Document:

<PAGE>

                                                                    EXHIBIT 4.20

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                          PASS THROUGH TRUST AGREEMENT

                            DATED ____________, 20__

                                     BETWEEN

                                US AIRWAYS, INC.

                                       AND

                      U.S. BANK TRUST NATIONAL ASSOCIATION

                                   AS TRUSTEE

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

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                                                     <C>
ARTICLE I    DEFINITIONS...............................................................................................   2

           Section 1.01.  Definitions..................................................................................   2
           Section 1.02.  Compliance Certificates and Opinions.........................................................  11
           Section 1.03.  Form of Documents Delivered to Trustee.......................................................  11
           Section 1.04.  Directions of Certificateholders.............................................................  12

ARTICLE II   ORIGINAL ISSUANCE OF CERTIFICATES: ACQUISITION OF TRUST PROPERTY..........................................  13

           Section 2.01.  Amount Unlimited; Issuable in Series.........................................................  13
           Section 2.02.  Acquisition of Equipment Notes...............................................................  16
           Section 2.03.  Acceptance by Trustee........................................................................  18
           Section 2.04.  Limitation of Powers.........................................................................  18

ARTICLE III  THE CERTIFICATES..........................................................................................  18

           Section 3.01.  Form, Denomination and Execution of Certificates.............................................  18
           Section 3.02.  Authentication of Certificates...............................................................  19
           Section 3.03.  Temporary Certificates.......................................................................  19
           Section 3.04.  Transfer and Exchange........................................................................  20
           Section 3.05.  Book-Entry and Definitive Certificates.......................................................  21
           Section 3.06.  Mutilated, Destroyed, Lost or Stolen Certificates............................................  23
           Section 3.07.  Persons Deemed Owners........................................................................  23
           Section 3.08.  Cancellation.................................................................................  23
           Section 3.09.  Limitation of Liability for Payments.........................................................  24
           Section 3.10.  CUSIP Numbers................................................................................  24

ARTICLE IV   DISTRIBUTIONS; STATEMENTS TO CERTIFICATEHOLDERS...........................................................  24

           Section 4.01.  Certificate Account and Special Payments Account.............................................  24
           Section 4.02.  Distributions from Certificate Account and Special Payments Account..........................  25
           Section 4.03.  Statements to Certificateholders.............................................................  26
           Section 4.04.  Investment of Special Payment Moneys.........................................................  27

ARTICLE V    THE COMPANY...............................................................................................  28

           Section 5.01.  Maintenance of Corporate Existence...........................................................  28
           Section 5.02.  Consolidation, Merger, Etc...................................................................  28

ARTICLE VI   DEFAULT...................................................................................................  29

           Section 6.01.  Indenture Events of Default and Triggering Events............................................  29
           Section 6.02.  Incidents of Sale of Equipment Notes.........................................................  30
           Section 6.03.  Judicial Proceedings Instituted by Trustee; Trustee May Bring Suit...........................  31
           Section 6.04.  Control by Certificateholders................................................................  31
           Section 6.05.  Waiver of Past Defaults......................................................................  31
           Section 6.06.  Right of Certificateholders to Receive Payments Not to Be Impaired...........................  32
           Section 6.07.  Certificateholders May Not Bring Suit Except Under Certain Conditions........................  32
</TABLE>

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                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                                                     <C>
           Section 6.08.  Remedies Cumulative..........................................................................  33
           Section 6.09.  Undertaking for Costs........................................................................  33

ARTICLE VII  THE TRUSTEE...............................................................................................  33

           Section 7.01.  Certain Duties and Responsibilities..........................................................  33
           Section 7.02.  Notice of Defaults...........................................................................  34
           Section 7.03.  Certain Rights of Trustee....................................................................  34
           Section 7.04.  Not Responsible for Recitals or Issuance of Certificates.....................................  36
           Section 7.05.  May Hold Certificates........................................................................  36
           Section 7.06.  Money Held in Trust..........................................................................  36
           Section 7.07.  Compensation and Reimbursement...............................................................  36
           Section 7.08.  Corporate Trustee Required; Eligibility......................................................  37
           Section 7.09.  Resignation and Removal; Appointment of Successor............................................  37
           Section 7.10.  Acceptance of Appointment by Successor.......................................................  39
           Section 7.11.  Merger, Conversion, Consolidation or Succession to Business..................................  39
           Section 7.12.  Maintenance of Agencies......................................................................  40
           Section 7.13.  Money for Certificate Payments to Be Held in Trust...........................................  41
           Section 7.14.  Registration of Equipment Notes in Trustee's Name............................................  41
           Section 7.15.  Representations and Warranties of Trustee....................................................  42
           Section 7.16.  Withholding Taxes; Information Reporting.....................................................  43
           Section 7.17.  Trustee's Liens..............................................................................  43
           Section 7.18.  Preferential Collection of Claims............................................................  43

ARTICLE VIII CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE..........................................................  44

           Section 8.01.  The Company to Furnish Trustee with Names and Addresses of Certificateholders................  44
           Section 8.02.  Preservation of Information; Communications to Certificateholders............................  44
           Section 8.03.  Reports by Trustee...........................................................................  44
           Section 8.04.  Reports by the Company.......................................................................  44

ARTICLE IX   SUPPLEMENTAL AGREEMENTS...................................................................................  45

           Section 9.01.  Supplemental Agreements Without Consent of Certificateholders................................  45
           Section 9.02.  Supplemental Agreements with Consent of Certificateholders...................................  47
           Section 9.03.  Documents Affecting Immunity or Indemnity....................................................  48
           Section 9.04.  Execution of Supplemental Agreements.........................................................  48
           Section 9.05.  Effect of Supplemental Agreements............................................................  48
           Section 9.06.  Conformity with Trust Indenture Act..........................................................  49
           Section 9.07.  Reference in Certificates to Supplemental Agreements.........................................  49

ARTICLE X    AMENDMENTS TO INDENTURES AND OTHER NOTE DOCUMENTS.........................................................  49

           Section 10.01. Amendments and Supplements to Indentures and Other Note Documents............................  49

ARTICLE XI   TERMINATION OF TRUSTS.....................................................................................  50
</TABLE>

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                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                                                     <C>
           Section 11.01. Termination of the Trusts....................................................................  50

ARTICLE XII  MISCELLANEOUS PROVISIONS..................................................................................  51

           Section 12.01. Limitation on Rights of Certificateholders...................................................  51
           Section 12.02. Certificates Nonassessable and Fully Paid....................................................  51
           Section 12.03. Registration of Equipment Notes in Name of Subordination Agent...............................  51
           Section 12.04. Notices......................................................................................  52
           Section 12.05. Governing Law and Venue; Waiver of Jury Trial................................................  53
           Section 12.06. Severability of Provisions...................................................................  54
           Section 12.07. Trust Indenture Act Controls.................................................................  54
           Section 12.08. Effect of Headings and Table of Contents.....................................................  54
           Section 12.09. Successors and Assigns.......................................................................  54
           Section 12.10. Benefits of Agreement........................................................................  54
           Section 12.11. Legal Holidays...............................................................................  55
           Section 12.12. Counterparts.................................................................................  55
           Section 12.13. Communication by Certificateholders with Other Certificateholders............................  55
           Section 12.14. Intention of Parties.........................................................................  55
           Section 12.15. No Recourse Against Others...................................................................  55
EXHIBIT A
           FORM OF CERTIFICATE......................................................................................... A-1
</TABLE>

                                       iii
<PAGE>

Reconciliation and tie between US Airways Pass Through Trust Agreement, dated
_________, 20__ 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
   310(a)(2)                   7.08
   312(a)                      3.05; 7.12; 8.01; 8.02
   313(a)                      8.03
   313(b)                      8.03
   314(a)(1)-(3)               8.04(a)-(c)
   314(a)(4)                   8.04(d)
   314 (c)(1)                  1.02
   314 (c)(2)                  1.02
   314 (d)(1)                  1.02; 7.13; 11.01
   314 (d)(2)                  1.02; 7.13; 11.01
   314 (d)(3)                  2.01
   314 (e)                     1.02
   315(b)                      7.02
   315(c)                      7.01(b)
   316(a)(last sentence)       1.04(c)
   316 (a)(1)(A)               6.04
   316 (a)(1)(B)               6.05
   316 (b)                     6.06
   316 (c)                     1.04(d)
   317(a)(1)                   6.03
   317(b)                      7.13
   318(a)                     12.07
</TABLE>

<PAGE>

                          PASS THROUGH TRUST AGREEMENT

      This PASS THROUGH TRUST AGREEMENT, dated as of _______, 20__ (the "BASIC
AGREEMENT"), between US AIRWAYS, INC., a Delaware corporation (the "COMPANY"),
and U.S. BANK TRUST NATIONAL ASSOCIATION, a national banking association, as
Trustee, is made with respect to the formation from time to time of separate US
Airways Pass Through Trusts, and the issuance from time to time of separate
series of Pass Through Certificates representing fractional undivided interests
in the respective Trusts.

                                   W I T N E S S E T H:

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

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

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

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

      WHEREAS, this Basic Agreement, as supplemented from time to time, is
subject to the provisions of the Trust Indenture Act and shall, to the extent
applicable, be governed by such provisions;

<PAGE>

      NOW, THEREFORE, in consideration of the mutual agreements herein
contained, and of other good and valuable consideration the receipt and adequacy
of which are hereby acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   DEFINITIONS

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

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

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

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

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

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

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

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

      AFFILIATE: Means, with respect to any specified Person, any other Person
directly or indirectly controlling or controlled by or under direct or indirect
common control with such Person. For the purposes of this definition, "CONTROL,"
when used with respect to any specified Person, means the power, directly or
indirectly, to direct the management and policies of such Person, whether
through the ownership of voting securities or by contract or otherwise, and the
terms "controlling" and "controlled" have meanings correlative to the foregoing.

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

                                       2
<PAGE>

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

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

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

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

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

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

      CERTIFICATEHOLDER OR HOLDER: Means, with respect to the Certificates of
any series, the Person in whose name a Certificate of such series is registered
in the Register for Certificates of such series.

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

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

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

      COMPANY: Means US Airways, Inc., a Delaware corporation, or its successor
in interest pursuant to Section 5.02, or (only in the context of provisions
hereof, if any, when such reference is required for purposes of compliance with
the Trust Indenture Act) any other "obligor" (within the meaning of the Trust
Indenture Act) with respect to the Certificates of any series.

      CONTROLLING PARTY: Means, with respect to the Certificates of any series,
the Person entitled to act as such pursuant to the terms of the related
Intercreditor Agreement.

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

                                       3
<PAGE>

      CUT-OFF DATE: Means, with respect to the Certificates of any series, the
date designated as such in the Trust Supplement establishing such series.

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

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

      DISTRIBUTION DATE: Means any Regular Distribution Date, Special
Distribution Date or Initial Regular Distribution Date.

      EQUIPMENT NOTES: Means, with respect to any Trust, any one of the notes,
certificates or instruments issued pursuant to any Indenture and described as
"Equipment Notes" in, or on a schedule attached to, the Trust Supplement in
respect of such Trust and to be held by the Trustee as part of such Trust,
including any Equipment Note (as so defined) issued under the applicable
Indenture in replacement thereof or substitution therefor.

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

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

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

      EVENT OF DEFAULT: Means, in respect of any Trust, an Indenture Event of
Default under any Indenture pursuant to which Equipment Notes held by such Trust
were issued and such other event as may be designated under the related Trust
Supplement as an "Event of Default."

      FRACTIONAL UNDIVIDED INTEREST: Means the fractional undivided interest in
a Trust that is evidenced by a Certificate relating to such Trust.

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

      INDENTURE EVENT OF DEFAULT: Means, with respect to any Indenture, any
Indenture Event of Default (as such term is defined in such Indenture).

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

      INTERCREDITOR AGREEMENT: Means (a) any agreement by and among the Trustee,
as trustee hereunder with respect to one or more Trusts, one or more Liquidity
Providers, if

                                       4
<PAGE>

applicable, and a Subordination Agent providing, among other things, for the
distribution of payments made in respect of Equipment Notes held by such Trusts,
or (b) such other agreement or agreements designated as an "Intercreditor
Agreement" in the Trust Supplement relating to any Trust.

      ISSUANCE DATE: Means, with respect to the Certificates of any series, the
date of the issuance of such Certificates.

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

      LETTER OF REPRESENTATIONS: Means, with respect to the Certificates of any
series, an agreement among the Company, the Trustee and the initial Clearing
Agency substantially in the form attached as an Exhibit to the related Trust
Supplement, as such letter may be modified or supplemented, or any successor
letter thereto.

      LIQUIDITY FACILITY: Means, with respect to the Certificates of any series
or any Equipment Notes, (a) any revolving credit agreement, letter of credit,
bank guarantee, insurance policy, surety bond or financial guaranty or any other
type of agreement or arrangement for the provision of insurance, a guarantee or
other credit enhancement or liquidity support relating to the Certificates of
such series between a Liquidity Provider and a Subordination Agent or one or
more other Persons, as amended, replaced, supplemented or otherwise modified
from time to time in accordance with its terms and, if applicable, the terms of
any Intercreditor Agreement, or (b) such other agreement or agreements
designated as a "Liquidity Facility" in the Trust Supplement relating to any
Trust.

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

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

      NOTE DOCUMENTS: Means, with respect to the Certificates of any series, the
Equipment Notes with respect to such Certificates and, with respect to such
Equipment Notes, the related Participation Agreement, Indenture, Note Purchase
Agreement, Purchase Agreement Assignment and, if the related Aircraft is leased
to the Company, the Lease and the Trust Agreement relating to such Aircraft,
and, if the Parent has guaranteed the obligations of the Company under any such
Equipment Notes or Leases, the Parent Guarantee.

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

                                       5
<PAGE>

      OFFICER'S CERTIFICATE: Means a certificate signed, (a) in the case of the
Company by (i) the Chairman or Vice Chairman of the Board of Directors, the
President, any Executive Vice President, any Senior Vice President or the
Treasurer of the Company signing alone, or (ii) any Vice President of the
Company signing together with the Secretary, the Assistant Secretary, the
Treasurer or any Assistant Treasurer of the Company or (b) in the case of the
Trustee or an Owner Trustee or a Loan Trustee, a Responsible Officer of the
Trustee or such Owner Trustee or such Loan Trustee, as the case may be.

      OPINION OF COUNSEL: Means a written opinion of legal counsel who (a) in
the case of counsel for the Company may be (i) a senior attorney of the Company
one of whose principal duties is furnishing advice as to legal matters, (ii)
McKenna Long & Aldridge LLP (and any affiliate thereof) or (iii) such other
counsel designated by the Company and reasonably acceptable to the Trustee and
(b) in the case of any Owner Trustee or any Loan Trustee, may be such counsel as
may be designated by any of them whether or not such counsel is an employee of
any of them, and who shall be reasonably acceptable to the Trustee.

      OTHER AGREEMENTS: Has the meaning specified in Section 6.01(b).

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

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

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

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

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

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

                                       6
<PAGE>

      PARENT: Means US Airways Group, Inc., a Delaware corporation, and its
successors and assigns.

      PARENT GUARANTEE: Means, with respect to the Certificates of any series, a
guarantee by the Parent of the obligations of the Company under any Equipment
Notes or any Leases related to Equipment Notes to be acquired and held in the
Trust as to which the Certificates of such series represent fractional undivided
interests.

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

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

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

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

      POOL FACTOR: Means, with respect to any series of Certificates as of any
date, except to the extent otherwise provided in the applicable Trust
Supplement, the quotient (rounded to the seventh decimal place, with 0.00000005
being rounded upward) computed by dividing (i) the Pool Balance of such series
as of such date by (ii) the original aggregate face amount of the Certificates
of such series. The Pool Factor as of any Distribution Date shall be computed
after giving effect to the payment of principal, if any, on the Equipment Notes
or other Trust Property held in the Trust relating to such series and the
distribution thereof to be made on such Distribution Date.

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

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

                                       7
<PAGE>

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

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

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

      PURCHASE AGREEMENT ASSIGNMENT: Has the meaning, with respect to the
Certificates of any series, specified therefor in the related Participation
Agreement.

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

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

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

      REGULAR DISTRIBUTION DATE: Means, with respect to distributions of
Scheduled Payments in respect of any series of Certificates, each date
designated as such in this Agreement, until payment of all the Scheduled
Payments to be made under the Equipment Notes held in the Trust have been made,
or until such Equipment Notes have been redeemed or otherwise prepaid in full.

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

                                       8
<PAGE>

      RESPONSIBLE OFFICER: Means, with respect to any Trustee, any Loan Trustee
and any Owner Trustee, any officer in the Corporate Trust Department or similar
department of the Trustee, Loan Trustee or Owner Trustee or any other officer
customarily performing functions similar to those performed by the persons who
at the time shall be such officers, respectively, or to whom any corporate trust
matter is referred because of his knowledge of and familiarity with a particular
subject.

      RESPONSIBLE PARTY: Means, with respect to the Certificates of any series,
the Person designated as such in the related Trust Supplement.

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

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

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

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

      SPECIAL PAYMENT: Means, except to the extent otherwise provided in the
applicable Trust Supplement, (i) any payment (other than a Scheduled Payment) in
respect of, or any proceeds of, any Equipment Note or Trust Indenture Estate (as
defined in each Indenture relating to such Trust), (ii) the amounts required to
be distributed pursuant to the last paragraph of Section 2.02(b), or (iii) the
amounts required to be distributed pursuant to the penultimate paragraph of
Section 2.02(b).

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

      SPECIFIED INVESTMENTS: Means, with respect to any Trust, unless otherwise
specified in the related Trust Supplement, (i) obligations of, or guaranteed by,
the United States Government

                                       9
<PAGE>

or agencies thereof, (ii) open market commercial paper of any corporation
incorporated under the laws of the United States of America or any state thereof
rated at least P-2 or its equivalent by Moody's Investor Service, Inc.
("Moody's") or at least A-2 or its equivalent by Standard & Poor's Rating
Services, a division of the McGraw-Hill Companies, Inc. ("S&P"), (iii)
certificates of deposit issued by commercial banks organized under the laws of
the United States or of any political subdivision thereof having a combined
capital and surplus in excess of $500,000,000 which banks or their holding
companies have a rating of A or its equivalent by Moody's or A2 or its
equivalent by S&P; provided, however, that the aggregate amount at any one time
so invested in certificates of deposit issued by any one bank shall not exceed
5% of such bank's capital and surplus, (iv) U.S. dollar-denominated offshore
certificates of deposit issued by, or offshore time deposits with, any
commercial bank described in clause (iii) above or any subsidiary thereof and
(v) repurchase agreements with any financial institution having combined capital
and surplus of at least $500,000,000 with any of the obligations described in
clauses (i) through (iv) above as collateral; provided further, that if all of
the above investments are unavailable, the entire amounts to be invested may be
used to purchase federal funds from an entity described in clause (iii) above.

      SUBORDINATION AGENT: Has the meaning, with respect to the Certificates of
any series, specified therefor in the relevant Intercreditor Agreement.

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

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

      TRIGGERING EVENT: Has the meaning, with respect to the Certificates of any
series, specified therefor in the relevant Intercreditor Agreement.

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

      TRUSTEE: Means U.S. Bank Trust National Association, a national banking
association, or its successor in interest, and any successor or other trustee
appointed as provided herein.

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

      TRUST PROPERTY: Means, with respect to any Trust, except to the extent
otherwise provided in the applicable Trust Supplement, (i) subject to any
related Intercreditor Agreement, the Equipment Notes held as the property of
such Trust, all monies at any time paid thereon and all monies due and to become
due thereunder, (ii) debt instruments issued by the Company in accordance with
the first paragraph of Section 2.02(b), (iii) funds from time to time deposited
in the related Escrow Account, the related Certificate Account and the related
Special Payments

                                       10
<PAGE>

Account and, subject to any related Intercreditor Agreement, any proceeds from
the sale by the Trustee pursuant to Article VI hereof of any Equipment Note
referred to in (i) above, (iv) all rights of such Trust and the Trustee, on
behalf of the Trust, under any Intercreditor Agreement, including, without
limitation, all monies receivable in respect of such rights, and (iv) all monies
receivable under any Liquidity Facility for such Trust.

      TRUST SUPPLEMENT: Means an agreement supplemental hereto pursuant to which
(i) a separate Trust is created for the benefit of the Holders of the
Certificates of a series, (ii) the issuance of the Certificates of such series
representing fractional undivided interests in such Trust is authorized and
(iii) the terms of the Certificates of such series are established, as such
agreement may from time to time be supplemented, amended or otherwise modified.

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

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

            (1) a statement that (x) each individual signing such certificate or
      (y) each firm or person executing such Opinion of Counsel has read such
      covenant or condition and the definitions in this Basic Agreement or this
      Agreement relating thereto;

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

            (3) a statement that, in the opinion of each such individual or
      firm, he or it has made such examination or investigation as is necessary
      to enable him or it 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 or firm, 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

                                       11
<PAGE>

necessary that all such matters be certified by, or covered by the opinion of,
only one such Person, or that they be so certified or covered by only one
document, but one such Person may certify or give an opinion with respect to
some matters and one or more other such Persons as to other matters and any such
Person may certify or give an opinion as to such matters in one or several
documents.

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

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

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

            (c) In determining whether the Certificateholders of the requisite
Fractional Undivided Interests of Certificates of any series Outstanding have
given any Direction under this Agreement, Certificates owned by the Company, any
related Owner Trustee, any related Owner Participant or any Affiliate of any
such Person shall be disregarded and deemed not to be Outstanding for purposes
of any such determination. In determining whether the Trustee shall be protected
in relying upon any such Direction, only Certificates which the Trustee knows to
be so owned shall be so disregarded. Notwithstanding the foregoing, (i) if any
such Person owns 100% of the Certificates of any series Outstanding, such
Certificates shall not be so disregarded, and (ii) if any amount of Certificates
of any series so owned by any such Person have been pledged in good faith, such
Certificates shall not be disregarded if the pledgee establishes to the
satisfaction of the Trustee the pledgee's right so to act with respect to such
Certificates and that

                                       12
<PAGE>

the pledgee is not the Company, any related Owner Trustee, any related Owner
Participant or any Affiliate of any such Person.

            (d) The Company may, at its option, by delivery of an Officer's
Certificate to the Trustee, set a record date to determine the
Certificateholders in respect of the Certificates of any series entitled to give
any Direction. Notwithstanding Section 316(c) of the Trust Indenture Act, such
record date shall be the record date specified in such Officer's Certificate,
which shall be a date not more than 30 days prior to the first solicitation of
Certificateholders of the applicable series in connection therewith. If such a
record date is fixed, such Direction may be given before or after such record
date, but only the Certificateholders of record of the applicable series at the
close of business on such record date shall be deemed to be Certificateholders
for the purposes of determining whether Certificateholders of the requisite
proportion of Outstanding Certificates of such series have authorized or agreed
or consented to such Direction, and for that purpose the Outstanding
Certificates of such series shall be computed as of such record date; provided,
however, that no such Direction by the Certificateholders on such record date
shall be deemed effective unless it shall become effective pursuant to the
provisions of this Agreement not later than one year after such record date.
Nothing in this paragraph shall be construed to prevent the Company from setting
a new record date for any action for which a record date has previously been set
pursuant to this paragraph (whereupon the record date previously set shall
automatically and with no action by any Person be deemed cancelled and of no
effect).

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

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

                                   ARTICLE II

                       ORIGINAL ISSUANCE OF CERTIFICATES:
                          ACQUISITION OF TRUST PROPERTY

      Section 2.01. Amount Unlimited; Issuable in Series. (a) The aggregate face
amount of Certificates that may be authenticated and delivered under this Basic
Agreement is unlimited. The Certificates may be issued from time to time in one
or more series and shall be designated generally as the "Pass Through
Certificates", with such further designations added or incorporated in such
title for the Certificates of each series as are specified in the related Trust
Supplement. Each Certificate shall bear upon its face the designation so
selected for the series to which it belongs. All Certificates of the same series
shall be substantially identical except that the Certificates of a series may
differ as to denomination and as may otherwise be provided in the Trust
Supplement establishing the Certificates of such series. Each series of
Certificates issued pursuant to this Agreement will evidence fractional
undivided interests in the related Trust and, except as may be specified in any
Intercreditor Agreement or in the applicable Trust

                                       13
<PAGE>

Supplement, will have no rights, benefits or interests in respect of any other
Trust or the Trust Property held therein. All Certificates of the same series
shall be in all respects equally and ratably entitled to the benefits of this
Agreement without preference, priority or distinction on account of the actual
time or times of authentication and delivery, all in accordance with the terms
and provisions of this Agreement.

            (b) The following matters shall be established with respect to the
Certificates of each series issued under this Agreement by a Trust Supplement
executed and delivered (x) by and between the Company and the Trustee, or (y) if
the Parent will guarantee the obligations of the Company under any Equipment
Notes or any Leases related to Equipment Notes to be acquired and held in the
Trust formed by such Trust Supplement, by and among the Parent, the Company and
the Trustee:

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

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

            (3) subject to Section 2.01(a) hereof, any limit upon the aggregate
      face amount of the Certificates of such series which may be authenticated
      and delivered under this Basic Agreement (which limit shall not pertain to
      Certificates authenticated and delivered upon registration of transfer of,
      or in exchange for, or in lieu of, other Certificates of the series
      pursuant to Sections 3.03, 3.04, 3.05(d) and 3.06);

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

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

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

            (7) if other than as provided in Sections 3.04 or 7.12(b), the
      Registrar or the Paying Agent for the Certificates of such series,
      including any Co-Registrar or additional Paying Agent;

            (8) if other than as provided in Section 3.01, the denominations in
      which the Certificates of such series shall be issuable;

            (9) if other than United States dollars, the currency or currencies
      (including composite currencies or currency units) in which the
      Certificates of such series shall be denominated or payable, in whole or
      in part;

            (10) the specific form of the Certificates of such series (including
      the interest rate applicable thereto) and whether or not Certificates of
      such series are to be issued as

                                       14
<PAGE>

      Book-Entry Certificates and, if such Certificates are to be Book-Entry
      Certificates, the form of Letter of Representations, if any (or, in the
      case of any Certificates denominated or payable in a currency other than
      United States dollars and if other than as provided in Section 3.05,
      whether and the circumstances under which beneficial owners of interests
      in such Certificates in permanent global form may exchange such interests
      for Certificates of such series and of like tenor of any authorized form
      and denomination);

            (11) a description of the Equipment Notes, and, if applicable, of
      any notes issued by a trust or other entity secured by Equipment Notes, to
      be acquired and held in the Trust formed by such Trust Supplement and of
      the related Aircraft, if determined, and Note Documents, if determined;

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

            (13) any restrictions (including legends) in respect of ERISA or tax
      matters;

            (14) the acceptance of appointment by the institution named to act
      as Trustee with respect to such Trust, if different from the institution
      executing this Basic Agreement or its successor;

            (15) whether such series will be subject to an Intercreditor
      Agreement and, if so, the specific designation of such Intercreditor
      Agreement and the rights of Potential Purchasers upon the occurrence of a
      Triggering Event;

            (16) whether such series will have the benefit of a Liquidity
      Facility or other form of credit enhancement and, if so, any terms
      appropriate thereto;

            (17) whether the Parent will guarantee the obligations of the
      Company under any Equipment Notes or any Leases related to Equipment Notes
      to be acquired and held in the Trust formed by such Trust Supplement and,
      if so, the specific form of such Parent Guarantee or Parent Guarantees and
      a statement that the Parent shall be an "obligor" as such term is defined
      in and solely for purposes of the Trust Indenture Act and shall be
      required to comply with those provisions of this Agreement compliance with
      which is required by an "obligor" under the Trust Indenture Act;

            (18) whether there will be a deposit agreement, escrow agreement or
      other arrangement prior to the delivery of one or more Aircraft or the
      commencement of the Lease with respect to one or more Aircraft, and, if
      so, any terms appropriate thereto;

            (19) the extent, if any, to which the Company may acquire
      Certificates and deliver such Certificates or cash to the respective
      Trusts and obtain the release of Equipment Notes or other Trust Property
      held by such Trusts;

                                       15
<PAGE>

            (20) if the Certificates of such series are to be issued in bearer
      form, the forms thereof and any other special terms relating thereto;

            (21) the "Responsible Party" for purposes of directing the Trustee
      to make Specified Investments; and

            (22) any other terms of the Certificates of such series or any
      related Parent Guarantee (which terms shall not be inconsistent with the
      provisions of the Trust Indenture Act but may modify, amend, supplement or
      delete any of the terms of this Basic Agreement), including any terms of
      the Certificates of such series which may be required or advisable under
      United States laws or regulations or advisable (as determined by the
      Company) in connection with the marketing of Certificates of the series.

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

      Section 2.02. Acquisition of Equipment Notes. (a) Unless otherwise
specified in the related Trust Supplement, on or prior to the Issuance Date of
the Certificates of a series, the Trustee shall execute and deliver the related
Note Purchase Agreements in the form delivered to the Trustee by the Company and
shall, subject to the respective terms thereof, perform its obligations under
such Note Purchase Agreements. Unless otherwise specified in the related Trust
Supplement, the Trustee shall issue and sell such Certificates, in authorized
denominations and in such Fractional Undivided Interests, so as to result in the
receipt of consideration in an amount equal to the aggregate purchase price of
the Equipment Notes (and/or, if applicable, any notes issued by a trust or other
entity secured by Equipment Notes) contemplated to be purchased by the Trustee
under the related Note Purchase Agreements and, concurrently therewith (unless
the Company shall have delivered to the Trustee the Postponement Notice relating
to one or more Postponed Notes pursuant to Subsection (b) below), the Trustee
shall purchase, pursuant to the terms and conditions of the Note Purchase
Agreements, such Equipment Notes (except Postponed Notes, if any)(or other
notes) at a purchase price equal to the amount of such consideration so
received. Except as provided in Sections 3.03, 3.04, 3.05 and 3.06 hereof, the
Trustee shall not execute, authenticate or deliver Certificates of such series
in excess of the aggregate amount specified in this paragraph. The provisions of
this Subsection (a) are subject to the provisions of Subsection (b) below.

            (b) If on or prior to the Issuance Date with respect to a series of
Certificates the Company shall deliver to the Trustee a Postponement Notice
relating to one or more Postponed Notes, the Trustee shall postpone the purchase
of such Postponed Notes and shall deposit into an escrow account (as to the
related Trust, the "ESCROW ACCOUNT") to be maintained as part of the related
Trust an amount equal to the purchase price of such Postponed Notes (the
"ESCROWED FUNDS"). The portion of the Escrowed Funds so deposited with respect
to any particular Postponed Notes shall be invested (a) by the Trustee at the
written direction and risk

                                       16
<PAGE>

of, and for the benefit of, the Responsible Party in Specified Investments or
(b) if provided in the Trust Supplement relating to such series of Certificates
and subject to the terms and conditions set forth therein, in debt instruments
of the Company, in each case (i) maturing no later than any scheduled Transfer
Date relating to such Postponed Notes, or (ii) if no such Transfer Date has been
scheduled, maturing on the next Business Day, or (iii) if subsequent to the
giving of the applicable Postponement Notice the Company has given notice to the
Trustee that such Postponed Notes will not be issued, maturing on the next
applicable Special Distribution Date, if such investments are reasonably
available for purchase. The Trustee shall make withdrawals from the Escrow
Account only as provided in this Agreement. Upon request of the Company on one
or more occasions and the satisfaction or waiver of the closing conditions
specified in the applicable Note Purchase Agreements on or prior to the related
Cut-off Date, the Trustee shall purchase the applicable Postponed Notes, on the
terms specified in such Note Purchase Agreements, with the Escrowed Funds
withdrawn from the Escrow Account.

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

      Subject to the provisions of the Intercreditor Agreement, any earnings on
Specified Investments received from time to time by the Trustee shall be
promptly distributed to the Responsible Party. The Responsible Party shall pay
to the Trustee for deposit to the relevant Escrow Account an amount equal to any
net losses on any Specified Investments made at its direction and risk as
incurred. On any Regular Distribution Date in respect of the Certificates of any
series occurring prior to the date of purchase of any Postponed Notes by the
Trustee, the Responsible Party will pay (in immediately available funds) to the
Trustee an amount equal to the interest that would have accrued on such
Postponed Notes if such Postponed Notes had been purchased on the later of the
Issuance Date or the previous Regular Distribution Date in respect of the
Certificates of such series to, but not including, such Regular Distribution
Date. On the first Regular Distribution Date in respect of the Certificates of
any series following the purchase of any Postponed Notes by the Trustee, the
Responsible Party will pay (in immediately available funds) to the Trustee an
amount equal to the interest that would have accrued on such Postponed Notes if
such Postponed Notes had been purchased on the later of the Issuance Date or the
previous Regular Distribution Date in respect of the Certificates of such series
to, but not including, the date of the purchase of such Postponed Notes by the
Trustee.

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

                                       17
<PAGE>

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

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

      Section 2.03. Acceptance by Trustee. The Trustee, by the execution and
delivery of a Trust Supplement creating a Trust and establishing a series of
Certificates, shall acknowledge its acceptance of all right, title and interest
in and to the Trust Property to be acquired pursuant to Section 2.02 hereof and
the related Note Purchase Agreements and shall declare that the Trustee holds
and will hold such right, title and interest for the benefit of all then present
and future Certificateholders of such series, upon the trusts herein and in such
Trust Supplement set forth. By the acceptance of each Certificate of such series
issued to it under this Agreement, each initial Holder of such series as grantor
of such Trust shall thereby join in the creation and declaration of such Trust.
No Certificateholder of any series shall have legal title to any part of the
Trust Property of the related Trust.

      Section 2.04. Limitation of Powers. Each Trust shall be constituted solely
for the purpose of making the investment in the Equipment Notes provided for in
the related Trust Supplement, and, except as set forth in this Agreement, 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 related
Indentures) by bidding for such Equipment Notes or otherwise, or taking any
action with respect to any such Aircraft once acquired).

                                   ARTICLE III

                                THE CERTIFICATES

      Section 3.01. Form, Denomination and Execution of Certificates. Except to
the extent otherwise provided in the applicable Trust Supplement, the
Certificates of each series shall be issued in fully registered form without
coupons and shall be substantially in the form attached

                                       18
<PAGE>

hereto as Exhibit A with such omissions, variations and insertions as are
permitted by this Agreement, and may have such letters, numbers or other marks
of identification and such legends or endorsements placed thereon as may be
required to comply with any applicable laws, rules, regulations, or the rules of
any securities exchange on which such Certificates may be listed or to conform
to any usage in respect thereof, or as may, consistently with this Agreement, be
determined by the Trustee or the officers executing such Certificates, as
evidenced by the Trustee's or such officers' execution of the Certificates.

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

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

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

      Section 3.02. Authentication of Certificates. (a) Except to the extent
otherwise provided in the applicable Trust Supplement, on the Issuance Date, the
Trustee shall duly execute, authenticate and deliver Certificates of each series
in authorized denominations equaling in the aggregate the aggregate face amount
of the Equipment Notes that may be purchased by the Trustee pursuant to the
related Note Purchase Agreements, and evidencing the entire ownership of the
related Trust. Thereafter, the Trustee shall duly execute, authenticate and
deliver the Certificates of such series as provided in this Agreement.

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

      Section 3.03. Temporary Certificates. Until definitive Certificates are
ready for delivery, the Trustee shall execute, authenticate and deliver
temporary Certificates of each series. Temporary Certificates of each series
shall be substantially in the form of definitive Certificates of such series but
may have insertions, substitutions, omissions and other variations determined to
be appropriate by the officers executing the temporary Certificates of such
series, as evidenced by their execution of such temporary Certificates. If
temporary Certificates of any series are

                                       19
<PAGE>

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

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

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

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

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

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

                                       20
<PAGE>

      Section 3.05. Book-Entry and Definitive Certificates. (a) Except for one
Certificate of each series that may be issued in a denomination of other than an
even multiple of $1,000, the Certificates of any series may be issued at the
option of the Company in the form of one or more typewritten Certificates
representing the Book-Entry Certificates of such series, to be delivered to The
Depository Trust Company, the initial Clearing Agency, by, or on behalf of, the
Company. In such case, the Certificates of such series delivered to The
Depository Trust Company shall initially be registered on the Register in the
name of Cede & Co., the nominee of the initial Clearing Agency, and no
Certificate Owner will receive a definitive certificate representing such
Certificate Owner's interest in the Certificates of such series, except as
provided above and in Subsection (d) below. As to the Certificates of any such
series (other than the one Certificate of such series issued in a denomination
of other than an even multiple of $1,000), unless and until definitive, fully
registered Certificates (the "DEFINITIVE CERTIFICATES") have been issued
pursuant to Subsection (d) below:

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

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

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

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

                  (v) such Certificates of such series may be transferred in
            whole, but not in part, and in the manner provided in Section 3.04,
            by the Clearing Agency holding such Certificates to a nominee of
            such Clearing Agency, or by such Clearing Agency to a successor
            Clearing Agency that has been selected or approved by the Company or
            to a nominee of such successor Clearing Agency; and

                  (vi) whenever this Agreement requires or permits actions to be
            taken based upon instructions or directions of Certificateholders of
            such series holding Certificates of such series evidencing a
            specified percentage of the Fractional Undivided Interests in the
            related Trust, the Clearing Agency shall be deemed to represent such
            percentage only to the extent that it has received instructions to
            such effect from Clearing Agency Participants owning or
            representing,

                                       21
<PAGE>

            respectively, such required percentage of the beneficial interest in
            Certificates of such series and has delivered such instructions to
            the Trustee. None of the Company, the Parent or the Trustee or any
            agent of any of them shall have any obligation to determine whether
            the Clearing Agency has in fact received any such instructions.

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

            (c) Unless and until Definitive Certificates of a series are issued
pursuant to Subsection (d) below, on the Record Date prior to each applicable
Regular Distribution Date and Special Distribution Date, the Trustee will
request from the Clearing Agency a securities position listing setting forth the
names of all Clearing Agency Participants reflected on the Clearing Agency's
books as holding interests in the Certificates on such Record Date.

            (d) If with respect to the Certificates of any series (i) the
Company advises the Trustee in writing that the Clearing Agency is no longer
willing or able to discharge properly its responsibilities and the Trustee or
the Company is unable to locate a qualified successor, (ii) the Company, at its
option, advises the Trustee in writing that it elects to terminate the
book-entry system through the Clearing Agency or (iii) after the occurrence of
an Event of Default, Certificate Owners of Book-Entry Certificates of such
series evidencing Fractional Undivided Interests aggregating not less than a
majority in interest in the related Trust, by Act of such Certificate Owners
delivered to the Company and the Trustee, advise the Company, the Trustee and
the Clearing Agency through the Clearing Agency Participants in writing that the
continuation of a book-entry system through the Clearing Agency Participants is
no longer in the best interests of the Certificate Owners of such series, then
the Trustee shall notify all Certificate Owners of such series, through the
Clearing Agency, of the occurrence of any such event and of the availability of
Definitive Certificates. Upon surrender to the Trustee of all the Certificates
of such series held by the Clearing Agency, accompanied by registration
instructions from the Clearing Agency Participants for registration of
Definitive Certificates in the names of Certificate Owners of such series, the
Trustee shall issue and deliver the Definitive Certificates of such series in
accordance with the instructions of the Clearing Agency. None of the Company,
the Registrar, the Paying Agent or the Trustee shall be liable for any delay in
delivery of such instructions and may conclusively rely on, and shall be
protected in relying on, such registration instructions. Upon the issuance of
Definitive Certificates of such series, the Trustee shall recognize the Persons
in whose names the Definitive Certificates are registered in the Register as
Certificateholders under this Agreement. Neither the Company nor the Trustee
shall be liable if the Trustee or the Company is unable to locate a qualified
successor Clearing Agency.

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

                                       22
<PAGE>

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

      Section 3.06. Mutilated, Destroyed, Lost or Stolen Certificates. If (a)
any mutilated Certificate is surrendered to the Registrar, or the Registrar
receives evidence to its satisfaction of the destruction, loss or theft of any
Certificate, and (b) there is delivered to the Registrar and the Trustee such
security, indemnity or bond, as may be required by them to save each of them and
the Company 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 of like series, 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
3.06, the Trustee shall require the payment of a sum sufficient to cover any tax
or other governmental charge that may be imposed in relation thereto and any
other expenses (including the fees and expenses of the Trustee and the
Registrar) connected therewith.

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

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

      Section 3.07. Persons Deemed Owners. Prior to due presentment of a
Certificate for registration of transfer, the Company, 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) on the Register as
the owner of such Certificate and the Certificateholder for the purpose of
receiving distributions pursuant to Article IV and for all other purposes
whatsoever, and none of the Company, the Trustee, the Registrar or any Paying
Agent shall be affected by any notice to the contrary. All payments or
distributions made to any such Person shall be valid and, to the extent of the
sum or sums so paid, effectual to satisfy and discharge the liability for moneys
payable on any such Certificate.

      Unless otherwise provided with respect to any Certificates pursuant to
Section 2.01(b), the Company, the Parent, any other obligor upon any
Certificates and any Affiliate of any thereof may acquire, tender for, purchase,
own, hold, become the pledgee of and otherwise deal with any Certificates.

      Section 3.08. Cancellation. All Certificates surrendered for payment or
transfer or exchange shall, if surrendered to the Trustee or any agent of the
Trustee other than the Registrar, be delivered to the Registrar for cancellation
and shall promptly be cancelled by it. No Certificates shall be authenticated in
lieu of or in exchange for any Certificates cancelled as

                                       23
<PAGE>

provided in this Section 3.08, except as expressly permitted by this Agreement.
All cancelled Certificates held by the Registrar shall be destroyed and a
certification of their destruction delivered to the Trustee.

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

      The Company is a party to this Agreement solely for purposes of meeting
the requirements of the Trust Indenture Act, and therefore the Company shall not
have any right, obligation or liability hereunder, or under the terms of any
Trust Supplement or any Certificates (except as otherwise expressly provided
herein or therein).

      Section 3.10. CUSIP Numbers. The Certificates may include "CUSIP" numbers
(if then generally in use), and if so, the Trustee may use the CUSIP numbers in
notices in respect of the Certificates; provided, however, that any such notice
may state that no representation is made as to the correctness or accuracy of
the CUSIP number printed in the notice or on the Certificates, that reliance may
be placed only on the other identification numbers printed on the Certificates,
and any such notice shall not be affected by any defect or omission of such
CUSIP numbers.

                                   ARTICLE IV

                          DISTRIBUTIONS; STATEMENTS TO
                               CERTIFICATEHOLDERS

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

            (b) The Trustee shall establish and maintain on behalf of the
Certificateholders of each series a Special Payments Account as one or more
accounts, which shall be non-interest bearing except as provided in Section
4.04. The Trustee shall hold the

                                       24
<PAGE>

Special Payments Account in trust for the benefit of the Certificateholders of
such series and shall make or permit withdrawals therefrom only as provided in
this Agreement or any Intercreditor Agreement. On each day when one or more
Special Payments are made to the Trustee with respect to the Certificates of any
series, the Trustee, upon receipt thereof, shall immediately deposit the
aggregate amount of such Special Payments in the applicable Special Payments
Account.

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

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

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

            (c) The Trustee shall, at the expense of the Company, cause notice
of each Special Payment with respect to a series of Certificates to be mailed to
each Certificateholder of

                                       25
<PAGE>

such series at such Certificateholder's address as it appears in the Register.
Subject to the provisions of the Intercreditor Agreement: (i) in the event of
redemption or purchase of Equipment Notes held in the related Trust, such notice
shall be mailed not less than 15 days prior to the Special Distribution Date for
the Special Payment resulting from such redemption or purchase, which Special
Distribution Date shall be the date of such redemption or purchase; (ii) in the
event that the Trustee receives a notice from the Company pursuant to Section
2.02 that Postponed Notes will not be purchased by the Trustee, such notice of
Special Payment shall be mailed as soon as practicable after receipt of such
notice from the Company and shall state the Special Distribution Date for such
Special Payment, which shall occur 20 days after the date of such notice of
Special Payment or (if such 20th day is not practicable) as soon as practicable
thereafter; (iii) in the event that any Special Payment is to be made pursuant
to the last paragraph of Section 2.02(b) hereof, such notice of Special Payment
shall be mailed on the Cut-off Date (or, if such mailing on the Cut-off Date is
not practicable, as soon as practicable after the Cut-off Date), and shall state
the Special Distribution Date for such Special Payment, which shall occur 20
days after the date of such notice of Special Payment (or, if such 20th day is
not practicable, as soon as practicable thereafter); and (iv) in the case of any
other Special Payments, such notice of Special Payment shall be mailed as soon
as practicable after the Trustee has confirmed that it has received funds for
such Special Payment, and shall state the Special Distribution Date for such
Special Payment, which shall occur 20 days after the date of such notice of
Special Payment or (if such 20th day is not practicable) as soon as practicable
thereafter. Notices mailed by the Trustee as provided in the paragraphs above
shall set forth:

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

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

                  (iii) the reason for the Special Payment; and

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

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

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

      Section 4.03. Statements to Certificateholders. (a) On each Regular
Distribution Date and Special Distribution Date, the Trustee will include with
each distribution of a Scheduled

                                       26
<PAGE>

Payment or Special Payment, as the case may be, to Certificateholders of the
related series a statement setting forth the information provided below. Such
statement shall, except to the extent otherwise provided in the applicable Trust
Supplement, set forth (per $1,000 aggregate face amount of Certificate as to (i)
and (ii) below) the following information:

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

                  (ii) the amount of such distribution under this Agreement
            allocable to interest; and

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

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

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

      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 by the Trustee in Permitted Investments selected by the Controlling
Party in telephonic (confirmed in writing) or written instructions to the
Trustee pending distribution of such Special Payment pursuant to Section 4.02.
Absent receipt of such instructions from the Controlling Party, such Special
Payment shall remain uninvested by the Trustee pending receipt of investment
instructions. 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

                                       27
<PAGE>

Permitted Investments until maturity. The Trustee shall have no liability with
respect to any investment made pursuant to this Section 4.04, other than by
reason of the willful misconduct or negligence of the Trustee. All income and
earnings from such investments shall be distributed on such Special Distribution
Date as part of such Special Payment.

                                    ARTICLE V

                                   THE COMPANY

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

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

            (a) the corporation formed by such consolidation or into which the
      Company is merged or the Person that acquires by conveyance, transfer or
      lease substantially all of the assets of the Company as an entirety shall
      (i) be organized and validly existing under the laws of the United States
      of America or any state thereof or the District of Columbia, (ii) be a
      "citizen of the United States" as defined in 49 U.S.C. Sections
      40102(a)(15), as amended, and (iii) hold an air carrier operating
      certificate issued pursuant to Chapter 447 of Title 49 of the United
      States Code for aircraft capable of carrying 10 or more individuals or
      6,000 pounds or more of cargo, if and so long as such status is a
      condition of entitlement to the benefits of Section 1110 of the Bankruptcy
      Reform Act of 1978, as amended (11 U.S.C. Sections 1110), with respect to
      the Leases or the Aircraft owned by the Company; and

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

      The Trustee may request an Officer's Certificate of the Company and an
Opinion of Counsel of the Company (that may be the Company's General Counsel,
Deputy General Counsel, Associate General Counsel or other senior attorney of
the Company) reasonably satisfactory to the Trustee, each stating that such
consolidation, merger, conveyance, transfer or lease and the assumption
agreement mentioned in clause (b) above comply with this Section 5.02

                                       28
<PAGE>

and that all conditions precedent herein provided for relating to such
transaction have been complied with.

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

                                   ARTICLE VI

                                     DEFAULT

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

            (b) By acceptance of its Certificate, each Certificateholder agrees
that at any time after the occurrence and during the continuation of a
Triggering Event, each Certificateholder of Certificates of certain series
(each, a "POTENTIAL PURCHASER" and, collectively, the "POTENTIAL PURCHASERS")
may have certain rights to purchase the Certificates of one or more other
series, all as set forth in the Trust Supplement applicable to the Certificates
held by such Potential Purchaser. The purchase price with respect to the
Certificates of any series shall be equal to the Pool Balance of the
Certificates of such series, together with accrued and unpaid interest thereon
to the date of such purchase, without premium, but including any other amounts
then due and payable to the Certificateholders of such series under this
Agreement, any related Intercreditor Agreement or any other Note Document or on
or in respect of the Certificates of such series; provided, however, that if
such purchase occurs after a Record Date, such purchase price shall be reduced
by the amount to be distributed under this Agreement on the related Distribution
Date (which deducted amounts shall remain distributable to, and may be retained
by, the Certificateholder as of such Record Date); provided, further, that no
such purchase of Certificates of such series shall be effective unless the
purchasing Certificateholder (each, a "PURCHASING CERTIFICATEHOLDER" and,
collectively, the "PURCHASING CERTIFICATEHOLDERS") shall certify to the Trustee
that contemporaneously with such purchase, one or more Purchasing
Certificateholders are purchasing, pursuant to the terms of this Agreement and
the other Agreements, if any, relating to the Certificates of a series that are
subject to the

                                       29
<PAGE>

same Intercreditor Agreement (such other Agreements, the "OTHER AGREEMENTS"),
the Certificates of each such series that the Trust Supplement applicable to the
Certificates held by the Purchasing Certificateholder specifies may be purchased
by such Purchasing Certificateholder. Each payment of the purchase price of the
Certificates of any series shall be made to an account or accounts designated by
the Trustee and each such purchase shall be subject to the terms of this Section
6.01. By acceptance of its Certificate, each Certificateholder (each, a "SELLING
CERTIFICATEHOLDER" and, collectively, the "SELLING CERTIFICATEHOLDERS") of a
series that is subject to purchase by Potential Purchasers, all as set forth in
the Trust Supplement applicable to the Certificates held by the Selling
Certificateholders, agrees that, at any time after the occurrence and during the
continuance of a Triggering Event, it will, upon payment of the purchase price
specified in this Agreement by one or more Purchasing Certificateholders,
forthwith sell, assign, transfer and convey to such Purchasing Certificateholder
(without recourse, representation or warranty of any kind except for its own
acts), all of the right, title, interest and obligation of such Selling
Certificateholder in this Agreement, any related Intercreditor Agreement, the
related Liquidity Facility, the related Note Documents and all Certificates of
such series held by such Selling Certificateholder (excluding all right, title
and interest under any of the foregoing to the extent such right, title or
interest is with respect to an obligation not then due and payable as respects
any action or inaction or state of affairs occurring prior to such sale) and the
Purchasing Certificateholder shall assume all of such Selling
Certificateholder's obligations under this Agreement, any related Intercreditor
Agreement, any related Liquidity Facility and the related Note Documents. The
Certificates of such series will be deemed to be purchased on the date payment
of the purchase price is made notwithstanding the failure of any Selling
Certificateholder to deliver any Certificates of such series and, upon such a
purchase, (i) the only rights of the Selling Certificateholders will be to
deliver the Certificates to the Purchasing Certificateholder and receive the
purchase price for such Certificates of such series and (ii) if the Purchasing
Certificateholder shall so request, such Selling Certificateholder will comply
with all of the provisions of Section 3.04 hereof to enable new Certificates of
such series to be issued to the Purchasing Certificateholder in such
denominations as it shall request. All charges and expenses in connection with
the issuance of any such new Certificates shall be borne by the Purchasing
Certificateholder.

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

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

            (2) Receipt of Trustee Shall Discharge Purchaser. The receipt of the
      Trustee making such sale shall be a sufficient discharge to any purchaser
      for its 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

                                       30
<PAGE>

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

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

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

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

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

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

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

      Section 6.05. Waiver of Past Defaults. Subject to any related
Intercreditor Agreement, the Certificateholders holding Certificates of a series
evidencing Fractional Undivided Interests aggregating not less than a majority
in interest in the related Trust (i) may on behalf of all of the
Certificateholders of such series waive any past default or Event of Default
under this Agreement

                                       31
<PAGE>

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, Indenture Event of Default, or, if applicable, the corresponding Lease
default, under any related Indenture and its consequences, and thereby annul any
Direction given by such Certificateholders or the Trustee to such Loan Trustee
with respect thereto, except a default:

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

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

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

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

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

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

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

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

                                       32
<PAGE>

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

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

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

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

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

                                   ARTICLE VII

                                   THE TRUSTEE

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

            (b) In case an Event of Default in respect of a Trust has occurred
and is continuing, the Trustee shall exercise such of the rights and powers
vested in it by this Agreement in respect of such Trust, and use the same degree
of care and skill in their exercise, as

                                       33
<PAGE>

a prudent person would exercise or use under the circumstances in the conduct of
his or her 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 (c) shall not be construed to limit the effect
      of Subsection (a) of this Section 7.01; and

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

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

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

            (b) The Trustee shall not be deemed to have knowledge of any Default
unless a Responsible Officer of the Trustee shall have received written notice
of such Default; provided, however, that the Trustee shall be deemed to have
notice of any failure to receive Scheduled Payments under this Agreement.

      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;

                                       34
<PAGE>

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

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

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

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

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

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

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

                  (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.

                                       35
<PAGE>

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

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

      Section 7.06. Money Held in Trust. Money held by the Trustee or the Paying
Agent in trust under this Agreement need not be segregated from other funds
except to the extent required in this Agreement 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 in this Agreement.

      Section 7.07. Compensation and Reimbursement. The Company agrees:

            (1) to pay, or cause to be paid, to the Trustee from time to time
      such reasonable compensation for all services rendered by it under this
      Agreement as the Company and the Trustee may agree in writing from time to
      time (which compensation shall not be limited by any provision of law in
      regard to the compensation of a trustee of an express trust); and

            (2) except as otherwise expressly provided herein or in any Trust
      Supplement, to reimburse, or cause to be reimbursed, the Trustee upon its
      request for all reasonable out-of-pocket expenses, disbursements and
      advances incurred or made by the Trustee in accordance with any provision
      of this Basic Agreement, any Trust Supplement, any Intercreditor Agreement
      or any Liquidity Facility to which the Trustee may be a party (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 the Trustee's 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 with
      respect to the Certificates of any series, pursuant to the particular
      sections of the Note Purchase Agreement specified in the related Trust
      Supplement.

                                       36
<PAGE>

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

      Section 7.08. Corporate Trustee Required; Eligibility. Each Trust shall at
all times have a Trustee which shall be a bank, trust company or other financial
institution organized and doing business under the laws of the United States or
any state thereof, 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
the District of Columbia and having a combined capital and surplus of at least
$75,000,000). If such bank, trust company or other financial institution or 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 bank, trust company or other financial
institution or such corporation shall be deemed to be its combined capital and
surplus as set forth in its most recent report of conditions so published.

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

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

            (b) The Trustee may resign at any time as Trustee of any or all
Trusts by giving prior written notice thereof to the Company, the Authorized
Agents, any related Owner Trustees and the related Loan Trustees. If an
instrument of acceptance by a successor Trustee shall not have been delivered to
the Company, any related Owner Trustees and the Trustee within 30 days after the
giving of such notice of resignation, the resigning Trustee may petition any
court of competent jurisdiction for the appointment of a successor Trustee.

            (c) The Trustee may be removed at any time as the Trustee of any
Trust by Direction of the Certificateholders of the related series holding
Certificates of such series evidencing Fractional Undivided Interests
aggregating not less than a majority in interest in such

                                       37
<PAGE>

Trust delivered to the Trustee and to the Company, any related Owner Trustees
and the related Loan Trustees.

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

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

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

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

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

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

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

                                       38
<PAGE>

such Trust appointed by the Company as provided above. If no successor Trustee
shall have been so appointed by the Company as provided above and accepted
appointment in the manner hereinafter provided, the resigning Trustee or any
Certificateholder who has been a bona fide Certificateholder of the related
series for at least six months may, on behalf of himself and all others
similarly situated, petition any court of competent jurisdiction for the
appointment of a successor Trustee of such Trust.

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

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

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

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

      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

                                       39
<PAGE>

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

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

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

            (c) Any corporation into which any Authorized Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, consolidation or conversion to which any Authorized Agent shall
be a party, or any corporation succeeding to the corporate trust business of any
Authorized Agent, shall be the successor of

                                       40
<PAGE>

such Authorized Agent, if such successor corporation is otherwise eligible under
this Section 7.12, without the execution or filing of any paper or any further
act on the part of the parties hereto or such Authorized Agent or such successor
corporation.

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

            (e) The Company agrees to pay, or cause to be paid, from time to
time to each Authorized Agent such compensation for its services as the Company
and the Trustee may agree in writing from time to time and to reimburse it for
its reasonable expenses to the extent set forth in Section 7.07(2).

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

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

      Section 7.14. Registration of Equipment Notes in Trustee's Name. Subject
to the provisions of any Intercreditor Agreement and Section 12.03 hereof, the
Trustee agrees that all Equipment Notes to be purchased by any Trust, Specified
Investments, if any, to be held by the Trustee on behalf of a Trust and
Permitted Investments, if any, to be held by the Trustee on behalf of a Trust
shall be issued in the name of the Trustee as trustee for the applicable Trust
or its nominee and held by the Trustee in trust for the benefit of the
Certificateholders of such series, or, if not so held, the Trustee or its
nominee shall be reflected as the owner of such Equipment Notes, Specified
Investments or Permitted Investments, as the case may be, in the

                                       41
<PAGE>

register of the issuer of such Equipment Notes, Specified Investments or
Permitted Investments, as the case may be. In no event shall the Trustee invest
in, or hold, Equipment Notes, Specified Investments or Permitted Investments in
a manner that would cause the Trustee not to have the ownership interest in (or
a securities entitlement with respect to) such Equipment Notes, Specified
Investments or Permitted Investments under the applicable provisions of the
Uniform Commercial Code in effect where the Trustee holds such Equipment Notes,
Specified Investments or Permitted Investments or other applicable law then in
effect.

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

                  (a) the Trustee is a national banking association duly
      organized and validly existing in good standing under the laws of the
      United States of America.

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

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

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

                  (e) this Agreement, any Intercreditor Agreement, any Liquidity
      Facility, the Certificates and the Note Purchase Agreements have been or
      will be duly executed and delivered by the Trustee and constitute or upon
      such execution and delivery

                                       42
<PAGE>

      will constitute the legal, valid and binding agreements of the Trustee,
      enforceable against it in accordance with their respective terms;
      provided, however, that enforceability may be limited by (i) applicable
      bankruptcy, insolvency, reorganization, moratorium or similar laws
      affecting the rights of creditors generally and (ii) general principles of
      equity; and

                  (f) the statements made by it in a Statement of Eligibility on
      Form T-1 supplied or to be supplied to the Company in connection with the
      registration of any Certificates are and will be true and accurate subject
      to the qualifications set forth therein; and that such statement complies
      and will comply in all material respects with the requirements of the
      Trust Indenture Act and the Securities Act.

      The representation and warranties set forth above shall be deemed to be
made by the Trustee on each Issuance Date, except as otherwise provided in the
applicable Trust Supplement.

      Section 7.16. Withholding Taxes; Information Reporting. As to the
Certificates of any series, the Trustee, as trustee of the related grantor trust
created by this Agreement, shall exclude and withhold from each distribution of
principal, premium, if any, and interest and other amounts due under this
Agreement or under the Certificates of such series any and all withholding taxes
applicable thereto as required by law. The Trustee agrees to act as such
withholding agent and, in connection therewith, whenever any present or future
taxes or similar charges are required to be withheld with respect to any amounts
payable in respect of the Certificates of such series, to withhold such amounts
and timely pay the same to the appropriate authority in the name of and on
behalf of the Certificateholders of such series, that it will file any necessary
withholding tax returns or statements when due, and that, as promptly as
possible after the payment thereof, it will deliver to each such
Certificateholder of such series appropriate documentation showing the payment
thereof, together with such additional documentary evidence as such
Certificateholders may reasonably request from time to time. The Trustee agrees
to file any other information reports as it may be required to file under United
States law.

      Section 7.17. Trustee's Liens. The Trustee in its individual capacity
agrees that it will, in respect of each Trust created by this Agreement, at its
own cost and expense (and without the right of indemnity hereunder, including
Section 7.07), promptly take any action as may be necessary to duly discharge
and satisfy in full any mortgage, pledge, lien, charge, encumbrance, security
interest or claim ("TRUSTEE'S LIENS") on or with respect to the Trust Property
of such Trust which is attributable to the Trustee either (i) in its individual
capacity and which is unrelated to the transactions contemplated by this
Agreement or the related Note Documents or (ii) as Trustee under this Agreement
or in its individual capacity and which arises out of acts or omissions which
are not contemplated by this Agreement.

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

                                       43
<PAGE>

                                  ARTICLE VIII

                CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE

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

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

      Section 8.03. Reports by Trustee. Within 60 days after May 15 of each year
commencing with the first full year following the issuance of any series of
Certificates, the Trustee shall transmit to the Certificateholders of such
series, as provided in Section 313(c) of the Trust Indenture Act, a brief report
dated as of such May 15, if required by and in compliance with Section 313(a) of
the Trust Indenture Act. The Trustee shall also transmit to Certificateholders
such reports, if any, as may be required pursuant to Section 313(b) of the Trust
Indenture Act at the times and in the manner provided pursuant thereto and to
Section 313(c) thereof.

      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;

                                       44
<PAGE>

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

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

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

                                   ARTICLE IX

                             SUPPLEMENTAL AGREEMENTS

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

            (1) to provide for the formation of a Trust, the issuance of a
      series of Certificates and other matters contemplated by Section 2.01(b)
      or to add, or to change or eliminate, any provision effecting a series of
      Certificates not yet issued, including to make appropriate provisions for
      a Parent Guarantee; or

            (2) to evidence the succession of another Person to the Company and
      the assumption by any such successor of the covenants of the Company
      herein contained or of the Company's obligations under any Intercreditor
      Agreement, any Note Purchase Agreement, or any Liquidity Facility or, if
      applicable, to evidence the succession of another Person to the Parent and
      the assumption by any such successor of the covenants of the Parent
      contained in this Agreement or of the Parent's obligations under any
      Parent Guarantee; or

            (3) to add to the covenants of the Company or the Parent for the
      benefit of the Certificateholders of any series, or to surrender any right
      or power conferred upon the

                                       45
<PAGE>

      Company or the Parent in this Agreement, any Note Purchase Agreement, any
      Intercreditor Agreement, any Liquidity Facility or any Parent Guarantee;
      or

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

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

            (6) to modify, eliminate or add to the provisions of this Agreement,
      any Intercreditor Agreement, any Note Purchase Agreement, any Liquidity
      Facility or Parent Guarantee to such extent as shall be necessary to
      continue or obtain the qualification of this Agreement, any Intercreditor
      Agreement, any Note Purchase Agreement, any Liquidity Facility or any
      Parent Guarantee under the Trust Indenture Act or under any similar
      Federal statute hereafter enacted, and to add to this Agreement, any
      Intercreditor Agreement, any Note Purchase Agreement, any Liquidity
      Facility or any Parent Guarantee 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 Basic Agreement was executed or any
      corresponding provision in any similar Federal statute hereafter enacted;
      or

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

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

            (9) to add to or change any of the provisions of the Certificate of
      any series or this Agreement to such extent as shall be necessary to
      facilitate the issuance of Certificates of such series in bearer form or
      to facilitate or provide for the issuance of

                                       46
<PAGE>

      Certificates of such series in global form in addition to or in place of
      Certificates in certificated form; or

            (10) to provide for the delivery of agreements supplemental to this
      Agreement or the Certificates of any series in or by any means of any
      computerized, electronic or other medium, including without limitation by
      computer diskette; or

            (11) to correct or supplement the description of any property
      constituting property of such Trust; or

            (12) to modify, eliminate or add to the provisions of this Basic
      Agreement, any Trust Supplement or any applicable Note Purchase Agreement
      in order to reflect the substitution of a Substitute Aircraft for any
      aircraft; or

            (13) to comply with any requirement of the SEC in connection with
      the qualification of this Agreement, any Parent Guarantee or any other
      agreement or instrument related to the Certificates of any series under
      the Trust Indenture Act; or

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

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

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

            (1) reduce in any manner the amount of, or delay the timing of, any
      receipt by the Trustee of payments on the Equipment Notes held in such
      Trust or distributions that are required to be made herein on any
      Certificate of such series, or change any date of payment on any
      Certificate of such series, or change the place of payment where, or the
      coin or currency in which, any Certificate of such series is payable
      (other than as provided for in such Certificate), or impair the right to
      institute suit for the enforcement

                                       47
<PAGE>

      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 of such Trust except as permitted by this Agreement, or
      otherwise deprive such Certificateholder of the benefit of the ownership
      of the Equipment Notes in such Trust; or

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

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

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

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

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

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

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

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

                                       48
<PAGE>

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

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

                                   ARTICLE X

                AMENDMENTS TO INDENTURES AND OTHER NOTE DOCUMENTS

      Section 10.01. Amendments and Supplements to Indentures and Other Note
Documents. In the event that the Trustee, as holder (or beneficial owner through
the Subordination Agent) of any Equipment Notes (or as a prospective purchaser
of any Postponed Notes) in trust for the benefit of the Certificateholders of
any series or as Controlling Party under an Intercreditor Agreement, receives
(directly or indirectly through the Subordination Agent) a request for a consent
to any amendment, modification, waiver or supplement under any Indenture, other
Note Document or any other related document, the Trustee shall forthwith send a
notice of such proposed amendment, modification, waiver or supplement to each
Certificateholder of such series registered on the Register as of the date of
such notice. The Trustee shall request from the Certificateholders of such
series a Direction as to (a) whether or not to take or refrain from taking (or
direct the Subordination Agent to take or refrain from taking) any action which
a holder of (or, with respect to Postponed Notes, a prospective purchaser of)
such Equipment Note has the option to direct, (b) whether or not to give or
execute (or direct the Subordination Agent to give or execute) any waivers,
consents, amendments, modifications or supplements as a holder of (or, with
respect to Postponed Notes, a prospective purchaser of) such Equipment Note or a
Controlling Party and (c) how to vote (or direct the Subordination Agent to
vote) any Equipment Note (or, with respect to a Postponed Note, its commitment
to acquire such Postponed Note) if a vote has been called for with respect
thereto. Provided such a request for Certificateholder Direction shall have been
made, in directing any action or casting any vote or giving any consent as the
holder of any Equipment Note (or in directing the Subordination Agent in any of
the foregoing), (i) other than as Controlling Party, the Trustee shall vote for
or give consent to any such action with respect to such Equipment Note (or
Postponed Note) in the same proportion as that of (A) the aggregate face amount
of all Certificates actually voted in favor of or for giving consent to such
action by such Direction of Certificateholders to (B) the aggregate face amount
of all Outstanding Certificates and (ii) as Controlling Party, the Trustee shall
vote as directed in such Certificateholder Direction by the Certificateholders
of such series evidencing a Fractional Undivided Interest aggregating not less
than a majority in interest in the Trust. For purposes of the immediately
preceding sentence, a Certificate shall have been "actually voted" if the Holder
of such Certificate has delivered to the Trustee an instrument evidencing such
Holder's consent to such Direction prior to one Business Day before the Trustee
directs such action or casts such vote or gives such consent. Notwithstanding
the foregoing, but subject to Section 6.04 and any Intercreditor Agreement, the
Trustee may, with respect to the Certificates of any series, in its

                                       49
<PAGE>

own discretion and at its own direction, consent and notify the relevant Loan
Trustee of such consent (or direct the Subordination Agent to consent and notify
the Loan Trustee of such consent) to any amendment, modification, waiver or
supplement under any related Indenture or any other related Note Document if an
Event of Default hereunder shall have occurred and be continuing or if such
amendment, modification, waiver or supplement will not materially adversely
affect the interests of the Certificateholders of such series.

                                   ARTICLE XI

                              TERMINATION OF TRUSTS

      Section 11.01. Termination of the Trusts. In respect of each Trust created
by the Basic Agreement as supplemented by a related Trust Supplement, the
respective obligations and responsibilities of the Company and the Trustee and,
if applicable, the Parent, with respect to such Trust shall terminate upon the
distribution to all Holders of Certificates of the series of such Trust and the
Trustee of all amounts required to be distributed to them pursuant to this
Agreement and the disposition of all property held as part of the Trust Property
of such Trust; provided, however, that in no event shall such Trust continue
beyond 21 years less one day following the death of the last survivor of all
descendants living on the date hereof of Joseph P. Kennedy, Sr., unless
applicable law shall permit a longer term, in which case such longer term shall
apply.

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

      In the event that all of the Certificateholders of such series shall not
surrender their Certificates for cancellation within six months after the date
specified in the above-mentioned written notice, the Trustee shall give a second
written notice to the remaining Certificateholders of such series to surrender
their Certificates for cancellation and receive the final distribution with
respect thereto. No additional interest shall accrue on the Certificates of such
series after any Regular Distribution Date (or Special Distribution Date, as the
case may be) of such series,

                                       50
<PAGE>

as specified in the first written notice. In the event that any money held by
the Trustee for the payment of distributions on the Certificates of such series
shall remain unclaimed for two years (or such lesser time as the Trustee shall
be satisfied, after 60 days' notice from the Company, is one month prior to the
escheat period provided under applicable law) after the final distribution date
with respect thereto, the Trustee shall pay to each Loan Trustee the appropriate
amount of money relating to such Loan Trustee and shall give written notice
thereof to any related Owner Trustees and the Company.

                                  ARTICLE XII

                            MISCELLANEOUS PROVISIONS

      Section 12.01. Limitation on Rights of Certificateholders. (a) The
insolvency, death or incapacity of any Certificateholder of any series shall not
operate to terminate this Agreement or the related Trust, nor entitle such
Certificateholder's legal representatives or heirs to claim an accounting or to
take any action or commence any proceeding in any court for a partition or
winding up of the Trust, nor otherwise affect the rights, obligations and
liabilities of the parties hereto or any of them. No Certificateholder of any
series shall be entitled to revoke the related Trust.

            (b) No transfer, by operation of law or otherwise, of any
Certificate or other right, title and interest of any Certificateholder in and
to the applicable Trust Property or under the related Trust shall operate to
terminate the Trust or entitle such Certificateholder or any successor or
transferee of such Certificateholder to an accounting or to the transfer to it
of legal title to any part of such Trust Property.

      Section 12.02. Certificates Nonassessable and Fully Paid. Except as set
forth in the last sentence of this Section 12.02, Certificateholders of each
series shall not be personally liable for obligations of the related Trust, the
Fractional Undivided Interests represented by the Certificates of such series
shall be nonassessable for any losses or expenses of such Trust or for any
reason whatsoever, and Certificates of such series upon authentication thereof
by the Trustee pursuant to Section 3.02 are and shall be deemed fully paid. No
Certificateholder of such series shall have any right (except as expressly
provided herein) to vote or in any manner otherwise control the operation and
management of the related Trust Property, the related Trust, or the obligations
of the parties hereto, nor shall anything set forth herein, or contained in the
terms of the Certificates of such series, be construed so as to constitute the
Certificateholders of such series from time to time as partners or members of an
association. Neither the existence of the Trust nor any provision in this
Agreement is intended to or shall limit the liability the Certificateholders
would otherwise incur if the Certificateholders owned Trust Property as
co-owners, or incurred any obligations of the Trust, directly rather than
through the Trust.

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

                                       51
<PAGE>

be reflected as the owner of such Equipment Notes in the register of the issuer
of such Equipment Notes.

      Section 12.04. Notices. (a) Unless otherwise specifically provided or
permitted herein or in the applicable Trust Supplement with respect to any
Trust, all notices required or permitted under the terms and provisions of this
Basic Agreement or such Trust Supplement with respect to such Trust shall be in
English and in writing, and any such notice may be given by United States mail,
courier service or facsimile, or any other customary means of communication, and
any such notice shall be effective when delivered or received or, if mailed,
three days after deposit in the United States mail with proper postage for
ordinary mail prepaid, and if delivered by facsimile, upon completion of
transmission and confirmation by the sender (by a telephone call to a
representative of the recipient or by machine confirmation) that the
transmission was received),

                      if to the Company:

                      US Airways, Inc.
                      111 West Rio Salado Parkway
                      Tempe, AZ 85281
                      Attention:  Treasurer
                      Telephone: (480) 693-3685
                      Fax: (480) 693-5886

                      with a copy to the attention of the Company's Office
                      of the General Counsel at the same address:

                      Attention: Aircraft Counsel
                      Fax: (480) 693-5932

                      if to the Trustee:

                      U.S. Bank Trust National Association
                      Corporate Trust Services
                      300 Delaware Ave., 9th Floor
                      Wilmington, DE 19801
                      Facsimile: (302) 576-3717

                      with a copy to:

                      U.S. Bank Trust National Association
                      One Federal Street, 3rd Floor
                      Boston, MA 02110
                      Attention: John Brennan
                      Telephone: (617) 603-6576
                      Facsimile: (617) 603-6668

                                       52
<PAGE>

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

            (c) Any notice or communication to Certificateholders of any series
shall be mailed by first-class mail to the addresses for Certificateholders of
such series shown on the Register kept by the Registrar and to addresses filed
with the Trustee for Certificate Owners of such series; provided, however, that
if The Depository Trust Company, or Cede & Co., as its nominee, is the sole
Certificateholder of record, such notices or communications need only be sent to
The Depository Trust Company and may be sent by any means permitted under
subsection (a) above. Failure so to mail a notice or communication or any defect
in such notice or communication shall not affect its sufficiency with respect to
other Certificateholders or Certificate Owners of such series.

            (d) If a notice or communication is mailed in the manner provided
above within the time prescribed, it is conclusively presumed to have been duly
given, whether or not the addressee receives it.

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

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

            (g) The Trustee shall promptly furnish the Company with a copy of
any report, demand, notice or written communication received by the Trustee
hereunder from, or sent or furnished by the Trustee hereunder to, any
Certificateholder, Owner Trustee, Loan Trustee, Liquidity Provider,
Subordination Agent or other Person.

      Section 12.05. Governing Law and Venue; Waiver of Jury Trial. (a) THIS
BASIC AGREEMENT, TOGETHER WITH ALL TRUST SUPPLEMENTS AND CERTIFICATES, SHALL BE
DEEMED TO BE MADE IN AND IN ALL RESPECTS SHALL BE INTERPRETED, CONSTRUED AND
GOVERNED BY AND IN ACCORDANCE WITH THE LAW OF THE STATE OF NEW YORK WITHOUT
REGARD TO THE CONFLICTS OF LAW PRINCIPLES THEREOF. The parties hereby
irrevocably submit to the jurisdiction of the courts of the State of New York
and the federal courts of the United States of America located in the State of
New York, solely in respect of the interpretation and enforcement of the
provisions of this Basic Agreement and of the documents referred to in this
Basic Agreement, and in respect of the transactions contemplated hereby, and
hereby waive, and agree not to assert, as a defense in any action, suit or
proceeding for the interpretation or enforcement hereof or of any such document,
that it is not subject thereto or that such action, suit or proceeding may not
be brought or is not maintainable in said courts or that the venue thereof may
not be appropriate or that this Basic Agreement or any such document may not be
enforced in or by such courts, and the parties hereto irrevocably agree that all
claims with respect to such action or proceeding shall be heard and determine in
such courts. The parties hereby consent to and grant any such court jurisdiction
over the person of such parties and consent to the jurisdiction of any such
court over the subject matter of such dispute and agree that mailing of process
or other papers in connection with any

                                       53
<PAGE>

such action or proceeding in the manner provided in Section 12.04 or in such
other manner as may be permitted by law shall be valid and sufficient service
thereof.

            (b) EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH
MAY ARISE UNDER THIS AGREEMENT IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT
ISSUES, AND THEREFORE EACH SUCH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY
WAIVES ANY RIGHT SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY
LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS BASIC
AGREEMENT, OR THE TRANSACTIONS CONTEMPLATED BY THIS BASIC AGREEMENT. EACH PARTY
CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY
OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD
NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER, (ii) EACH
PARTY UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (iii) EACH
PARTY MAKES THIS WAIVER VOLUNTARILY, AND (iv) EACH PARTY HAS BEEN INDUCED TO
ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION 12.05.

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

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

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

      Section 12.09. Successors and Assigns. All covenants, agreements,
representations and warranties in this Agreement by the Trustee and the Company
shall bind and, to the extent permitted hereby, shall inure to the benefit of
and be enforceable by their respective successors and assigns, whether so
expressed or not. Any request, notice, direction, consent, waiver or other
instrument or action by any Certificateholder shall bind the successors and
assigns of such Certificateholder.

      Section 12.10. Benefits of Agreement. Nothing in this Agreement or in the
Certificates of any series, express or implied, shall give to any Person, other
than the parties to this Agreement and their successors under this Agreement,
and the Certificateholders of each series,

                                       54
<PAGE>

any benefit or any legal or equitable right, remedy or claim under this
Agreement, except as provided expressly herein.

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

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

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

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

      Section 12.15. No Recourse Against Others. No past, present or future
director, officer, employee, agent, member, manager, trustee or stockholder, as
such, of the Company, the Parent or any successor Person or any Affiliate of any
thereof shall have any liability for any obligations of the Company, the Parent
or any successor Person or any Affiliate of any thereof, either directly or
through the Company, the Parent or any successor Person or any Affiliate of any
thereof, under the Certificates, this Agreement or any Parent Guarantee or for
any claim based on, in respect of or by reason of such obligations or their
creation, whether by virtue of any rule of law, statute or constitutional
provision or by the enforcement of any assessment or by any legal or equitable
proceeding or otherwise. By accepting a Certificate, each Certificateholder
agrees to the provisions of this Section 12.15 and waives and releases all such
liability. Such waiver and release shall be part of the consideration for the
issue of the Certificates.

                                       55
<PAGE>

      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.

                                US AIRWAYS, INC.

                                By: __________________________________
                                    Name:
                                    Title:

                                U.S. BANK TRUST NATIONAL ASSOCIATION,
                                as Trustee

                                By: _________________________________
                                    Name:
                                    Title:

                                       56
<PAGE>

                                                                       EXHIBIT A

                               FORM OF CERTIFICATE

      UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE
ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO
CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.*

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

                   US AIRWAYS ____________ PASS THROUGH TRUST

                   Pass Through Certificate, Series __________

                  Final Regular Distribution Date: _____, ____

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

Certificate
No._________

$__________ Fractional Undivided Interest representing ._____% of the Trust per
$1,000 face amount

      THIS CERTIFIES THAT __________________, for value received, is the
registered owner of a $___________ (________ dollars) Fractional Undivided
Interest in the US Airways Pass Through Trust, Series [___] (the "Trust")
created by U.S. Bank Trust National Association, as trustee (the "Trustee"),
pursuant to a Pass Through Trust Agreement dated as of __________ __, 20__ (the
"Basic Agreement"), between the Trustee and US Airways, Inc., a corporation
incorporated under Delaware law (the "Company"), as supplemented by Trust
Supplement No. _______ thereto dated __________, ____, between the Trustee and
the Company, (collectively, the "Agreement"), a summary of certain of the
pertinent provisions of which is set forth below. To the extent not otherwise
defined herein, the capitalized terms used herein have the meanings assigned to
them in the Agreement. This Certificate is one of the duly authorized
Certificates designated as "___% US Airways Pass Through Certificate, Series
____" (herein called the "Certificates"). This Certificate is issued under and
is subject to the terms, provisions and conditions of the Agreement. By virtue
of its acceptance hereof, the Certificateholder of this Certificate assents to
and agrees to be bound by the provisions of the Agreement and any related

                                      A-1
<PAGE>

Intercreditor Agreement. The property of the Trust includes certain Equipment
Notes and all rights of the Trust to receive any payments under any
Intercreditor Agreement or Liquidity Facility (the "Trust Property"). Each issue
of the Equipment Notes is or will be secured by, among other things, a security
interest in aircraft leased to or owned by the Company.

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

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

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

      The Certificates do not represent a direct obligation of, or an obligation
guaranteed by, or an interest in, the Company or the Trustee or any affiliate
thereof. The Certificates are limited in right of payment, all as more
specifically set forth on the face hereof and in the Agreement. All payments or
distributions made to Certificateholders under the Agreement shall be made only
from the Trust Property and only to the extent that the Trustee shall have
sufficient income or proceeds from the Trust Property to make such payments in
accordance with the terms of the Agreement. Each Certificateholder of this
Certificate, by its acceptance hereof, agrees that it will look solely to the
income and proceeds from the Trust Property to the extent available for

                                      A-2
<PAGE>

distribution to such Certificateholder as provided in the Agreement. This
Certificate does not purport to summarize the Agreement and reference is made to
the Agreement for information with respect to the interests, rights, benefits,
obligations, proceeds, and duties evidenced hereby. A copy of the Agreement may
be examined during normal business hours at the principal office of the Trustee,
and at such other places, if any, designated by the Trustee, by any
Certificateholder upon request.

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

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

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

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

      The Trustee, the Registrar, and any agent of the Trustee or the Registrar
may treat the person in whose name this Certificate is registered as the owner
hereof for all purposes, and neither the Trustee, the Registrar, nor any such
agent shall be affected by any notice to the contrary.

      The obligations and responsibilities created by the Agreement and the
Trust created thereby shall terminate upon the distribution to
Certificateholders of all amounts required to be

                                      A-3
<PAGE>

distributed to them pursuant to the Agreement and the disposition of all
property held as part of the Trust Property.

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

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

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

                               US AIRWAYS PASS THROUGH TRUST
                               By:  U.S. BANK TRUST NATIONAL ASSOCIATION,
                               as Trustee

                               By: _____________________________________
                               Title: __________________________________

Dated: _________________

                                      A-4
<PAGE>

              [FORM OF THE TRUSTEE'S CERTIFICATE OF AUTHENTICATION]

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

                               U.S. BANK TRUST NATIONAL ASSOCIATION,
                               as Trustee

                               By: ___________________________
                                   Authorized Officer

                                      A-5exv10w1

 

Exhibit 10.1

FIRST AMENDMENT TO 

STOCK PURCHASE AGREEMENT

     FIRST AMENDMENT TO STOCK PURCHASE AGREEMENT dated as of September 28, 2006 by and between
Zila, Inc, a Delaware corporation (“Seller”) and NBTY, Inc., a Delaware corporation (“Buyer”).

WITNESSETH:

     WHEREAS, the above parties have entered into a Stock Purchase Agreement dated as of August 13,
2006 (“Stock Purchase Agreement”); and

     WHEREAS, the Stock Purchase Agreement provides in Section 7.10 that it may be amended by the
written agreement of the Buyer and Seller; and

     WHEREAS, the undersigned parties wish to amend the Stock Purchase Agreement in the manner set
forth below;

     NOW, THEREFORE, the undersigned parties agree as follows:

     1. The last sentence of paragraph 25 (c)(ii) of Exhibit B is hereby amended by deleting it in
its entirety and replacing it with the following:

“The Seller will take all necessary steps and bear all related costs to affect a transfer,
assignment and/or sublicense of the Patent Licenses to the Company.”.

     2. Paragraph 25 of Exhibit B is hereby further amended by adding a new subsection to
subsection (a) as follows:

“(vii) all domain names owned or controlled by the Company (the “Domain Names”).”.

     3. Paragraph 25 of Exhibit B is hereby further amended by adding a new subsection as follows:

“(h) Domain Names.

     The Disclosure Letter contains a complete and accurate list of all Domain Names.”.

     4. All references to the Stock Purchase Agreement in the Stock Purchase Agreement or in any
documents delivered in connection therewith, shall be deemed to mean the Stock Purchase Agreement
as amended hereby.

     5. Except as modified by this First Amendment, the Stock Purchase Agreement shall remain in
full force and effect.

 

 

     IN WITNESS WHEREOF, the undersigned have executed this First Amendment on the date first
written above by their duly authorized officers.

	 	 	 	 	 
	 	ZILA, INC.

 	 
	 	By:  	                       /s/ Gary V. Klinefelter
 	 
	 	 	Its:       Vice President 	 
	 	 	 	 
	 
	 	NBTY, INC.

 	 
	 	By:  	                        /s/ Michael C. Slade
 	 
	 	 	Its:       Senior Vice President

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