<PAGE>   1
                                                                     EXHIBIT 4.5










                          PASS THROUGH TRUST AGREEMENT

                           Dated as of October 6, 1998

                                     between

                           AMERICA WEST AIRLINES, INC.

                                       And

                            WILMINGTON TRUST COMPANY,

                                   as Trustee

           America West Airlines Pass Through Trust, Series 1998-1A-S

            6.87% Initial Pass Through Certificates, Series 1998-1A-S
           6.87% Exchange Pass Through Certificates, Series 1998-1A-S





<PAGE>   2
Reconciliation and tie between America West Airlines Pass Through Trust
Agreement, Series 1998-1A-S dated as of October 6, 1998, and the Trust Indenture
Act of 1939. This reconciliation does not constitute part of the Pass Through
Trust Agreement.

          Trust Indenture Act                        Pass Through Trust
            of 1939 Section                           Agreement Section
            ---------------                           -----------------
            310(a)(1)                                  7.08
               (a)(2)                                  7.08
            312(a)                                     3.05; 8.01; 8.02
            313(a)                                     7.06; 8.03
            314(a)                                     8.04(a),(c) & (d)
            (a)(4)                                     8.04(e)
            (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)                      1.04(c)
               (a)(1)(A)                               6.04
               (a)(1)(B)                               6.05
               (b)                                     6.06
               (c)                                     1.04(e)
            317(a)(1)                                  6.03
               (b)                                     7.13
            318(a)                                    12.06
<PAGE>   3
                                TABLE OF CONTENTS

SECTION                                                                     PAGE
-------                                                                     ----

ARTICLE I  DEFINITIONS.........................................................2
      Section 1.01.     Definitions............................................2
      Section 1.02.     Compliance Certificates and Opinions..................13
      Section 1.03.     Form of Documents Delivered to Trustee................14
      Section 1.04.     Directions of Certificateholders......................14

ARTICLE II  ACQUISITION OF TRUST PROPERTY.....................................15
      Section 2.01.     Acquisition of Trust Property.........................15
      Section 2.02.     Acceptance by Trustee.................................16
      Section 2.03.     Limitation of Powers..................................16

ARTICLE III  THE CERTIFICATES.................................................16
      Section 3.01.     Title, Form, Denomination and Execution of
                        Certificates..........................................16
      Section 3.02.     Restrictive Legends...................................18
      Section 3.03.     Authentication of Certificates........................20
      Section 3.04.     Transfer and Exchange.................................20
      Section 3.05.     Book-Entry Provisions for Restricted Global
                        Certificates and Regulation S Global
                        Certificates..........................................21
      Section 3.06.     Special Transfer Provisions...........................23
      Section 3.07.     Mutilated, Destroyed, Lost or Stolen
                        Certificates..........................................25
      Section 3.08.     Persons Deemed Owners.................................26
      Section 3.09.     Cancellation..........................................26
      Section 3.10.     Temporary Certificates................................26
      Section 3.11.     Limitation of Liability for Payments..................27

ARTICLE IV  DISTRIBUTIONS; STATEMENTS TO CERTIFICATEHOLDERS...................27
      Section 4.01.     Certificate Account and Special Payments Account......27
      Section 4.02.     Distributions from Certificate Account and
                        Special Payments Account..............................27
      Section 4.03.     Statements to Certificateholders......................29
      Section 4.04.     Investment of Special Payment Moneys..................30

ARTICLE V  THE COMPANY........................................................30
      Section 5.01.     Maintenance of Corporate Existence....................30
      Section 5.02.     Consolidation, Merger, Etc............................31

ARTICLE VI  DEFAULT...........................................................31
      Section 6.01.     Events of Default.....................................31
      Section 6.02.     Incidents of Sale of Equipment Notes..................34
      Section 6.03.     Judicial Proceedings Instituted by Trustee;
                        Trustee May Bring Suit................................34
      Section 6.04.     Control by Certificateholders.........................34
      Section 6.05.     Waiver of Past Defaults...............................35
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SECTION                                                                     PAGE
-------                                                                     ----

      Section 6.06.     Right of Certificateholders to Receive Payments
                        Not to Be Impaired....................................35
      Section 6.07.     Certificateholders May Not Bring Suit Except
                        Under Certain Conditions..............................36
      Section 6.08.     Remedies Cumulative...................................36

ARTICLE VII  THE TRUSTEE......................................................36
      Section 7.01.     Certain Duties and Responsibilities...................36
      Section 7.02.     Notice of Defaults....................................37
      Section 7.03.     Certain Rights of Trustee.............................37
      Section 7.04.     Not Responsible for Recitals or Issuance of
                        Certificates..........................................38
      Section 7.05.     May Hold Certificates.................................39
      Section 7.06.     Money Held in Trust...................................39
      Section 7.07.     Compensation and Reimbursement........................39
      Section 7.08.     Corporate Trustee Required; Eligibility...............40
      Section 7.09.     Resignation and Removal; Appointment of
                        Successor.............................................40
      Section 7.10.     Acceptance of Appointment by Successor................42
      Section 7.11.     Merger, Conversion, Consolidation or Succession
                        to Business...........................................42
      Section 7.12.     Maintenance of Agencies...............................42
      Section 7.13.     Money for Certificate Payments to Be Held in
                        Trust.................................................44
      Section 7.14.     Registration of Equipment Notes in Name of
                        Subordination Agent...................................44
      Section 7.15.     Representations and Warranties of Trustee.............44
      Section 7.16.     Withholding Taxes, Information Reporting..............45
      Section 7.17.     Trustee's Liens.......................................46
      Section 7.18.     Preferential Collection of Claims.....................46

ARTICLE VIII  CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE................46
      Section 8.01.     The Company to Furnish Trustee with Names and
                        Addresses of Certificateholders.......................46
      Section 8.02.     Preservation of Information; Communications to
                        Certificateholders....................................46
      Section 8.03.     Reports by Trustee....................................46
      Section 8.04.     Reports by the Company................................46

ARTICLE IX  SUPPLEMENTAL AGREEMENTS...........................................48
      Section 9.01.     Supplemental Agreements Without Consent of
                        Certificateholders....................................48
      Section 9.02.     Supplemental Agreements with Consent of
                        Certificateholders....................................49
      Section 9.03.     Documents Affecting Immunity or Indemnity.............50
      Section 9.04.     Execution of Supplemental Agreements..................50
      Section 9.05.     Effect of Supplemental Agreements.....................50
      Section 9.06.     Conformity with Trust Indenture Act...................50
      Section 9.07.     Reference in Certificates to Supplemental
                        Agreements............................................50


                                       ii
<PAGE>   5
SECTION                                                                     PAGE
-------                                                                     ----

ARTICLE X  AMENDMENTS TO INDENTURES AND FINANCING DOCUMENTS...................51
      Section 10.01.    Amendments and Supplements to Indentures and
                        Financing Documents...................................51

ARTICLE XI  TERMINATION OF TRUST..............................................51
      Section 11.01.    Termination of the Trust..............................51

ARTICLE XII  MISCELLANEOUS PROVISIONS.........................................52
      Section 12.01.    Limitation on Rights of Certificateholders............52
      Section 12.02.    Certificates Nonassessable and Fully Paid.............52
      Section 12.03.    Notices...............................................53
      Section 12.04.    Governing Law.........................................54
      Section 12.05.    Severability of Provisions............................54
      Section 12.06.    Trust Indenture Act Controls..........................54
      Section 12.07.    Effect of Headings and Table of Contents..............54
      Section 12.08.    Successors and Assigns................................54
      Section 12.09.    Benefits of Agreement.................................54
      Section 12.10.    Legal Holidays........................................55
      Section 12.11.    Counterparts..........................................55
      Section 12.12.    Intention of Parties..................................55


Exhibit A - Form of Certificate to Request Removal of Restricted Legend
Exhibit B - Form of Certificate to be Delivered by an Institutional Accredited
            Investor


                                       iii
<PAGE>   6
                          PASS THROUGH TRUST AGREEMENT


            This PASS THROUGH TRUST AGREEMENT, dated as of October 6, 1998, (the
"Agreement") between AMERICA WEST AIRLINES, INC., a Delaware corporation, and
WILMINGTON TRUST COMPANY, as Trustee, is made with respect to the formation of
America West Airlines Pass Through Trust, Series 1998-1A-S and the 6.87% America
West Airlines Pass Through Trust, Series 1998-1A-S Pass Through Certificates
representing fractional undivided interests in the Trust.

                                   WITNESSETH:

            WHEREAS, the Company has obtained commitments from AVSA for the
delivery of certain Aircraft;

            WHEREAS, as of the Transfer Date, the Company will have financed (or
refinanced) the acquisition all or a portion of the Aircraft either (i) through
separate leveraged lease transactions in which the Company leases such aircraft
(collectively, the "Leased Aircraft") or (ii) through separate secured loan
transactions in which the Company owns such Aircraft (collectively, the "Owned
Aircraft");

            WHEREAS, as of the Transfer Date, in the case of each Leased
Aircraft, each Owner Trustee, acting on behalf of the corresponding Owner
Participant, will have issued pursuant to an Indenture, on a non-recourse basis,
three (or, subject to satisfaction of certain preconditions contained in the
Note Purchase Agreement, four) series of Equipment Notes in order to finance a
portion of its purchase price of such Leased Aircraft;

            WHEREAS, as of the Transfer Date, in the case of each Owned
Aircraft, the Company, will have issued pursuant to an Indenture, on a recourse
basis, three (or, subject to satisfaction of certain preconditions contained in
the Note Purchase Agreement, four) series of Equipment Notes to finance a
portion of the purchase price of such Owned Aircraft;

            WHEREAS, as of the Transfer Date, the Related Trustee will assign,
transfer and deliver all of such trustee's right, title and interest to the
trust property held by the Related Trustee to the Trustee pursuant to the
Assignment and Assumption Agreement;

            WHEREAS, the Trustee, effective only, but automatically, upon
execution and delivery of the Assignment and Assumption Agreement, will be
deemed to have declared the creation of the Trust for the benefit of the
Certificateholders, and each Holder of Certificates outstanding as of the
Transfer Date, as the grantors of the Trust, by their respective acceptances of
the Certificates, will join in the creation of this Trust with the Trustee;

            WHEREAS, all Certificates deemed issued by the Trust will evidence
fractional undivided interests in the Trust and will convey no rights, benefits
or interests in respect of any property other than the Trust Property except for
those Certificates to which an Escrow Receipt (as defined below) has been
affixed;
<PAGE>   7
                                      -2-


            WHEREAS, the Company has duly authorized the execution, delivery and
effectiveness of this Agreement as the "issuer", as such term is defined in and
solely for purposes of the Securities Act, of the Certificates deemed to be
issued pursuant hereto and as the "obligor", as such term is defined in and
solely for purposes of the Trust Indenture Act of 1939, as amended, with respect
to all such Certificates and is undertaking to perform certain administrative
and ministerial duties hereunder and is also undertaking to pay the ongoing fees
and expenses of the Trustee;

            WHEREAS, upon the execution and delivery of the Assignment and
Assumption Agreement, all of the conditions and requirements necessary to make
this Agreement a valid, binding and legal instrument, enforceable in accordance
with its terms and for the purposes herein expressed, will have been done,
performed and fulfilled, and the execution and delivery of this Agreement in the
form and with the terms hereof will have been in all respects duly authorized;
and

            WHEREAS, upon issuance of the Exchange Certificates, if any, or the
effectiveness of the Shelf Registration Statement, this Agreement, as amended or
supplemented from time to time, will be subject to the provisions of the Trust
Indenture Act of 1939, and shall, to the extent applicable, be governed by such
provisions;

            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 Agreement,
except as otherwise expressly provided or unless the context otherwise requires:

            (1) the terms used in this Agreement, including in the recitals to
this Agreement, that are defined in this Article have the meanings assigned to
them in this Article, 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 Agreement to designated "Articles",
"Sections", "Subsections" and other subdivisions are to the designated Articles,
Sections, Subsections and other subdivisions of this Agreement;

            (4) the words "herein", "hereof" and "hereunder" and other words of
similar import refer to this Agreement as a whole and not to any particular
Article, Section, Subsection or other subdivision; and
<PAGE>   8
                                      -3-


            (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".

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

            Agent Members: Has the meaning specified in Section 3.05.

            Agreement: Has the meaning specified in the initial paragraph
      hereto.

            Aircraft: Has the meaning specified in the Note Purchase Agreement.

            Aircraft Purchase Agreement: Has the meaning specified in the Note
      Purchase Agreement.

            Assignment and Assumption Agreement: Means the assignment and
      assumption agreement substantially in the form of Exhibit D to the Related
      Trust to be executed and delivered in accordance with Section 11.01 of the
      Related Pass Through Trust Agreement.

            Authorized Agent: Means any Paying Agent or Registrar for the
      Certificates.

            Avoidable Tax: Means a state or local tax (i) upon (w) the Trust,
      (x) the Trust Property, (y) Certificateholders or (z) the Trustee for
      which the Trustee is entitled to seek reimbursement from the Trust
      Property, and (ii) which would be avoided if the Trustee were located in
      another state, or jurisdiction within a state, within the United States. A
      tax shall not be an Avoidable Tax if the Company or any Owner Trustee
      shall agree to pay, and shall pay, such tax.

            AVSA: Means AVSA S.A.R.L., an affiliate of Airbus Industrie G.I.E.

            Business Day: Means any day other than a Saturday, a Sunday or a day
      on which commercial banks are required or authorized to close in Phoenix,
      Arizona, New York, New York, Wilmington, Delaware or, so long as any
      Certificate is outstanding, the city and state in which the Trustee or any
      Loan Trustee maintains its Corporate Trust Office or receives and
      disburses funds.

            Cedel: Means Cedel Bank societe anonyme.

            Certificate: Means any one of the Initial Certificates or Exchange
      Certificates issued by the Related Trust and that are "Outstanding" (as
      defined in the Related Pass Through Trust Agreement) as of the Transfer
      Date (the "Transfer Date Certificates") and
<PAGE>   9
                                      -4-


      any such Initial Certificates or Exchange Certificates issued in exchange
      therefor or replacement thereof pursuant to this Agreement.

            Certificate Account: Means the account or accounts created and
      maintained pursuant to Section 4.01(a).

            Certificate Purchase Agreement: Means the Purchase Agreement dated
      September 24, 1998 among the Initial Purchasers and the Company, as the
      same may be amended, supplemented or otherwise modified from time to time
      in accordance with its terms.

            Certificateholder or Holder: Means the Person in whose name a
      Certificate is registered in the Register.

            Class D Certificateholder: Means, at any time, any holder of one or
      more pass through certificates issued by the America West Airlines Pass
      Through Trust, Series 1998-1D, if and when established.

            Company: Means America West Airlines, Inc., a Delaware corporation,
      or its successor in interest pursuant to Section 5.02, or (only in the
      context of provisions hereof, if any, where 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.

            Controlling Party: Has the meaning specified in the Intercreditor
      Agreement.

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

            Definitive Certificates: Has the meaning specified in Section
      3.01(e).

            Delivery Period Termination Date: Has the meaning specified in the
      Related Pass Through Trust Agreement.

            Deposits: Has the meaning specified in the Deposit Agreement.

            Deposit Agreement: Means the Deposit Agreement dated as of October
      6, 1998 relating to the Certificates between the Depositary and the Escrow
      Agent, as the same may be amended, supplemented or otherwise modified from
      time to time in accordance with its terms.

            Depositary: Means ABN AMRO Bank N.V., acting through its Chicago
      branch.

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

            Distribution Date: Means any Regular Distribution Date or Special
      Distribution Date as the context requires.
<PAGE>   10
                                      -5-


            DTC: Means The Depository Trust Company, its nominees and their
      respective successors.

            EBO Date: Means the date set forth on Schedule 1 to the Lease as the
      "EBO Date".

            Equipment Notes: Means the equipment notes issued under the
      Indentures.

            Escrow Agent: Means, initially, Wilmington Trust Company, and any
      replacement or successor therefor appointed in accordance with the Escrow
      Agreement.

            Escrow Agreement: Means the Escrow and Paying Agent Agreement dated
      as of October 6, 1998 relating to the Certificates, among the Escrow
      Agent, the Escrow Paying Agent, the Related Trustee (and after the
      Transfer Date, the Trustee) and the Initial Purchasers, as the same may be
      amended, supplemented or otherwise modified from time to time in
      accordance with its terms.

            Escrow Paying Agent: Means the Person acting as paying agent under
      the Escrow Agreement.

            Escrow Receipt: Means the receipt substantially in the form annexed
      to the Escrow Agreement representing a fractional undivided interest in
      the funds held in escrow thereunder.

            Euroclear: Means Morgan Guaranty Trust Company of New York, Brussels
      Office, as operator of the Euroclear System.

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

            Exchange Certificates: Means the pass through certificates issued in
      exchange for the Initial Certificates pursuant to the Registration Rights
      Agreement and authenticated under the Related Pass Through Trust Agreement
      (prior to the Transfer Date) or hereunder (after the Transfer Date).

            Exchange Offer: Means the exchange offer which may be made pursuant
      to the Registration Rights Agreement to exchange Initial Certificates for
      Exchange Certificates.

            Exchange Offer Registration Statement: Means the registration
      statement that, pursuant to the Registration Rights Agreement, is filed by
      the Company with the SEC with respect to the exchange of Initial
      Certificates for Exchange Certificates.

            Final Legal Distribution Date: Means July 2, 2018.

            Final Withdrawal: Has the meaning specified in the Escrow Agreement.

            Final Withdrawal Date: Has the meaning specified in the Escrow
      Agreement.
<PAGE>   11
                                      -6-


            Financing Documents: With respect to any Equipment Note, means (i)
      the Indenture and the Participation Agreement relating to such Equipment
      Note, and (ii) in the case of any Equipment Note related to a Leased
      Aircraft, the Lease relating to such Leased Aircraft.

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

            Global Certificates: Has the meaning specified in Section 3.01(d).

            Global Exchange Certificate: Has the meaning specified in Section
      3.01(f).

            Indenture: Means each of the separate trust indentures and mortgages
      relating to the Aircraft, each as specified or described in a Delivery
      Notice delivered pursuant to the Note Purchase Agreement or the related
      Participation Agreement, in each case as the same may be amended,
      supplemented or otherwise modified from time to time in accordance with
      its terms.

            Indenture Default: With respect to any Indenture, means any Event of
      Default (as such term is defined in such Indenture).

            Initial Certificates: Means the "Initial Certificates" issued and
      authenticated under the Related Pass Through Trust Agreement, and any
      certificates issued and authenticated hereunder, in each case, other than
      the Exchange Certificates.

            Initial Purchasers: Means, collectively, Morgan Stanley & Co.
      Incorporated, Donaldson, Lufkin & Jenrette Securities Corporation, Merrill
      Lynch, Pierce, Fenner & Smith Incorporated and Salomon Smith Barney Inc.

            Institutional Accredited Investor: Means an institutional investor
      that is an "accredited investor" within the meaning set forth in Rule
      501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act.

            Intercreditor Agreement: Means the Intercreditor Agreement dated as
      of October 6, 1998 among the Related Trustee (and after the Transfer Date,
      the Trustee), the Related Other Trustees (and after the Transfer Date, the
      Other Trustees), the Liquidity Provider, the liquidity provider relating
      to the Certificates issued under (and as defined in) each of the Related
      Other Pass Through Trust Agreements, and Wilmington Trust Company, as
      Subordination Agent and as trustee thereunder, as amended, supplemented or
      otherwise modified from time to time in accordance with its terms.

            Investors: Means the Initial Purchasers together with all subsequent
      beneficial owners of the Certificates.

            Issuance Date: Means the date of the issuance of the Initial
      Certificates.

            Lease: Means, with respect to each Leased Aircraft, the lease
      between an Owner Trustee, as the lessor, and the Company, as the lessee,
      referred to in the related Indenture,
<PAGE>   12
                                      -7-


      as such lease may be amended, supplemented or otherwise modified in
      accordance with its terms.

            Leased Aircraft: Has the meaning specified in the second recital to
      this Agreement.

            Liquidity Facility: Means, initially, the Revolving Credit Agreement
      dated as of October 6, 1998 relating to the Certificates, between the
      Liquidity Provider and the Subordination Agent, as agent and trustee for
      the Trustee, and, from and after the replacement of such Agreement
      pursuant to the Intercreditor Agreement, the replacement liquidity
      facility therefor, in each case as amended, supplemented or otherwise
      modified from time to time in accordance with their respective terms.

            Liquidity Provider: Means, initially, ABN AMRO Bank N.V., acting
      through its Chicago branch, and any replacement or successor therefor
      appointed in accordance with the Intercreditor Agreement.

            Loan Trustee: With respect to any Equipment Note or the Indenture
      applicable thereto, means the bank or trust company designated as trustee
      under such Indenture, together with any successor to such trustee
      appointed pursuant thereto.

            Material Adverse Tax Event: Has the meaning specified in Section
      17.3(a)(4) of the Lease.

            Non-U.S. Person: Means a Person that is not a "U.S. person", as
      defined in Regulation S.

            Note Purchase Agreement: Means the Note Purchase Agreement dated as
      of October 6, 1998 among the Related Trustee (and after the Transfer Date,
      the Trustee), the Related Other Trustees (and after the Transfer Date, the
      Other Trustees), the Company, the Escrow Agent, the Escrow Paying Agent
      and the Subordination Agent, as the same may be amended, supplemented or
      otherwise modified from time to time, in accordance with its terms.

            Offering Circular: Means the Offering Memorandum dated September 24,
      1998 relating to the offering of the Certificates and the other
      certificates under the Related Other Pass Through Trust Agreements.

            Officer's Certificate: Means a certificate signed, (a) in the case
      of the Company, by any Vice President or more senior officer of the
      Company or, (b) in the case of an Owner Trustee or a Loan Trustee, a
      Responsible Officer of 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) the General Counsel of
      the Company, (ii) Cooley Godward LLP, (iii) Vedder, Price, Kaufman,
      Kammholz & Day, or (iv) such other counsel designated by the Company and
      reasonably acceptable to the Trustee and (b) in the case of counsel for
      any Owner Trustee or any Loan Trustee may be such counsel as
<PAGE>   13
                                      -8-


      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 Pass Through Trust Agreements: Means each of the two other
      America West Airlines 1998-1 Pass Through Trust Agreements relating to
      America West Airlines Pass Through Trust, Series 1998-1B-S and America
      West Airlines Pass Through Trust, Series 1998-1C-S, dated the date hereof.

            Other Trustees: Means the trustees under the Other Pass Through
      Trust Agreements, and any successor or other trustee appointed as provided
      therein.

            Other Trusts: Means the America West Airlines Pass Through Trust,
      Series 1998-1B-S and America West Airlines Pass Through Trust, Series
      1998-1C-S, created under the Other Pass Through Trust Agreements.

            Outstanding: When used with respect to Certificates, means, as of
      the date of determination, all Transfer Date Certificates, and all other
      Certificates theretofore authenticated and delivered under this Agreement,
      in each case except:

                         (i) Certificates theretofore canceled by the Registrar
            or delivered to the Trustee or the Registrar for cancellation;

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

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

            Owned Aircraft: Has the meaning specified in the second recital to
      this Agreement.

            Owner Participant: With respect to any Equipment Note relating to a
      Leased Aircraft, means the "Owner Participant" 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: With respect to any Equipment Note relating to a
      Leased Aircraft, means the "Owner Trustee", 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 Indentures.
<PAGE>   14
                                      -9-


            Participation Agreement: Means each Participation Agreement to be
      entered into by the Related Trustee pursuant to the Note Purchase
      Agreement, as the same may be amended, supplemented or otherwise modified
      in accordance with its terms.

            Paying Agent: Means the paying agent maintained and appointed for
      the Certificates 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, as of any date, (i) the original aggregate face
      amount of the "Certificates" as defined in the Related Pass Through Trust
      Agreement, 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 less (iii) the aggregate amount of unused Deposits
      distributed as a Final Withdrawal other than payments in respect of
      interest or premium thereon. 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 such Trust and the
      distribution thereof to be made on such Distribution Date and the
      distribution of the Final Withdrawal to be made on such Distribution Date.

            Pool Factor: Means, as of any date, the quotient (rounded to the
      seventh decimal place) computed by dividing (i) the Pool Balance as at
      such date by (ii) the original aggregate face amount of the "Certificates"
      as defined in the Related Pass Through Trust Agreement. 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 and the distribution thereof to be made on such Distribution Date
      and the distribution of the Final Withdrawal to be made on such
      Distribution Date.

            PTC Event of Default: Means any failure to pay within 10 Business
      Days of the due date thereof: (i) the outstanding Pool Balance on the
      Final Legal Distribution Date or (ii) interest due on the Certificates on
      any Distribution Date (unless the Subordination Agent shall have made an
      Interest Drawing or Drawings (as defined in the Intercreditor Agreement),
      or a withdrawal or withdrawals pursuant to section 3.6(f) of the
      Intercreditor Agreement, with respect thereto in an aggregate amount
      sufficient to pay such interest and shall have distributed such amount to
      the Trustee).

            QIB: Means a qualified institutional buyer as defined in Rule 144A.
<PAGE>   15
                                      -10-


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

            Register and Registrar: Mean the register maintained and the
      registrar appointed pursuant to Sections 3.04 and 7.12.

            Registration Event: Means the declaration of the effectiveness by
      the SEC of the Exchange Offer Registration Statement or the Shelf
      Registration Statement.

            Registration Rights Agreement: Means the Exchange and Registration
      Rights Agreement dated as of October 6, 1998, among the Initial
      Purchasers, the Related Trustee (and after the Transfer Date, the
      Trustee), the Related Other Trustees (and after the Transfer Date, the
      Other Trustees) and the Company, as amended, supplemented or otherwise
      modified from time to time in accordance with its terms.

            Regular Distribution Date: With respect to distributions of
      Scheduled Payments in respect of the Certificates, means each date
      designated as a Regular Distribution Date in the Certificates issued
      pursuant to this Agreement, until payment of all the Scheduled Payments to
      be made under the Equipment Notes held in the Trust have been made;
      provided, however, that, if any such day shall not be a Business Day, the
      related distribution shall be made on the next succeeding Business Day
      without additional interest.

            Regulation S: Means Regulation S under the Securities Act or any
      successor regulation thereto.

            Regulation S Definitive Certificates: Has the meaning specified in
      Section 3.01(e).

            Regulation S Global Certificates: Has the meaning specified in
      Section 3.01(d).

            Related Other Pass Through Trust Agreements: Means the "Other Pass
      Through Trust Agreements" as defined in the Related Pass Through Trust
      Agreement.

            Related Other Trustee: Means the "Other Trustees" as defined in the
      Related Pass Through Trust Agreement.

            Related Other Trusts: Means the "Other Trusts" as defined in the
      Related Pass Through Trust Agreement.

            Related Pass Through Trust Agreement: Means the Pass Through Trust
      Agreement relating to America West Airlines Pass Through Trust, Series
      1998-1A-O, dated as of the date hereof, between the Company and the
      institution acting as trustee thereunder, as amended, supplemented or
      otherwise modified from time to time in accordance with its terms.
<PAGE>   16
                                      -11-


            Related Trust: Means the America West Pass Through Trust, Series
      1998-1A-O, formed under the Related Pass Through Trust Agreement.

            Related Trustee:  Means the trustee under the Related Pass
      Through Trust Agreement.

            Responsible Officer: With respect to the Trustee, any Loan Trustee
      and any Owner Trustee, means any officer in the Corporate Trust Office 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.

            Restricted Definitive Certificates: Has the meaning specified in
      Section 3.01(e).

            Restricted Global Certificate: Has the meaning specified in Section
      3.01(c).

            Restricted Legend: Has the meaning specified in Section 3.02.

            Restricted Period: Has the meaning specified in Section 3.01(d).

            Rule 144A: Means Rule 144A under the Securities Act and any
      successor rule thereto.

            Scheduled Payment: With respect to any Equipment Note, means (i) any
      payment of principal or interest on such Equipment Note (other than any
      such payment which is not in fact received by the Subordination Agent
      within five days of the date on which such payment is scheduled to be
      made) due from the obligor thereon or (ii) any payment of interest on the
      Certificates with funds drawn under any Liquidity Facility, which payment
      represents the installment of principal at the stated maturity of such
      installment of principal on such Equipment Note, the payment of regularly
      scheduled interest accrued on the unpaid principal amount of such
      Equipment Note, or both; provided 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 United States 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.

            Securities Act: Means the United States Securities Act of 1933, as
      amended from time to time, or any successor thereto.

            Shelf Registration Statement: Means the shelf registration statement
      which may be required to be filed by the Company with the SEC pursuant to
      any Registration Rights Agreement, other than an Exchange Offer
      Registration Statement.
<PAGE>   17
                                      -12-


            Special Distribution Date: Means each date on which a Special
      Payment is to be distributed as specified in this Agreement; provided,
      however, that, if any such day shall not be a Business Day, the related
      distribution shall be made on the next succeeding Business Day without
      additional interest.

            Special Redemption Premium: Means the premium payable by the Company
      in respect of the Final Withdrawal pursuant to the Note Purchase
      Agreement.

            Special Payment: Means 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) or Special Redemption Premium.

            Special Payments Account:  Means the account or accounts created
      and maintained pursuant to Section 4.01(b).

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

            Substitute Aircraft: Has the meaning specified in the Note Purchase
      Agreement.

            Tax: Means all license, recording, documentary, registration and
      other similar fees and all taxes, levies, imposts, duties, charges,
      assessments or withholdings of any nature whatsoever imposed by any Taxing
      Authority, together with any penalties, additions to tax, fines or
      interest thereon or additions thereto.

            Taxing Authority: Means any federal, state or local government or
      other taxing authority in the United States, any foreign government or any
      political subdivision or taxing authority thereof, any international
      taxing authority or any territory or possession of the United States or
      any taxing authority thereof.

            Transfer Date: Means the moment of execution and delivery of the
      Assignment and Assumption Agreement by each of the parties thereto.

            Transfer Date Certificates: Has the meaning specified in the
      definition of "Certificates".

            Trust: Means the trust created by this Agreement, the estate of
      which consists of the Trust Property.

            Trust Indenture Act: Means the United States Trust Indenture Act of
      1939, as amended from time to time, or any successor thereto.

            Trust Property: Means (i) the Equipment Notes held as the property
      of the Trust and, subject to the Intercreditor Agreement, all monies at
      any time paid thereon and all monies due and to become due thereunder,
      (ii) funds from time to time deposited in the Certificate Account and the
      Special Payments Account and, subject to the Intercreditor Agreement, any
      proceeds from the sale by the Trustee pursuant to Article VI hereof of any
      Equipment Note and (iii) all rights of the Trust and the Trustee, on
      behalf of the
<PAGE>   18
                                      -13-


      Trust, under the Intercreditor Agreement, the Escrow Agreement, the Note
      Purchase Agreement and the Liquidity Facilities, including, without
      limitation, all rights to receive certain payments thereunder, and all
      monies paid to the Trustee on behalf of the Trust pursuant to the
      Intercreditor Agreement or the Liquidity Facilities, provided, that rights
      with respect to the Deposits or under the Escrow Agreement will not
      constitute Trust Property.

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

            Trustee's Lien: Has the meaning specified in Section 7.17.

            Unindemnified Tax: Means (i) any Tax imposed on the net income, net
      worth or capital, any franchise Tax or similar doing business Tax of the
      Pass Through Trustee (other than any such Tax imposed as a result of the
      Company's assumption of the Equipment Notes pursuant to the purchase of an
      aircraft on an EBO Date or a Material Adverse Tax Event), (ii) any
      withholding Tax imposed by the United States (including, without
      limitation, any withholding Tax imposed by the United States which is
      imposed or increased as a result of the Pass Through Trustee failing to
      deliver to the Company any certificate or document necessary to establish
      that payments under this Agreement are exempt from withholding Tax), and
      (iii) any Avoidable Tax.

            Section 1.02. Compliance Certificates and Opinions. Upon any
application or request (except with respect to matters set forth in Article II)
by the Company, any Owner Trustee or any Loan Trustee to the Trustee to take any
action under any provision of 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 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 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 Agreement (other than a certificate
provided pursuant to Section 8.04(e)) shall include:

            (1) a statement that each individual signing such certificate or
      opinion has read such covenant or condition and the definitions in 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
<PAGE>   19
                                      -14-


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

            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 Agreement or, in respect of the Certificates, 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 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, where it is hereby expressly required pursuant to this
Agreement, to the Company or any Loan Trustee. 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 Agreement and conclusive in favor of the
Trustee, the Company and any Loan Trustee, if made in the manner provided in
this Section.

            (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 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 Outstanding,
such Certificates shall not be so disregarded, and (ii) if any amount of
Certificates so owned by any such Person have been pledged in good faith, such
<PAGE>   20
                                      -15-


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) For all purposes of this Agreement, all Initial Certificates
constituting Certificates and all Exchange Certificates constituting
Certificates shall vote and take all other actions of Certificateholders
together as one series of Certificates.

            (e) The Company may at its option, by delivery of an Officer's
Certificate to the Trustee, set a record date to determine the
Certificateholders 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 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 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 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 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.

            (f) 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.

            (g) Except as otherwise provided in Section 1.04(c), Certificates
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.


                                   ARTICLE II

                          ACQUISITION OF TRUST PROPERTY

            Section 2.01. Acquisition of Trust Property. The Trustee is hereby
irrevocably authorized and directed to execute and deliver the Assignment and
Assumption Agreement on the date specified in Section 11.01 of the Related Pass
Through Trust Agreement, subject only to the satisfaction of the conditions to
such execution set forth in said Section 11.01. This Agreement (except only for
the immediately preceding sentence hereof, which is effective upon execution and
delivery hereof) shall become effective upon the execution and delivery of the
Assignment and Assumption Agreement by the Trustee and the Related Trustee,
automatically and without any further signature or action on the part of the
Company and the Trustee, and shall thereupon constitute the legal, valid and
binding obligation of the parties hereto enforceable against each of the parties
hereto in accordance with its terms. Upon such execution and delivery of the
Assignment and Assumption Agreement, the Related Trust shall be terminated, the
Certificateholders shall receive beneficial interests in the Trust in exchange
for their interests in the Related Trust equal to their respective beneficial
interests in the Related Trust and the
<PAGE>   21
                                      -16-


"Outstanding" (as defined in the Related Pass Through Trust Agreement) pass
through certificates representing fractional undivided interests in the Related
Trust shall be deemed for all purposes of this Agreement and the Related Pass
Through Trust Agreement, without further signature or action of any party or
Certificateholder, to be Certificates representing the same Fractional Undivided
Interests in the Trust and the Trust Property. By acceptance of its Certificate,
each Certificateholder consents to and ratifies such assignment, transfer and
delivery of the trust property of the Related Trust to the Trustee upon the
execution and delivery of the Assignment and Assumption Agreement.

            Section 2.02. Acceptance by Trustee . The Trustee, upon the
execution and delivery of the Assignment and Assumption Agreement, acknowledges
its acceptance of all right, title and interest in and to the Trust Property and
declares that the Trustee holds and will hold such right, title and interest for
the benefit of all then present and future Certificateholders, upon the trusts
herein set forth. Subject to Section 7.14, the Trustee shall take all actions
reasonably necessary to maintain the registration of all such Equipment Notes in
the name of the Subordination Agent. By the acceptance of each Certificate
issued to it under the Related Pass Through Trust Agreement and deemed issued
under this Agreement, each Holder of any such Certificate as grantor of the
Trust thereby joins in the creation and declaration of the Trust.

            Section 2.03. Limitation of Powers . The Trust is constituted solely
for the purpose of making the investment in the Equipment Notes, 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. Title, Form, Denomination and Execution of
Certificates. (a) The Initial Certificates constituting Certificates shall be
known as the "6.87% Initial Pass Through Certificates, Series 1998-1A-S" and the
Exchange Certificates constituting Certificates shall be known as the "6.87%
Exchange Pass Through Certificates, Series 1998-1A-S", in each case, of the
Trust. Each Certificate will represent a fractional undivided interest in the
Trust and shall be substantially in the form set forth as Exhibit A to the
Related Pass Through Trust Agreement, with such appropriate insertions,
omissions, substitutions and other variations as are required or permitted by
the Related Pass Through Trust Agreement or this Agreement, as the case may be,
or as the Trustee may deem appropriate to reflect the fact that the Certificates
are being issued hereunder as opposed to the Related Pass Through Trust
Agreement, and may have such letters, numbers or other marks of identification
and such legends or endorsements placed thereon as may be required to comply
with the rules of any securities exchange or as may, consistently herewith, be
determined by the Trustee or the officers executing such Certificates, as
evidenced by the Trustee's or officer's execution of the Certificates (provided
that such letters, numbers or other marks of identification and such legends or
endorsements are in a form acceptable to the
<PAGE>   22
                                      -17-


Company). At the Escrow Agent's request under the Escrow Agreement, the Trustee
shall affix the corresponding Escrow Receipt to any Certificate issued
hereunder. Any transfer or exchange of any Certificate shall also effect a
transfer or exchange of the related Escrow Receipt. Prior to the Final
Withdrawal Date, no transfer or exchange of any Certificate shall be permitted
unless the corresponding Escrow Receipt is attached thereto and also is so
transferred or exchanged. By acceptance of any Certificate to which an Escrow
Receipt is attached, each Holder of such a Certificate acknowledges and accepts
the restrictions on transfer of the Escrow Receipt set forth herein and in the
Escrow Agreement.

            (b) The Initial Certificates shall be issued only in fully
registered form without coupons and only in denominations of $100,000 or
integral multiples of $1,000 in excess thereof, except that one Certificate may
be issued in a different denomination. The Exchange Certificates will be issued
in denominations of $1,000 or integral multiples thereof, except that one
Certificate may be issued in a different denomination. Each Certificate shall be
dated the date of its authentication. The aggregate Fractional Undivided
Interest of Certificates shall not at any time exceed $131,670,000.

            (c) The Initial Certificates offered and sold in reliance on Rule
144A shall be in the form of one or more Global Certificates substantially in
the form of Exhibit A to the Related Pass Through Trust Agreement with such
applicable legends as are provided for in Section 3.02 (each a "Restricted
Global Certificate"). Such Restricted Global Certificates shall be in registered
form and be registered in the name of DTC and deposited with the Trustee, at its
Corporate Trust Office, as custodian for DTC. The aggregate principal amount of
any Restricted Global Certificate may from time to time be increased or
decreased by adjustments made on the records of the Trustee, as custodian for
DTC for such Restricted Global Certificate, as provided in Section 3.06 hereof,
which adjustments shall be conclusive as to the aggregate principal amount of
any such Global Certificate.

            (d) The Initial Certificates offered and sold outside the United
States in reliance on Regulation S shall be in the form of one or more global
Certificates substantially in the form of Exhibit A to the Related Pass Through
Trust Agreement (each a "Regulation S Global Certificate"). Such Regulation S
Global Certificates shall be in registered form and be registered in the name of
DTC and deposited with the Trustee, at its Corporate Trust Office, as custodian
for DTC, for credit initially and during the Restricted Period (hereinafter
defined) to the respective accounts of beneficial owners of such Certificates
(or to such other accounts as they may direct) at Morgan Guaranty Trust Company
of New York, Brussels office, as operator of Euroclear or Cedel. As used herein,
the term "Restricted Period", with respect to the Regulation S Global
Certificates offered and sold in reliance on Regulation S, means the period of
40 consecutive days beginning on and including the later of (i) the day on which
the "Certificates" (as defined in the Related Pass Through Trust Agreement are
first offered to persons other than distributors (as defined in Regulation S) in
reliance on Regulation S and (ii) the date of the closing of the offering under
the Certificate Purchase Agreement. The aggregate principal amount of any
Regulation S Global Certificate may from time to time be increased or decreased
by adjustments made on the records of the Trustee, as custodian for DTC for such
Global Certificate, as provided in Section 3.06 hereof, which adjustments shall
be conclusive as to the aggregate principal amount of any such Global
Certificate. The Restricted
<PAGE>   23
                                      -18-


Global Certificate and Regulation S Global Certificate are sometimes
collectively referred to herein as the "Global Certificates".

            (e) Initial Certificates offered and sold to any Institutional
Accredited Investor which is not a QIB in a transaction exempt from registration
under the Securities Act (and other than as described in Section 3.01(d)) shall
be substantially in the form of Exhibit A to the Related Pass Through Trust
Agreement in definitive, fully registered form without interest coupons with
such applicable legends as are provided for in Section 3.02 (the "Restricted
Definitive Certificates"). Such Certificates issued pursuant to Section 3.05(b)
in exchange for interests in a Regulation S Global Certificate shall be issued
in definitive, fully registered form without interest coupons (the "Regulation S
Definitive Certificates"). The Restricted Definitive Certificates and the
Regulation S Definitive Certificates are sometimes collectively referred to
herein as the "Definitive Certificates".

            (f) The Exchange Certificates exchanged for Initial Certificates
under the Related Trust shall be in the form of one or more global Certificates
substantially in the form of Exhibit A thereto (each, a "Global Exchange
Certificate"). Exchange Certificates issued under this Trust (each, also a
"Global Exchange Certificate") shall be in the form of one or more global
certificates substantially in the form of Exhibit A to the Related Pass Through
Trust Agreement except that (i) the Restricted Legend (hereinafter defined)
shall be omitted and (ii) such Exchange Certificates shall contain such
appropriate insertions, omissions, substitutions and other variations from the
form set forth in Exhibit A to the Related Pass Through Trust Agreement relating
to the nature of the Exchange Certificates or to reflect the fact that the
Certificates are being issued hereunder as opposed to the Related Pass Through
Trust Agreement, as the Responsible Officer of the Trustee executing such
Exchange Certificates on behalf of the Trust may determine, as evidenced by such
officer's execution on behalf of the Trust of such Exchange Certificates. Such
Global Exchange Certificates shall be in registered form and be registered in
the name of DTC and deposited with the Trustee, at its Corporate Trust Office,
as custodian for DTC. The aggregate principal amount of any Global Exchange
Certificate may from time to time be increased or decreased by adjustments made
on the records of the Trustee, as custodian for DTC for such Global Exchange
Certificate, which adjustments shall be conclusive as to the aggregate principal
amount of any such Global Exchange Certificate. Subject to clause (i) and (ii)
of the second sentence of this Section 3.01(f), the terms hereof applicable to
Restricted Global Certificates and/or Global Certificates shall apply to the
Global Exchange Certificates, mutatis mutandis.

            (g) The Definitive Certificates shall be in registered form and
shall be typed, printed, lithographed or engraved or produced by any combination
of these methods or may be produced in any other manner, all as determined by
the officers executing such Certificates, as evidenced by their execution of
such Certificates.

            Section 3.02. Restrictive Legends . All Initial Certificates issued
for resale pursuant to Rule 144A or offered and sold to any Institutional
Accredited Investor which is not a QIB (including any Global Certificate issued
upon registration of transfer, in exchange for or in lieu of such Certificates)
shall be "Restricted Certificates" and shall bear a legend to the following
effect (the "Restricted Legend") unless the Company and the Trustee determine
otherwise consistent with applicable law:
<PAGE>   24
                                      -19-


            THIS CERTIFICATE HAS NOT BEEN REGISTERED UNDER THE U.S. SECURITIES
      ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND ACCORDINGLY, MAY NOT
      BE OFFERED OR SOLD WITHIN THE UNITED STATES OR TO, OR FOR THE ACCOUNT OR
      BENEFIT OF, ANY PERSONS EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE. BY
      ITS ACQUISITION HEREOF, THE HOLDER (1) REPRESENTS THAT (A) IT IS A
      "QUALIFIED INSTITUTIONAL BUYER" (AS DEFINED IN RULE 144A UNDER THE
      SECURITIES ACT), (B) IT IS AN INSTITUTIONAL "ACCREDITED INVESTOR" (AS
      DEFINED IN RULE 501(a)(1), (2), (3) OR (7) OF REGULATION D UNDER THE
      SECURITIES ACT) (AN "INSTITUTIONAL ACCREDITED INVESTOR") OR (C) IT IS NOT
      A U.S. PERSON AND IS ACQUIRING THIS CERTIFICATE IN AN OFFSHORE TRANSACTION
      IN COMPLIANCE WITH REGULATION S UNDER THE SECURITIES ACT; (2) AGREES THAT
      IT WILL NOT WITHIN TWO YEARS AFTER THE LATER OF THE ORIGINAL ISSUANCE OF
      THIS CERTIFICATE OR THE LAST DATE ON WHICH THIS CERTIFICATE WAS HELD BY
      AMERICA WEST AIRLINES, INC., THE TRUSTEE OR ANY AFFILIATE OF ANY OF SUCH
      PERSONS RESELL OR OTHERWISE TRANSFER THIS CERTIFICATE EXCEPT (A) TO
      AMERICA WEST AIRLINES, INC., (B) TO A QUALIFIED INSTITUTIONAL BUYER IN
      COMPLIANCE WITH RULE 144A UNDER THE SECURITIES ACT, (C) OUTSIDE THE UNITED
      STATES IN AN OFFSHORE TRANSACTION IN COMPLIANCE WITH RULE 904 UNDER THE
      SECURITIES ACT, (D) PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED
      BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE) OR (E) PURSUANT TO AN
      EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT; AND (3) AGREES
      THAT IF IT SHOULD RESELL OR OTHERWISE TRANSFER THIS CERTIFICATE IT WILL
      DELIVER TO EACH PERSON TO WHOM THIS CERTIFICATE IS TRANSFERRED A NOTICE
      SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. IN CONNECTION WITH ANY
      TRANSFER OF THIS CERTIFICATE WITHIN TWO YEARS AFTER THE LATER OF THE
      ORIGINAL ISSUANCE OF THIS CERTIFICATE OR THE LAST DATE ON WHICH THIS
      CERTIFICATE WAS HELD BY AMERICA WEST AIRLINES, INC., THE TRUSTEE OR ANY
      AFFILIATE OF ANY OF SUCH PERSONS, THE HOLDER MUST CHECK THE APPROPRIATE
      BOX SET FORTH ON THE REVERSE HEREOF RELATING TO THE MANNER OF SUCH
      TRANSFER AND SUBMIT THIS CERTIFICATE TO THE TRUSTEE. AS USED HEREIN, THE
      TERMS "OFFSHORE TRANSACTION", "UNITED STATES" AND "U.S. PERSON" HAVE THE
      MEANINGS GIVEN TO THEM BY REGULATION S UNDER THE SECURITIES ACT. THE PASS
      THROUGH TRUST AGREEMENT CONTAINS A PROVISION REQUIRING THE TRUSTEE TO
      REFUSE TO REGISTER ANY TRANSFER OF THIS CERTIFICATE IN VIOLATION OF THE
      FOREGOING RESTRICTIONS.

            Each Global Certificate shall bear the following legend on the face
      thereof:

            UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
      OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE
      TRUSTEE OR ITS AGENT FOR
<PAGE>   25
                                      -20-


      REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED
      IN EXCHANGE FOR THIS CERTIFICATE 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 HEREON 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.

            TRANSFERS OF THIS GLOBAL CERTIFICATE SHALL BE LIMITED TO TRANSFERS
      IN WHOLE, BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR
      SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL
      CERTIFICATE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE
      RESTRICTIONS SET FORTH IN SECTIONS 3.05 AND 3.06 OF THE PASS THROUGH TRUST
      AGREEMENT REFERRED TO HEREIN.

            Section 3.03. Authentication of Certificates. (a) No Certificate
shall be entitled to any benefit under this Agreement or be valid or obligatory
for any purpose, unless there appears on such Certificate a certificate of
authentication substantially in the form provided for herein executed by the
Trustee by the manual signature of one of its authorized signatories, and such
certificate upon any Certificate shall be conclusive evidence, and the only
evidence, that such Certificate has been duly authenticated and delivered
hereunder.

            (b) Certificates 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
Trust 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 on the date of such 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") of the Certificates in
which, subject to such reasonable regulations as it may prescribe, the Trustee
shall provide for the registration of such Certificates 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 and transfers and exchanges of such Certificates as herein
provided. The Company, upon notice to the Trustee, may change the Registrar at
any time.

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

            A Certificateholder may transfer a Certificate, or request that a
Certificate be exchanged for Certificates in an aggregate Fractional Undivided
Interest equal to the Fractional
<PAGE>   26
                                      -21-


Undivided Interest of such Certificate surrendered for exchange of other
authorized denominations, by surrender of such Certificate to the Trustee with
the form of transfer notice thereon duly completed and executed, and otherwise
complying with the terms of this Agreement, including providing evidence of
compliance with any restrictions on transfer, in form satisfactory to the
Trustee and the Registrar; provided that no exchanges of Initial Certificates
for Exchange Certificates shall occur until an Exchange Offer Registration
Statement shall have been declared effective by the SEC (notice of which shall
be provided to the Trustee by the Company). No such transfer shall be effected
until, and such transferee shall succeed to the rights of a Certificateholder
only upon, final acceptance and registration of the transfer by the Registrar in
the Register. Prior to the registration of any transfer by a Certificateholder
as provided herein, the Trustee shall treat the person in whose name the
Certificate is registered as the owner thereof for all purposes, and the Trustee
shall not be affected by notice to the contrary. Furthermore, DTC shall, by
acceptance of a Global Certificate, agree that transfers of beneficial interests
in such Global Certificate may be effected only through a book-entry system
maintained by DTC (or its agent), and that ownership of a beneficial interest in
the Certificate shall be required to be reflected in book-entry. When
Certificates are presented to the Registrar with a request to register the
transfer thereof or to exchange them for other authorized denominations of a
Certificate in a Fractional Undivided Interest equal to the aggregate Fractional
Undivided Interest of Certificates surrendered for exchange, the Registrar shall
register the transfer or make the exchange as requested if its requirements for
such transactions are met.

            To permit registrations of transfers and exchanges in accordance
with the terms, conditions and restrictions hereof, the Trustee shall execute
and authenticate Certificates at the Registrar's request. 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 canceled and
subsequently destroyed by the Trustee.

            Section 3.05. Book-Entry Provisions for Restricted Global
Certificates and Regulation S Global Certificates. (a) Members of, or
participants in, DTC ("Agent Members") shall have no rights under this Agreement
with respect to any Global Certificate held on their behalf by DTC, or the
Trustee as its custodian, and DTC may be treated by the Trustee and any agent of
the Trustee as the absolute owner of such Global Certificate for all purposes
whatsoever. Notwithstanding the foregoing, nothing herein shall prevent the
Trustee or any agent of the Trustee from giving effect to any written
certification, proxy or other authorization furnished by DTC or shall impair, as
between DTC and its Agent Members, the operation of customary practices
governing the exercise of the rights of a holder of any Certificate. Upon the
issuance of any Global Certificate, the Registrar or its duly appointed agent
shall record DTC as the registered holder of such Global Certificate.

            (b) Transfers of any Global Certificate shall be limited to
transfers of such Restricted Global Certificate or Regulation S Global
Certificate in whole, but not in part, to DTC. Beneficial interests in the
Restricted Global Certificate and any Regulation S Global Certificate may be
transferred in accordance with the rules and procedures of DTC and the
provisions of Section 3.06. Beneficial interests in a Restricted Global
Certificate or a Regulation S Global Certificate shall be (or, under the Related
Pass Through Trust Agreement,
<PAGE>   27
                                      -22-


may have been) delivered to all beneficial owners thereof in the form of
Restricted Definitive Certificates or Regulation S Definitive Certificates, as
the case may be, if (i) DTC notifies the Trustee that it is unwilling or unable
to continue as depositary for such Restricted Global Certificate or Regulation S
Global Certificate, as the case may be, and a successor depositary is not
appointed by the Trustee within 90 days of such notice, and (ii) after the
occurrence and during the continuance of an Event of Default, owners of
beneficial interests in a Global Certificate with Fractional Undivided Interests
aggregating not less than a majority in interest in the Trust advise the
Trustee, the Company and DTC through Agent Members in writing that the
continuation of a book-entry system through DTC or its successor is no longer in
their best interests.

            (c) Any beneficial interest in one of the Global Certificates that
is transferred to a Person who takes delivery in the form of an interest in
another Global Certificate will, upon such transfer, cease to be an interest in
such Global Certificate and become an interest in the other Global Certificate
and, accordingly, will thereafter be subject to all transfer restrictions, if
any, and other procedures applicable to beneficial interests in such other
Global Certificate for as long as it remains such an interest.

            (d) In connection with the transfer of an entire Restricted Global
Certificate or an entire Regulation S Global Certificate to the beneficial
owners thereof pursuant to paragraph (b) of this Section 3.05, such Restricted
Global Certificate or Regulation S Global Certificate, as the case may be, shall
be deemed to be surrendered to the Trustee for cancellation, and the Trustee
shall execute, authenticate and deliver, to each beneficial owner identified by
DTC in exchange for its beneficial interest in such Restricted Global
Certificate or Regulation S Global Certificate, as the case may be, an equal
aggregate principal amount of Restricted Definitive Certificates or Regulation S
Definitive Certificates, as the case may be, of authorized denominations. None
of 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, 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) Any Definitive Certificate delivered in exchange for an interest
in the Restricted Global Certificate pursuant to paragraph (b) of this Section
3.05 shall, except as otherwise provided by paragraph (e) of Section 3.06, bear
the Restricted Legend.

            (f) Prior to the expiration of the Restricted Period, any Regulation
S Definitive Certificate delivered in exchange for an interest in a Regulation S
Global Certificate pursuant to paragraph (b) of this Section shall bear the
Restricted Legend.

            (g) The registered holder of any Restricted Global Certificate or
Regulation S Global Certificate may grant proxies and otherwise authorize any
Person, including Agent Members and Persons that may hold interests through
Agent Members, to take any action which a Holder is entitled to take under this
Agreement or the Certificates.
<PAGE>   28
                                      -23-


            Section 3.06. Special Transfer Provisions Unless and until (i) an
Initial Certificate is sold under an effective Shelf Registration Statement, or
(ii) an Initial Certificate is exchanged for an Exchange Certificate pursuant to
an effective Exchange Offer Registration Statement, in each case pursuant to the
terms of the Registration Rights Agreement, the following provisions shall apply
to such Initial Certificates:

            (a) Transfers to Non-QIB Institutional Accredited Investors. The
      following provisions shall apply with respect to the registration of any
      proposed transfer of a Certificate to any Institutional Accredited
      Investor which is neither a QIB nor a Non-U.S. Person:

                         (i) The Registrar shall register the transfer of any
            Certificate, whether or not bearing the Restricted Legend, only if
            (x) the requested transfer is at least two years after the later of
            the original issue date of the Certificates and the last date on
            which such Certificate was held by the Company, the Trustee or any
            affiliate of any of such Persons or (y) the proposed transferor is
            an Initial Purchaser who is transferring Certificates purchased
            under the Certificates Purchase Agreement and the proposed
            transferee has delivered to the Registrar a letter substantially in
            the form of Exhibit B hereto and the aggregate principal amount of
            the Certificates being transferred is at least $100,000. Except as
            provided in the foregoing clause (y), the Registrar shall not
            register the transfer of any Certificate to any Institutional
            Accredited Investor which is neither a QIB nor a Non-U.S. Person.

                         (ii) If the proposed transferor is an Agent Member
            holding a beneficial interest in a Restricted Global Certificate,
            upon receipt by the Registrar of (x) the documents, if any, required
            by paragraph (i) and (y) instructions given in accordance with DTC's
            and the Registrar's procedures, the Registrar shall reflect on its
            books and records the date of the transfer and a decrease in the
            principal amount of such Restricted Global Certificate in an amount
            equal to the principal amount of the beneficial interest in such
            Restricted Global Certificate to be transferred, and the Trustee
            shall execute, authenticate and deliver to the transferor or at its
            direction, one or more Restricted Definitive Certificates of like
            tenor and amount.

            (b) Transfers to QIBs. The following provisions shall apply with
      respect to the registration of any proposed transfer of an Initial
      Certificate to a QIB (excluding Non-U.S. Persons):

                         (i) If the Certificate to be transferred consists of
            Restricted Definitive Certificates, or of an interest in any
            Regulation S Global Certificate during the Restricted Period, the
            Registrar shall register the transfer if such transfer is being made
            by a proposed transferor who has checked the box provided for on the
            form of Initial Certificate stating, or has otherwise advised the
            Trustee and the Registrar in writing, that the sale has been made in
            compliance with the provisions of Rule 144A to a transferee who has
            signed the certification provided for on the form of Initial
            Certificate stating, or has otherwise advised the Trustee 
<PAGE>   29
                                      -24-

            and the Registrar in writing, that it is purchasing the Initial
            Certificate for its own account or an account with respect to which
            it exercises sole investment discretion and that it, or the Person
            on whose behalf it is acting with respect to any such account, is a
            QIB within the meaning of Rule 144A, and is aware that the sale to
            it is being made in reliance on Rule 144A and acknowledges that it
            has received such information regarding the Trust and/or the Company
            as it has requested pursuant to Rule 144A or has determined not to
            request such information and that it is aware that the transferor is
            relying upon its foregoing representations in order to claim the
            exemption from registration provided by Rule 144A.

                         (ii) Upon receipt by the Registrar of the documents
            required by clause (i) above and instructions given in accordance
            with DTC's and the Registrar's procedures therefor, the Registrar
            shall reflect on its books and records the date of such transfer and
            an increase in the principal amount of a Restricted Global
            Certificate in an amount equal to the principal amount of the
            Restricted Definitive Certificates or interests in such Regulation S
            Global Certificate, as the case may be, being transferred, and the
            Trustee shall cancel such Definitive Certificates or decrease the
            amount of such Regulation S Global Certificate so transferred.

            (c) Transfers of Interests in the Regulation S Global Certificate or
      Regulation S Definitive Certificates. After the expiration of the
      Restricted Period, the Registrar shall register any transfer of interests
      in any Regulation S Global Certificate or Regulation S Definitive
      Certificates without requiring any additional certification. Until the
      expiration of the Restricted Period, interests in the Regulation S Global
      Certificate may only be held through Agent Members acting for and on
      behalf of Euroclear and Cedel.

            (d) Transfers to Non-U.S. Persons at Any Time. The following
      provisions shall apply with respect to any registration of any transfer of
      an Initial Certificate to a Non-U.S. Person:

                         (i) Prior to the expiration of the Restricted Period,
            the Registrar shall register any proposed transfer of an Initial
            Certificate to a Non-U.S. Person upon receipt of a certificate
            substantially in the form set forth as Exhibit A hereto from the
            proposed transferor.

                         (ii) After the expiration of the Restricted Period, the
            Registrar shall register any proposed transfer to any Non-U.S.
            Person if the Certificate to be transferred is a Restricted
            Definitive Certificate or an interest in a Restricted Global
            Certificate, upon receipt of a certificate substantially in the form
            of Exhibit A from the proposed transferor. The Registrar shall
            promptly send a copy of such certificate to the Company.

                         (iii) Upon receipt by the Registrar of (x) the
            documents, if any, required by clause (ii) and (y) instructions in
            accordance with DTC's and the Registrar's procedures, the Registrar
            shall reflect on its books and records the date of such transfer and
            a decrease in the principal amount of such Restricted Global
<PAGE>   30
                                      -25-


            Certificate in an amount equal to the principal amount of the
            beneficial interest in such Restricted Global Certificate to be
            transferred, and, upon receipt by the Registrar of instructions
            given in accordance with DTC's and the Registrar's procedures, the
            Registrar shall reflect on its books and records the date and an
            increase in the principal amount of the Regulation S Global
            Certificate in an amount equal to the principal amount of the
            Restricted Definitive Certificate or the Restricted Global
            Certificate, as the case may be, to be transferred, and the Trustee
            shall cancel the Definitive Certificate, if any, so transferred or
            decrease the amount of such Restricted Global Certificate.

            (e) Restricted Legend. Upon the transfer, exchange or replacement of
      Certificates not bearing the Restricted Legend, the Registrar shall
      deliver Certificates that do not bear the Restricted Legend. Upon the
      transfer, exchange or replacement of Certificates bearing the Restricted
      Legend, the Registrar shall deliver only Certificates that bear the
      Restricted Legend unless either (i) the circumstances contemplated by
      paragraph (d)(ii) of this Section 3.06 exist or (ii) there is delivered to
      the Registrar an Opinion of Counsel to the effect that neither such legend
      nor the related restrictions on transfer are required in order to maintain
      compliance with the provisions of the Securities Act.

            (f) General. By acceptance of any Certificate bearing the Restricted
      Legend, each Holder of such a Certificate acknowledges the restrictions on
      transfer of such Certificate set forth in this Agreement and agrees that
      it will transfer such Certificate only as provided in this Agreement. The
      Registrar shall not register a transfer of any Certificate unless such
      transfer complies with the restrictions on transfer, if any, of such
      Certificate set forth in this Agreement. In connection with any transfer
      of Certificates, each Certificateholder agrees by its acceptance of the
      Certificates to furnish the Registrar or the Trustee such certifications,
      legal opinions or other information as either of them may reasonably
      require to confirm that such transfer is being made pursuant to an
      exemption from, or a transaction not subject to, the registration
      requirements of the Securities Act and in accordance with the terms and
      provisions of this Article III; provided that the Registrar shall not be
      required to determine the sufficiency of any such certifications, legal
      opinions or other information.

            Until such time as no Certificates remain Outstanding, the Registrar
shall retain copies of all letters, notices and other written communications
received pursuant to Section 3.05 or this Section 3.06. The Trustee, if not the
Registrar at such time, shall have the right to inspect and make copies of all
such letters, notices or other written communications at any reasonable time
upon the giving of reasonable written notice to the Registrar.

            Section 3.07. 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 protected
purchaser, and provided that the requirements of Section 8-405 of the Uniform
Commercial Code in effect in any applicable
<PAGE>   31
                                      -26-


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, in authorized denominations and
of like Fractional Undivided Interest and bearing a number not contemporaneously
outstanding.

            In connection with the issuance of any new Certificate under this
Section 3.07, the Trustee may 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 3.07 shall
constitute conclusive evidence of the appropriate Fractional Undivided Interest
in the 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 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 3.08. 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 3.09. 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 canceled by it. No Certificates shall be authenticated in
lieu of or in exchange for any Certificates canceled as provided in this
Section, except as expressly permitted by this Agreement. All canceled
Certificates held by the Registrar shall be destroyed and a certification of
their destruction delivered to the Trustee.

            Section 3.10. Temporary Certificates. Until definitive Certificates
are ready for delivery, the Trustee shall authenticate temporary Certificates.
Temporary Certificates shall be substantially in the form of definitive
Certificates but may have insertions, substitutions, omissions and other
variations determined to be appropriate by the officers executing the temporary
Certificates, as evidenced by their execution of such temporary Certificates. If
temporary Certificates are issued, the Trustee will cause definitive
Certificates to be prepared without unreasonable delay. After the preparation of
definitive Certificates, the temporary Certificates shall be exchangeable for
definitive Certificates upon surrender of the 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 authorized denominations. Until so exchanged, the temporary
Certificates shall be entitled to the same benefits under this Agreement as
definitive Certificates.
<PAGE>   32
                                      -27-


            Section 3.11. Limitation of Liability for Payments. All payments and
distributions made to Certificateholders in respect of the Certificates 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 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 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 Liquidity Providers, the Owner Trustees or the Owner
Participants, except as otherwise expressly provided herein or in the
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).


                                   ARTICLE IV

                          DISTRIBUTIONS; STATEMENTS TO
                               CERTIFICATEHOLDERS

            Section 4.01. Certificate Account and Special Payments Account. (a)
The Trustee shall maintain on behalf of the Certificateholders a Certificate
Account as one or more non-interest-bearing accounts. The Trustee shall hold the
Certificate Account in trust for the benefit of the Certificateholders, 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 the
Intercreditor Agreement, the Trustee upon receipt thereof shall immediately
deposit the aggregate amount of such Scheduled Payment in the Certificate
Account.

            (b) The Trustee shall maintain on behalf of the Certificateholders 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 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 the
Intercreditor Agreement and upon the payment of the Special Redemption Premium
to the Trustee under the Note Purchase Agreement, the Trustee, upon receipt
thereof, shall immediately deposit the aggregate amount of such Special Payments
in the Special Payments Account.

            (c) The Trustee shall 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 or as soon thereafter as
the Trustee has confirmed receipt of the payment of all or any part of the
Scheduled Payments due on such date, the Trustee shall distribute out of the
Certificate Account the entire amount deposited therein
<PAGE>   33
                                      -28-


pursuant to Section 4.01(a). There shall be so distributed to each
Certificateholder of record 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 Certificate Account, except that, with respect to
Certificates registered on the Record Date in the name of DTC, such distribution
shall be made by wire transfer in immediately available funds to the account
designated by DTC.

            (b) On each Special Distribution Date with respect to any Special
Payment or as soon thereafter as the Trustee has confirmed receipt of any
Special Payments due on the Equipment Notes held in the related Trust or
realized upon the sale of such Equipment Notes or receipt of the Special
Redemption Premium, the Trustee shall distribute out of the Special Payments
Account the entire amount of such Special Payment deposited therein pursuant to
Section 4.01(b). There shall be so distributed to each Certificateholder of
record 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 Trust held by such Certificateholder) of the total amount in the Special
Payments Account on account of such Special Payment, except that, with respect
to Certificates registered on the Record Date in the name of DTC, such
distribution shall be made by wire transfer in immediately available funds to
the account designated by DTC.

            (c) The Trustee shall cause notice of each Special Payment to be
mailed to each Certificateholder at his address as it appears in the Register.
In the event of redemption or purchase of Equipment Notes held in the Trust,
such notice shall be mailed not less than 20 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 of the payment of a Special Redemption Premium by the
Company to the Trustee under the Note Purchase Agreement, such notice shall be
mailed, together with the notice by the Escrow Paying Agent under Section 2.06
of the Escrow Agreement, not less than 20 days prior to the Special Distribution
Date for such amount, which Special Distribution Date shall be the Final
Withdrawal Date. 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 20 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 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>   34
                                      -29-


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

If the amount of (i) premium, if any, payable upon the redemption or purchase of
an Equipment Note or (ii) the Special Redemption Premium, if any, 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 the Trust is
canceled, the Trustee, as soon as possible after learning thereof, shall cause
notice thereof to be mailed to each Certificateholder at its address as it
appears on the Register.

            Section 4.03. Statements to Certificateholders. (a) On each
Distribution Date, the Trustee will include with each distribution to
Certificateholders of a Scheduled Payment or Special Payment, as the case may
be, a statement setting forth the information provided below (in the case of a
Special Payment, including any Special Redemption Premium, reflecting in part
the information provided by the Escrow Paying Agent under the Escrow Agreement).
Such statement shall set forth (per $1,000 face amount Certificate as to (ii),
(iii), (iv) and (v) below) the following information:

            (i) the aggregate amount of funds distributed on such Distribution
      Date hereunder and under the Escrow Agreement, indicating the amount
      allocable to each source;

            (ii) the amount of such distribution hereunder allocable to
      principal and the amount allocable to premium (including the Special
      Redemption Premium), if any;

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

            (iv) the amount of such distribution under the Escrow Agreement
      allocable to interest;

            (v) the amount of such distribution under the Escrow Agreement
      allocable to Deposits; and

            (vi) the Pool Balance and the Pool Factor.

            With respect to the Certificates registered in the name of DTC, on
the Record Date prior to each Distribution Date, the Trustee will request from
DTC a securities position listing setting forth the names of all Agent Members
reflected on DTC's books as holding interests in the Certificates on such Record
Date. On each Distribution Date, the Trustee will mail to each such Agent Member
the statement described above and will make available additional copies as
requested by such Agent Member 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
<PAGE>   35
                                      -30-


of the amounts determined pursuant to clauses (a)(i), (a)(ii), (a)(iii), (a)(iv)
and (a)(v) above for such calendar year or, in the event such Person was a
Certificateholder of record during a portion of such calendar year, for such
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. Such statement and such other items shall be prepared on the basis of
information supplied to the Trustee by the Agent Members and shall be delivered
by the Trustee to such Agent Members to be available for forwarding by such
Agent Members to the holders of interests in the Certificates in the manner
described in Section 4.03(a).

            (c) Promptly following (i) the Transfer Date, if there has been any
change in the information set forth in clauses (x), (y) and (z) below from that
set forth in page 69 of the Offering Circular, and (ii) any early redemption or
purchase of, or any default in the payment of principal or interest in respect
of, any of the Equipment Notes held in the Trust, or any Final Withdrawal, the
Trustee shall furnish to Certificateholders of record on such date a statement
setting forth (x) the expected Pool Balances for each subsequent Regular
Distribution Dates following the Delivery Period Termination Date, (y) the
related Pool Factors for such Regular Distribution Dates and (z) the expected
principal distribution schedule of the Equipment Notes, in the aggregate, held
as Trust Property at the date of such notice. With respect to the Certificates
registered in the name of DTC, on the Transfer Date, the Trustee will request
from DTC a securities position listing setting forth the names of all Agent
Members reflected on DTC's books as holding interests in the "Certificates" (as
defined in the Related Pass Through Trust Agreement) on the Delivery Period
Termination Date. The Trustee will mail to each such Agent Member the statement
described above and will make available additional copies as requested by such
Agent Member for forwarding to holders of interests in the Certificates.

            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, except as
permitted by Section 5.02.
<PAGE>   36
                                      -31-


            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. 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);

            (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 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 this Agreement, the Other Pass Through Trust Agreements and
      each Financing Document 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 reasonably satisfactory to the Trustee, 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 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 Financing Document 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 Default under any
Indenture, the Trustee may, to the extent it is the Controlling Party at such
time (as determined pursuant to the
<PAGE>   37
                                      -32-


Intercreditor Agreement), direct the exercise of remedies as provided in the
Intercreditor Agreement.

            (b) Purchase Rights of Certificateholders. By acceptance of its
Certificate, each Certificateholder agrees that at any time after the occurrence
and during the continuation of a Triggering Event,

            (i) each Class B Certificateholder shall have the right to purchase
      all, but not less than all, of the Certificates upon ten days' written
      notice to the Trustee and each other Class B Certificateholder, provided
      that (A) if prior to the end of such ten-day period any other Class B
      Certificateholder notifies such purchasing Class B Certificateholder that
      such other Class B Certificateholder wants to participate in such
      purchase, then such other Class B Certificateholder may join with the
      purchasing Class B Certificateholder to purchase all, but not less than
      all, of the Certificates pro rata based on the Fractional Undivided
      Interest in the Class B Trust held by each such Class B Certificateholder
      and (B) if prior to the end of such ten-day period any other Class B
      Certificateholder fails to notify the purchasing Class B Certificateholder
      of such other Class B Certificateholder's desire to participate in such a
      purchase, then such other Class B Certificateholder shall lose its right
      to purchase the Certificates pursuant to this Section 6.01(b); and

            (ii) each Class C Certificateholder shall have the right (which
      shall not expire upon any purchase of the Certificates pursuant to clause
      (i) above) to purchase all, but not less than all, of the Certificates,
      the Class B Certificates and the Class C Certificates upon ten days'
      written notice to the Trustee, the Class B Trustee and each other Class C
      Certificateholder, provided that (A) if prior to the end of such ten-day
      period any other Class C Certificateholder notifies such purchasing Class
      C Certificateholder that such other Class C Certificateholder wants to
      participate in such purchase, then such other Class C Certificateholder
      may join with the purchasing Class C Certificateholder to purchase all,
      but not less than all, of the Certificates and the Class B Certificates
      pro rata based on the Fractional Undivided Interest in the Class C Trust,
      taken as a whole, held by each such Class C Certificateholder and (B) if
      prior to the end of such ten day period any other Class C
      Certificateholder fails to notify the purchasing Class C Certificateholder
      of such other Class C Certificateholder's desire to participate in such a
      purchase, then such other Class C Certificateholder shall lose its right
      to purchase the Certificates pursuant to this Section 6.01(b); and

            (iii) each Class D Certificateholder shall have the right (which
      shall not expire upon any purchase of the Certificates pursuant to clause
      (i) or (ii) above) to purchase all, but not less than all, of the
      Certificates, the Class B Certificates and the Class C Certificates upon
      ten days' written notice to the Trustee, the Class B Trustee, the Class C
      Trustee and each other Class D Certificateholder, provided that (A) if
      prior to the end of such ten-day period any other Class D
      Certificateholder notifies such purchasing Class D Certificateholder that
      such other Class D Certificateholder wants to participate in such
      purchase, then such other Class D Certificateholder may join with the
      purchasing Class D Certificateholder to purchase all, but not less than
      all, of the Certificates, the Class B Certificates and the Class C
      Certificates pro rata based on the Fractional Undivided Interest in the
      Class D Trust, taken as a whole, held by each such Class D
<PAGE>   38
                                      -33-


      Certificateholder and (B) if prior to the end of such ten day period any
      other Class D Certificateholder fails to notify the purchasing Class D
      Certificateholder of such other Class D Certificateholder's desire to
      participate in such a purchase, then such other Class D Certificateholder
      shall lose its right to purchase the Certificates pursuant to this Section
      6.01(b).

            The purchase price with respect to the Certificates shall be equal
to the Pool Balance of the Certificates, together with accrued and unpaid
interest thereon to the date of such purchase, without premium, but including
any other amounts then due and payable to the Certificateholders under this
Agreement, the Intercreditor Agreement, the Escrow Agreement or any Financing
Document or on or in respect of the Certificates; provided, however, that (i) if
such purchase occurs after the record date specified in Section 2.03(b) of the
Escrow Agreement relating to the distribution of unused Deposits and accrued and
unpaid interest thereunder, such purchase price shall be reduced by the
aggregate amount of unused deposits and interest to be distributed under the
Escrow Agreement (which deducted amounts shall remain distributable to, and may
be retained by, the Certificateholder as of such Record Date) and (ii) 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 shall be effective unless the purchaser(s) shall
certify to the Trustee that contemporaneously with such purchase, such
purchaser(s) is purchasing, pursuant to the terms of this Agreement and the
Other Pass Through Trust Agreements, the Certificates, the Class B Certificates
and the Class C Certificates which are senior to the securities held by such
purchaser(s). Each payment of the purchase price of the Certificates referred to
in the first sentence hereof 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(b). Each Certificateholder agrees by its acceptance of its
Certificate that it will, subject to Section 3.04 hereof, upon payment from such
Class B Certificateholder(s), Class C Certificateholder(s) or Class D
Certificateholder(s), as the case may be, of the purchase price set forth in the
first sentence of this paragraph, forthwith sell, assign, transfer and convey to
the purchaser(s) thereof (without recourse, representation or warranty of any
kind except for its own acts), all of the right, title, interest and obligation
of such Certificateholder in this Agreement, the Escrow Agreement, the Deposit
Agreement, the Intercreditor Agreement, the Liquidity Facility, the Financing
Documents and all Certificates and Escrow Receipts held by such
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 purchaser shall assume all of
such Certificateholder's obligations under this Agreement, the Escrow Agreement,
the Deposit Agreement, the Intercreditor Agreement, the Liquidity Facility, the
Financing Documents and all such Certificates and Escrow Receipts. The
Certificates will be deemed to be purchased on the date payment of the purchase
price is made notwithstanding the failure of the Certificateholders to deliver
any Certificates (whether in the form of Definitive Certificates or beneficial
interests in Global Certificates) and, upon such a purchase, (i) the only rights
of the Certificateholders will be to deliver the Certificates to the
purchaser(s) and receive the purchase price for such Certificates and (ii) if
the purchaser(s) shall so request, such Certificateholder will comply with all
the provisions of Section 3.04 hereof to enable new Certificates to be issued to
the purchaser in such denominations as it shall request.
<PAGE>   39
                                      -34-


All charges and expenses in connection with the issuance of any such new
Certificates shall be borne by the purchaser thereof.

            As used in this Section 6.01(b), the terms "Class B Certificate",
"Class B Certificateholder", "Class B Trust", "Class B Trustee", "Class C
Certificate", "Class C Certificateholder", "Class C Trust", "Class C Trustee",
"Class D Certificate", and "Class D Trust", shall have the respective meanings
assigned to such terms in the Intercreditor Agreement.

            Section 6.02. Incidents of Sale of Equipment Notes. Upon any sale of
all or any part of the Equipment Notes made either under the power of sale given
under 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, 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, 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 the Intercreditor Agreement and the Financing
Documents (subject to the 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 the Intercreditor Agreement, the Certificateholders holding Certificates
evidencing Fractional Undivided Interests aggregating not less than a majority
in interest in the Trust shall have the
<PAGE>   40
                                      -35-


right to direct the time, method and place of conducting any proceeding for any
remedy available to the Trustee with respect to the Trust or pursuant to the
terms of the Intercreditor Agreement, or exercising any trust or power conferred
on the Trustee under this Agreement or the Intercreditor Agreement, including
any right of the Trustee as Controlling Party under the Intercreditor Agreement
or as holder of the Equipment Notes, provided that:

            (1) such Direction shall not 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 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 the Intercreditor
Agreement, the Certificateholders holding Certificates 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 Default under any 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, or

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

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

            Upon any such waiver, such default shall cease to exist with respect
to the Certificates 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 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 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 the
Intercreditor Agreement, the right of any Certificateholder to receive
distributions of payments required pursuant to Section 4.02 hereof on the
Certificates when due, or to institute suit for the enforcement of any such
payment on or after
<PAGE>   41
                                      -36-


the applicable Regular Distribution Date or Special Distribution Date, shall not
be impaired or affected without the consent of such Certificateholder.

            Section 6.07. Certificateholders May Not Bring Suit Except Under
Certain Conditions. A Certificateholder 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 evidencing Fractional
      Undivided Interests aggregating not less than 25% of the 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 such an
      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 evidencing Fractional Undivided Interests aggregating
      not less than a majority in interest in the Trust.

            It is understood and intended that no one or more of the
Certificateholders shall have any right in any manner whatsoever hereunder or
under the Certificates to (i) surrender, impair, waive, affect, disturb or
prejudice any property in the Trust Property or the lien of any Indenture on any
property subject thereto, or the rights of the Certificateholders or the holders
of the Equipment Notes, (ii) obtain or seek to obtain priority over or
preference with respect to any other such Certificateholder 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 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 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.


                                   ARTICLE VII

                                   THE TRUSTEE

            Section 7.01. Certain Duties and Responsibilities. (a) Except during
the continuance of an Event of Default, the Trustee undertakes to perform such
duties as are specifically set forth in this Agreement, and no implied covenants
or obligations shall be read into this Agreement against the Trustee.
<PAGE>   42
                                      -37-


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

            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, the Trustee shall transmit by mail to the
Company, the Owner Trustees, the Owner Participants, the Loan Trustees and the
Certificateholders 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 on the payment of the principal, premium, if any, or interest on any
Equipment Note held in the Trust, 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 determine that the withholding of such notice is in the interests of
the Certificateholders. For the purpose of this Section, the term "default"
means any event that is, or after notice or lapse of time or both would become,
an Event of Default.

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

            (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 written description of the subject matter
      thereof accompanied by an Officer's Certificate and an Opinion of Counsel
      as provided in Section 1.02 of this Agreement;
<PAGE>   43
                                      -38-


            (c) whenever in the administration of this 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 Owner Trustee or any 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 at the Direction of any of
      the Certificateholders pursuant to this 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 perform any duties under this 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;

            (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 evidencing
      Fractional Undivided Interests aggregating not less than a majority in
      interest in the 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; and

            (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, 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 Agreement, any Equipment Notes, the Intercreditor
Agreement, the Deposit Agreement, the Escrow Agreement, the Certificates or any
other Financing Document, except that the Trustee hereby represents and warrants
that this Agreement has been, and the Intercreditor Agreement, the Registration
Rights Agreement, the Note Purchase Agreement, the Escrow Agreement and each
Certificate will be, executed, authenticated and delivered by one of
<PAGE>   44
                                      -39-


its officers who is duly authorized to execute, authenticate 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, the 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 hereunder 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 as set
      forth in a written fee letter dated the date hereof between the Company
      and the Trustee, which letter is incorporated herein by reference (which
      compensation shall not be limited by any provision of law in regard to the
      compensation of a trustee of an express trust);

            (2) except as otherwise expressly provided herein, 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 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 undertaking its normal administrative functions, or
      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

            (3) to indemnify, or cause to be indemnified, the Trustee for, and
      to hold it harmless against, any loss, liability, expense or Tax (other
      than for or with respect to any Unindemnified Tax) incurred without
      negligence, willful misconduct or bad faith, on its part, arising out of
      or in connection with the acceptance or administration of this Trust,
      including the costs and expenses of defending itself against any claim or
      liability in connection with the exercise or performance of any of its
      powers or duties hereunder, except for any such loss, liability or expense
      incurred by reason of the Trustee's breach of its covenants hereunder or
      under any Financing Document to which it is a party or its representations
      and warranties set forth in Section 7.15 or in any other Financing
      Document, the authorization or giving or withholding of any future
      amendments, supplements, waivers or consents with respect hereto or any of
      the Financing Documents, which amendments, supplements, waivers or
      consents are not required pursuant to the terms of the Financing Documents
      and not requested by the Company, any loss of tax benefits, any
      Unindemnified Tax, or increase in tax liability under any tax law whether
      or not the Company is required to indemnify thereof or pursuant to this
      Agreement or any
<PAGE>   45
                                      -40-


      costs associated with overhead or normal administration hereunder or
      any voluntary resignation pursuant to Section 7.09.

            With respect to paragraph (3) above, the Trustee shall notify the
Company promptly of any claim for which it may seek indemnity and the Company
shall make payment on any such claim within 30 days of written demand thereof
(delivered together with supporting documentation). The Company shall defend the
claim and the Trustee shall cooperate in the defense. The Trustee may have
separate counsel with the consent of the Company and the Company will pay the
reasonable fees and expenses of such counsel. The Company need not pay for any
settlement made, in settlement or otherwise, without its consent.

            With respect to any Tax other than an Unindemnified Tax, the Trustee
shall be entitled to reimbursement from, and shall have a lien prior to the
Certificates upon, the Trust Property for any such 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. 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 circumstances
thereof to all Certificateholders as their names and addresses appear in the
Register.

            Section 7.08. Corporate Trustee Required; Eligibility. There shall
at all times be a Trustee hereunder 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, the
Trustee shall resign immediately as Trustee 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 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 by giving prior
written notice thereof to the Company, the Authorized Agents, the Owner Trustees
and the Loan Trustees. If an instrument of acceptance by a successor Trustee
shall not have been delivered to the Company, the Authorized Agents, the Owner
Trustees, the Loan Trustees and the Trustee
<PAGE>   46
                                      -41-


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.

            (c) The Trustee may be removed at any time by Direction of the
Certificateholders holding Certificates evidencing Fractional Undivided
Interests aggregating not less than a majority in interest in the Trust
delivered to the Trustee and to the Company, the Owner Trustees and the Loan
Trustees.

            (d) If at any time:

            (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 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.

            (e) If a Responsible Officer of the Trustee shall obtain actual
knowledge of an Avoidable Tax 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 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 in a jurisdiction where there
are no Avoidable Taxes.

            (f) If the Trustee shall resign, be removed or become incapable of
acting or if a vacancy shall occur in the office of the Trustee for any cause,
the Company shall promptly appoint a successor Trustee. If, within one year
after such resignation, removal or incapability, or other occurrence of such
vacancy, a successor Trustee shall be appointed by Direction of the
Certificateholders holding Certificates evidencing Fractional Undivided
Interests aggregating not less than a majority in interest in the Trust
delivered to the Company, the Owner Trustees, the Loan Trustees and the retiring
Trustee, and the Company approves such appointment, which approval shall not be
unreasonably withheld, then the successor Trustee so appointed shall, forthwith
upon its acceptance of such appointment, become the successor Trustee and
supersede the successor Trustee appointed as provided above. If no successor
Trustee shall have been so appointed as provided above and accepted appointment
in the manner hereinafter provided, any Certificateholder who has been a bona
fide Certificateholder 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.
<PAGE>   47
                                      -42-


            (g) The successor Trustee 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 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,
the Authorized Agents, the Owner Trustees and the Loan Trustees and to the
retiring Trustee an instrument accepting such appointment, and thereupon the
resignation or removal of the retiring Trustee 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 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.

            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.

            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 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) There shall at all times
be maintained an office or agency in the location set forth in Section 12.03
where Certificates 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 (e.g., the Certificates 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, the Owner Trustees, the Loan Trustees (in the case of
any Owner
<PAGE>   48
                                      -43-


Trustee or Loan Trustee, at its address specified in the Financing Documents or
such other address as may be notified to the Trustee) and the
Certificateholders. 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. 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, if the Trustee shall be acting as the
Registrar or Paying Agent hereunder, 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. 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, 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 hereunder, if
such successor corporation is otherwise eligible under this Section, 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, the Owner Trustees and the
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 (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. The
Company shall give written notice of any such appointment made by it to the
Trustee, the Owner Trustees and the Loan Trustees; and in each case the Trustee
shall mail notice of such appointment to all Certificateholders as their names
and addresses appear on the Register.

            (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 as set forth in the letter agreement
referred to in Section 7.07 hereof.
<PAGE>   49
                                      -44-


            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. 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 Name of
Subordination Agent. The Trustee agrees that all Equipment Notes to be purchased
by the Trust shall be issued in the name of the Subordination Agent or its
nominee and held by the Subordination Agent in trust for the benefit of the
Certificateholders, or, if not so held, the 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 7.15. Representations and Warranties of Trustee. The Trustee
hereby represents and warrants on the Transfer Date 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 receive
      the Trust Property assigned by the Related Trustee, assume the obligations
      under, and perform, the Assignment and Assumption Agreement, this
      Agreement, the Intercreditor Agreement, the Registration Rights Agreement,
      the Escrow Agreement, the Note Purchase Agreement and the Financing
      Documents to which it is a party and has taken all necessary action to
      authorize such receipt, assumption and performance by it of the Assignment
      and Assumption Agreement, this Agreement, the Intercreditor Agreement, the
      Registration Rights Agreement, the Escrow Agreement, the Note Purchase
      Agreement and the Financing Documents to which it is a party;

            (c) the receipt of the Trust Property under the Assignment and
      Assumption Agreement and the performance by the Trustee of the Assignment
      and Assumption Agreement, this Agreement, the Intercreditor Agreement, the
      Registration Rights Agreement, the Escrow Agreement, the Note Purchase
      Agreement and the Financing Documents to which it is a party (i) will not
      violate any provision of 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, or (iii) will not violate any
      provision of, or constitute, with or without notice or lapse of time, a
<PAGE>   50
                                      -45-


      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 receipt of the Trust Property under the Assignment and
      Assumption Agreement and the performance by the Trustee of the Assignment
      and Assumption Agreement, this Agreement, the Intercreditor Agreement, the
      Registration Rights Agreement, the Escrow Agreement, the Note Purchase
      Agreement, and the Financing Documents to which it is a party 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) the Assignment and Assumption Agreement has been duly executed
      and delivered by the Trustee and this Agreement, the Assignment and
      Assumption Agreement, the Intercreditor Agreement, the Registration Rights
      Agreement, the Escrow Agreement, the Note Purchase Agreement, and the
      Financing Documents to which it is a party constitute the legal, valid,
      and binding agreements of the Trustee, enforceable against it in
      accordance with their respective terms, provided 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, regardless of whether applied in a
      proceeding in equity or at law.

            Section 7.16. Withholding Taxes, Information Reporting. The Trustee,
as trustee of the grantor trust created by this Agreement, shall exclude and
withhold from each distribution of principal, premium, if any, and interest and
other amounts due under this Agreement or under the Certificates 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, to withhold such amounts and
timely pay the same to the appropriate authority in the name of and on behalf of
the Certificateholders, 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 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. Each Certificateholder or Investor
that is not a United States person within the meaning of section 7701(a)(30) of
the Internal Revenue Code, as amended, by its acceptance of a Certificate or a
beneficial interest therein, agrees to indemnify and hold harmless the Trust and
the Trustee from and against any improper failure to withhold taxes from amounts
payable to it or for its benefit, other than an improper failure attributable to
the gross negligence or willful misconduct of the Trustee.
<PAGE>   51
                                      -46-


            Section 7.17. Trustee's Liens. The Trustee in its individual
capacity agrees that it will 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 which is attributable to the
Trustee either (i) in its individual capacity and which is unrelated to the
transactions contemplated by this Agreement, the Intercreditor Agreement, the
Note Purchase Agreement or the Financing Documents, or (ii) as Trustee hereunder
or in its individual capacity and which arises out of acts or omissions on the
part of the Trustee 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, 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, 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 addresses of Certificateholders 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 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 date hereof, the
Trustee shall transmit to the Certificateholders, 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
<PAGE>   52
                                      -47-


      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) during any period, prior to the consummation of the Exchange
      Offer and during which the Shelf Registration Statement is not in effect,
      in which the Company is not subject to Section 13(a), 13(c) or 15(d) under
      the Securities Exchange Act of 1934, make available to any Holder of the
      Certificates in connection with any sale thereof and any prospective
      purchaser of the Certificates from such Holder, in each case upon request,
      the information specified in, and meeting the requirements of, Rule
      144A(d)(4) under the Securities Act but only for so long as any of the
      Certificates remain outstanding and are "restricted securities" within the
      meaning of Rule 144(a)(3) under the Securities Act and, in any event, only
      until the second anniversary of the Issuance Date;

            (c) 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 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;

            (d) 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 (c) of this Section 8.04 as
      may be required by rules and regulations prescribed by the SEC; and

            (e) furnish to the Trustee, not less often than annually, a brief
      certificate from the principal executive officer, principal financial
      officer, any Vice President (or more senior ranking officer) or the
      principal accounting officer as to his or her knowledge of the Company's
      compliance with all conditions and covenants under this Agreement (it
      being understood that for purposes of this paragraph (e), such compliance
      shall be determined without regard to any period of grace or requirement
      of notice provided under this Agreement).
<PAGE>   53
                                      -48-


                                   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 the
Intercreditor Agreement, the Escrow Agreement, the Note Purchase Agreement, the
Deposit Agreement, the Registration Rights Agreement or any Liquidity Facility
in form satisfactory to the Trustee, for any of the following purposes:

            (1) to evidence the succession of another corporation 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 the Note Purchase
      Agreement, the Registration Rights Agreement or any Liquidity Facility; or

            (2) to add to the covenants of the Company for the benefit of the
      Certificateholders, or to surrender any right or power conferred upon the
      Company in this Agreement, the Note Purchase Agreement, the Registration
      Rights Agreement or any Liquidity Facility; or

            (3) to correct or supplement any provision in this Agreement, the
      Intercreditor Agreement, the Escrow Agreement, the Deposit Agreement, the
      Note Purchase Agreement, the Registration Rights Agreement or any
      Liquidity Facility which may be defective or inconsistent with any other
      provision herein or therein or to cure any ambiguity or correct any
      mistake or to modify any other provision with respect to matters or
      questions arising under this Agreement, the Escrow Agreement, the Deposit
      Agreement, the Note Purchase Agreement, the Intercreditor Agreement, the
      Registration Rights Agreement or any Liquidity Facility, provided that any
      such action shall not materially adversely affect the interests of the
      Certificateholders; or

            (4) to comply with any requirement of the SEC, any applicable law,
      rules or regulations of any exchange or quotation system on which the
      Certificates are listed, any regulatory body or the Registration Rights
      Agreement to effectuate the Exchange Offer; or

            (5) to modify, eliminate or add to the provisions of this Agreement
      to such extent as shall be necessary to continue the qualification of this
      Agreement (including any supplemental agreement) under the Trust Indenture
      Act or under any similar Federal statute hereafter enacted, and to add to
      this Agreement 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 which this instrument was executed or any corresponding provision in
      any similar Federal statute hereafter enacted; or
<PAGE>   54
                                      -49-


            (6) to evidence and provide for the acceptance of appointment under
      this Agreement by the Trustee of a successor Trustee and to add to or
      change any of the provisions of this Agreement as shall be necessary to
      provide for or facilitate the administration of the Trust, pursuant to the
      requirements of Section 7.10; or

            (7) to provide the information required under Section 7.12 and
      Section 12.03 as to the Trustee; or

            (8) to modify or eliminate provisions relating to the transfer or
      exchange of Exchange Certificates or the Initial Certificates upon
      consummation of the Exchange Offer (as defined in the Registration Rights
      Agreement) or effectiveness of the Shelf Registration Statement or the
      Exchange Offer Registration Statement;

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 the consent of the Certificateholders holding
Certificates (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 the 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, which consent shall not be
unreasonably withheld), and the Trustee (subject to Section 9.03) shall, enter
into an agreement or agreements for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Agreement,
the Intercreditor Agreement, any Liquidity Facility, the Registration Rights
Agreement, the Escrow Agreement, the Deposit Agreement or the Note Purchase
Agreement to the extent applicable to such Certificateholders or of modifying in
any manner the rights and obligations of such Certificateholders under this
Agreement, the Intercreditor Agreement, any Liquidity Facility, the Registration
Rights Agreement, the Escrow Agreement, the Deposit Agreement or the Note
Purchase Agreement; 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 (or, with respect to the Deposits, the
      Certificateholders) of payments on the Equipment Notes held in the Trust
      or on the Deposits or distributions that are required to be made herein on
      any Certificate, or change any date of payment on any Certificate, or
      change the place of payment where, or the coin or currency in which, any
      Certificate 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

            (2) permit the disposition of any Equipment Note included in the
      Trust Property except as permitted by this Agreement, or otherwise deprive
      such Certificateholder of the benefit of the ownership of the Equipment
      Notes in the Trust; or
<PAGE>   55
                                      -50-


            (3) reduce the specified percentage of the aggregate Fractional
      Undivided Interests of the Trust which 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

            (4) waive, amend or modify Section 2.4, 3.2 or 3.3 of the
      Intercreditor Agreement in a manner adverse to the Certificateholders; 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 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 Certificateholders
under this Section 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 Agreement, 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 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
Agreement shall be modified in accordance therewith, and such supplemental
agreement shall form a part of this Agreement for all purposes; and every Holder
of a Certificate theretofore or thereafter authenticated and delivered hereunder
shall be bound thereby.

            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 authenticated and delivered after the execution of any supplemental
agreement 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 after
proper presentation and demand.
<PAGE>   56
                                      -51-


                                    ARTICLE X

                AMENDMENTS TO INDENTURES AND FINANCING DOCUMENTS

            Section 10.01. Amendments and Supplements to Indentures and
Financing Documents. In the event that the Trustee, as holder (or beneficial
owner through the Subordination Agent) of any Equipment Note in trust for the
benefit of the Certificateholders or as Controlling Party under the
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, any other Financing Document, any
Equipment Note or any other related document, the Trustee shall forthwith send a
notice of such proposed amendment, modification, waiver or supplement to each
Certificateholder registered on the Register as of the date of such notice. The
Trustee shall request from the Certificateholders 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 such Equipment Note 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 such Equipment Note or a Controlling
Party and (c) how to vote (or direct the Subordination Agent to vote) any
Equipment 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 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 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 of such Certificate has delivered
to the Trustee an instrument evidencing such Holder's consent to such Direction
prior to two Business Days before the Trustee directs such action or casts such
vote or gives such consent. Notwithstanding the foregoing, but subject to
Section 6.04 and the Intercreditor Agreement, the Trustee may, 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 the relevant Indenture, any other Financing Document, any
Equipment Note or any other related 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.


                                   ARTICLE XI

                              TERMINATION OF TRUST

            Section 11.01. Termination of the Trust. The respective obligations
and responsibilities of the Company and the Trustee with respect to the Trust
shall terminate upon
<PAGE>   57
                                      -52-


the distribution to all Holders of Certificates 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; provided,
however, that in no event shall the Trust continue beyond one hundred ten (110)
years following the date of the earliest execution of this Trust Agreement.

            Notice of any termination, specifying the Distribution Date upon
which the Certificateholders may surrender their Certificates to the Trustee for
payment of the final Distribution Date and cancellation, shall be mailed
promptly by the Trustee to Certificateholders not earlier than the 60th day and
not later than the 20th day next preceding such final Distribution Date
specifying (A) the Distribution Date upon which the proposed final payment of
the Certificates will be made upon presentation and surrender of Certificates 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 Distribution Date is not applicable, payments being made only upon
presentation and surrender of the Certificates 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. Upon presentation and
surrender of the Certificates in accordance with such notice, the Trustee shall
cause to be distributed to Certificateholders such final payments.

            In the event that all of the Certificateholders 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 to surrender their Certificates for
cancellation and receive the final distribution with respect thereto. No
additional interest shall accrue on the Certificates after the Distribution Date
specified in the first written notice. In the event that any money held by the
Trustee for the payment of distributions on the Certificates shall remain
unclaimed for two years (or such lesser time as the Trustee shall be satisfied,
after sixty 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, the Owner Participants and the Company.


                                   ARTICLE XII

                            MISCELLANEOUS PROVISIONS

            Section 12.01. Limitation on Rights of Certificateholders. The death
or incapacity of any Certificateholder shall not operate to terminate this
Agreement or the 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. Certificates Nonassessable and Fully Paid. Except as
set forth in the last sentence of this Section 12.02, Certificateholders shall
not be personally liable for obligations of the Trust, the Fractional Undivided
Interests represented by the Certificates shall be nonassessable for any losses
or expenses of the Trust or for any reason whatsoever, and Certificates, upon
authentication thereof by the Trustee pursuant to Section 3.03, are and shall be
<PAGE>   58
                                      -53-


deemed fully paid. No Certificateholder shall have any right (except as
expressly provided herein) to vote or in any manner otherwise control the
operation and management of the Trust Property, the Trust, or the obligations of
the parties hereto, nor shall anything set forth herein, or contained in the
terms of the Certificates, be construed so as to constitute the
Certificateholders from time to time as partners or members of an association.
Neither the existence of the Trust nor any provision herein 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. Notices. (a) Unless otherwise specifically provided
herein, all notices required under the terms and provisions of this Agreement
shall be in English and in writing, and any such notice may be given by United
States mail, courier service or telecopy, and any such notice shall be effective
when received or, if made, given, furnished or filed by facsimile or
telecommunication transmission, when received unless received outside of
business hours, in which case on the next open of business on a Business Day,

            if to the Company, to:

                  America West Airlines, Inc.
                  4000 East Sky Harbor Boulevard
                  Phoenix, Arizona  85043

                  Attention: Vice President-
                             Treasurer
                  Facsimile: (602) 693-5886


            if to the Trustee, to:

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

                  Attention: Corporate Trust Department
                  Facsimile: (302) 651-8882
                  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 shall be
mailed by first-class mail to the addresses for Certificateholders shown on the
Register kept by the Registrar. 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.
<PAGE>   59
                                      -54-


            (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, it shall mail a copy to the Trustee and to the Paying Agent
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.

            Section 12.04. Governing Law. THIS AGREEMENT HAS BEEN DELIVERED IN
THE STATE OF NEW YORK AND THIS AGREEMENT AND THE CERTIFICATES SHALL BE GOVERNED
BY AND 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 12.05. 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 Trust, or of the
Certificates or the rights of the Certificateholders thereof.

            Section 12.06. Trust Indenture Act Controls. Upon the occurrence of
any Registration Event, this Agreement shall become subject to the provisions of
the Trust Indenture Act and shall, to the extent applicable, be governed by such
provisions. From and after any Registration Event, 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 12.07. 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 12.08. 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 12.09. Benefits of Agreement. Nothing in this Agreement or
in the Certificates, express or implied, shall give to any Person, other than
the parties hereto and their successors hereunder, and the Certificateholders,
any benefit or any legal or equitable right, remedy or claim under this
Agreement.
<PAGE>   60
                                      -55-


            Section 12.10. Legal Holidays. In any case where any Regular
Distribution Date or Special Distribution Date relating to any Certificate shall
not be a Business Day, 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 12.11. 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.

            Section 12.12. Intention of Parties. The parties hereto intend that
the 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. Each Certificateholder and Investor, by its acceptance of its
Certificate or a beneficial interest therein, agrees to treat the Trust as a
grantor trust for all U.S. federal, state and local income tax purposes. The
powers granted and obligations undertaken pursuant to this Agreement shall be so
construed so as to further such intent.
<PAGE>   61
                                      -56-



            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.


                                    AMERICA WEST AIRLINES, INC.


                                    By: /s/ W. Douglas Parker
                                       ------------------------------- 
                                          Name: W. Douglas Parker
                                          Title: Sr. Vice President & CFO


                                    WILMINGTON TRUST COMPANY,
                                      as Trustee


                                    By: /s/ Jill K. Morrison
                                       --------------------------------
                                          Name: Jill K. Morrison
                                          Title: Administrative Account
                                                 Manager
<PAGE>   62
                                                                       EXHIBIT A

             FORM OF CERTIFICATE TO BE DELIVERED IN CONNECTION WITH
               TRANSFERS OF CERTIFICATES PURSUANT TO REGULATION S

                                                    [date]

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

Attention:  Corporate Trust Trustee Administration

      Re:   America West Airlines Pass Through Trust, Series 1998-1A-S (the
            "Trust") America West Airlines Pass Through Certificates, Series
            1998-1A-S (the "Certificates")

Sirs:

            In connection with our proposed sale of $_____ Fractional Undivided
Interest of the Certificates, we confirm that such sale has been effected
pursuant to and in accordance with Regulation S under the Securities Act of
1933, as amended, and, accordingly, we represent that:

            (1) the offer of the Certificates was not made to a person in the
      United States or to or for the account or benefit of a U.S. person;

            (2) either (a) at the time the buy order was originated, the
      transferee was outside the United States or we and any person acting on
      our behalf reasonably believed that the transferee was outside the United
      States or (b) the transaction was executed in, on or through the
      facilities of a designated off-shore securities market and neither we nor
      any person acting on our behalf knows that the transaction has been
      pre-arranged with a buyer in the United States;

            (3) no directed selling efforts have been made in the United States
      in contravention of the requirements of Rule 903(a) or Rule 904(a) of
      Regulation S, as applicable; and

            (4) the transaction is not part of a plan or scheme to evade the
      registration requirements of the Securities Act.

            In addition, if the sale is made during a restricted period and the
provisions of Rule 903(b)(2) or Rule 904(b)(1) of Regulation S are applicable
thereto, we confirm that such sale has been made in accordance with the
applicable provisions of Rule 903(b)(2) or Rule 904(b)(1), as the case may be.

            You and America West Airlines, Inc. are entitled to rely upon this
letter and are irrevocably authorized to produce this letter or a copy hereof to
any interested party in any
<PAGE>   63
                                       A-2


administrative or legal proceedings or official inquiry with respect to the
matters covered hereby. Terms used in this certificate have the meanings set
forth in Regulation S.

                                    Very truly yours,


                                    [Name of Transferor]
<PAGE>   64
                                                                       EXHIBIT B

                FORM OF CERTIFICATE TO BE DELIVERED IN CONNECTION
                        WITH TRANSFERS OF CERTIFICATES TO
                   NON-QIB INSTITUTIONAL ACCREDITED INVESTORS

                                                [date]

Wilmington Trust Company
Rodney Square North
1100 North Market Street
Wilmington, DE 19890-0001
Attention:  Corporate Trust Trustee Administration

America West Airlines, Inc.
4000 East Sky Harbor Boulevard
Phoenix, Arizona  85043


                              AMERICA WEST AIRLINES
               PASS THROUGH TRUST, SERIES 1998-1A-S (the "Trust")
                   Pass Through Certificates, Series 1998-1A-S
                              (the "Certificates")


Ladies and Gentlemen:

            In connection with our proposed purchase of U.S. $[_____________]
Fractional Undivided Interest of Certificates, we confirm that:

            1. We understand that any subsequent transfer of the Certificates is
subject to certain restrictions and conditions set forth in the Pass Through
Trust Agreement, dated as of October 6, 1998, between America West Airlines,
Inc. (the "Company") and Wilmington Trust Company (the "Trustee") relating to
the Certificates, and we agree to be bound by, and not to resell, pledge or
otherwise transfer the Certificates except in compliance with, such restrictions
and conditions and the Securities Act of 1933, as amended (the "Securities
Act").

            2. We are purchasing Certificates having an aggregate principal
amount of not less than $100,000 and each account (if any) for which we are
purchasing Certificates is purchasing Certificates having an aggregate principal
amount of not less than $100,000.

            3. We understand that the Certificates have not been registered
under the Securities Act, that the Certificates are being sold to us in a
transaction that is exempt from the registration requirements of the Securities
Act and that the Certificates may not be offered or resold except as permitted
in the following sentence. We agree, on our own behalf and on behalf of any
accounts for which we are acting as hereinafter stated, that, if we should sell
any Certificates within three years after the later of the original issuance of
such Certificate and the last date on which such Certificate is owned by the
Company, the Trustee or any affiliate of any
<PAGE>   65
                                       B-2


of such persons, we will do so only (A) to the Company, (B) in accordance with
Rule 144A under the Securities Act to a "qualified institutional buyer" (as
defined therein), (C) outside the United States in accordance with Rule 904 of
Regulation S under the Securities Act, (D) pursuant to the exemption from
registration provided by Rule 144 under the Securities Act or (E) pursuant to an
effective registration statement under the Securities Act, and we further agree
to provide to any person purchasing any of the Certificates from us a notice
advising such purchaser that resales of the Certificates are restricted as
stated herein.

            4. We understand that, on any proposed resale of any Certificates,
we will be required to furnish to the Company and the Trustee such
certifications, legal opinions and other information as the Trustee may
reasonably require to confirm that the proposed sale complies with the foregoing
restrictions. We further understand that the Certificates purchased by us will
bear a legend to the foregoing effect.

            5. We are an institutional "accredited investor" (as defined in Rule
501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act) and have
such knowledge and experience in financial and business matters as to be capable
of evaluating the merits and risks of our investment in the Certificates, and we
and any accounts for which we are acting are each able to bear the economic risk
of our or their investments.

            6. We are acquiring the Certificates purchased by us for our own
account or for one or more accounts (each of which is an institutional
"accredited investor") as to each of which we exercise sole investment
discretion and not with a view to any distribution of the Certificates, subject,
nevertheless to the understanding that the disposition of our property shall at
all times be and remain within our control.

            You are entitled to rely upon this letter and are irrevocably
authorized to produce this letter or a copy thereof to any interested party in
any administrative or legal proceedings or official inquiry with respect to the
matters covered hereby.

                                    Very truly yours,


                                    By:_____________________________
                                        Name:
                                        Title: