<PAGE>   1
                                                                     EXHIBIT 4.4


                                                                  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 1999-1C-S

            8.54% Initial Pass Through Certificates, Series 1999-1C-S
           8.54% Exchange Pass Through Certificates, Series 1999-1C-S



--------------------------------------------------------------------------------
<PAGE>   2
Reconciliation and tie between America West Airlines Pass Through Trust
Agreement, Series 1999-1C-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.................................................................   26
         Section 3.09.     Cancellation..........................................................................   26
         Section 3.10.     Temporary Certificates................................................................   27
         Section 3.11.     Limitation of Liability for Payments..................................................   27
         Section 3.12.     ERISA Restrictive Legend..............................................................   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...............................................................   35
</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.................   36
         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.................................................................   39
         Section 7.06.     Money Held in Trust...................................................................   39
         Section 7.07.     Compensation and Reimbursement........................................................   39
         Section 7.08.     Corporate Trustee Required; Eligibility...............................................   41
         Section 7.09.     Resignation and Removal; Appointment of Successor.....................................   41
         Section 7.10.     Acceptance of Appointment by Successor................................................   42
         Section 7.11.     Merger, Conversion, Consolidation or Succession to Business...........................   43
         Section 7.12.     Maintenance of Agencies...............................................................   43
         Section 7.13.     Money for Certificate Payments to Be Held in Trust....................................   44
         Section 7.14.     Registration of Equipment Notes in Name of Subordination Agent........................   44
         Section 7.15.     Representations and Warranties of Trustee.............................................   45
         Section 7.16.     Withholding Taxes, Information Reporting..............................................   46
         Section 7.17.     Trustee's Liens.......................................................................   46
         Section 7.18.     Preferential Collection of Claims.....................................................   46

ARTICLE VIII  CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE...................................................   46
         Section 8.01.     The Company to Furnish Trustee with Names and Addresses of Certificateholders.........   46
         Section 8.02.     Preservation of Information; Communications to Certificateholders.....................   47
         Section 8.03.     Reports by Trustee....................................................................   47
         Section 8.04.     Reports by the Company................................................................   47

ARTICLE IX  SUPPLEMENTAL AGREEMENTS..............................................................................   48
         Section 9.01.     Supplemental Agreements Without Consent of Certificateholders.........................   48
         Section 9.02.     Supplemental Agreements with Consent of Certificateholders............................   49
         Section 9.03.     Documents Affecting Immunity or Indemnity.............................................   50
         Section 9.04.     Execution of Supplemental Agreements..................................................   50
         Section 9.05.     Effect of Supplemental Agreements.....................................................   51
         Section 9.06.     Conformity with Trust Indenture Act...................................................   51
         Section 9.07.     Reference in Certificates to Supplemental Agreements..................................   51

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



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

<S>                                                                                                                <C>
ARTICLE XI  TERMINATION OF TRUST.................................................................................   52
         Section 11.01.    Termination of the Trust..............................................................   52

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


Exhibit A           -      Form of Certificate to Request Removal of Restricted Legend
Exhibit B           -      Form of Certificate to be Delivered by an Institutional Accredited Investor
</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 1999-1C-S and
the 8.54% America West Airlines Pass Through Trust, Series 1999-1C-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.

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

                  ERISA Legend: Has the meaning specified in Section 3.12.

                  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, 2007.
<PAGE>   11
                                       6


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

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

                  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.
<PAGE>   12
                                       7


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

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

                  Lease: Means, with respect to each Leased Aircraft, the lease
         between an Owner Trustee, as the lessor, and the Company, as the
         lessee, referred to in the related Indenture, 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 issued 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
<PAGE>   13
                                       8


         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 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 1999-1G-S, dated the date
         hereof.

                  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 1999-1G-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
<PAGE>   14
                                       9


         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.

                  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.
<PAGE>   15
                                       10


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

                  QIB: Means a qualified institutional buyer as defined in
         Rule 144A.

                  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.
<PAGE>   16
                                       11


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

                  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 the America West Airlines Pass Through
         Trust, Series 1999-1C-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 1999-1C-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.
<PAGE>   17
                                       12


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

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

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

                  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".
<PAGE>   18
                                       13


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

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

                  Trust Property: Means (i) the Equipment Notes held as the
         property of the Trust and, subject to the Intercreditor Agreement, all
         monies at any time paid thereon and all monies due and to become due
         thereunder, (ii) funds from time to time deposited in the Certificate
         Account and the Special Payments Account and, subject to the
         Intercreditor Agreement, any proceeds from the sale by the Trustee
         pursuant to Article VI hereof of any Equipment Note and (iii) all
         rights of the Trust and the Trustee, on behalf of the Trust, under the
         Intercreditor Agreement, the Escrow Agreement, the Note Purchase
         Agreement and the Liquidity Facilities, including, without limitation,
         all rights to receive certain payments thereunder, and all monies paid
         to the Trustee on behalf of the Trust pursuant to the Intercreditor
         Agreement or the Liquidity Facilities, provided, that rights with
         respect to the Deposits or under the Escrow Agreement, 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, or 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. (a) 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 "8.54% Initial Pass Through Certificates, Series 1999-1C-S" and the
Exchange Certificates constituting Certificates shall be known as the "8.54%
Exchange Pass Through Certificates, Series 1999-1C-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 $20,158,000.

                  (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
Certificate may from time to
<PAGE>   24
                                       19


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
<PAGE>   28
                                       23


Definitive Certificates, the Trustee shall recognize the Person in whose name
the Definitive Certificates are registered in the Register as Certificateholders
hereunder. Neither the Company nor the Trustee shall be liable if the Trustee or
the Company is unable to locate a qualified successor clearing agency.

                  (e) Any Definitive Certificate delivered in exchange for an
interest in the Restricted Global Certificate pursuant to paragraph (b) of this
Section 3.05 shall, except as otherwise provided by paragraph (e) of Section
3.06, bear the Restricted Legend.

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

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

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

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

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

                           (ii) If the proposed transferor is an Agent Member
                  holding a beneficial interest in a Restricted Global
                  Certificate, upon receipt by the Registrar of (x) the
                  documents, if any, required by paragraph (i) and (y)
                  instructions given in accordance with DTC's and the
                  Registrar's procedures, the Registrar shall reflect on its
                  books and records the date of the transfer and a decrease in
                  the principal amount of such Restricted Global Certificate in
                  an amount equal to the principal
<PAGE>   29
                                       24


                  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 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).

                  Section 3.12 ERISA Restrictive Legend. All Certificates issued
pursuant to this Agreement shall bear a legend to the following effect (the
"ERISA Legend") unless the Company and the Trustee determine otherwise
consistent with applicable law:

                  "BY ITS ACQUISITION HEREOF, THE HOLDER REPRESENTS THAT (A) NO
PLAN ASSETS HAVE BEEN USED TO PURCHASE THIS CERTIFICATE OR AN INTEREST HEREIN OR
(B) THE PURCHASE AND HOLDING OF THIS CERTIFICATE OR AN INTEREST HEREIN IS EXEMPT
FROM THE PROHIBITED TRANSACTION RESTRICTIONS OF ERISA AND THE CODE PURSUANT TO
ONE OR MORE PROHIBITED TRANSACTION STATUTORY OR ADMINISTRATIVE EXEMPTIONS. 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."
<PAGE>   33
                                       28


                  By acceptance of any Certificate bearing the ERISA 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 Trustee 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 such legend.


                                   ARTICLE IV

                          DISTRIBUTIONS; STATEMENTS TO
                               CERTIFICATEHOLDERS

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

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

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

                  Section 4.02. Distributions from Certificate Account and
Special Payments Account. (a) On each Regular Distribution Date or as soon
thereafter as the Trustee has confirmed receipt of the payment of all or any
part of the Scheduled Payments due on such date, the Trustee shall distribute
out of the Certificate Account the entire amount deposited therein 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.
<PAGE>   34
                                       29


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

                  (c) The Trustee shall cause notice of each Special Payment to
be mailed to each Certificateholder at his address as it appears in the
Register. In the event of redemption or purchase of Equipment Notes held in the
Trust, such notice shall be mailed not less than 20 days prior to the Special
Distribution Date for the Special Payment resulting from such redemption or
purchase, which Special Distribution Date shall be the date of such redemption
or purchase. In the event of the payment of a Special Redemption Premium by the
Company to the Trustee under the Note Purchase Agreement, such notice shall be
mailed, together with the notice by the Escrow Paying Agent under Section 2.06
of the Escrow Agreement, not less than 20 days prior to the Special Distribution
Date for such amount, which Special Distribution Date shall be the Final
Withdrawal Date. In the case of any other Special Payments, such notice shall be
mailed as soon as practicable after the Trustee has confirmed that it has
received funds for such Special Payment, stating the Special Distribution Date
for such Special Payment which shall occur not less than 20 days after the date
of such notice and as soon as practicable thereafter. Notices mailed by the
Trustee shall set forth:

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

                  (ii) the amount of the Special Payment for each $1,000 face
         amount Certificate and the amount thereof constituting principal,
         premium, if any, and interest,

                  (iii)  the reason for the Special Payment, and

                  (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.
<PAGE>   35
                                       30


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

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

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

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

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

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

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

                  (vi) the Pool Balance and the Pool Factor.

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

                  (b) Within a reasonable period of time after the end of each
calendar year but not later than the latest date permitted by law, the Trustee
shall furnish to each Person who at any time during such calendar year was a
Certificateholder of record a statement containing the sum 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).
<PAGE>   36
                                       31


                  (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.

                  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
<PAGE>   37
                                       32


         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.

                  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. (i) At any time
         within 180 days after the occurrence and during the continuation of a
         Triggering Event, each Certificateholder shall have the right to
         purchase, for the purchase price set forth in the Class G Trust
         Agreement, all, but not less than all, of the Class G Certificates upon
         ten days' written notice to the Class G Trustee and each other
         Certificateholder, provided that (i) if prior to the end of such
         ten-day period any other Certificateholder notifies such purchasing
         Certificateholder that such other Certificateholder wants to
         participate in such purchase, then such other Certificateholder may
         join with the purchasing Certificateholder to
<PAGE>   38
                                       33


         purchase all, but not less than all, of the Class G Certificates pro
         rata based on the Fractional Undivided Interest in the Trust held by
         each such Certificateholder and (ii) if prior to the end of such
         ten-day period any other Certificateholder fails to notify the
         purchasing Certificateholder of such other Certificateholder's desire
         to participate in such a purchase, then such other Certificateholder
         shall lose its right to purchase the Class G Certificates pursuant to
         this Section 6.01(b);

                  (ii) 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, each Class D Certificateholder
         shall have the right (which shall not expire upon any purchase of the
         Class G Certificates pursuant to clause (b)(i) above) to purchase all,
         but not less than all, of the Class G Certificates and the Certificates
         upon ten days' written notice to the Class G Trustee and the Trustee
         and each other Class D Certificateholder, provided that (1) 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
         Class G Certificates and the Certificates pro rata based on the
         Fractional Undivided Interest in the Class D Trust, taken as a whole,
         held by each such Class D Certificateholder and (2) 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) by acceptance of its Certificate, each Certificateholder
         agrees that at any time after 180 days have elapsed since the
         occurrence of a Triggering Event that is continuing, regardless of
         whether the Certificateholders exercise their right to purchase the
         Class G Certificates pursuant to clause (b)(i) above, the Policy
         Provider, if it is then the Controlling Party, shall have the right
         (except in the event of a Policy Provider Default) to purchase all, but
         not less than all, of the Class G Certificates upon ten days' written
         notice to the Class G Trustee and the Class G 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
<PAGE>   39
                                       34


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 and the Class G 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 D Certificateholder(s) of the purchase price set
forth in the first sentence of this paragraph, forthwith sell, assign, transfer
and convey to the purchaser(s) thereof (without recourse, representation or
warranty of any kind except for its own acts), all of the right, title, interest
and obligation of such Certificateholder in this Agreement, the Escrow
Agreement, the Deposit Agreement, the Intercreditor Agreement, the Liquidity
Facility, the Financing Documents and all Certificates and Escrow Receipts held
by such Certificateholder (excluding all right, title and interest under any of
the foregoing to the extent such right, title or interest is with respect to an
obligation not then due and payable as respects any action or inaction or state
of affairs occurring prior to such sale) and the purchaser shall assume all of
such Certificateholder's obligations under this Agreement, the Escrow Agreement,
the Deposit Agreement, the Intercreditor Agreement, the Liquidity Facility, the
Financing Documents and all such Certificates and Escrow Receipts. The
Certificates will be deemed to be purchased on the date payment of the purchase
price is made notwithstanding the failure of the Certificateholders to deliver
any Certificates (whether in the form of Definitive Certificates or beneficial
interests in Global Certificates) and, upon such a purchase, (i) the only rights
of the Certificateholders will be to deliver the Certificates to the
purchaser(s) and receive the purchase price for such Certificates and (ii) if
the purchaser(s) shall so request, such Certificateholder will comply with all
the provisions of Section 3.04 hereof to enable new Certificates to be issued to
the purchaser in such denominations as it shall request. 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 G
Certificate", "Class G Certificateholder", "Class G Trust", "Class G Trust
Agreement", "Class G Trustee", "Class D Certificate", and "Class D Trust", shall
have the respective meanings assigned to such terms in the Intercreditor
Agreement.

                  Section 6.02. Incidents of Sale of Equipment Notes. Upon any
sale of all or any part of the Equipment Notes made either under the power of
sale given under this Agreement or otherwise for the enforcement of this
Agreement, the following shall be applicable:

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

                  (2) Receipt of Trustee Shall Discharge Purchaser. The receipt
         of the Trustee making such sale shall be a sufficient discharge to any
         purchaser for his purchase money, and, after paying such purchase money
         and receiving such receipt, such purchaser or its personal
         representative or assigns shall not be obliged to see to the
         application of such
<PAGE>   40
                                       35


         purchase money, or be in any way answerable for any loss,
         misapplication or non-application thereof.

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

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

                  Section 6.04. Control by Certificateholders. Subject to
Section 6.03 and the Intercreditor Agreement, the Certificateholders holding
Certificates evidencing Fractional Undivided Interests aggregating not less than
a majority in interest in the Trust shall have the 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
<PAGE>   41
                                       36


Direction given by such Certificateholders or the Trustee to such Loan Trustee
with respect thereto, except a default:

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

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

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

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

                  Section 6.06. Right of Certificateholders to Receive Payments
Not to Be Impaired. Anything in this Agreement to the contrary notwithstanding,
including, without limitation, Section 6.07 hereof, but subject to the
Intercreditor Agreement, the right of any Certificateholder to receive
distributions of payments required pursuant to Section 4.02 hereof on the
Certificates when due, or to institute suit for the enforcement of any such
payment on or after 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
<PAGE>   42
                                       37


         evidencing Fractional Undivided Interests aggregating not less than a
         majority in interest in the Trust.

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

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


                                   ARTICLE VII

                                   THE TRUSTEE

                  Section 7.01. Certain Duties and Responsibilities. (a) Except
during the 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.
<PAGE>   43
                                       38


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

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

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

                  (b) any request or direction of the Company mentioned herein
         shall be sufficiently evidenced by a written description of the subject
         matter thereof accompanied by an Officer's Certificate and an Opinion
         of Counsel as provided in Section 1.02 of this Agreement;

                  (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;
<PAGE>   44
                                       39


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

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

                  (i) the Trustee shall not be required to expend or risk its
         own funds in the performance of any of its duties under this Agreement,
         or in the exercise of any of its rights or powers, if it shall have
         reasonable grounds for believing that repayment of such funds or
         adequate indemnity against such risk is not reasonably assured to it.

                  Section 7.04. Not Responsible for Recitals or Issuance of
Certificates. The recitals contained herein and in the Certificates, except the
certificates of authentication, shall not be taken as the statements of the
Trustee, and the Trustee assumes no responsibility for their correctness.
Subject to Section 7.15, the Trustee makes no representations as to the validity
or sufficiency of this Agreement, any Equipment Notes, the Intercreditor
Agreement, the Deposit Agreement, the Escrow Agreement, the Certificates or any
other Financing Document, except that the Trustee hereby represents and warrants
that this Agreement has been, and the Intercreditor Agreement, the Registration
Rights Agreement, the Note Purchase Agreement, the Escrow Agreement and each
Certificate will be, executed, authenticated and delivered by one of 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
<PAGE>   45
                                       40


         herein by reference (which compensation shall not be limited by any
         provision of law in regard to the compensation of a trustee of an
         express trust);

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

                  (3) to indemnify, or cause to be indemnified, the Trustee for,
         and to hold it harmless against, any loss, liability, expense or Tax
         (other than for or with respect to any Unindemnified Tax) incurred
         without negligence, willful misconduct or bad faith, on its part,
         arising out of or in connection with the acceptance or administration
         of this Trust, including the costs and expenses of defending itself
         against any claim or liability in connection with the exercise or
         performance of any of its powers or duties hereunder, except for any
         such loss, liability or expense incurred by reason of the Trustee's
         breach of its covenants hereunder or under any Financing Document to
         which it is a party or its representations and warranties set forth in
         Section 7.15 or in any other Financing Document, the authorization or
         giving or withholding of any future amendments, supplements, waivers or
         consents with respect hereto or any of the Financing Documents, which
         amendments, supplements, waivers or consents are not required pursuant
         to the terms of the Financing Documents and not requested by the
         Company, any loss of tax benefits, any Unindemnified Tax, or increase
         in tax liability under any tax law whether or not the Company is
         required to indemnify thereof or pursuant to this Agreement or any
         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.
<PAGE>   46
                                       41


                  Section 7.08. Corporate Trustee Required; Eligibility. There
shall at all times be a Trustee hereunder which shall be eligible to act as a
trustee under Section 310(a) of the Trust Indenture Act and shall have a
combined capital and surplus of at least $75,000,000 (or a combined capital and
surplus in excess of $5,000,000 and the obligations of which, whether now in
existence or hereafter incurred, are fully and unconditionally guaranteed by a
corporation organized and doing business under the laws of the United States,
any state or territory thereof or of the District of Columbia and having a
combined capital and surplus of at least $75,000,000). If such corporation
publishes reports of conditions at least annually, pursuant to law or to the
requirements of federal, state, territorial or District of Columbia supervising
or examining authority, then for the purposes of this Section 7.08, the combined
capital and surplus of such corporation shall be deemed to be its combined
capital and surplus as set forth in its most recent report of conditions so
published.

                  In case at any time the Trustee shall cease to be eligible in
accordance with the provisions of this Section 7.08 to act as Trustee, the
Trustee shall resign immediately as Trustee in the manner and with the effect
specified in Section 7.09.

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

                  (b) The Trustee may resign at any time as trustee by giving
prior written notice thereof to the Company, the Authorized Agents, the Owner
Trustees and the Loan Trustees. If an instrument of acceptance by a successor
Trustee shall not have been delivered to the Company, the Authorized Agents, the
Owner Trustees, the Loan Trustees and the Trustee 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;
<PAGE>   47
                                       42


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

                  (e) If a Responsible Officer of the Trustee shall obtain
actual knowledge of an Avoidable Tax which has been or is likely to be asserted,
the Trustee shall promptly notify the Company and shall, within 30 days of such
notification, resign hereunder unless within such 30-day period the Trustee
shall have received notice that the Company has agreed to pay such tax. The
Company shall promptly appoint a successor Trustee in a jurisdiction where there
are no Avoidable Taxes.

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

                  (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.
<PAGE>   48
                                       43


                  No institution shall accept its appointment as a Trustee
hereunder unless at the time of such acceptance such institution shall be
qualified and eligible under this Article VII.

                  Section 7.11. Merger, Conversion, Consolidation or Succession
to Business. Any corporation into which the Trustee may be merged or converted
or with which it may be consolidated, or any corporation resulting from any
merger, conversion or consolidation to which the Trustee shall be a party, or
any corporation succeeding to all or substantially all of the corporate trust
business of the Trustee, shall be the successor of the Trustee hereunder,
provided such corporation shall be otherwise qualified and eligible under this
Article VII, without the execution or filing of any paper or any further act on
the part of any of the parties hereto. In case any Certificates shall have been
executed or authenticated, but not delivered, by the Trustee then in office, any
successor by merger, conversion or consolidation to such authenticating Trustee
may adopt such execution or authentication and deliver the Certificates so
executed or authenticated with the same effect as if such successor Trustee had
itself executed or authenticated such Certificates.

                  Section 7.12. Maintenance of Agencies. (a) There shall at all
times be maintained an office or agency in the location set forth in Section
12.03 where Certificates may be presented or surrendered for registration of
transfer or for exchange, and for payment thereof and where notices and demands
to or upon the Trustee in respect of such certificates or this Agreement may be
served; provided, however, that, if it shall be necessary that the Trustee
maintain an office or agency in another location (e.g., the Certificates shall
be represented by Definitive Certificates and shall be listed on a national
securities exchange), the Trustee will make all reasonable efforts to establish
such an office or agency. Written notice of the location of each such other
office or agency and of any change of location thereof shall be given by the
Trustee to the Company, the Owner Trustees, the Loan Trustees (in the case of
any Owner 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.
<PAGE>   49
                                       44


                  (c) Any corporation into which any Authorized Agent may be
merged or converted or with which it may be consolidated, or any corporation
resulting from any merger, consolidation or conversion to which any Authorized
Agent shall be a party, or any corporation succeeding to the corporate trust
business of any Authorized Agent, shall be the successor of such Authorized
Agent hereunder, if such successor corporation is otherwise eligible under this
Section, without the execution or filing of any paper or any further act on the
part of the parties hereto or such Authorized Agent or such successor
corporation.

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

                  (e) The Company agrees to pay, or cause to be paid, from time
to time to each Authorized Agent reasonable compensation for its services and to
reimburse it for its reasonable expenses as set forth in the letter agreement
referred to in Section 7.07 hereof.

                  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.
<PAGE>   50
                                       45


                  Section 7.15. Representations and Warranties of Trustee. The
Trustee hereby represents and warrants on the Transfer Date that:

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

                  (b) the Trustee has full power, authority and legal right to
receive the Trust Property assigned by the Related Trustee, assume the
obligations under, and perform, the Assignment and Assumption Agreement, this
Agreement, the Intercreditor Agreement, the Registration Rights Agreement, the
Escrow Agreement, the Note Purchase Agreement and the Financing Documents to
which it is a party and has taken all necessary action to authorize such
receipt, assumption, and performance by it of the Assignment and Assumption
Agreement, this Agreement, the Intercreditor Agreement, the Registration Rights
Agreement, the Escrow Agreement, the Note Purchase Agreement and the Financing
Documents to which it is a party;

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

                  (d) the 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) this 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
<PAGE>   51
                                       46


and (ii) general principles of equity, regardless of whether applied in a
proceeding in equity or at law.

                  Section 7.16. Withholding Taxes, Information Reporting. The
Trustee, as trustee of the grantor trust created by this Agreement, shall
exclude and withhold from each distribution of principal, premium, if any, and
interest and other amounts due under this Agreement or under the Certificates
any and all withholding taxes applicable thereto as required by law. The Trustee
agrees to act as such withholding agent and, in connection therewith, whenever
any present or future taxes or similar charges are required to be withheld with
respect to any amounts payable in respect of the Certificates, to withhold such
amounts and timely pay the same to the appropriate authority in the name of and
on behalf of the Certificateholders, that it will file any necessary withholding
tax returns or statements when due, and that, as promptly as possible after the
payment thereof, it will deliver to each such Certificateholder appropriate
documentation showing the payment thereof, together with such additional
documentary evidence as such Certificateholders may reasonably request from time
to time. The Trustee agrees to file any other information reports as it may be
required to file under United States law. Each Certificateholder or Investor
that is not a United States person within the meaning of Section 7701(a)(30) of
the Internal Revenue Code, as amended, by its acceptance of a Certificate or a
beneficial interest therein, agrees to indemnify and hold harmless the Trust and
the Trustee from and against any improper failure to withhold taxes from amounts
payable to it or for its benefit, other than an improper failure attributable to
the gross negligence or willful misconduct of the Trustee.

                  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
<PAGE>   52
                                       47


Company as to the names and addresses of the Certificateholders, in each case as
of a date not more than 15 days prior to the time such list is furnished;
provided, however, that so long as the Trustee is the sole Registrar, no such
list need be furnished; and provided further, however, that no such list need be
furnished for so long as a copy of the Register is being furnished to the
Trustee pursuant to Section 7.12.

                  Section 8.02. Preservation of Information; Communications to
Certificateholders. The Trustee shall preserve, in as current a form as is
reasonably practicable, the names and addresses of Certificateholders contained
in the most recent list furnished to the Trustee as provided in Section 7.12 or
Section 8.01, as the case may be, and the names and addresses of
Certificateholders received by the Trustee in its capacity as Registrar, if so
acting. The Trustee may destroy any list furnished to it as provided in Section
7.12 or Section 8.01, as the case may be, upon receipt of a new list so
furnished.

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

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

                  (a) file with the Trustee, within 30 days after the Company is
         required to file the same with the SEC, copies of the annual reports
         and of the information, documents 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
<PAGE>   53
                                       48


         for in this Agreement, as may be required by such rules and
         regulations, including, in the case of annual reports, if required by
         such rules and regulations, certificates or opinions of independent
         public accountants, conforming to the requirements of Section 1.02;

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

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


                                   ARTICLE IX

                             SUPPLEMENTAL AGREEMENTS

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

                  (1) to evidence the succession of another corporation to the
         Company and the assumption by any such successor of the covenants of
         the Company herein contained or of the Company's obligations under the
         Note Purchase Agreement, the Registration Rights Agreement or any
         Liquidity Facility; or

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

                  (3) to correct or supplement any provision in this Agreement,
         the Intercreditor Agreement, the Escrow Agreement, the Deposit
         Agreement, the Note Purchase Agreement, the Registration Rights
         Agreement or any Liquidity Facility which may be defective or
         inconsistent with any other provision herein or therein or to cure any
         ambiguity or correct any mistake or to modify any other provision with
         respect to matters or questions arising under this Agreement, the
         Escrow Agreement, the Deposit Agreement, the Note Purchase Agreement,
         the Intercreditor Agreement, the Registration
<PAGE>   54
                                       49


         Rights Agreement or any Liquidity Facility, provided that any such
         action shall not materially adversely affect the interests of the
         Certificateholders; or

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

                  (5) to modify, eliminate or add to the provisions of this
         Agreement to such extent as shall be necessary to continue the
         qualification of this Agreement (including any supplemental agreement)
         under the Trust Indenture Act or under any similar Federal statute
         hereafter enacted, and to add to this Agreement such other provisions
         as may be expressly permitted by the Trust Indenture Act, excluding,
         however, the provisions referred to in Section 316(a)(2) of the Trust
         Indenture Act as in effect at the date as of which this instrument was
         executed or any corresponding provision in any similar Federal statute
         hereafter enacted; or

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

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

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

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

                  Section 9.02. Supplemental Agreements with Consent of
Certificateholders. With the consent of the Certificateholders holding
Certificates (including consents obtained in connection with a tender offer or
exchange offer for the Certificates) evidencing Fractional Undivided Interests
aggregating not less than a majority in interest in the Trust, by Direction of
said Certificateholders delivered to the Company and the Trustee, the Company
may (with the consent of the Owner Trustees, if any, which consent shall not be
unreasonably withheld), and the Trustee (subject to Section 9.03) shall, enter
into an agreement or agreements for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Agreement,
the Intercreditor Agreement, any Liquidity Facility, the Registration Rights
Agreement, the Escrow Agreement, the Deposit Agreement or the Note Purchase
Agreement to the extent applicable to such Certificateholders or of modifying in
any manner the rights and obligations of such Certificateholders under this
Agreement, the Intercreditor Agreement, any Liquidity Facility, the Registration
Rights Agreement, the Escrow Agreement, the Deposit
<PAGE>   55
                                       50


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

                  (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. 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.
<PAGE>   56
                                       51


                  Section 9.05. Effect of Supplemental Agreements. Upon the
execution of any agreement supplemental to this Agreement under this Article,
this Agreement shall be modified in accordance therewith, and such supplemental
agreement shall form a part of this Agreement for all purposes; and every Holder
of a Certificate theretofore or thereafter authenticated and delivered hereunder
shall be bound thereby.

                  Section 9.06. Conformity with Trust Indenture Act. Every
supplemental agreement executed pursuant to this Article shall conform to the
requirements of the Trust Indenture Act as then in effect.

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


                                    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
<PAGE>   57
                                       52


gives such consent. Notwithstanding the foregoing, but subject to Section 6.04
and the Intercreditor Agreement, the Trustee may, in its own discretion and at
its own direction, consent and notify the relevant Loan Trustee of such consent
(or direct the Subordination Agent to consent and notify the Loan Trustee of
such consent) to any amendment, modification, waiver or supplement under the
relevant Indenture, any other Financing Document, any Equipment Note or any
other related document, if an Event of Default hereunder shall have occurred and
be continuing, or if such amendment, modification, waiver or supplement will not
materially adversely affect the interests of the Certificateholders.


                                   ARTICLE XI

                              TERMINATION OF TRUST

                  Section 11.01. Termination of the Trust. The respective
obligations and responsibilities of the Company and the Trustee with respect to
the Trust shall terminate upon 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.
<PAGE>   58
                                       53


                                   ARTICLE XII

                            MISCELLANEOUS PROVISIONS

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

                  Section 12.02. Certificates Nonassessable and Fully Paid.
Except as set forth in the last sentence of this Section 12.02,
Certificateholders shall not be personally liable for obligations of the Trust,
the Fractional Undivided Interests represented by the Certificates shall be
nonassessable for any losses or expenses of the Trust or for any reason
whatsoever, and Certificates, upon authentication thereof by the Trustee
pursuant to Section 3.03, are and shall be 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
<PAGE>   59
                                       54


                           Attention:  Corporate Trust Department
                           Facsimile:  (302) 651-8882
                           Telephone:   (302) 651-8584

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

                  (c) Any notice or communication to Certificateholders shall be
mailed by first-class mail to the addresses for Certificateholders shown on the
Register kept by the Registrar. Failure so to mail a notice or communication or
any defect in such notice or communication shall not affect its sufficiency with
respect to other Certificateholders.

                  (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.
<PAGE>   60
                                       55


                  Section 12.07. Effect of Headings and Table of Contents. The
Article and Section headings herein and the Table of Contents are for
convenience only and shall not affect the construction hereof.

                  Section 12.08. Successors and Assigns. All covenants,
agreements, representations and warranties in this Agreement by the Trustee and
the Company shall bind and, to the extent permitted hereby, shall inure to the
benefit of and be enforceable by their respective successors and assigns,
whether so expressed or not.

                  Section 12.09. Benefits of Agreement. Nothing in this
Agreement or in the Certificates, express or implied, shall give to any Person,
other than the parties hereto and their successors hereunder, and the
Certificateholders, any benefit or any legal or equitable right, remedy or claim
under this Agreement.

                  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:  /s/ James P. Lawler
                                     ----------------------------------------
                                      Name:  James P. Lawler
                                     Title:  Vice President
<PAGE>   62
                                                                       EXHIBIT A

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

                                                   [date]

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

Attention:  Corporate Trust Trustee Administration

         Re:      America West Airlines Pass Through Trust (the "Trust"),
                  Series 1999-1C-S, America West Airlines Pass Through
                  Certificates, Series 1999-1C-S (the "Certificates")
                  ---------------------------------------------------

Sirs:

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

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

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

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

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

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

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


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

                                Very truly yours,

                               [Name of Transferor]
<PAGE>   64
                                                                       EXHIBIT B

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

                                                   [date]

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


Attention:  Corporate Trust Trustee Administration

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


                              AMERICA WEST AIRLINES
               PASS THROUGH TRUST, SERIES 1999-1C-S (the "Trust")
                   Pass Through Certificates, Series 1999-1C-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
<PAGE>   65
                                       B-2



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 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:









                                       2