equipment Notes held in the related Trust, or

            (3) in respect of a covenant or provision hereof which under Article
      IX hereof cannot be modified or amended without the consent of each
      Certificateholder holding an Outstanding Certificate of a series affected
      thereby.

Upon any such waiver, such default shall cease to exist with respect to the
Certificates of such series and any Event of Default arising therefrom shall be
deemed to have been cured for every purpose and any direction given by the
Trustee on behalf of the Certificateholders of such series to the relevant Loan
Trustee shall be annulled with respect thereto; but no such waiver shall extend
to any subsequent or other default or Event of Default or impair any right
consequent thereon. Upon any such waiver, the Trustee shall vote the Equipment
Notes issued under the relevant Indenture to waive the corresponding Indenture
Event of Default.

            Section 6.06. Right of Certificateholders to Receive Payments Not to
Be Impaired. Anything in this Agreement to the contrary notwithstanding,
including, without limitation, Section 6.07 hereof, but subject to any related
Intercreditor Agreement, the right of any Certificateholder to receive
distributions of payments required pursuant to Section 4.02 hereof on the
applicable Certificates when due, or to institute suit for the enforcement of
any such payment on or after the applicable Regular Distribution Date or Special
Distribution Date, shall not be impaired or affected without the consent of such
Certificateholder.
<PAGE>
                                                                              31

            Section 6.07. Certificateholders May Not Bring Suit Except Under
Certain Conditions. A Certificateholder of any series shall not have the right
to institute any suit, action or proceeding at law or in equity or otherwise
with respect to this Agreement, for the appointment of a receiver or for the
enforcement of any other remedy under this Agreement, unless:

            (1)   such Certificateholder previously shall have given written
      notice to the Trustee of a continuing Event of Default;

            (2) Certificateholders holding Certificates of such series
      evidencing Fractional Undivided Interests aggregating not less than 25% of
      the related Trust shall have requested the Trustee in writing to institute
      such action, suit or proceeding and shall have offered to the Trustee
      indemnity as provided in Section 7.03(e);

            (3) the Trustee shall have refused or neglected to institute any
      such action, suit or proceeding for 60 days after receipt of such notice,
      request and offer of indemnity; and

            (4) no direction inconsistent with such written request shall have
      been given to the Trustee during such 60-day period by Certificateholders
      holding Certificates of such series evidencing Fractional Undivided
      Interests aggregating not less than a majority in interest in the related
      Trust.

            It is understood and intended that no one or more of the
Certificateholders of any series shall have any right in any manner whatsoever
hereunder or under the related Trust Supplement or under the Certificates of
such series to (i) surrender, impair, waive, affect, disturb or prejudice any
property in the Trust Property of the related Trust, or the lien of any related
Indenture on any property subject thereto, or the rights of the
Certificateholders of such series or the holders of the related Equipment Notes,
(ii) obtain or seek to obtain priority over or preference with respect to any
other such Certificateholder of such series or (iii) enforce any right under
this Agreement, except in the manner herein provided and for the equal, ratable
and common benefit of all the Certificateholders of such series subject to the
provisions of this Agreement.

            Section 6.08. Remedies Cumulative. Every remedy given hereunder to
the Trustee or to any of the Certificateholders of any series shall not be
exclusive of any other remedy or remedies, and every such remedy shall be
cumulative and in addition to every other remedy given hereunder or now or
hereafter given by statute, law, equity or otherwise.

            Section 6.09. Undertaking for Costs. In any suit for the enforcement
of any right or remedy under this Agreement, or in any suit against the Trustee
for any action taken, suffered or omitted by it as Trustee, a court may require
any party litigant in such suit to file an undertaking to pay the costs of such
suit, and may assess costs against any such party litigant, in the manner and to
the extent provided in the Trust Indenture Act; provided, however, that neither
this Section 6.09 nor the Trust Indenture Act shall be deemed to authorize any
court to require such an undertaking or to make such an assessment in any suit
instituted by the Company.
<PAGE>
                                                                              32

                                   ARTICLE VII

                                   THE TRUSTEE

            Section 7.01. Certain Duties and Responsibilities. (a) Except during
the continuance of an Event of Default in respect of a Trust, the Trustee
undertakes to perform such duties in respect of such Trust as are specifically
set forth in this Agreement, and no implied covenants or obligations shall be
read into this Agreement against the Trustee.

            (b) In case an Event of Default in respect of a Trust has occurred
and is continuing, the Trustee shall exercise such of the rights and powers
vested in it by this Agreement in respect of such Trust, and 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.

            (c) No provision of this Agreement shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act, or its own willful misconduct, except that

            (1)   this Subsection shall not be construed to limit the effect
      of Subsection (a)of this Section 7.01; and

            (2) the Trustee shall not be liable for any error of judgment made
      in good faith by a Responsible Officer of the Trustee, unless it shall be
      proved that the Trustee was negligent in ascertaining the pertinent facts.

            (d) Whether or not herein expressly so provided, every provision of
this Agreement relating to the conduct or affecting the liability of or
affording protection to the Trustee shall be subject to the provisions of this
Section 7.01.

            Section 7.02. Notice of Defaults. As promptly as practicable after,
and in any event within 90 days after, the occurrence of any default (as such
term is defined below) hereunder known to the Trustee, the Trustee shall
transmit by mail to the Company, any related Owner Trustees, any related Owner
Participants, the related Loan Trustees and the Certificateholders holding
Certificates of the related series in accordance with Section 313(c) of the
Trust Indenture Act, notice of such default hereunder known to the Trustee,
unless such default shall have been cured or waived; provided, however, that,
except in the case of a default in the payment of the principal, premium, if
any, or interest on any Equipment Note, the Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee or a trust committee of directors and/or Responsible Officers of the
Trustee in good faith shall determine that the withholding of such notice is in
the interests of the Certificateholders of the related series. For the purpose
of this Section 7.02 in respect of any Trust, the term "default" means any event
that is, or after notice or lapse of time or both would become, an Event of
Default in respect of that Trust.

            Section 7.03.  Certain Rights of Trustee.  Subject to the
provisions of Section 315 of the Trust Indenture Act:
<PAGE>
                                                                              33


            (a) the Trustee may rely and shall be protected in acting or
      refraining from acting in reliance upon any resolution, certificate,
      statement, instrument, opinion, report, notice, request, direction,
      consent, order, bond, debenture or other paper or document believed by it
      to be genuine and to have been signed or presented by the proper party or
      parties;

            (b)   any request or direction of the Company mentioned herein
      shall be sufficiently evidenced by a Request;

            (c) whenever in the administration of this Agreement or any
      Intercreditor Agreement, the Trustee shall deem it desirable that a matter
      be proved or established prior to taking, suffering or omitting any action
      hereunder, the Trustee (unless other evidence be herein specifically
      prescribed) may, in the absence of bad faith on its part, rely upon an
      Officer's Certificate of the Company, any related Owner Trustee or any
      related Loan Trustee;

            (d) the Trustee may consult with counsel and the advice of such
      counsel or any Opinion of Counsel shall be full and complete authorization
      and protection in respect of any action taken, suffered or omitted by it
      hereunder in good faith and in reliance thereon;

            (e) the Trustee shall be under no obligation to exercise any of the
      rights or powers vested in it by this Agreement or any Intercreditor
      Agreement at the Direction of any of the Certificateholders pursuant to
      this Agreement or any Intercreditor Agreement, unless such
      Certificateholders shall have offered to the Trustee reasonable security
      or indemnity against the cost, expenses and liabilities which might be
      incurred by it in compliance with such Direction;

            (f) the Trustee shall not be bound to make any investigation into
      the facts or matters stated in any resolution, certificate, statement,
      instrument, opinion, report, notice, request, direction, consent, order,
      bond, debenture or other paper or document;

            (g) the Trustee may execute any of the trusts or powers under this
      Agreement or any Intercreditor Agreement or perform any duties under this
      Agreement or any Intercreditor Agreement either directly or by or through
      agents or attorneys, and the Trustee shall not be responsible for any
      misconduct or negligence on the part of any agent or attorney appointed
      with due care by it under this Agreement or any Intercreditor Agreement;

            (h) the Trustee shall not be liable with respect to any action taken
      or omitted to be taken by it in good faith in accordance with the
      Direction of the Certificateholders holding Certificates of any series
      evidencing Fractional Undivided Interests aggregating not less than a
      majority in interest in the related Trust relating to the time, method and
      place of conducting any proceeding for any remedy available to the
      Trustee, or exercising any trust or power conferred upon the Trustee,
      under this Agreement or any Intercreditor Agreement; and
<PAGE>
                                                                              34

            (i) the Trustee shall not be required to expend or risk its own
      funds in the performance of any of its duties under this Agreement, 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 is not reasonably assured to it.

            Section 7.04. Not Responsible for Recitals or Issuance of
Certificates. The recitals contained herein and in the Certificates of each
series, except the certificates of authentication, shall not be taken as the
statements of the Trustee, and the Trustee assumes no responsibility for their
correctness. Subject to Section 7.15, the Trustee makes no representations as to
the validity or sufficiency of this Basic Agreement, any Equipment Notes, any
Intercreditor Agreement, the Certificates of any series, any Trust Supplement or
any Note Documents, except that the Trustee hereby represents and warrants that
this Basic Agreement has been, and each Trust Supplement, each Certificate, each
Note Purchase Agreement and each Intercreditor Agreement of, or relating to,
each series will be executed and delivered by one of its officers who is duly
authorized to execute and deliver such document on its behalf.

            Section 7.05. May Hold Certificates. The Trustee, any Paying Agent,
Registrar or any of their Affiliates or any other agent, in their respective
individual or any other capacity, may become the owner or pledgee of
Certificates and, subject to Sections 310(b) and 311 of the Trust Indenture Act,
if applicable, may otherwise deal with the Company, any Owner Trustees or the
Loan Trustees with the same rights it would have if it were not Trustee, Paying
Agent, Registrar or such other agent.

            Section 7.06. Money Held in Trust. Money held by the Trustee or the
Paying Agent in trust under this Agreement need not be segregated from other
funds except to the extent required herein or by law and neither the Trustee nor
the Paying Agent shall have any liability for interest upon any such moneys
except as provided for herein.

            Section 7.07. Compensation and Reimbursement. The Company agrees:

            (1) to pay, or cause to be paid, to the Trustee from time to time
      reasonable compensation for all services rendered by it hereunder (which
      compensation shall not be limited by any provision of law in regard to the
      compensation of a trustee of an express trust); and

            (2) except as otherwise expressly provided herein or in any Trust
      Supplement, to reimburse, or cause to be reimbursed, the Trustee upon its
      request for all reasonable out-of-pocket expenses, disbursements and
      advances incurred or made by the Trustee in accordance with any provision
      of this Basic Agreement, any Trust Supplement or any Intercreditor
      Agreement (including the reasonable compensation and the expenses and
      disbursements of its agents and counsel), except any such expense,
      disbursement or advance as may be attributable to its negligence, willful
      misconduct or bad faith or as may be incurred due to the Trustee's breach
      of its representations and warranties set forth in Section 7.15; and
<PAGE>
                                                                              35

            (3) to indemnify, or cause to be indemnified, the Trustee with
      respect to the Certificates of any series, pursuant to the particular
      sections of the Note Purchase Agreements specified in the related Trust
      Supplement.

            The Trustee shall be entitled to reimbursement from, and shall have
a lien prior to the Certificates of each series upon, all property and funds
held or collected by the Trustee in its capacity as Trustee with respect to such
series or the related Trust for any tax incurred without negligence, bad faith
or willful misconduct, on its part, arising out of or in connection with the
acceptance or administration of such Trust (other than any tax attributable to
the Trustee's compensation for serving as such), including any costs and
expenses incurred in contesting the imposition of any such tax. The Trustee
shall notify the Company of any claim for any tax for which it may seek
reimbursement. If the Trustee reimburses itself from the Trust Property of such
Trust for any such tax, it will mail a brief report within 30 days setting forth
the amount of such tax and the circumstances thereof to all Certificateholders
of such series as their names and addresses appear in the Register.

            Section 7.08. Corporate Trustee Required; Eligibility. Each Trust
shall at all times have a Trustee which shall be eligible to act as a trustee
under Section 310(a) of the Trust Indenture Act and shall have a combined
capital and surplus of at least $75,000,000 (or a combined capital and surplus
in excess of $5,000,000 and the obligations of which, whether now in existence
or hereafter incurred, are fully and unconditionally guaranteed by a corporation
organized and doing business under the laws of the United States, any state or
territory thereof or of the District of Columbia and having a combined capital
and surplus of at least $75,000,000). 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 7.08 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 Trustee shall cease to be eligible in
accordance with the provisions of this Section 7.08 to act as Trustee of any
Trust, the Trustee shall resign immediately as Trustee of such Trust in the
manner and with the effect specified in Section 7.09.

            Section 7.09. Resignation and Removal; Appointment of Successor. (a)
No resignation or removal of the Trustee and no appointment of a successor
Trustee of any Trust pursuant to this Article shall become effective until the
acceptance of appointment by the successor Trustee under Section 7.10.

            (b) The Trustee may resign at any time as Trustee of any or all
Trusts by giving prior written notice thereof to the Company, the Authorized
Agents, the related Owner Trustees and the related Loan Trustees. If an
instrument of acceptance by a successor Trustee shall not have been delivered to
the Company, the related Owner Trustees and the Trustee within 30 days after the
giving of such notice of resignation, the resigning Trustee may petition any
court of competent jurisdiction for the appointment of a successor Trustee.
<PAGE>
                                                                              36
            (c) The Trustee may be removed at any time by Direction of the
Certificateholders of the related series holding Certificates evidencing
Fractional Undivided Interests aggregating not less than a majority in interest
in such Trust delivered to the Trustee and to the Company, the related Owner
Trustees and the related Loan Trustees.

            (d)   If at any time in respect of any Trust:

            (1) the Trustee shall fail to comply with Section 310 of the Trust
      Indenture Act, if applicable, after written request therefor by the
      Company or by any Certificateholder who has been a bona fide
      Certificateholder for at least six months; or

            (2) the Trustee shall cease to be eligible under Section 7.08 and
      shall fail to resign after written request therefor by the Company or by
      any such Certificateholder; or

            (3) the Trustee shall become incapable of acting or shall be
      adjudged a bankrupt or insolvent, or a receiver of the Trustee or of its
      property shall be appointed or any public officer shall take charge or
      control of the Trustee or of its property or affairs for the purpose of
      rehabilitation, conservation or liquidation;

then, in any case, (i) the Company may remove the Trustee or (ii) any
Certificateholder of the related series who has been a bona fide
Certificateholder for at least six months may, on behalf of itself and all
others similarly situated, petition any court of competent jurisdiction for the
removal of the Trustee and the appointment of a successor Trustee of such Trust.

            (e) If a Responsible Officer of the Trustee shall obtain actual
knowledge of an Avoidable Tax (as defined below) in respect of any Trust which
has been or is likely to be asserted, the Trustee shall promptly notify the
Company and shall, within 30 days of such notification, resign as Trustee of
such Trust hereunder unless within such 30-day period the Trustee shall have
received notice that the Company has agreed to pay such tax. The Company shall
promptly appoint a successor Trustee of such Trust in a jurisdiction where there
are no Avoidable Taxes. As used herein, an "Avoidable Tax" in respect of such
Trust means a state or local tax: (i) upon (w) such Trust, (x) such Trust
Property, (y) Certificateholders of such Trust or (z) the Trustee for which the
Trustee is entitled to seek reimbursement from the Trust Property of such Trust,
and (ii) which would be avoided if the Trustee were located in another state, or
jurisdiction within a state, within the United States of America. A tax shall
not be an Avoidable Tax in respect of any Trust if the Company or any Owner
Trustee shall agree to pay, and shall pay, such tax.

            (f) If the Trustee shall resign, be removed or become incapable of
acting as Trustee of any Trust or if a vacancy shall occur in the office of the
Trustee of any Trust for any cause, the Company shall promptly appoint a
successor Trustee of such Trust. If, within one year after such resignation,
removal or incapability, or other occurrence of such vacancy, a successor
Trustee of such Trust shall be appointed by Direction of the Certificateholders
of the related series holding Certificates of such series evidencing Fractional
Undivided Interests aggregating not less than a majority in interest in such
Trust delivered to the Company, the related Owner Trustees, the related Loan
Trustee and the retiring Trustee, then the successor
<PAGE>
                                                                              37

Trustee of such Trust so appointed shall, with the approval of the Company of
such appointment, which approval shall not be unreasonably withheld, forthwith
upon its acceptance of such appointment, become the successor Trustee of such
Trust and supersede the successor Trustee of such Trust appointed as provided
above. If no successor Trustee shall have been so appointed as provided above
and accepted appointment in the manner hereinafter provided, the resigning
Trustee or any Certificateholder who has been a bona fide Certificateholder of
the related series for at least six months may, on behalf of himself and all
others similarly situated, petition any court of competent jurisdiction for the
appointment of a successor Trustee of such Trust.

            (g) The successor Trustee of a Trust shall give notice of the
resignation and removal of the Trustee and appointment of the successor Trustee
by mailing written notice of such event by first-class mail, postage prepaid, to
the Certificateholders of the related series as their names and addresses appear
in the Register. Each notice shall include the name of such successor Trustee
and the address of its Corporate Trust Office.

            Section 7.10. Acceptance of Appointment by Successor. Every
successor Trustee appointed hereunder shall execute and deliver to the Company
and to the retiring Trustee with respect to any or all Trusts an instrument
accepting such appointment, and thereupon the resignation or removal of the
retiring Trustee with respect to such Trusts shall become effective and such
successor Trustee, without any further act, deed or conveyance, shall become
vested with all the rights, powers, trusts and duties of the retiring Trustee;
but, on request of the Company or the successor Trustee, such retiring Trustee
shall execute and deliver an instrument transferring to such successor Trustee
all such rights, powers and trusts of the retiring Trustee and shall duly
assign, transfer and deliver to such successor Trustee all Trust Property held
by such retiring Trustee in respect of such Trusts hereunder, subject
nevertheless to its lien, if any, provided for in Section 7.07. Upon request of
any such successor Trustee, the Company, the retiring Trustee and such successor
Trustee shall execute and deliver any and all instruments containing such
provisions as shall be necessary or desirable to transfer and confirm to, and
for more fully and certainly vesting in, such successor Trustee all such rights,
powers and trusts.

            If a successor Trustee is appointed with respect to one or more (but
not all) Trusts, the Company, the predecessor Trustee and each successor Trustee
with respect to any Trust shall execute and deliver a supplemental agreement
hereto which shall contain such provisions as shall be deemed necessary or
desirable to confirm that all the rights, powers, trusts and duties of the
predecessor Trustee with respect to the Trusts as to which the predecessor
Trustee is not retiring shall continue to be vested in the predecessor Trustee,
and shall add to or change any of the provisions of this Basic Agreement and the
applicable Trust Supplements as shall be necessary to provide for or facilitate
the administration of the Trusts hereunder by more than one Trustee, it being
understood that nothing herein or in such supplemental agreement shall
constitute such Trustees as co-Trustees of the same Trust and that each such
Trustee shall be Trustee of separate Trusts.

            No institution shall accept its appointment as a Trustee hereunder
unless at the time of such acceptance such institution shall be qualified and
eligible under this Article VII.
<PAGE>
                                                                              38
            Section 7.11. Merger, Conversion, Consolidation or Succession to
Business. Any corporation into which the Trustee may be merged or converted or
with which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of the Trustee, shall be the successor of the Trustee hereunder;
provided, however, that such corporation shall be otherwise qualified and
eligible under this Article VII, without the execution or filing of any paper or
any further act on the part of any of the parties hereto. In case any
Certificates shall have been executed or authenticated, but not delivered, by
the Trustee then in office, any successor by merger, conversion or consolidation
to such authenticating Trustee may adopt such execution or authentication and
deliver the Certificates so executed or authenticated with the same effect as if
such successor Trustee had itself executed or authenticated such Certificates.

            Section 7.12. Maintenance of Agencies. (a) With respect to each
series of Certificates, there shall at all times be maintained an office or
agency in the location set forth in Section 12.04 where Certificates of such
series may be presented or surrendered for registration of transfer or for
exchange, and for payment thereof, and where notices and demands, to or upon the
Trustee in respect of such Certificates or this Agreement may be served;
provided, however, that, if it shall be necessary that the Trustee maintain an
office or agency in another location with respect to the Certificates of any
series (e.g., the Certificates of such series shall be represented by Definitive
Certificates and shall be listed on a national securities exchange), the Trustee
will make all reasonable efforts to establish such an office or agency. Written
notice of the location of each such other office or agency and of any change of
location thereof shall be given by the Trustee to the Company, any Owner
Trustees, the Loan Trustees (in the case of any Owner Trustee or Loan Trustee,
at its address specified in the Note Documents or such other address as may be
notified to the Trustee) and the Certificateholders of such series. In the event
that no such office or agency shall be maintained or no such notice of location
or of change of location shall be given, presentations and demands may be made
and notices may be served at the Corporate Trust Office of the Trustee.

            (b) There shall at all times be a Registrar and a Paying Agent
hereunder with respect to the Certificates of each series. Each such Authorized
Agent shall be a bank or trust company, shall be a corporation organized and
doing business under the laws of the United States or any state, with a combined
capital and surplus of at least $75,000,000, or a corporation having a combined
capital and surplus in excess of $5,000,000, the obligations of which are
guaranteed by a corporation organized and doing business under the laws of the
United States or any state, with a combined capital and surplus of at least
$75,000,000, and shall be authorized under such laws to exercise corporate trust
powers, subject to supervision by federal or state authorities. The Trustee
shall initially be the Paying Agent and, as provided in Section 3.04, Registrar
hereunder with respect to the Certificates of each series. Each Registrar shall
furnish to the Trustee, at stated intervals of not more than six months, and at
such other times as the Trustee may request in writing, a copy of the Register
maintained by such Registrar.

            (c) Any corporation into which any Authorized Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger,
<PAGE>
                                                                              39

consolidation or conversion to which any Authorized Agent shall be a party, or
any corporation succeeding to the corporate trust business of any Authorized
Agent, shall be the successor of such Authorized Agent, if such successor
corporation is otherwise eligible under this Section 7.12, without the execution
or filing of any paper or any further act on the part of the parties hereto or
such Authorized Agent or such successor corporation.

            (d) Any Authorized Agent may at any time resign by giving written
notice of resignation to the Trustee, the Company, any related Owner Trustees
and the related Loan Trustees. The Company may, and at the request of the
Trustee shall, at any time terminate the agency of any Authorized Agent by
giving written notice of termination to such Authorized Agent and to the
Trustee. Upon the resignation or termination of an Authorized Agent or in case
at any time any such Authorized Agent shall cease to be eligible under this
Section 7.12 (when, in either case, no other Authorized Agent performing the
functions of such Authorized Agent shall have been appointed), the Company shall
promptly appoint one or more qualified successor Authorized Agents, reasonably
satisfactory to the Trustee, to perform the functions of the Authorized Agent
which has resigned or whose agency has been terminated or who shall have ceased
to be eligible under this Section 7.12. The Company shall give written notice of
any such appointment made by it to the Trustee, any related Owner Trustees and
the related Loan Trustees; and in each case the Trustee shall mail notice of
such appointment to all Certificateholders of the related series as their names
and addresses appear on the Register for such series.

            (e) The Company agrees to pay, or cause to be paid, from time to
time to each Authorized Agent reasonable compensation for its services and to
reimburse it for its reasonable expenses.

            Section 7.13. Money for Certificate Payments to Be Held in Trust.
All moneys deposited with any Paying Agent for the purpose of any payment on
Certificates shall be deposited and held in trust for the benefit of the
Certificateholders entitled to such payment, subject to the provisions of this
Section 7.13. Moneys so deposited and held in trust shall constitute a separate
trust fund for the benefit of the Certificateholders with respect to which such
money was deposited.

            The Trustee may at any time, for the purpose of obtaining the
satisfaction and discharge of this Agreement or for any other purpose, direct
any Paying Agent to pay to the Trustee all sums held in trust by such Paying
Agent, such sums to be held by the Trustee upon the same trusts as those upon
which such sums were held by such Paying Agent; and, upon such payment by any
Paying Agent to the Trustee, such Paying Agent shall be released from all
further liability with respect to such money.

            Section 7.14. Registration of Equipment Notes in Trustee's Name.
Subject to the provisions of any Intercreditor Agreement, the Trustee agrees
that all Equipment Notes to be purchased by any Trust and Permitted Investments,
if any, shall be issued in the name of the Trustee as trustee for the applicable
Trust or its nominee and held by the Trustee in trust for the benefit of the
Certificateholders of such series, or, if not so held, the Trustee or its
nominee shall
<PAGE>
                                                                              40

be reflected as the owner of such Equipment Notes or Permitted Investments, as
the case may be, in the register of the issuer of such Equipment Notes or
Permitted Investments, as the case may be.

            Section 7.15.  Representations and Warranties of Trustee.  The
Trustee hereby represents and warrants that:

            (a)   the Trustee is a Delaware banking corporation organized and
      validly existing in good standing under the laws of the State of
      Delaware;

            (b) the Trustee has full power, authority and legal right to
      execute, deliver and perform this Agreement, any Intercreditor Agreement
      and the Note Purchase Agreements and has taken all necessary action to
      authorize the execution, delivery and performance by it of this Agreement,
      any Intercreditor Agreement and the Note Purchase Agreements;

            (c) the execution, delivery and performance by the Trustee of this
      Agreement, any Intercreditor Agreement and the Note Purchase Agreements
      (i) will not violate any provision of any United States federal law or the
      law of the state of the United States where it is located governing the
      banking and trust powers of the Trustee or any order, writ, judgment, or
      decree of any court, arbitrator or governmental authority applicable to
      the Trustee or any of its assets, (ii) will not violate any provision of
      the articles of association or by-laws of the Trustee, and (iii) will not
      violate any provision of, or constitute, with or without notice or lapse
      of time, a default under, or result in the creation or imposition of any
      lien on any properties included in the Trust Property pursuant to the
      provisions of any mortgage, indenture, contract, agreement or other
      undertaking to which it is a party, which violation, default or lien could
      reasonably be expected to have an adverse effect on the Trustee's
      performance or ability to perform its duties hereunder or thereunder or on
      the transactions contemplated herein or therein;

            (d) the execution, delivery and performance by the Trustee of this
      Agreement, any Intercreditor Agreement and the Note Purchase Agreements
      will not require the authorization, consent, or approval of, the giving of
      notice to, the filing or registration with, or the taking of any other
      action in respect of, any governmental authority or agency of the United
      States or the state of the United States where it is located regulating
      the banking and corporate trust activities of the Trustee; and

            (e) this Agreement, any Intercreditor Agreement and the Note
      Purchase Agreements have been duly executed and delivered by the Trustee
      and constitute the legal, valid and binding agreements of the Trustee,
      enforceable against it in accordance with their respective terms;
      provided, however, that enforceability may be limited by (i) applicable
      bankruptcy, insolvency, reorganization, moratorium or similar laws
      affecting the rights of creditors generally and (ii) general principles of
      equity.

            Section 7.16. Withholding Taxes; Information Reporting. As to the
Certificates of any series, the Trustee, as trustee of the related grantor trust
created by this Agreement, shall exclude and withhold from each distribution of
principal, premium, if any, and interest and other
<PAGE>
                                                                              41

amounts due under this Agreement or under the Certificates of such series any
and all withholding taxes applicable thereto as required by law. The 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 of the Certificates of such series, to
withhold such amounts and timely pay the same to the appropriate authority in
the name of and on behalf of the Certificateholders of such series, 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 such
Certificateholder of such series appropriate documentation showing the payment
thereof, together with such additional documentary evidence as such
Certificateholders may reasonably request from time to time. The Trustee agrees
to file any other information reports as it may be required to file under United
States law.

            Section 7.17. Trustee's Liens. The Trustee in its individual
capacity agrees that it will, in respect of each Trust created by this
Agreement, at its own cost and expense promptly take any action as may be
necessary to duly discharge and satisfy in full any mortgage, pledge, lien,
charge, encumbrance, security interest or claim ("Trustee's Liens") on or with
respect to the Trust Property of such Trust which is attributable to the Trustee
either (i) in its individual capacity and which is unrelated to the transactions
contemplated by this Agreement or the related Note Documents or (ii) as Trustee
hereunder or in its individual capacity and which arises out of acts or
omissions which are not contemplated by this Agreement.

            Section 7.18. Preferential Collection of Claims. The Trustee shall
comply with Section 311(a) of the Trust Indenture Act, excluding any creditor
relationship listed in Section 311(b) of the Trust Indenture Act. If the Trustee
shall resign or be removed as Trustee, it shall be subject to Section 311(a) of
the Trust Indenture Act to the extent provided therein.


                                  ARTICLE VIII

                CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE

            Section 8.01. The Company to Furnish Trustee with Names and
Addresses of Certificateholders. The Company will furnish to the Trustee within
15 days after each Record Date with respect to a Scheduled Payment, and at such
other times as the Trustee may request in writing within 30 days after receipt
by the Company of any such request, a list, in such form as the Trustee may
reasonably require, of all information in the possession or control of the
Company as to the names and addresses of the Certificateholders of each series,
in each case as of a date not more than 15 days prior to the time such list is
furnished; provided, however, that so long as the Trustee is the sole Registrar
for such series, no such list need be furnished; and provided further, however,
that no such list need be furnished for so long as a copy of the Register is
being furnished to the Trustee pursuant to Section 7.12.

            Section 8.02. Preservation of Information; Communications to
Certificateholders. The Trustee shall preserve, in as current a form as is
reasonably practicable, the names and
<PAGE>
                                                                              42

addresses of Certificateholders of each series contained in the most recent list
furnished to the Trustee as provided in Section 7.12 or Section 8.01, as the
case may be, and the names and addresses of Certificateholders of each series
received by the Trustee in its capacity as Registrar, if so acting. The Trustee
may destroy any list furnished to it as provided in Section 7.12 or Section
8.01, as the case may be, upon receipt of a new list so furnished.

            Section 8.03. Reports by Trustee. Within 60 days after May 15 of
each year commencing with the first full year following the issuance of any
series of Certificates, the Trustee shall transmit to the Certificateholders of
such series, as provided in Section 313(c) of the Trust Indenture Act, a brief
report dated as of such May 15, if required by Section 313(a) of the Trust
Indenture Act.

            Section 8.04.  Reports by the Company.  The Company shall:

            (a) file with the Trustee, within 30 days after the Company is
      required to file the same with the SEC, copies of the annual reports and
      of the information, documents and other reports (or copies of such
      portions of any of the foregoing as the SEC may from time to time by rules
      and regulations prescribe) which the Company is required to file with the
      SEC pursuant to section 13 or section 15(d) of the Securities Exchange Act
      of 1934, as amended; or, if the Company is not required to file
      information, documents or reports pursuant to either of such sections,
      then to file with the Trustee and the SEC, in accordance with rules and
      regulations prescribed by the SEC, such of the supplementary and periodic
      information, documents and reports which may be required pursuant to
      section 13 of the Securities Exchange Act of 1934, as amended, in respect
      of a security listed and registered on a national securities exchange as
      may be prescribed in such rules and regulations;

            (b) file with the Trustee and the SEC, in accordance with the rules
      and regulations prescribed by the SEC, such additional information,
      documents and reports with respect to compliance by the Company with the
      conditions and covenants of the Company provided for in this Agreement, as
      may be required by such rules and regulations, including, in the case of
      annual reports, if required by such rules and regulations, certificates or
      opinions of independent public accountants, conforming to the requirements
      of Section 1.02;

            (c) transmit to all Certificateholders, in the manner and to the
      extent provided in Section 313(c) of the Trust Indenture Act such
      summaries of any information, documents and reports required to be filed
      by the Company pursuant to subsections (a) and (b) of this Section 8.04 as
      may be required by rules and regulations prescribed by the SEC; and

            (d) furnish to the Trustee, not less often than annually, a brief
      certificate from the principal executive officer, principal financial
      officer or principal accounting officer as to his knowledge of the
      Company's compliance with all conditions and covenants under this
      Agreement (it being understood that for purposes of this paragraph (d),
      such compliance shall be determined without regard to any period of grace
      or requirement of notice provided under this Agreement).
<PAGE>
                                                                              43
                                   ARTICLE IX

                             SUPPLEMENTAL AGREEMENTS

            Section 9.01. Supplemental Agreements Without Consent of
Certificateholders. Without the consent of the Certificateholders, the Company
may (but will not be required to), and the Trustee (subject to Section 9.03)
shall, at the Company's request, at any time and from time to time, enter into
one or more agreements supplemental hereto or, if applicable, to an
Intercreditor Agreement or a Liquidity Facility, in form satisfactory to the
Trustee, for any of the following purposes:

            (1)   to provide for the formation of a Trust, the issuance of a
      series of Certificates and other matters contemplated by Section
      2.01(b); or

            (2) to evidence the succession of another Person to the Company and
      the assumption by any such successor of the covenants of the Company
      herein contained or of the Company's obligations under any Intercreditor
      Agreement or any Liquidity Facility; or

            (3) to add to the covenants of the Company for the benefit of the
      Certificateholders of any series, or to surrender any right or power
      conferred upon the Company in this Agreement, any Intercreditor Agreement
      or any Liquidity Facility; or

            (4) to correct or supplement any provision in this Agreement, any
      Intercreditor Agreement or any Liquidity Facility which may be defective
      or inconsistent with any other provision herein or therein or to cure any
      ambiguity or to modify any other provision with respect to matters or
      questions arising under this Agreement, any Intercreditor Agreement or any
      Liquidity Facility, provided, however, that any such action shall not
      materially adversely affect the interests of the Certificateholders of any
      series; to correct any mistake in this Agreement, any Intercreditor
      Agreement or any Liquidity Facility; or, as provided in any Intercreditor
      Agreement, to give effect to or provide for a Replacement Liquidity
      Facility (as defined in such Intercreditor Agreement); or

            (5) to comply with any requirement of the SEC, any applicable law,
      rules or regulations of any exchange or quotation system on which the
      Certificates of any series are listed or of any regulatory body; or

            (6) to modify, eliminate or add to the provisions of this Agreement,
      any Intercreditor Agreement or any Liquidity Facility to such extent as
      shall be necessary to continue the qualification of this Agreement, any
      Intercreditor Agreement or any Liquidity Facility (including any
      supplemental agreement) under the Trust Indenture Act or under any similar
      Federal statute hereafter enacted, and to add to this Agreement, any
      Intercreditor Agreement or any Liquidity Facility such other provisions as
      may be expressly permitted by the Trust Indenture Act, excluding, however,
      the provisions referred to in Section 316(a)(2) of the Trust Indenture Act
      as in effect at the date as of
<PAGE>
                                                                              44

      which this Basic Agreement was executed or any corresponding provision in
      any similar Federal statute hereafter enacted; or

            (7) to evidence and provide for the acceptance of appointment under
      this Agreement, any Intercreditor Agreement or any Liquidity Facility by a
      successor Trustee with respect to one or more Trusts and to add to or
      change any of the provisions of this Agreement, any Intercreditor
      Agreement or any Liquidity Facility as shall be necessary to provide for
      or facilitate the administration of the Trust, pursuant to the
      requirements of Section 7.10; or

            (8)   to provide the information required under Section 7.12 and
      Section 12.04 as to the Trustee; or

            (9) to make any other amendments or modifications hereto, provided,
      however, that such amendments or modifications shall apply to Certificates
      of any series to be thereafter issued;

provided, however, that no such supplemental agreement shall adversely affect
the status of any Trust as a grantor trust under Subpart E, Part I of Subchapter
J of Chapter 1 of Subtitle A of the Internal Revenue Code of 1986, as amended,
for U.S. federal income tax purposes.

            Section 9.02. Supplemental Agreements with Consent of
Certificateholders. With respect to each separate Trust and the series of
Certificates relating thereto, with the consent of the Certificateholders
holding Certificates of such series (including consents obtained in connection
with a tender offer or exchange offer for the Certificates) evidencing
Fractional Undivided Interests aggregating not less than a majority in interest
in such Trust, by Direction of said Certificateholders delivered to the Company
and the Trustee, the Company may (with the consent of the Owner Trustees, if
any, relating to such Certificates, which consent shall not be unreasonably
withheld), but shall not be obligated to, and the Trustee (subject to Section
9.03) shall, enter into an agreement or agreements supplemental hereto for the
purpose of adding any provisions to or changing in any manner or eliminating any
of the provisions of this Agreement, any Intercreditor Agreement or any
Liquidity Facility to the extent applicable to such Certificateholders or of
modifying in any manner the rights and obligations of such Certificateholders
under this Agreement, any Intercreditor Agreement or any Liquidity Facility;
provided, however, that no such agreement shall, without the consent of the
Certificateholder of each Outstanding Certificate affected thereby:

            (1) reduce in any manner the amount of, or delay the timing of, any
      receipt by the Trustee of payments on the Equipment Notes held in such
      Trust or distributions that are required to be made herein on any
      Certificate of such series, or change any date of payment on any
      Certificate of such series, or change the place of payment where, or the
      coin or currency in which, any Certificate of such series is payable, or
      impair the right to institute suit for the enforcement of any such payment
      or distribution on or after the Regular Distribution Date or Special
      Distribution Date applicable thereto; or
<PAGE>
                                                                              45
            (2) permit the disposition of any Equipment Note included in the
      Trust Property of such Trust except as permitted by this Agreement, or
      otherwise deprive such Certificateholder of the benefit of the ownership
      of the Equipment Notes in such Trust; or

            (3)   alter the priority of distributions specified in the
      Intercreditor Agreement in a manner materially adverse to the interests
      of the Certificateholders of any series; or

            (4) reduce the specified percentage of the aggregate Fractional
      Undivided Interests of such Trust that is required for any such
      supplemental agreement, or reduce such specified percentage required for
      any waiver (of compliance with certain provisions of this Agreement or
      certain defaults hereunder and their consequences) provided for in this
      Agreement; or

            (5) modify any of the provisions of this Section 9.02 or Section
      6.05, except to increase any such percentage or to provide that certain
      other provisions of this Agreement cannot be modified or waived without
      the consent of the Certificateholder of each Certificate of such series
      affected thereby; or

            (6) adversely affect the status of any Trust as a grantor trust
      under Subpart E, Part I of Subchapter J of Chapter 1 of Subtitle A of the
      Internal Revenue Code of 1986, as amended, for U.S. federal income tax
      purposes.

            It shall not be necessary for any Direction of such
Certificateholders under this Section 9.02 to approve the particular form of any
proposed supplemental agreement, but it shall be sufficient if such Direction
shall approve the substance thereof.

            Section 9.03. Documents Affecting Immunity or Indemnity. If in the
opinion of the Trustee any document required to be executed by it pursuant to
the terms of Section 9.01 or 9.02 affects any interest, right, duty, immunity or
indemnity in favor of the Trustee under this Basic Agreement or any Trust
Supplement, the Trustee may in its discretion decline to execute such document.

            Section 9.04. Execution of Supplemental Agreements. In executing, or
accepting the additional trusts created by, any supplemental agreement permitted
by this Article or the modifications thereby of the trusts created by this
Agreement, the Trustee shall be entitled to receive, and shall be fully
protected in relying upon, an Opinion of Counsel stating that the execution of
such supplemental agreement is authorized or permitted by this Agreement.

            Section 9.05. Effect of Supplemental Agreements. Upon the execution
of any agreement supplemental to this Agreement under this Article, this Basic
Agreement shall be modified in accordance therewith, and such supplemental
agreement shall form a part of this Basic Agreement for all purposes; and every
Certificateholder of each series theretofore or thereafter authenticated and
delivered hereunder shall be bound thereby to the extent applicable to such
series.
<PAGE>
                                                                              46
            Section 9.06. Conformity with Trust Indenture Act. Every
supplemental agreement executed pursuant to this Article shall conform to the
requirements of the Trust Indenture Act as then in effect.

            Section 9.07. Reference in Certificates to Supplemental Agreements.
Certificates of each series authenticated and delivered after the execution of
any supplemental agreement applicable to such series pursuant to this Article
may bear a notation in form approved by the Trustee as to any matter provided
for in such supplemental agreement; and, in such case, suitable notation may be
made upon Outstanding Certificates of such series after proper presentation and
demand.


                                    ARTICLE X

                   AMENDMENTS TO INDENTURE AND NOTE DOCUMENTS

            Section 10.01. Amendments and Supplements to Indenture and Other
Note Documents. In the event that the Trustee, as holder (or beneficial owner
through the Subordination Agent) of any Equipment Notes (or as a prospective
purchaser of any Postponed Notes) in trust for the benefit of the
Certificateholders of any series or as Controlling Party under an Intercreditor
Agreement, receives (directly or indirectly through the Subordination Agent) a
request for a consent to any amendment, modification, waiver or supplement under
any Indenture, other Note Document or any other related document, the Trustee
shall forthwith send a notice of such proposed amendment, modification, waiver
or supplement to each Certificateholder of such series registered on the
Register as of the date of such notice. The Trustee shall request from the
Certificateholders of such series a Direction as to (a) whether or not to take
or refrain from taking (or direct the Subordination Agent to take or refrain
from taking) any action which a holder of (or, with respect to Postponed Notes,
a prospective purchaser of) such Equipment Note or a Controlling Party has the
option to direct, (b) whether or not to give or execute (or direct the
Subordination Agent to give or execute) any waivers, consents, amendments,
modifications or supplements as a holder of (or, with respect to Postponed
Notes, a prospective purchaser of) such Equipment Note or as Controlling Party
and (c) how to vote (or direct the Subordination Agent to vote) any Equipment
Note (or, with respect to a Postponed Note, its commitment to acquire such
Postponed Note) if a vote has been called for with respect thereto. Provided
such a request for Certificateholder Direction shall have been made, in
directing any action or casting any vote or giving any consent as the holder of
any Equipment Note (or in directing the Subordination Agent in any of the
foregoing), (i) other than as Controlling Party, the Trustee shall vote for or
give consent to any such action with respect to such Equipment Note (or
Postponed Note) in the same proportion as that of (A) the aggregate face amounts
of all Certificates actually voted in favor of or for giving consent to such
action by such Direction of Certificateholders to (B) the aggregate face amount
of all Outstanding Certificates and (ii) as Controlling Party, the Trustee shall
vote as directed in such Certificateholder Direction by the Certificateholders
of such series evidencing a Fractional Undivided Interest aggregating not less
than a majority in interest in the Trust. For purposes of the immediately
preceding sentence, a Certificate shall have been "actually voted" if the Holder

<PAGE>
                                                                              47
of such Certificate has delivered to the Trustee an instrument evidencing such
Holder's consent to such Direction prior to one Business Day before the Trustee
directs such action or casts such vote or gives such consent. Notwithstanding
the foregoing, but subject to Section 6.04 and any Intercreditor Agreement, the
Trustee may, with respect to the Certificates of any series, in its own
discretion and at its own direction, consent and notify the relevant Loan
Trustee of such consent (or direct the Subordination Agent to consent and notify
the Loan Trustee of such consent) to any amendment, modification, waiver or
supplement under any related Indenture or any other related Note Document if an
Event of Default hereunder shall have occurred and be continuing or if such
amendment, modification, waiver or supplement will not materially adversely
affect the interests of the Certificateholders of such series.


                                   ARTICLE XI

                              TERMINATION OF TRUSTS

            Section 11.01. Termination of the Trusts. In respect of each Trust
created by the Basic Agreement as supplemented by a related Trust Supplement,
the respective obligations and responsibilities of the Company and the Trustee
with respect to such Trust shall terminate upon the distribution to all Holders
of Certificates of the series of such Trust and the Trustee of all amounts
required to be distributed to them pursuant to this Agreement and the
disposition of all property held as part of the Trust Property of such Trust;
provided, however, that in no event shall such Trust continue beyond one hundred
ten (110) years following the date of the execution of the Trust Supplement with
respect to such Trust (or such other final expiration date as may be specified
in such Trust Supplement).

            Notice of any termination of a Trust, specifying the applicable
Regular Distribution Date (or applicable Special Distribution Date, as the case
may be) upon which the Certificateholders of any series may surrender their
Certificates to the Trustee for payment of the final distribution and
cancellation, shall be mailed promptly by the Trustee to Certificateholders of
such series not earlier than the minimum number of days and not later than the
maximum number of days specified therefor in the related Trust Supplement
preceding such final distribution specifying (A) the Regular Distribution Date
(or Special Distribution Date, as the case may be) upon which the proposed final
payment of the Certificates of such series will be made upon presentation and
surrender of Certificates of such series at the office or agency of the Trustee
therein specified, (B) the amount of any such proposed final payment, and (C)
that the Record Date otherwise applicable to such Regular Distribution Date (or
Special Distribution Date, as the case may be) is not applicable, payments being
made only upon presentation and surrender of the Certificates of such series at
the office or agency of the Trustee therein specified. The Trustee shall give
such notice to the Registrar at the time such notice is given to
Certificateholders of such series. Upon presentation and surrender of the
Certificates of such series in accordance with such notice, the Trustee shall
cause to be distributed to Certificateholders of such series amounts
distributable on such Regular Distribution Date (or Special Distribution Date,
as the case may be) pursuant to Section 4.02.
<PAGE>
                                                                              48

            In the event that all of the Certificateholders of such series shall
not surrender their Certificates for cancellation within six months after the
date specified in the above-mentioned written notice, the Trustee shall give a
second written notice to the remaining Certificateholders of such series to
surrender their Certificates for cancellation and receive the final distribution
with respect thereto. No additional interest shall accrue on the Certificates of
such series after any Regular Distribution Date (or Special Distribution Date,
as the case may be) of such series, as specified in the first written notice. In
the event that any money held by the Trustee for the payment of distributions on
the Certificates of such series shall remain unclaimed for two years (or such
lesser time as the Trustee shall be satisfied, after 60 days' notice from the
Company, is one month prior to the escheat period provided under applicable law)
after the final distribution date with respect thereto, the Trustee shall pay to
each Loan Trustee the appropriate amount of money relating to such Loan Trustee
and shall give written notice thereof to the related Owner Trustees and the
Company.

                                   ARTICLE XII

                            MISCELLANEOUS PROVISIONS

            Section 12.01. Limitation on Rights of Certificateholders. The death
or incapacity of any Certificateholder of any series shall not operate to
terminate this Agreement or the related Trust, nor entitle such
Certificateholder's legal representatives or heirs to claim an accounting or to
take any action or commence any proceeding in any court for a partition or
winding up of the Trust, nor otherwise affect the rights, obligations, and
liabilities of the parties hereto or any of them.

            Section 12.02. Liabilities of Certificateholders. Neither the
existence of the Trust nor any provision in this Agreement is intended to or
shall limit the liability the Certificateholders would otherwise incur if the
Certificateholders owned Trust Property as co-owners, or incurred any
obligations of the Trust, directly rather than through the Trust.

            Section 12.03. Registration of Equipment Notes in Name of
Subordination Agent. If a Trust is party to an Intercreditor Agreement, the
Trustee agrees that all Equipment Notes to be purchased by such Trust shall be
issued in the name of the Subordination Agent under such Intercreditor Agreement
or its nominee and held by such Subordination Agent in trust for the benefit of
the Certificateholders, or, if not so held, such Subordination Agent or its
nominee shall be reflected as the owner of such Equipment Notes in the register
of the issuer of such Equipment Notes.

            Section 12.04. Notices. (a) Unless otherwise specifically provided
herein or in the applicable Trust Supplement with respect to any Trust, all
notices required under the terms and provisions of this Basic Agreement or such
Trust Supplement with respect to such Trust shall be in English and in writing,
and any such notice may be given by United States mail, courier service or
telecopy, and any such notice shall be effective when delivered or received or,
if mailed, three days after deposit in the United States mail with proper
postage for ordinary mail prepaid,
<PAGE>
                                                                              49

            if to the Company:

                  Southwest Airlines Co.
                  2702 Love Field Drive
                  Dallas, Texas  75235
                  Attention:  Vice President-Finance
                  Facsimile:  (214) 792-4022
                  Telephone:  (214) 792-4000

            if to the Trustee:

                  Wilmington Trust Company
                  Rodney Square North
                  1100 North Market Street
                  Wilmington,  DE  19890-0001
                  Attention:  Corporate Trust Department
                  Facsimile:  (302) 651-1000
                  Telephone:  (302) 651-8584

            (b) The Company or the Trustee, by notice to the other, may
designate additional or different addresses for subsequent notices or
communications.

            (c) Any notice or communication to Certificateholders of any series
shall be mailed by first-class mail to the addresses for Certificateholders of
such series shown on the Register kept by the Registrar and to addresses filed
with the Trustee for Certificate Owners of such series. 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 Certificateholders or Certificate
Owners of such series.

            (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) If the Company mails a notice or communication to the
Certificateholders of such series, it shall mail a copy to the Trustee and to
each Paying Agent for such series at the same time.

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

            (g) The Trustee shall promptly furnish the Company with a copy of
any demand, notice or written communication received by the Trustee hereunder
from any Certificateholder, Owner Trustee or Loan Trustee.
<PAGE>
                                                                              50

            Section 12.05. Governing Law. THIS BASIC AGREEMENT HAS BEEN
DELIVERED IN THE STATE OF NEW YORK AND, TOGETHER WITH ALL TRUST SUPPLEMENTS AND
CERTIFICATES, SHALL BE CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW
YORK AND THE OBLIGATIONS, RIGHTS AND REMEDIES OF THE PARTIES HEREUNDER SHALL BE
DETERMINED IN ACCORDANCE WITH SUCH LAWS.

            Section 12.06. Severability of Provisions. If any one or more of the
covenants, agreements, provisions or terms of this Agreement shall be for any
reason whatsoever held invalid, then such covenants, agreements, provisions, or
terms shall be deemed severable from the remaining covenants, agreements,
provisions or terms of this Agreement and shall in no way affect the validity or
enforceability of the other provisions of this Agreement or the related Trust,
or of the Certificates of such series or the rights of the Certificateholders
thereof.

            Section 12.07. Trust Indenture Act Controls. This Agreement is
subject to the provisions of the Trust Indenture Act and shall, to the extent
applicable, be governed by such provisions. If any provision of this Agreement
limits, qualifies or conflicts with another provision which is required to be
included in this Agreement by the Trust Indenture Act, the required provision
shall control.

            Section 12.08. Effect of Headings and Table of Contents. The Article
and Section headings herein and the Table of Contents are for convenience only
and shall not affect the construction hereof.

            Section 12.09. Successors and Assigns. All covenants, agreements,
representations and warranties in this Agreement by the Trustee and the Company
shall bind and, to the extent permitted hereby, shall inure to the benefit of
and be enforceable by their respective successors and assigns, whether so
expressed or not.

            Section 12.10. Benefits of Agreement. Nothing in this Agreement or
in the Certificates of any series, express or implied, shall give to any Person,
other than the parties hereto and their successors hereunder, and the
Certificateholders of each series, any benefit or any legal or equitable right,
remedy or claim under this Agreement.

            Section 12.11. Legal Holidays. In any case where any Regular
Distribution Date or Special Distribution Date relating to any Certificate of
any series shall not be a Business Day with respect to such series, then
(notwithstanding any other provision of this Agreement) payment need not be made
on such date, but may be made on the next succeeding Business Day with the same
force and effect as if made on such Regular Distribution Date or Special
Distribution Date, and no interest shall accrue during the intervening period.

            Section 12.12. Counterparts. For the purpose of facilitating the
execution of this Agreement and for other purposes, this Agreement may be
executed simultaneously in any number of counterparts, each of which
counterparts shall be deemed to be an original, and all of which counterparts
shall constitute but one and the same instrument.
<PAGE>
                                                                              51

            Section 12.13. Communication by Certificateholders with Other
Certificateholders. Certificateholders of any series may communicate with other
Certificateholders of such series with respect to their rights under this Basic
Agreement, the related Trust Supplement or the Certificates of such series
pursuant to Section 312(b) of the Trust Indenture Act. The Company, the Trustee
and any and all other persons benefitted by this Agreement shall have the
protection afforded by Section 312(c) of the Trust Indenture Act.

            Section 12.14. Intention of Parties. The parties hereto intend that
each Trust be classified for U.S. federal income tax purposes as a grantor trust
under Subpart E, Part I of Subchapter J of the Internal Revenue Code of 1986, as
amended, and not as a trust or association taxable as a corporation or as a
partnership. The powers granted and obligations undertaken pursuant to this
Agreement shall be so construed so as to further such intent.
<PAGE>
                                                                              52

            IN WITNESS WHEREOF, the parties have caused this Agreement to be
duly executed by their respective officers thereunto duly authorized as of the
day and year first written above.
                                          SOUTHWEST AIRLINES CO.


                                          By:  /s/ Deborah Ackerman
                                               -------------------------------
                                               Name: Deborah Ackerman
                                               Title: Vice President -
                                                      General Counsel


                                          WILMINGTON TRUST COMPANY,
                                               as Trustee


                                          By:  /s/ W. Chris Sponenberg
                                               -------------------------------
                                               Name: W. Chris Sponenberg
                                               Title: Vice President

<PAGE>

                                                                       EXHIBIT A

                               FORM OF CERTIFICATE



            Unless this certificate is presented by an authorized representative
of The Depository Trust Company, a New York corporation ("DTC"), to Issuer or
its agent for registration of transfer, exchange or payment, and any certificate
issued is registered in the name of Cede & Co. or in such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.(1)

             SOUTHWEST AIRLINES CO. ____________ PASS THROUGH TRUST

                                  Pass Through
                         Certificate, Series __________

                  Final Regular Distribution Date: _____, ____

             evidencing a fractional undivided interest in a trust, the
             property of which includes certain equipment notes each
             secured by Aircraft owned by or leased to Southwest Airlines Co.

Certificate
No.____________         Fractional Undivided Interest representing
                        _____% of the Trust per $1,000 face amount

            THIS CERTIFIES THAT __________________, for value received, is the
registered owner of a Fractional Undivided Interest, having a face amount of
$[___] (_____ dollars), in the Southwest Airlines Co. Pass Through Trust, Series
[___] (the "Trust") created by Wilmington Trust Company, as trustee (the
"Trustee"), pursuant to a Pass Through Trust Agreement dated as of October ___,
2001 (the "Basic Agreement"), as supplemented by Trust Supplement No. _______
thereto dated __________, 200_ (collectively, the "Agreement"), between the
Trustee and Southwest Airlines Co., a corporation incorporated under Texas law
(the "Company"), a summary of certain of the pertinent provisions of which is
set forth below. To the extent not otherwise defined herein, the capitalized
terms used herein have the meanings assigned to them in the Agreement. This
Certificate is one of the duly authorized Certificates designated as "___%
Southwest Airlines Co. Pass Through Certificate, Series ____" (herein called the
"Certificates"). This Certificate is issued under and is subject to the terms,
provisions and

(1).    This legend to appear on Book-Entry Certificates to be deposited with
      The Depository Trust Company.

<PAGE>

conditions of the Agreement. By virtue of its acceptance hereof, the
Certificateholder of this Certificate assents to and agrees to be bound by the
provisions of the Agreement and any related Intercreditor Agreement. The
property of the Trust includes certain Equipment Notes and all rights of the
Trust to receive any payments under any Intercreditor Agreement or Liquidity
Facility (the "Trust Property"). Each issue of the Equipment Notes is or will be
secured by, among other things, a security interest in aircraft leased to or
owned by the Company.

            The Certificates represent fractional undivided interests in the
Trust and the Trust Property, and have no rights, benefits or interest in
respect of any other separate trust established pursuant to the terms of the
Basic Agreement for any other series of certificates issued pursuant thereto.

            Subject to and in accordance with the terms of the Agreement and any
related Intercreditor Agreement, from funds then available to the Trustee, there
will be distributed on each __________ and ___________ (a "Regular Distribution
Date"), commencing on _________, 200_, to the Person in whose name this
Certificate is registered at the close of business on the 15th day preceding the
Regular Distribution Date, an amount in respect of the Scheduled Payments on the
Equipment Notes due on such Regular Distribution Date, the receipt of which has
been confirmed by the Trustee, equal to the product of the percentage interest
in the Trust evidenced by this Certificate and an amount equal to the sum of
such Scheduled Payments. Subject to and in accordance with the terms of the
Agreement and any related Intercreditor Agreement, in the event that Special
Payments on the Equipment Notes are received by the Trustee, from funds then
available to the Trustee, there shall be distributed on the applicable Special
Distribution Date, to the Person in whose name this Certificate is registered at
the close of business on the 15th day preceding the Special Distribution Date,
an amount in respect of such Special Payments on the Equipment Notes, the
receipt of which has been confirmed by the Trustee, equal to the product of the
percentage interest in the Trust evidenced by this Certificate and an amount
equal to the sum of such Special Payments so received. If a Regular Distribution
Date or Special Distribution Date is not a Business Day, distribution shall be
made on the immediately following Business Day with the same force and effect as
if made on such Regular Distribution Date or Special Distribution Date and no
interest shall accrue during the intervening period. The Trustee shall mail
notice of each Special Payment and the Special Distribution Date therefor to the
Certificateholder of this Certificate.

            Distributions on this Certificate will be made by the Trustee by
check mailed to the Person entitled thereto, without the presentation or
surrender of this Certificate or the making of any notation hereon. Except as
otherwise provided in the Agreement and notwithstanding the above, the final
distribution on this Certificate will be made after notice mailed by the Trustee
of the pendency of such distribution and only upon presentation and surrender of
this Certificate at the office or agency of the Trustee specified in such
notice.

            The Certificates do not represent a direct obligation of, or an
obligation guaranteed by, or an interest in, the Company or the Trustee or any
affiliate thereof. The Certificates are limited in right of payment, all as more
specifically set forth on the face hereof and in the Agreement. All payments or
distributions made to Certificateholders under the

<PAGE>
Agreement shall be made only from the Trust Property and only to the extent that
the Trustee shall have sufficient income or proceeds from the Trust Property to
make such payments in accordance with the terms of the Agreement. Each
Certificateholder of this Certificate, by its acceptance hereof, agrees that it
will look solely to the income and proceeds from the Trust Property to the
extent available for distribution to such Certificateholder as provided in the
Agreement. This Certificate does not purport to summarize the Agreement and
reference is made to the Agreement for information with respect to the
interests, rights, benefits, obligations, proceeds, and duties evidenced hereby.
A copy of the Agreement may be examined during normal business hours at the
principal office of the Trustee, and at such other places, if any, designated by
the Trustee, by any Certificateholder upon request.

            The Agreement permits, with certain exceptions therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Certificateholders under the Agreement at any time
by the Company and the Trustee with the consent of the Certificateholders
holding Certificates evidencing Fractional Undivided Interests aggregating not
less than a majority in interest in the Trust. Any such consent by the
Certificateholder of this Certificate shall be conclusive and binding on such
Certificateholder and upon all future Certificateholders of this Certificate and
of any Certificate issued upon the transfer hereof or in exchange hereof or in
lieu hereof whether or not notation of such consent is made upon this
Certificate. The Agreement also permits the amendment thereof, in certain
limited circumstances, without the consent of the Certificateholders of any of
the Certificates.

            As provided in the Agreement and subject to certain limitations set
forth, the transfer of this Certificate is registrable in the Register upon
surrender of this Certificate for registration of transfer at the offices or
agencies maintained by the Trustee in its capacity as Registrar, or by any
successor Registrar duly endorsed or accompanied by a written instrument of
transfer in form satisfactory to the Trustee and the Registrar, duly executed by
the Certificateholder hereof or such Certificateholder's attorney duly
authorized in writing, and thereupon one or more new Certificates of authorized
denominations evidencing the same aggregate Fractional Undivided Interest in the
Trust will be issued to the designated transferee or transferees.

            The Certificates are issuable only as registered Certificates
without coupons in minimum denominations of $1,000 Fractional Undivided Interest
and integral multiples thereof except that one Certificate may be issued in a
different denomination. As provided in the Agreement and subject to certain
limitations therein set forth, the Certificates are exchangeable for new
Certificates of authorized denominations evidencing the same aggregate
Fractional Undivided Interest in the Trust, as requested by the
Certificateholder surrendering the same.

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

            The Trustee, the Registrar, and any agent of the Trustee or the
Registrar may treat the person in whose name this Certificate is registered as
the owner hereof for all purposes, and

<PAGE>
neither the Trustee, the Registrar, nor any such agent shall be affected by
any notice to the contrary.

            The obligations and responsibilities created by the Agreement and
the Trust created thereby shall terminate upon the distribution to
Certificateholders of all amounts required to be distributed to them pursuant to
the Agreement and the disposition of all property held as part of the Trust
Property.

            THIS CERTIFICATE AND THE AGREEMENT HAVE EACH BEEN DELIVERED IN THE
STATE OF NEW YORK AND SHALL BE CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE
STATE OF NEW YORK AND THE OBLIGATIONS, RIGHTS AND REMEDIES OF THE PARTIES AND
CERTIFICATEHOLDERS HEREUNDER AND THEREUNDER SHALL BE DETERMINED IN ACCORDANCE
WITH SUCH LAWS.

            Unless the certificate of authentication hereon has been executed by
the Trustee, by manual signature, this Certificate shall not be entitled to any
benefit under the Agreement or be valid for any purpose.
<PAGE>

            IN WITNESS WHEREOF, the Trustee has caused this Certificate to be
duly executed.

                                          SOUTHWEST AIRLINES CO.


                                          By: WILMINGTON TRUST COMPANY,
                                              as Trustee


                                          By:  _______________________________
                                          Title:______________________________

Dated:   _____________________
<PAGE>


              [FORM OF THE TRUSTEE'S CERTIFICATE OF AUTHENTICATION]

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


                                          WILMINGTON TRUST COMPANY,
                                               as Trustee


                                          By:  _______________________________
                                                     Authorized Officer