<PAGE>   1
                                                                     EXHIBIT 4.6
                                                                  EXECUTION COPY


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

                          PASS THROUGH TRUST AGREEMENT

                         Dated as of September 21, 1999

                                     between

                           AMERICA WEST AIRLINES, INC.

                                       and

                            WILMINGTON TRUST COMPANY,

                                   as Trustee

           America West Airlines Pass Through Trust, Series 1999-1G-S

            7.93% Initial Pass Through Certificates, Series 1999-1G-S
           7.93% Exchange Pass Through Certificates, Series 1999-1G-S





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<PAGE>   2
Reconciliation and tie between America West Airlines Pass Through Trust
Agreement, Series 1999-1G-S dated as of September 21, 1999, and the Trust
Indenture Act of 1939. This reconciliation does not constitute part of the Pass
Through Trust Agreement.

<TABLE>
<CAPTION>
            Trust Indenture Act                             Pass Through Trust
              of 1939 Section                               Agreement Section
            -------------------                             -----------------
<S>                                                         <C>
          310(a)(1)                                           7.08
               (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
</TABLE>
<PAGE>   3
                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
SECTION                                                                                                                         PAGE


<S>                                                                                                                             <C>
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 .....................................................................................   16
         Section 2.01.  Acquisition of Trust Property .........................................................................   16
         Section 2.02.  Acceptance by the Trustee .............................................................................   16
         Section 2.03.  Limitation of Powers ..................................................................................   16

ARTICLE III  THE CERTIFICATES .................................................................................................   17
         Section 3.01.  Title, Form, Denomination and Execution of Certificates ...............................................   17
         Section 3.02.  Restrictive Legends ...................................................................................   19
         Section 3.03.  Authentication of Certificates ........................................................................   20
         Section 3.04.  Transfer and Exchange .................................................................................   21
         Section 3.05.  Book-Entry Provisions for Restricted Global Certificates and Regulation S Global Certificates .........   22
         Section 3.06.  Special Transfer Provisions ...........................................................................   23
         Section 3.07.  Mutilated, Destroyed, Lost or Stolen Certificates .....................................................   26
         Section 3.08.  Persons Deemed Owners .................................................................................   27
         Section 3.09.  Cancellation ..........................................................................................   27
         Section 3.10.  Temporary Certificates ................................................................................   27
         Section 3.11.  Limitation of Liability for Payments ..................................................................   27

ARTICLE IV  DISTRIBUTIONS; STATEMENTS TO CERTIFICATEHOLDERS ...................................................................   28
         Section 4.01.  Certificate Account and Special Payments Account ......................................................   28
         Section 4.02.  Distributions from Certificate Account and Special Payments Account ...................................   28
         Section 4.03.  Statements to Certificateholders ......................................................................   30
         Section 4.04.  Investment of Special Payment Moneys ..................................................................   31

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

ARTICLE VI  DEFAULT ...........................................................................................................   32
         Section 6.01.  Events of Default .....................................................................................   32
         Section 6.02.  Incidents of Sale of Equipment Notes ..................................................................   34
         Section 6.03.  Judicial Proceedings Instituted by Trustee; Trustee May Bring Suit ....................................   35
         Section 6.04.  Control by Certificateholders .........................................................................   35
         Section 6.05.  Waiver of Past Defaults ...............................................................................   36

</TABLE>
<PAGE>   4
<TABLE>
<CAPTION>
SECTION                                                                                                                         PAGE


<S>                                                                                                                             <C>
         Section 6.06.  Right of Certificateholders to Receive Payments Not to Be Impaired ....................................   36
         Section 6.07.  Certificateholders May Not Bring Suit Except Under Certain Conditions .................................   37
         Section 6.08.  Remedies Cumulative ...................................................................................   37

ARTICLE VII  THE TRUSTEE ......................................................................................................   37
         Section 7.01.  Certain Duties and Responsibilities ...................................................................   37
         Section 7.02.  Notice of Defaults ....................................................................................   38
         Section 7.03.  Certain Rights of Trustee .............................................................................   38
         Section 7.04.  Not Responsible for Recitals or Issuance of Certificates ..............................................   39
         Section 7.05.  May Hold Certificates .................................................................................   40
         Section 7.06.  Money Held in Trust ...................................................................................   40
         Section 7.07.  Compensation and Reimbursement ........................................................................   40
         Section 7.08.  Corporate Trustee Required; Eligibility ...............................................................   41
         Section 7.09.  Resignation and Removal; Appointment of Successor .....................................................   42
         Section 7.10.  Acceptance of Appointment by Successor ................................................................   43
         Section 7.11.  Merger, Conversion, Consolidation or Succession to Business ...........................................   43
         Section 7.12.  Maintenance of Agencies ...............................................................................   44
         Section 7.13.  Money for Certificate Payments to Be Held in Trust ....................................................   45
         Section 7.14.  Registration of Equipment Notes in Name of Subordination Agent ........................................   45
         Section 7.15.  Representations and Warranties of Trustee .............................................................   45
         Section 7.16.  Withholding Taxes, Information Reporting ..............................................................   46
         Section 7.17.  Trustee's Liens .......................................................................................   47
         Section 7.18.  Preferential Collection of Claims .....................................................................   47

ARTICLE VIII  CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE ................................................................   47
         Section 8.01.  The Company to Furnish Trustee with Names and Addresses of Certificateholders .........................   47
         Section 8.02.  Preservation of Information; Communications to Certificateholders .....................................   48
         Section 8.03.  Reports by Trustee ....................................................................................   48
         Section 8.04.  Reports by the Company ................................................................................   48

ARTICLE IX  SUPPLEMENTAL AGREEMENTS ...........................................................................................   49
         Section 9.01.  Supplemental Agreements Without Consent of Certificateholders .........................................   49
         Section 9.02.  Supplemental Agreements with Consent of Certificateholders ............................................   50
         Section 9.03.  Documents Affecting Immunity or Indemnity .............................................................   51
         Section 9.04.  Execution of Supplemental Agreements ..................................................................   52
         Section 9.05.  Effect of Supplemental Agreements .....................................................................   52
         Section 9.06.  Conformity with Trust Indenture Act ...................................................................   52
         Section 9.07.  Reference in Certificates to Supplemental Agreements ..................................................   52
</TABLE>

                                       ii
<PAGE>   5
<TABLE>
<CAPTION>
SECTION                                                                                                                         PAGE


<S>                                                                                                                             <C>
ARTICLE X  AMENDMENTS TO INDENTURES AND FINANCING DOCUMENTS ...................................................................   52
         Section 10.01. Amendments and Supplements to Indentures and Financing Documents ......................................   52

ARTICLE XI  TERMINATION OF TRUST ..............................................................................................   53
         Section 11.01. Termination of the Trust ..............................................................................   53

ARTICLE XII  MISCELLANEOUS PROVISIONS .........................................................................................   54
         Section 12.01. Limitation on Rights of Certificateholders ............................................................   54
         Section 12.02. Certificates Nonassessable and Fully Paid .............................................................   54
         Section 12.03. Notices ...............................................................................................   55
         Section 12.04. Governing Law .........................................................................................   56
         Section 12.05. Severability of Provisions ............................................................................   56
         Section 12.06. Trust Indenture Act Controls ..........................................................................   56
         Section 12.07. Effect of Headings and Table of Contents ..............................................................   56
         Section 12.08. Successors and Assigns ................................................................................   56
         Section 12.09. Benefits of Agreement .................................................................................   56
         Section 12.10. Legal Holidays ........................................................................................   56
         Section 12.11. Counterparts ..........................................................................................   57
         Section 12.12. Intention of Parties ..................................................................................   57


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


                                      iii
<PAGE>   6
                          PASS THROUGH TRUST AGREEMENT


         This PASS THROUGH TRUST AGREEMENT, dated as of September 21, 1999, (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 1999-1G-S and the 7.93% America
West Airlines Pass Through Trust, Series 1999-1G-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 of all or a portion of the Aircraft either (i)
through separate leveraged lease transactions in which the Company will lease
such aircraft (collectively, the "Leased Aircraft") or (ii) through separate
secured loan transactions in which the Company will own 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, two (or,
subject to satisfaction of certain preconditions contained in the Note Purchase
Agreement, three) 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, two
(or, subject to satisfaction of certain preconditions contained in the Note
Purchase Agreement, three) 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 Pass
Through Trust Agreement 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 14, 1999 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 1999-1D, 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 September
21, 1999 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 September 21, 1999 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, 2020.

         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 thereunder substantially in the form of
Exhibit A thereto 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
September 21, 1999 among the Related Trustee (and after the Transfer Date, the
Trustee), the Related Other Trustee (and after the Transfer Date, the Other
Trustee), the Liquidity Provider, the liquidity provider relating to the
Certificates issued under (and as defined in) the Related Other Pass Through
Trust Agreement, the Policy Provider 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.
<PAGE>   12
                                      -7-


         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, 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 September 21, 1999 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, Morgan Stanley Capital Services,
Inc., 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
September 21, 1999 among the Related Trustee (and after the Transfer Date, the
Trustee), the Related Other Trustee (and after the Transfer Date, the Other
Trustee), 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 14,
1999 relating to the offering of the Certificates and the other certificates
under the Related Other Pass Through Trust Agreement.

         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, or
(iv) such other counsel
<PAGE>   13
                                      -8-


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 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 Agreement: Means the other America West
Airlines 1999-1 Pass Through Trust Agreement relating to America West Airlines
Pass Through Trust, Series 1999-1C-S.

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

         Other Trust: Means the America West Airlines Pass Through Trust, Series
1999-1C-S, created under the Other Pass Through Trust Agreement.

         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.

         Policy: Has the meaning specified in the Intercreditor Agreement.

         Policy Provider: Has the meaning specified in the Intercreditor
Agreement.

         Policy Provider Agreement: Has the meaning specified in the
Intercreditor Agreement.

         Policy Provider Default: Has the meaning specified in the Intercreditor
Agreement.

         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. 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
<PAGE>   15
                                      -10-


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.

         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 September 21, 1999, among the Initial Purchasers,
the Related Trustee (and after the Transfer Date, the Trustee), the Related
Other Trustee (and after the Transfer Date, the Other Trustee) 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 Agreement: Means the "Other Pass
Through Trust Agreement" as defined in the Related Pass Through Trust Agreement.

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

<PAGE>   16
                                      -11-


         Related Other Trust: Means the "Other Trust" 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
1999-1G-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.

         Related Trust: Means the America West Pass Through Trust, Series
1998-1G-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 or in respect of 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, or any payment of interest on or
principal of the Certificates with funds drawn under the Policy, which payment
in any such case 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
<PAGE>   17
                                      -12-


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.

         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.
<PAGE>   18
                                      -13-


                  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 Trust, under the
         Intercreditor Agreement, the Escrow Agreement, the Note Purchase
         Agreement, the Policy 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, the Policy or the Liquidity Facilities,
         provided, that rights with respect to the Deposits or under the Escrow
         Agreement, except for the right to direct withdrawals for the purchase
         of Equipment Notes to be held in the Related Pass Through Trust
         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.
<PAGE>   19
                                      -14-


         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

               (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
<PAGE>   20
                                      -15-


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
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.
<PAGE>   21
                                      -16-



                                   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 "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 the 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).
<PAGE>   22
                                      -17-



                                   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
"7.93% Initial Pass Through Certificates, Series 1999-1G-S" and the Exchange
Certificates constituting Certificates shall be known as the "7.93% Exchange
Pass Through Certificates, Series 1999-1G-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 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 $233,668,000.

         (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 a nominee 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.
<PAGE>   23
                                      -18-


         (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
a nominee 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 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"). 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 Pass Through Trust Agreement 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
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
<PAGE>   24
                                      -19-


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:

          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
<PAGE>   25
                                      -20-


     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 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
<PAGE>   26
                                      -21-


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 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.
<PAGE>   27
                                      -22-


         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,
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
<PAGE>   28
                                      -23-


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.

         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
<PAGE>   29
                                      -24-


          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 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:
<PAGE>   30
                                      -25-


               (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 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;
<PAGE>   31
                                      -26-


     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 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
<PAGE>   32
                                      -27-


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.

         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 Provider, the Policy Provider, 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.
<PAGE>   33
                                      -28-


         (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 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
<PAGE>   34
                                      -29-


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 distributions pursuant to Section 3.7(c) or Section 3.7(e) of the
Intercreditor Agreement, the Trustee will mail notice to the Certificateholders
stating the Special Distribution Date, the related Record Date, the amount of
such distribution and the reason for such distribution. 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

               (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;
<PAGE>   35
                                      -30-


          (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 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 pages 61-62 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 Date 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.
<PAGE>   36
                                      -31-


         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.

         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 Agreement 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.
<PAGE>   37
                                      -32-


         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, with ten days' written notice to the Trustee and each
Certificateholder, the Trustee may, to the extent it is the Controlling Party at
such time (as determined pursuant to the 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 within 180 days
     after the occurrence and during the continuation of a Triggering Event,

          (i) each Class C 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 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 pro rata based on the Fractional Undivided Interest in the
     Class C Trust 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);

          (ii) each Class D 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 and the
     Class C Certificates upon ten days' written notice to the 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 and the Class C Certificates pro rata based on the
<PAGE>   38
                                      -33-


     Fractional Undivided Interest in the Class D Trust, taken as a whole, held
     by each such Class D 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); and

          (iii) whether or not any Class C Certificateholders or Class D
     Certificateholders exercise their right to purchase pursuant to clause (i)
     or (ii) above, the Policy Provider, if it is then the Controlling Party and
     180 days have elapsed since the occurrence of a Triggering Event that is
     continuing, shall have the right (except in the event of a Policy Provider
     Default) to purchase all, but not less than all, of the Certificates upon
     ten days' written notice to the Trustee and the Certificateholders.

         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 Agreement, the Certificates, the Class C Certificates
and the Class D 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 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 Policy, 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 Policy, 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
<PAGE>   39
                                      -34-


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. 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 C Certificate",
"Class C Certificateholder", "Class C Trust", "Class C Trustee", "Class D
Certificate", "Class D Trust" and "Class D Trustee", 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
<PAGE>   40
                                      -35-


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 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.
<PAGE>   41
                                      -36-


         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 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.
<PAGE>   42
                                      -37-



                                   ARTICLE VII

                                   THE TRUSTEE

         Section 7.01. Certain Duties and Responsibilities. (a) Except during
the continuation 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.

         (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
<PAGE>   43
                                      -38-


     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;

          (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
<PAGE>   44
                                      -39-


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 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
<PAGE>   45
                                      -40-


     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 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
<PAGE>   46
                                      -41-


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 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
<PAGE>   47
                                      -42-


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.

         (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
<PAGE>   48
                                      -43-


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 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
<PAGE>   49
                                      -44-


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.

         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
<PAGE>   50
                                      -45-


     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
     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.
<PAGE>   51
                                      -46-


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.

         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
<PAGE>   52
                                      -47-


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 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
<PAGE>   53
                                      -48-


     determined without regard to any period of grace or requirement of notice
     provided under this Agreement).


                                   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, the Policy, the Policy
Provider 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, the Policy Provider 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, the Policy, the Policy Provider 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, the Policy, the
     Policy Provider 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, the Policy, the
     Policy Provider 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
<PAGE>   54
                                      -49-


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

          (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 Policy, the Policy Provider 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 Policy, the
Policy Provider 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 or other Trust
     Property 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
<PAGE>   55
                                      -50-


          (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

          (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. Except for the
performance of its covenants herein, 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 adversely 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.
<PAGE>   56
                                      -51-


         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.


                                    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.
<PAGE>   57
                                      -52-



                                   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 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 on 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.
<PAGE>   58
                                      -53-


         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
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
<PAGE>   59
                                      -54-


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.

         (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.
<PAGE>   60
                                      -55-


         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.

         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
                  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: Executive Vice President

                            WILMINGTON TRUST COMPANY,
                               as Trustee

                       By:
                          ------------------------------
                          Name:
                          Title:
<PAGE>   62
                  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:
                          ------------------------------
                          Name:
                          Title:

                            WILMINGTON TRUST COMPANY,
                               as Trustee

                       By: /s/ James P. Lawler
                          ------------------------------
                          Name: James P. Lawler
                          Title: Vice President
<PAGE>   63
                                                                       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 1999-1G-S (the
          "Trust") America West Airlines Pass Through Certificates, Series
          1999-1G-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>   64
                                      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>   65
                                                                       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 1999-1G-S (the "Trust")
                   Pass Through Certificates, Series 1999-1G-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 September 21, 1999, 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 two 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>   66
                                      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: