<PAGE>

                                                                     Exhibit 4.6

                         PASS THROUGH TRUST AGREEMENT

                          dated as of August 22, 2001

                                    between

                            UNITED AIR LINES, INC.,

                                      and

                      STATE STREET BANK AND TRUST COMPANY
                     OF CONNECTICUT, NATIONAL ASSOCIATION
                                  as Trustee



<PAGE>

                               TABLE OF CONTENTS

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

     Section 1.01     Definitions..................................................................   2

     Section 1.02     Compliance Certificates and Opinions.........................................  12

     Section 1.03     Form of Documents Delivered to Trustee.......................................  13

     Section 1.04     Directions of Certificateholders.............................................  13

ARTICLE II     ORIGINAL ISSUANCE OF CERTIFICATES; ACQUISITION OF NOTES.............................  14

     Section 2.01     Amount Unlimited; Issuable in Classes........................................  14

     Section 2.02     Issuance of Certificates; Acquisition of Notes...............................  16

     Section 2.03     Acceptance by Trustee........................................................  18

     Section 2.04     Limitation of Powers.........................................................  19

ARTICLE III    THE CERTIFICATES....................................................................  19

     Section 3.01     Form, Denomination and Execution of Certificates.............................  19

     Section 3.02     Restrictive Legends..........................................................  20

     Section 3.03     Authentication of Certificates...............................................  20

     Section 3.04     Transfer and Exchange........................................................  21

     Section 3.05     Global, Book-Entry and Definitive Certificates...............................  21

     Section 3.06     [Intentionally Omitted.].....................................................  23

     Section 3.07     Mutilated, Destroyed, Lost or Stolen Certificates............................  23

     Section 3.08     Persons Deemed Owners........................................................  24

     Section 3.09     Cancellation.................................................................  24

     Section 3.10     Temporary Certificates.......................................................  24

     Section 3.11     Limitation of Liability for Payments.........................................  24

ARTICLE IV     DISTRIBUTIONS; STATEMENTS TO CERTIFICATEHOLDERS.....................................  25

     Section 4.01     Certificate Account and Special Payments Account.............................  25

     Section 4.02     Distributions from Certificate Account and Special Payments Account..........  25

     Section 4.03     Statements to Certificateholders.............................................  27

     Section 4.04     Investment of Special Payment Moneys.........................................  27

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

     Section 5.01     Maintenance of Corporate Existence...........................................  28
</TABLE>

                                       i
<PAGE>

                               TABLE OF CONTENTS
                                 (continued)

<TABLE>
<S>                                                                                                 <C>
     Section 5.02     Consolidation, Merger, etc...................................................  28

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

     Section 6.01     Events of Default............................................................  29

     Section 6.02     Judicial Proceedings Instituted by Trustee; Trustee May Bring Suit...........  32

     Section 6.03     Control by Certificateholders................................................  32

     Section 6.04     Waiver of Past Defaults......................................................  33

     Section 6.05     Right of Certificateholders to Receive Payments Not to Be Impaired...........  33

     Section 6.06     Certificateholders May Not Bring Suit Except Under Certain Conditions........  33

     Section 6.07     Remedies Cumulative..........................................................  34

ARTICLE VII    THE TRUSTEE.........................................................................  34

     Section 7.01     Certain Duties and Responsibilities..........................................  34

     Section 7.02     Notice of Defaults...........................................................  35

     Section 7.03     Certain Rights of Trustee....................................................  35

     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..........................................................  37

     Section 7.07     Compensation and Reimbursement...............................................  37

     Section 7.08     Corporate Trustee Required; Eligibility......................................  37

     Section 7.09     Resignation and Removal; Appointment of Successor............................  38

     Section 7.10     Acceptance of Appointment by Successor.......................................  39

     Section 7.11     Merger, Conversion, Consolidation or Succession to Business..................  40

     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 Notes in Name of Subordination Agent.........................  42

     Section 7.15     Representations and Warranties of Trustee....................................  42

     Section 7.16     Withholding Taxes; Information Reporting.....................................  43

     Section 7.17     Tax Returns and Reports......................................................  44

     Section 7.18     Trustee's Liens..............................................................  44
</TABLE>


ii
<PAGE>

                              TABLE OF CONTENTS
                                 (continued)

<TABLE>
<S>                                                                                                 <C>
     Section 7.19     Preferential Collection of Claims............................................  44

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...........................................................  45

     Section 8.04     Reports by the Company.......................................................  45

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..........................................  48

     Section 9.07     Reference in Certificates to Supplemental Agreements.........................  48

ARTICLE X      AMENDMENTS TO INDENTURES AND NOTE DOCUMENTS.........................................  48

     Section 10.01    Amendments and Supplements to Indentures and Other Note Documents............  48

ARTICLE XI     TERMINATION OF TRUSTS...............................................................  49


     Section 11.01    Termination of the Trusts....................................................  49

ARTICLE XII    MISCELLANEOUS PROVISIONS............................................................  50

     Section 12.01    Limitation on Rights of Certificateholders...................................  50

     Section 12.02    Certificates Nonassessable and Fully Paid....................................  50

     Section 12.03    Notices......................................................................  51

     Section 12.04    Governing Law................................................................  52

     Section 12.05    Severability of Provisions...................................................  52

     Section 12.06    Trust Indenture Act Controls.................................................  52

     Section 12.07    Effect of Headings and Table of Contents.....................................  52

     Section 12.08    Successors and Assigns.......................................................  52

     Section 12.09    Benefits of Agreement........................................................  52
</TABLE>

                                      iii
<PAGE>

                              TABLE OF CONTENTS
                                 (continued)

<TABLE>
<S>                                                                                                 <C>
     Section 12.10    Legal Holidays...............................................................  53

     Section 12.11    Counterparts.................................................................  53

     Section 12.12    Intention of Parties.........................................................  53

     Section 12.13    Communication by Certificateholders with other Certificateholders............  53
</TABLE>

Schedule I     Indentures

                                      iv
<PAGE>

Reconciliation and tie between United Air Lines Pass Through Trust Agreement,
dated as of August  22, 2001, and the Trust Indenture Act of 1939.  This
reconciliation does not constitute part of the Pass Through Trust Agreement.

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

                    (a)(2)                          7.08

                    312(a)                    3.05; 8.01; 8.02

                    313(a)                          8.03

                    314(a)                      8.04(a) - (c)

                    (a)(4)                         8.04(d)

                    (c)(1)                          1.02

                    (c)(2)                          1.02

                    (d)(1)                       7.13; 11.01

                    (d)(2)                       7.13; 11.01

                    (d)(3)                          2.01

                      (e)                           1.02

                    315(b)                          7.02

             316(a)(last sentence)                 1.04(c)

                   (a)(1)(A)                        6.03

                   (a)(1)(B)                        6.04

                      (b)                           6.05

                      (c)                          1.04(d)

                   317(a)(1)                        6.02

                      (b)                           7.13

                    318(a)                          12.06
</TABLE>

                                      ii
<PAGE>

                         PASS THROUGH TRUST AGREEMENT

     This PASS THROUGH TRUST AGREEMENT, dated as of August 22, 2001, between
UNITED AIR LINES, INC., a Delaware corporation, and STATE STREET BANK AND TRUST
COMPANY OF CONNECTICUT, NATIONAL ASSOCIATION, a national banking association, as
Trustee, is made with respect to the formation from time to time of separate
United Air Lines Pass Through Trusts and the issuance from time to time of
separate classes of Certificates representing fractional undivided interests in
the respective Trusts.

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

     WHEREAS, all Certificates to be issued in respect of each separate Trust
shall be issued and designated as Class A-1, Class A-2, Class A-3, Class B,
Class C or Class D pursuant to this Agreement, shall evidence fractional
undivided interests in the Trusts of the same class and shall have no rights,
benefits or interests in respect of any separate Trust of any other class or the
property held therein, subject, however, to the provisions of the Intercreditor
Agreement.

     WHEREAS, from time to time, pursuant to the terms and conditions of this
Agreement with respect to each separate Trust formed hereunder, the Trustee on
behalf of such Trust shall purchase one or more issues of Notes having, in each
case, the same interest rate as the class of Certificates issued in respect of
such Trust and, subject to the terms of the Intercreditor Agreement, shall hold
such Notes in trust for the benefit of the Certificateholders of such Trust;

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

     WHEREAS, this Basic Agreement, as amended or supplemented from time to
time, is subject to the provisions of the Trust Indenture Act of 1939, as
amended, and shall, to the extent applicable, be governed by such provisions;

     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:
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


                                   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:

          (a)  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;

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

          (c)  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;

          (d)  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; and

          (e)  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".

     Additional Payments:  Means a payment of Make-Whole Amount, if any.
     -------------------

     Affiliate:  With respect to any specified Person, means 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 to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise,
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

     Agreement:  Means, unless the context otherwise requires, this Basic
     ---------
Agreement as supplemented by the Trust Supplement creating a particular Trust
and establishing the class of Certificates issued or to be issued in respect
thereof, with reference to such Trust and each class of Certificates, as this
Basic Agreement as so supplemented may be further supplemented with respect to
such Trust and such class of Certificates.

     Aircraft:  Means each of the ten (10) Airbus A319-131 aircraft, six (6)
     --------
Airbus A320-232 aircraft, five (5) Boeing 747-422 aircraft, five (5) Boeing 767-
322ER aircraft and four (4) Boeing 777-222ER aircraft bearing aircraft
registration numbers N831UA, N833UA, N834UA, N835UA, N836UA, N837UA, N838UA,
N839UA, N840UA, N841UA, N467UA, N468UA, N469UA, N470UA, N471UA, N472UA, N117UA,
N118UA, N122UA, N127UA, N128UA, N664UA, N667UA, N669UA, N670UA, N671UA, N794UA,
N795UA, N204UA, N205UA, respectively, owned by United Air Lines, Inc.

                                       2
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

     Authorized Agent:  With respect to the Certificates of any class, means any
     ----------------
Paying Agent or Registrar for the Certificates of such class.

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

     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 Global Certificates of
     -----------------------
any class, a beneficial interest in the Global Certificates of such class,
ownership and transfers of which shall be made through book entries as described
in Section 3.05.

     Business Day:  With respect to the Certificates of any class, means any day
     ------------
(x) other than a Saturday or Sunday or a day on which commercial banks are
required or authorized to close in Chicago, Illinois or New York, New York, or,
so long as any such Certificate is outstanding, a city and state in which the
Trustee or any related Indenture Trustee maintains its Corporate Trust Office or
receives and disburses funds and (y) on which dealings are carried on in the
London interbank market.

     Certificate:  Means any one of the certificates executed and authenticated
     -----------
by the Trustee, substantially in the form of an exhibit attached to the
applicable Trust Supplement pursuant to which such Certificate was issued.

     Certificate Account:  With respect to the Certificates of any class, means
     -------------------
the account or accounts created and maintained for such class pursuant to
Section 4.01(a).
---------------

     Certificateholder or Holder:  With respect to the Certificates of any
     ---------------------------
class, means the Person in whose name a Certificate of such class is registered
in the Register for Certificates of such class.

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

     Class A-1 Certificates:  Means Certificates designated as "Class A-1
     ----------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

     Class A-2 Certificates:  Means Certificates designated as "Class A-2
     ----------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

     Class A-3 Certificates:  Means Certificates designated as "Class A-3
     ----------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

     Class B Certificates:  Means Certificates designated as "Class B
     --------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

                                       3
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

     Class C Certificates:  Means Certificates designated as "Class C
     --------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

     Class D Certificates:  Means Certificates designated as "Class D
     --------------------
Certificates" in the Trust Supplement pursuant to which such Certificates are
issued.

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

     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 United Air Lines, 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.

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

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

     Cut-off Date:  With respect to the Certificates of a Trust of any class,
     ------------
means the date designated as such in the related Trust Supplement.

     Default:  Means an event that is, or after notice or lapse of time or both
     -------
would become, an Event of Default or a Triggering Event.

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

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

     Distribution:  Has the meaning specified in Section 7.16.
     ------------                                ------------

     Distribution Date:  With respect to the Certificates of any class, means
     -----------------
any Regular Distribution Date or Special Distribution Date.

     Eligible Account:  Means an account established by and with an Eligible
     ----------------
Institution at the request of the Trustee, which institution agrees, for all
purposes of the applicable Uniform Commercial Code ("U.C."), including Article 8
thereof, that (a) such account shall be a "securities account" (as defined in
Section 8-501 of the Uniform Commercial Code in effect in the State of New
York), (b) all property credited to such account shall be treated as a
"financial asset" (as defined in Section 8-102(a)(9) of the Uniform Commercial
Code in effect in the State of New York), (c) the Trustee shall be the
"entitlement holder" (as defined in

                                       4
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

Section 8-102(a)(7) of the Uniform Commercial Code in effect in the State of New
York) in respect of such account, (d) such Eligible Institution shall comply
with all entitlement orders issued by the Trustee to the exclusion of any other
Person and (e) the "securities intermediary jurisdiction" (under Section 8-
110(e) of the U.C.) shall be the State of Illinois.

     Eligible Institution:  Means the corporate trust department of (a)  State
     --------------------
Street Bank and Trust Company of Connecticut, National Association, acting
solely in its capacity as a "securities intermediary" (as defined in Section 8-
102(a)(14) of the Uniform Commercial Code in effect in the State of New York, or
(b) a depositary institution organized under the laws of the United States of
America or any one of the states thereof or the District of Columbia (or any
U.S. branch of a foreign bank), which has a long-term unsecured debt rating from
Moody's and S&P, of at least "A-3" or its equivalent.

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

     Escrow Account:  With respect to the Certificates of any class, has the
     --------------
meaning specified in Section 2.02(b).
                     ---------------

     Escrowed Funds:  With respect to the Trusts of any class, has the meaning
     --------------
specified in Section 2.02(b).
             ---------------

     Event of Default:  Means an Indenture Default under any Indenture pursuant
     ----------------
to which Notes were issued.

     Exchange Act:  Means the United States Securities Exchange Act of 1934, as
     ------------
amended from time to time, or any successor thereto.

     Financing Documents:  Means with respect to a Note, the related
     -------------------
Participation Agreement and Indenture.

     Fractional Cumulative Interest:  Means, with respect to any outstanding
     ------------------------------
Certificate of a class, the principal amount of such Certificate divided by the
aggregate principal amount of all Certificates of such class issued pursuant to
all Trust Supplements creating Trusts of such class.

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

     Global Certificates:  Means, with respect to Certificates of any class,
     -------------------
certificates representing the Book-Entry Certificates of such class delivered to
and held by a Clearing Agency or its nominee.

     Indenture:  Means, with respect to the Notes, each of the one or more
     ---------
separate trust indentures and mortgages described on Schedule 1 attached to this
Agreement, as each such indenture may be amended or supplemented in accordance
with its respective terms; and Indentures means all of such agreements.
                               ----------

                                       5
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

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

     Initial Regular Distribution Date:  With respect to the Certificates of any
     ---------------------------------
class, means the first Regular Distribution Date on which a Scheduled Payment is
to be made.

     Intercreditor Agreement:  Means the Intercreditor Agreement, dated as of
     -----------------------
the date hereof, between State Street Bank and Trust Company of Connecticut,
National Association, as Trustee, Westdeutsche Landesbank Girozentrale, acting
through its New York Branch, as Liquidity Provider, and State Street Bank and
Trust Company of Connecticut, National Association, as Subordination Agent
thereunder, as amended, supplemented or otherwise modified from time to time in
accordance with its terms.

     Issuance Date:  With respect to the Certificates of a Trust of any class,
     -------------
means the date of the original issuance of such Certificates.

     Letter of Representations:  Means, with respect to the  Certificates of any
     -------------------------
class, an agreement between 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:  Has the meaning specified in the Intercreditor
     ------------------
Agreement.

     Liquidity Provider:  Has the meaning specified in the Intercreditor
     ------------------
Agreement.

     Make-Whole Amount:  Has the meaning specified therefor in the applicable
     -----------------
Indenture or Indentures.

     Moody's:  Means Moody's Investors Service, Inc.
     -------

     Note Documents:  With respect to the Certificates of any class, the Notes
     --------------
related to such Certificates and, with respect to such Notes, the related
Financing Documents.

     Note Purchase Agreement:  Means the Note Purchase Agreement, relating to
     -----------------------
the Notes in respect of the Aircraft, dated as of August 22, 2001, between the
Company, the Subordination Agent, the Indenture Trustee and the Trustee.

     Notes:  Means the notes, certificates or instruments issued pursuant to the
     ------
Indentures in respect of the Aircraft, collectively, and in each case, any Notes
issued in exchange therefor or replacement thereof pursuant to the terms of such
Indentures.

     Officer's Certificate:  Means a certificate signed, (a) in the case of the
     ---------------------
Company, by the Chairman of the Board of Directors, the President, any Vice
President, the Secretary or

                                       6
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

the Treasurer, or (b) in the case of an Owner Trustee or an Indenture Trustee, a
Responsible Officer of such Owner Trustee, such Indenture 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) an attorney of the Company, (ii)
Vedder, Price, Kaufman & Kammholz, or (iii) such other counsel designated by the
Company and reasonably acceptable to the Trustee and (b) in the case of counsel
for any Indenture Trustee may be such counsel as may be designated by it whether
or not such counsel is an employee of such Indenture Trustee, and who shall be
reasonably acceptable to the Trustee.

     Outstanding:  With respect to Certificates of any class, means, as of the
     -----------
date of determination, all Certificates of such class theretofore authenticated
and delivered under this Agreement, except:

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

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

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

     Participation Agreement:  With respect to any Aircraft, means the
     -----------------------
Participation Agreement referred to in the related Indenture.

     Paying Agent:  With respect to the Certificates of any class, means the
     ------------
paying agent maintained and appointed for the Certificates of such class
pursuant to Section 7.12.
            ------------

     Permitted Investments:  Means any United States dollar denominated
     ---------------------
investment that, at the time it is delivered to the Trustee, is:

          (a)  any U.S. money market fund with a credit rating of not less than
"Aaa" or "AAAm" by Moody's and S&P, respectively; or

          (b)  one or more of the following obligations or securities: (i)
obligations of the United States or agencies or instrumentalities of the United
States the payment of which is backed by the full faith and credit of the United
States; (ii) demand and time deposits in, certificates of deposit of, or
bankers' acceptances issued by, any depository institution or trust company
incorporated under the laws of the United States of America or any state thereof
and subject to supervision and examination by federal and/or state banking
authorities so long as the commercial paper and/or the debt obligations of such
depository institution or trust company (or, in the case of the principal
depository institution in a holding company system, the commercial paper or debt
obligations of such holding company) at the time of such investment or
contractual

                                       7
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

commitment providing for such investment have a credit rating of "Aaa" and
"AAA", in the case of long-term debt obligations, or "P-1" and "A-1+", in the
case of commercial paper and short-term debt obligations, by Moody's and S&P,
respectively and that, in the case of banker's acceptances, have a maturity of
not more than 183 days from their date of issuances; provided that in the case
                                                     --------
of commercial paper and short-term debt obligations with a maturity of longer
than 91 days, the issuer thereof must also have at the time of such investment a
long-term credit rating of "Aaa" and "AAA" by Moody's and S&P, respectively;
(iii) unleveraged repurchase obligations having a maturity of not more than 183
days from their date of issuance with respect to (a) any security described in
clause (i) above or (b) any other security issued or guaranteed by an agency or
instrumentality of the United States of America, in either case entered into
with a depository institution or trust company (acting as principal) described
in clause (ii) above or entered into with a corporation (acting as principal)
whose long-term rating is "Aaa" and "AAA", or whose short-term credit rating is
"P-1" and "A-1+" by Moody's and S&P, respectively at the time of such
investment; provided that if such repurchase obligation has a maturity of longer
            --------
than 91 days, the obligor thereunder must also have at the time of such
investment a long-term credit rating of "Aaa" and "AAA" by Moody's and S&P,
respectively; provided, further, that the value of the securities transferred by
              --------  -------
the obligor under any such repurchase agreement must equal or exceed the
proceeds received by the obligor; (iv) registered debt securities bearing
interest or sold at a discount issued by any corporation incorporated under the
laws of the United States of America or any state thereof that have a credit
rating of "Aaa" and "AAA" or "P-1" and "A-1+" by Moody's and S&P, respectively,
at the time of such investment or contractual commitment providing for such
investment; (v) commercial paper or other shorter-term debt obligations of a
corporation, partnership, limited liability company or trust, or any branch or
agency thereof, organized, incorporated or otherwise located in the United
States or any of its territories, such commercial paper or other short-term
obligations having at the time of such investment a credit rating of "P-1" and
"A-1+" by Moody's and S&P, respectively, and that are in any case either are
interest bearing or are sold at a discount from the face amount thereof and have
a maturity of not more than 183 days from their date of issuance; provided that
                                                                  --------
if such debt security has a maturity of longer than 91 days, the issuer thereof
must also have at the time of such investment a long-term credit rating of "Aaa"
and "AAA" by Moody's and S&P, respectively; and (vi) a reinvestment agreement
issued by any bank (if treated as a deposit by such bank), or a registered
reinvestment agreement issued by any insurance company or other corporation or
entity, in each case that has a credit rating of not less than "P-1" and "A-1+"
by Moody's and S&P, respectively; provided, that if such security has a maturity
of longer than 91 days, the issuer thereof must also have at the time of such
investment a long-term credit rating of not less than "Aaa" and "AAA" by Moody's
and S&P, respectively;

and, with respect to the Permitted Investments listed in subparagraph (b) above:
mature (giving effect to any applicable grace period) in not more than such time
as is required for the distribution of any funds on a Regular Distribution Date
or Special Distribution Date, as applicable; provided, however, that Permitted
                                             --------  -------
Investments listed in subparagraph (b) shall not include any interest-only
security, any security purchased at a price in excess of 100% of par, any
security that is subject to withholding or similar taxes or any security whose
repayment is subject to substantial non-credit related risk as reasonably
determined by the applicable trustee; and provided, further, that the maturity
                                          --------  -------
of an investment listed in subparagraph (b) shall be the date on which the
holder of such a security may put the security to the issuer thereof for
redemption if each put is either to the issuer of such security or to another
entity rated at least

                                       8
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

"P-1" and "A-1+" by Moody's and S&P, respectively. Permitted Investments may
include, without limitation, those investments for which the Trustee or an
Affiliate of the Trustee provides services, and the Trustee is hereby authorized
in making or disposing of any Permitted Investments to deal with itself (in its
individual capacity) or with any one or more of its Affiliates, whether it or
such Affiliates are acting as an agent of the Trustee or for any other Person or
dealing as principal for its own account.

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

     Pool Balance:  With respect to the Certificates issued pursuant to the
     ------------
Trusts of the same class, means, as of any date, (i) the original aggregate face
amount of the Certificates of such class less (ii) the aggregate amount of all
payments made in respect of such Certificates of such class other than payments
made in respect of interest or Additional Payments thereon or reimbursement of
any costs or expenses incurred in connection therewith.  The Pool Balance as of
any Distribution Date, with respect to the Certificates of such Trusts, shall be
computed after giving effect to the payment of principal, if any, on the Notes
or other Trust Property held in such Trusts and the distribution thereof to be
made on such Distribution Date.  The Pool Balance with respect to the
Certificates of such Trusts shall be recomputed at any time there is an early
redemption or default in the payment of principal, if any, or interest on the
Notes held in such Trusts.

     Pool Factor:  With respect to the Certificates issued pursuant to the
     -----------
Trusts of the same class, means, as of any date, the quotient (rounded to the
seventh decimal place) computed by dividing (i) the Pool Balance of such class
as at such date by (ii) the original aggregate face amount of the Certificates
of such Trusts.  The Pool Factor as of any Distribution Date, with respect to
such Trusts, shall be computed after giving effect to the payment of principal,
if any, on the Notes or other Trust Property held in such Trusts and the
distribution thereof to be made on such Distribution Date.  The Pool Factor with
respect to the Certificates of such Trusts shall be recomputed at any time there
is an early redemption or default in the payment of principal, if any, or
interest on the Notes held in such Trusts.

     Postponed Notes:  Means the Notes to be held in the 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 class
     -------------------
of Certificates, an Officer's Certificate of the Company (1) requesting that the
Trustee temporarily postpone the purchase of the related Notes to a date which
is later than the Issuance Date of such class of Certificates, (2) identifying
the amount of the purchase price of each such Note and the aggregate purchase
price for all such Notes, (3) setting forth the reasons for such postponement
and (4) with respect to each such 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 Note,
or (b) indicating that such new Transfer Date (which shall be on or prior to the
applicable Cut-off Date) shall be set by subsequent written notice not less than
one Business Day prior to such new Transfer Date.

                                       9
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

     Register and Registrar:  With respect to the Certificates of any class,
     ----------------------
means the register maintained and the registrar appointed for such class
pursuant to Sections 3.04 and 7.12.
            -------------     ----

     Regular Distribution Date:  With respect to distributions of Scheduled
     -------------------------
Payments in respect of any class of Certificates, means each date designated as
a Regular Distribution Date in this Agreement; provided, however, that, if any
                                               --------  -------
such day shall not be a Business Day, the related distribution shall be made on
the next Business Day together without additional interest.

     Responsible Officer:  With respect to any Trustee and any Indenture Trustee
     -------------------
means any officer in the Corporate Trust Department of the Trustee or Indenture
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.

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

     S&P:  Means Standard & Poor's Ratings Services, a Division of The McGraw-
     ---
Hill Companies, Inc.

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

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

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

     Special Distribution Date:  With respect to the Certificates of any class,
     -------------------------
means each date on which a Special Payment is to be distributed as specified in
this Agreement; provided,
                --------

                                      10
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

however, that, if any such day shall not be a Business Day, the related
-------
distribution shall be made on the next Business Day together without additional
interest.

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

     Special Payments Account:  With respect to the Certificates of any class,
     ------------------------
means the account or accounts created and maintained for such class pursuant to
Section 4.01(b).
---------------

     Specified Investments:  With respect to any Trust, means, unless otherwise
     ---------------------
specified in the related Trust Supplement, each of (i) obligations of, or
guaranteed by, the United States Government or agencies thereof, (ii) open
market commercial paper of any corporation incorporated under the laws of the
United States of America or any State thereof rated at least P-1 or its
equivalent by Moody's or at least A-1 or its equivalent by 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 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) 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) as collateral; and,
                                    -----------         ----
provided further, that if all of the above investments are unavailable, the
-------- -------
entire amount to be invested may be used to purchase federal funds from an
entity described in clause (iii) above.  All Specified Investments held by the
                    ------------
Trustee pursuant to Section 2.02(b) shall either be (a) registered in the name
                    ---------------
of, payable to the order of, or specially endorsed to the Trustee, or (b) held
in an Eligible Account.

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

     Transfer Date:  Has the meaning assigned to the term Closing Date in the
     -------------
Note Purchase Agreement or, alternatively, means the date specified in a
Postponement Notice on which the Postponed Notes specified therein will be
purchased by the applicable Trust.

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

     Trust:  With respect to the Certificates of any class, means any trust of
     -----
such class under this Agreement.

     Trust Indenture Act:  Except as otherwise provided in Section 9.06, means
     -------------------                                   ------------
the United States Trust Indenture Act of 1939 as in force at the date as of
which this Basic Agreement was executed.

                                      11
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

     Trust Property:  With respect to any Trust, means (i) the 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) funds from time to time deposited in the
related Escrow Account, the related Certificate Account and the related Special
Payments Account, (iii) all rights of such Trust and the Trustee, on behalf of
such Trust, under the Intercreditor Agreement and the Note Purchase Agreement,
including all rights to receive certain payments thereunder and all monies paid
to such Trustee on behalf of such Trust pursuant to the Intercreditor Agreement
or the Note Purchase Agreement and (iv) for the Trusts relating to the Class A-1
Certificates, the Class A-2 Certificates, the Class A-3 Certificates, the Class
B Certificates and the Class C Certificates, all monies receivable by the
Subordination Agent under the Liquidity Facilities for such Trusts.

     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 class, (ii) the issuance of the Certificates of such class
representing fractional undivided interests in such Trust is authorized and
(iii) the terms of the Certificates of such class are established.

     Trustee:  Means State Street Bank and Trust Company of Connecticut,
     -------
National Association, or its successor-in-interest, and any successor or other
trustee appointed as provided in the Agreements; provided, however, that if the
                                                 --------  -------
same institution is not acting as Trustee in respect of all classes of
Certificates, the phrase "the Trustee" shall, unless the context otherwise
requires, mean, as to any Class of Certificates, the institution acting as the
Trustee in respect of such class.

     Trustee's Lien:  Has the meaning specified in Section 7.18.
     --------------                                ------------

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

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

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

                                      12
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

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

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

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

     Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Basic Agreement or, in respect of the Certificates of any
class, 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 class 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 otherwise expressly provided herein, such action shall become
effective when such instrument or instruments are delivered to the Trustee and,
where it is hereby expressly required pursuant to this Agreement, to the Company
or any Indenture Trustee. Proof of execution of any such instrument or of a
writing appointing any such agent or proxy shall be sufficient for any purpose
of this Agreement and conclusive in favor of the Trustee, the Company and any
Indenture 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.

                                      13
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

          (d)  The Company may at its option, by delivery of an Officer's
Certificate to the Trustee, set a record date to determine the
Certificateholders in respect of the Certificates of any class 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 class 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 class 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 class have authorized or agreed
or consented to such Direction, and for that purpose the Outstanding
Certificates of such class shall be computed as of such record date. 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
Basic Agreement not later than one year after such record date.

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

          (f)  Except as otherwise provided in Section 1.04(c), Certificates of
                                               ---------------
any class 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
class.

                                  ARTICLE II

                      ORIGINAL ISSUANCE OF CERTIFICATES;
                             ACQUISITION OF NOTES

     Section 2.01  Amount Unlimited; Issuable in Classes.  (a)  The aggregate
                   -------------------------------------
principal amount of Certificates which may be authenticated and delivered under
this Basic Agreement is unlimited.  The Certificates may be issued from time to
time in one or more classes 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 class as specified in the related Trust
Supplement.  Each Certificate shall bear upon its face the designation so
selected for the class to

                                      14
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

which it belongs. All Certificates of the same class shall be substantially
identical except that the Certificates of a class may differ as to denomination
and as may otherwise be provided in the Trust Supplement establishing the
Certificates of such class. Each class of Certificates issued pursuant to this
Agreement shall evidence fractional undivided interests in the related Trust and
Fractional Cumulative Interests in all Trusts of such class and shall have no
rights, benefits or interests in respect of any Trust of any other class or the
Trust Property held therein. All Certificates of the same class 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 class issued hereunder by a Trust Supplement executed and
delivered by and between the Company and the Trustee:

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

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

               (iii)  any limit upon the aggregate principal amount of the
     Certificates of such class which may be authenticated and delivered (which
     limit shall not pertain to Certificates authenticated and delivered upon
     registration of transfer of, or in exchange for, or in lieu of, other
     Certificates of the class pursuant to Sections 3.04, 3.07 and 3.10);
                                           -------------  ----     ----
               (iv)   the Cut-off Date with respect to the Certificates of such
     class;

               (v)    the Regular Distribution Dates applicable to the
     Certificates of such class;

               (vi)   the Special Distribution Dates applicable to the
     Certificates of such class and the related Trust;

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

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

               (ix)   the specific form of the Certificates of such class
     (including the interest rate applicable thereto) and whether or not
     Certificates of such class are to be issued as Global Certificates and, if
     such Certificates are to be Global Certificates, the form of Letter of
     Representations (or, in the case of any Certificates denominated or

                                      15
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

     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 represented by such Global Certificates may
     exchange such Global Certificates for Definitive Certificates of such class
     and of like tenor of any authorized form and denomination);

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

               (xi)   provisions with respect to the terms for which the
     definitions set forth in Article I permit or require further specification
                              ---------
     in the related Trust Supplement;

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

               (xiii) 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;

               (xiv)  whether such class will have the benefit of Liquidity
     Facilities and, if so, any terms appropriate thereto; and

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

          (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 class, Certificates of such class
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 of any conditions precedent set forth in such Trust Supplement.

     Section 2.02  Issuance of Certificates; Acquisition of Notes.  (a)  Unless
                   ----------------------------------------------
otherwise specified in the related Trust Supplement, the Trustee is hereby
directed to execute and deliver the Intercreditor Agreement and the Note
Purchase Agreement on or prior to the Issuance Date of the Certificates of a
class, each in the form delivered to the Trustee by the Company, and is hereby
directed to and shall, subject to the respective terms thereof, perform its
obligations thereunder.  Upon request of the Company and the satisfaction of the
closing conditions specified in the Note Purchase Agreement, the Trustee shall
execute, deliver and authenticate such Certificates equaling in the aggregate
the aggregate principal amount of the Notes to be purchased by the Trustee
pursuant to the Note Purchase Agreement on the Transfer Date, and evidencing the
entire ownership interest in the related Trust.  The Trustee shall issue and
sell such Certificates, in authorized denominations and in such Fractional
Undivided Interests, so as to result in the receipt by the Trustee of
consideration in an amount equal to the aggregate principal amount of such Notes
and, concurrently therewith, the Trustee shall purchase, pursuant to the terms
and conditions of the Note Purchase Agreement, the Notes to be purchased
thereunder at a purchase price equal to the amount of such consideration so
received.  Except as provided in Sections 3.04 and 3.07, the Trustee shall not
                                 -------------     ----
execute, authenticate or deliver

                                      16
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

Certificates of any class in excess of the aggregate amount specified in this
Section 2.02(a).  The provisions of this Section 2.02(a) are subject to the
---------------                          ---------------
provision of Section 2.02(b) below.
              ---------------

          (b)  On or prior to the Issuance Date with respect to a class of
Certificates, the Company may deliver to the Trustee a Postponement Notice
relating to one or more Postponed Notes, which Postponement Notice may be given
by the Company only if one or more conditions to the purchase of such Postponed
Notes by the Trustee shall not have been satisfied or waived pursuant to the
Note Purchase Agreement. The Trustee shall postpone the purchase of the
Postponed Notes from the consideration received from the sale of such
Certificates and shall promptly deposit funds in an amount equal to the purchase
price of such Postponed Notes (the "Escrowed Funds") into an escrow account (the
"Escrow Account") with the Trustee to be maintained as a part of the related
Trust. The Escrowed Funds so deposited shall be invested by the Trustee at the
direction and risk of, and for the benefit of, the Company in Specified
Investments (i) maturing no later than any scheduled Transfer Date relating to
the Postponed Notes or (ii) if no such Transfer Date has been scheduled,
maturing on the next Business Day, or (iii) if the Company has given notice to
the Trustee that any Postponed Notes shall not be issued or be available for
purchase, with respect to the portion of the Escrowed Funds relating to such
Postponed Notes, 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 Note Purchase Agreement on or prior
to the Cut-off Date, the Trustee shall purchase the applicable Postponed Notes
with the Escrowed Funds withdrawn from the Escrow Account. The purchase price
shall equal the principal amount of such Postponed Notes.

          The Trustee shall hold all Specified Investments until the maturity
thereof and shall 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 direction and risk of, and for the benefit of, the Company in Specified
Investments maturing as provided in the preceding paragraph.

          On the Initial Regular Distribution Date in respect of the
Certificates of any class, the Company shall pay (in immediately available
funds) to the Trustee an amount equal to (i) the sum of (A) the interest that
would have accrued on any Postponed Notes purchased on or prior to the Initial
Regular Distribution Date if such Postponed Notes had been purchased on the
Issuance Date, from and including the Issuance Date to but excluding the date of
such purchase and (B) the interest that would have accrued on any Postponed
Notes not purchased on or prior to the Initial Regular Distribution Date (other
than any Postponed Notes for which a Special Distribution Date specified in the
next paragraph has occurred on or prior to the Initial Regular Distribution
Date) if such Postponed Notes had been purchased on the Issuance Date, from and
including the Issuance Date to but excluding the Initial Regular Distribution
Date, minus (ii) the earnings on Specified Investments received by the Trustee
from and including the later of the Issuance Date or the date preceding the
Initial Regular Distribution Date on which an amount has been paid pursuant to
the next paragraph to but excluding the Initial Regular Distribution Date. On
the second Regular Distribution Date, the Company shall pay (in immediately
available funds) to the Trustee an amount equal to (i) the interest that would
have accrued on any

                                      17
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

Postponed Notes purchased after the Initial Regular Distribution Date and on or
prior to the Cut-off Date if such Postponed Notes had been purchased on the
Initial Regular Distribution Date, from and including the Initial Regular
Distribution Date to but excluding the date of such purchase, minus (ii) the
earnings on Specified Investments received by the Trustee from and including the
later of the Initial Regular Distribution Date or the date preceding the second
Regular Distribution Date on which an amount has been paid pursuant to either of
the next two paragraphs to but excluding the second Regular Distribution Date.
The Company shall pay to the Trustee for deposit to the relevant Escrow Account
an amount equal to any losses on such Specified Investments as incurred.

     If, in respect of the Certificates of any class, the Company notifies the
Trustee prior to the Cut-off Date that any Postponed Notes shall not be issued
or be available for purchase on or prior to the Cut-off Date for any reason, on
the next Special Distribution Date for such Certificates occurring more than 20
days following the date of such notice (i) the Company shall pay to the Trustee
for deposit in the related Special Payments Account, in immediately available
funds, an amount equal to the interest that would have accrued on the Postponed
Notes designated in such notice at a rate equal to the interest rate applicable
to such Certificates from and including the Issuance Date (if such Special
Distribution Date shall occur on or prior to the Initial Regular Distribution
Date) or the Initial Regular Distribution Date (if such Special Distribution
Date occurs after the Initial Regular Distribution Date) to but excluding such
Special Distribution Date and (ii) the Trustee shall transfer an amount equal to
that amount of Escrowed Funds that would have been used to purchase the
Postponed Notes designated in such notice plus the amount paid by the Company
pursuant to the preceding clause (i) to the related Special Payments Account for
                          ----------
distribution as a Special Payment in accordance with the provisions hereof.

     If, on the Cut-off Date, an amount equal to less than all of the Escrowed
Funds (other than Escrowed Funds referred to in the preceding paragraph) has
been used to purchase Postponed Notes, on the next Special Distribution Date
occurring more than 20 days following the Cut-off Date (i) the Company shall pay
to the Trustee for deposit in the Special Payments Account, in immediately
available funds, an amount equal to the interest that would have accrued on the
Postponed Notes originally contemplated to be purchased with such unused
Escrowed Funds (other than Escrowed Funds referred to in the preceding
paragraph) but not so purchased at a rate equal to the interest rate applicable
to the Certificates from and including the Initial Regular Distribution Date to
but excluding such Special Distribution Date and (ii) the Trustee shall transfer
such unused Escrowed Funds and the amount paid by the Company pursuant to the
preceding clause (i) to such Special Payments Account for distribution as a
          ----------
Special Payment in accordance with the provisions hereof.

     Section 2.03  Acceptance by Trustee.  The Trustee, upon the execution and
                   ---------------------
delivery of a Trust Supplement creating a Trust and issuing a class of
Certificates, acknowledges its acceptance of all right, title and interest in
and to the Notes acquired pursuant to Section 2.02 and the Note Purchase
                                      ------------
Agreement and declares that the Trustee holds and shall hold such right, title
and interest, together with all other property constituting the Trust Property
of such Trust, for the benefit of all then present and future Certificateholders
of such class, upon the trusts herein and in such Trust Supplement set forth.
Subject to Section 7.14, the Trustee shall take all actions reasonably necessary
           ------------
to effect the registration of all such Notes in the name of the Subordination

                                      18
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

Agent.  By its payment for and acceptance of each Certificate of such class
issued to it under this Agreement, each initial Certificateholder of such class
as grantor of such Trust thereby joins in the creation and declaration of such
Trust and grants to the Trustee the powers conferred by this Agreement.

     Section 2.04  Limitation of Powers. Each Trust is constituted solely for
                   --------------------
the purpose of making the investment in the Notes provided for in the related
Trust Supplement, and, except as set forth herein or 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
respective related Indentures) by bidding such 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.  Each
                   ------------------------------------------------
Certificate shall represent a fractional undivided interest in a Trust.  The
Class A-1 Certificates, the Class A-2 Certificates, the Class A-3 Certificates,
the Class B Certificates, the Class C Certificates and the Class D Certificates,
shall be issued in fully registered form without coupons and shall be
substantially in the forms attached as exhibits to the related Trust
Supplements, in each case with such appropriate insertions, omissions,
substitutions and other variations as are required or 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 the rules of any securities exchange or as may, consistently herewith, be
determined by the officers executing such Certificates, as evidenced by their
execution of the Certificates.  Any portion of the text of any Certificate may
be set forth on the reverse thereof, with an appropriate reference thereto on
the face of the Certificate.

     Except as provided in Section 3.05, the definitive Certificates 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.

     Each Certificate shall be dated the date of its authentication.  Except as
otherwise provided in the related Trust Supplement, the Certificates of each
class shall be issued in minimum denominations of $1,000 or integral multiples
thereof, except that one Certificate of such class may be issued in a different
denomination.  The Certificates of such class shall be executed on behalf of the
Trustee by manual or facsimile signature of a Responsible Officer of the
Trustee. Certificates of any class 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.

                                      19
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

     Section 3.02  Restrictive Legends.  Each Global Certificate shall bear the
                   -------------------
following legend on the face thereof:

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

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

     Section 3.03  Authentication of Certificates.  (a)  The Trustee shall duly
                   ------------------------------
execute, authenticate and deliver Certificates of each class in authorized
denominations equaling in the aggregate the aggregate principal amount of the
Notes to be purchased by the Trustee pursuant to the Note Purchase Agreement and
evidencing the entire ownership of the related Trust.  Thereafter, the Trustee
shall duly execute, authenticate and deliver the Certificates of a class as
herein provided.

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

     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 class of Certificates in
------------
which, subject to such reasonable regulations as it

                                      20
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

may prescribe, the Trustee shall provide for the registration of Certificates of
such class 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 Certificates of each class and transfers and exchanges of
such Certificates as herein provided. A Certificateholder may transfer a
Certificate by written application to the Registrar stating the name of the
proposed transferee and otherwise complying with the terms of this Agreement,
including providing a written certificate or other evidence of compliance with
any restrictions on transfer. No such transfer shall be effected until, and such
transferee shall succeed to the rights of a Certificateholder only upon, final
acceptance and registration of the transfer by the Registrar in the Register.
Prior to the registration of any transfer by a Certificateholder as provided
herein, the Trustee shall treat the person in whose name the Certificate is
registered as the owner thereof for all purposes, and the Trustee shall not be
affected by notice to the contrary. Furthermore, the Clearing Agency shall, by
acceptance of a Global Certificate, agree that transfers of Book-Entry
Certificates therein may be effected only through a book-entry system maintained
by the Clearing Agency (or its agent), and that ownership of Book-Entry
Certificates shall be required to be reflected in a book entry. When
Certificates of a class are presented to the Registrar with a request to
register the transfer or to exchange them for an equal aggregate Fractional
Undivided Interest of Certificates of like class of other authorized
denominations, the Registrar shall register the transfer or make the exchange as
requested if its requirements for such transactions are met. To permit
registrations of transfers and exchanges in accordance with the terms,
conditions and restrictions hereof, the Trustee shall execute and authenticate
Certificates at the Registrar's request. No service charge shall be made for any
registration of transfer or exchange of the Certificates, but the Trustee may
require payment by the transferor of a sum sufficient to cover any transfer tax
or similar governmental charge payable in connection therewith (other than any
such transfer taxes or other similar governmental charges payable upon exchanges
pursuant to Section 3.10 or 9.07).
            ------------    ----

     Section 3.05  Global, Book-Entry and Definitive Certificates. (a) Except
                   ----------------------------------------------
for one Certificate of each class that may be issued in a denomination of other
than an even multiple of $1,000, except as provided in the following sentence,
the Certificates of any class may be issued at the option of the Company in the
form of one or more typewritten Global Certificates representing the Book-Entry
Certificates of such class, to be delivered to The Depository Trust Company, the
initial Clearing Agency, by the Trustee on behalf of the related Trust. In the
case of the issuance of Global Certificates, such Global Certificates 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 class, except as
provided in Subsection (d) below. As to Global Certificates, 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 Global Certificates);

                                      21
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

               (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 in respect of the Book-Entry Certificates among the
     Clearing Agency Participants and receive and transmit distributions of
     principal, interest and premium, if any, on the Global Certificates to such
     Clearing Agency Participants;

               (v)   Global Certificates may be transferred in whole, but not in
     part, and in the manner provided in Section 3.04, by the Clearing Agency
                                         ------------
     holding such Global 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 a
     particular class holding Certificates of such class evidencing a specified
     percentage of the Fractional Undivided Interests in the related Trust, the
     Clearing Agency shall be deemed to represent such percentage only to the
     extent that it has received instructions to such effect from Clearing
     Agency Participants owning or representing, respectively, such required
     percentage of the Book-Entry Certificates of such class and has delivered
     such instructions to the Trustee. Neither the Company nor the Trustee 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 class is required under this Agreement, unless and until Definitive
     Certificates shall have been issued pursuant to Subsection (d) below, the
     Trustee shall give all such notices and communications specified herein to
     be given to Certificateholders of such class to the Clearing Agency.

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

          (d)  If with respect to the Global Certificates of any class (i) the
     Company advises the Trustee in writing that the Clearing Agency that holds
     such Global Certificates 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 class evidencing
     Fractional Undivided Interests aggregating not less than a majority in
     interest in

                                      22
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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 class, then the Trustee shall notify
all Certificate Owners of such class, 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 Global Certificates of such class 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 class, the Trustee shall issue and deliver
the Definitive Certificates of such class in accordance with the instructions of
the Clearing Agency. Neither the Company, the Registrar, the Paying Agent nor
the Trustee shall be liable for any delay in delivery of such instructions and
may conclusively rely on, and shall be protected in relying on, such
registration instructions. Upon the issuance of Definitive Certificates of such
class, the Trustee shall recognize the Persons in whose names the Definitive
Certificates are registered in the Register as Certificateholders hereunder.
Neither the Company nor the Trustee shall be liable if the Trustee or the
Company is unable to locate a qualified successor Clearing Agency.

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

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

     Section 3.06   [Intentionally Omitted.]
                     ---------------------

     Section 3.07   Mutilated, Destroyed, Lost or Stolen Certificates. If (a)
any mutilated Certificate is surrendered to the Registrar or the Registrar
receives evidence to its satisfaction of the destruction, loss or theft of any
Certificate and (b) there is delivered to the Registrar and the Trustee such
security, indemnity or bond, as may be required by them to save each of them
harmless, then, in the absence of notice to the Registrar or the Trustee that
such destroyed, lost or stolen Certificate has been acquired by a bona fide
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 class, in authorized denominations and of like Fractional
Undivided Interest and bearing a number not contemporaneously outstanding. In
connection with the issuance of any new Certificate under this Section 3.07, the
                                                               ------------
Trustee may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto and any other
expenses (including the fees and expenses of the Trustee and the Registrar)
connected therewith.  Any duplicate Certificate issued pursuant to this Section
                                                                        -------
3.07 shall constitute conclusive evidence of the appropriate Fractional
----
Undivided Interest in the related Trust, as if originally issued, whether or not
the lost, stolen or destroyed Certificate shall be found at any time.

                                      23
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     The provisions of this Section 3.07 are exclusive and shall preclude (to
                            ------------
the extent lawful) all other rights and remedies with respect to the replacement
or payment of mutilated, destroyed, lost or stolen Certificates.

     Section 3.08   Persons Deemed Owners. Prior to due presentment of a
                    ---------------------
Certificate for registration of transfer, the Trustee, the Registrar and any
Paying Agent may treat the Person in whose name any Certificate is registered
(as of the day of determination) as the owner of such Certificate for the
purpose of receiving distributions pursuant to Article IV and for all other
                                               ----------
purposes whatsoever, and none of the Trustee, the Registrar or any Paying Agent
shall be affected by any notice to the contrary.

     Section 3.09   Cancellation.  All Certificates surrendered for payment or
                    ------------
transfer or exchange shall, if surrendered to the Trustee or any agent of the
Trustee other than the Registrar, be delivered to the Registrar for cancellation
and shall promptly be canceled by it.  No Certificates shall be authenticated in
lieu of or in exchange for any Certificates canceled as provided in this Section
                                                                         -------
3.09, except as expressly permitted by this Agreement.  All canceled
----
Certificates held by the Registrar shall be destroyed and a certification of
their destruction delivered to the Trustee.

     SECTION 3.10   Temporary Certificates. Until definitive Certificates of any
                    ----------------------
class are ready for delivery, the Trustee shall execute, authenticate and
deliver temporary Certificates of such class.  Temporary Certificates of each
class shall be substantially in the form of definitive Certificates of such
class but may have insertions, substitutions, omissions and other variations
determined to be appropriate by the officers executing the temporary
Certificates of such class, as evidenced by their execution of such temporary
Certificates.  If temporary Certificates of any class are issued, the Trustee
shall cause definitive Certificates of like class to be prepared without
unreasonable delay.  After the preparation of definitive Certificates of such
class, the temporary Certificates shall be exchangeable for definitive
Certificates upon surrender of such temporary Certificates at the Corporate
Trust Office 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 class, in authorized denominations and of a like Fractional
Undivided Interest.  Until so exchanged, the temporary Certificates shall be
entitled to the same benefits under this Agreement as definitive Certificates.

     Section 3.11   Limitation of Liability for Payments.  All payments and
                    ------------------------------------
distributions made to Certificateholders of any class in respect of the
Certificates of such class shall be made only from the Trust Property of the
Trusts of the same class 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.  Each Certificateholder, by its
                             ----------
acceptance of a Certificate, agrees that it shall look solely to the income and
proceeds from the Trust Property of the Trusts of the same class for any payment
or distribution due to such Certificateholder pursuant to the terms of this
Agreement and that it shall not have any recourse to the Company, the Trustee,
the Indenture Trustees or the Liquidity Providers, except as otherwise expressly
provided herein or in the Intercreditor Agreement.

                                      24
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

                                  ARTICLE IV

                         DISTRIBUTIONS; STATEMENTS TO
                              CERTIFICATEHOLDERS

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

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

     Section 4.02   Distributions from Certificate Account and Special Payments
                    -----------------------------------------------------------
Account.  (a)  On each Regular Distribution Date with respect to a class 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 Notes held in
the related Trusts 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 class on the Record Date with respect to such Regular
Distribution Date (other than as provided in Section 11.01 concerning the final
                                             -------------
distribution) by check mailed to such Certificateholder, at the address
appearing in the Register, such Certificateholder's pro rata share (based on the
Fractional Cumulative Interest in the Trusts of such class 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 the nominee of the Clearing Agency (initially, such nominee to be Cede &
Co.), such distribution shall be made by wire transfer in immediately available
funds to the account designated by such nominee.

                                      25
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


               (b)  On each Special Distribution Date with respect to any
Special Payment with respect to a class of Certificates or as soon thereafter as
the Trustee has confirmed receipt of the Special Payments due on the Notes held
in the related Trusts or realized upon the sale of such Notes, the Trustee shall
distribute out of the applicable Special Payments Account the entire amount of
such Special Payment deposited therein pursuant to Section 4.01(b). There shall
                                                   ---------------
be so distributed to each Certificateholder of record of such class on the
Record Date with respect to such Special Distribution Date (other than as
provided in Section 11.01 concerning the final distribution) by check mailed to
            -------------
such Certificateholder, at the address appearing in the Register, such
Certificateholder's pro rata share (based on the Fractional Cumulative Interest
in the Trusts of such class 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 the nominee of the Clearing Agency (initially, such nominee to be Cede &
Co.), such distribution shall be made by wire transfer in immediately available
funds to the account designated by such nominee.

               (c)  The Trustee shall, at the expense of the Company, cause
notice of each Special Payment with respect to a class of Certificates to be
mailed to each Certificateholder of such class at his address as it appears in
the Register. In the event of redemption or purchase of Notes held in the
related Trust, such notice shall be mailed not less than 20 days prior to the
Special Distribution Date for the Special Payment resulting from such redemption
or purchase, which Special Distribution Date shall be the date of such
redemption or purchase. In the case of any other Special Payments, such notice
shall be mailed as soon as practicable after the Trustee has confirmed that it
has received funds for such Special Payment, stating the Special Distribution
Date for such Special Payment which shall occur not less than 20 days after the
date of such notice and as soon as practicable thereafter. Notices mailed by the
Trustee shall set forth:

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

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

                    (iii) the reason for the Special Payment, if any; and

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

If the Additional Payments, if any, payable upon the redemption or purchase of a
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 Additional Payments received shall
also be distributed.

                                      26
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

     Section 4.03   Statements to Certificateholders. (a) On each Distribution
                    --------------------------------
Date with respect to a class of Certificates, the Trustee shall include with
each distribution to Certificateholders of the related class of a Scheduled
Payment or Special Payment, as the case may be, a statement setting forth the
following information (per $1,000 face amount Certificate as to (i) and (ii)
                                                                ---     ----
below):

                    (i)   the amount of such distribution allocable to principal
     and the amount allocable to Additional Payments;

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

                    (iii) the Pool Balance and the Pool Factor of the Trusts of
     such class.

     With respect to the Certificates registered in the name of Cede & Co., as
nominee for the Clearing Agency on the Record Date prior to each Distribution
Date, the Trustee shall 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 Trustee shall
mail to each such Clearing Agency Participant the statement described above and
shall make available additional copies as requested by such Clearing Agency
Participant for forwarding to holders of interests in the Certificates.

               (b)  Within a reasonable period of time after the end of each
calendar year but not later than the latest date permitted by law, the Trustee
shall furnish to each Person who at any time during such calendar year was a
Certificateholder of record a report containing the sum of the amounts
determined pursuant to clauses (a)(i) and (a)(ii) above with respect to the
                       --------------     -------
related Trusts for such calendar year or, if such Person was a Certificateholder
of record during a portion of such calendar year, for such portion of such year,
and such other items as are readily available to the Trustee and which a
Certificateholder shall reasonably request as necessary for the purpose of such
Certificateholder's preparation of its United States federal income tax returns.
The Trustee shall prepare such report and such other items on the basis of
information supplied to the Trustee by the Clearing Agency Participants and
shall deliver such report and such other items to such Clearing Agency
Participants to be available for forwarding by such Clearing Agency Participants
to the holders of interests in the Certificates in the manner described in
Section 4.03(a). If the Trustee issues any Certificates in the form of
---------------
Definitive Certificates pursuant to Section 3.05(d), the Trustee will prepare
                                    ---------------
and deliver such report and such other items to the Person in whose name the
Definitive Certificates are registered in the Register as Certificateholders
hereunder.

     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 to be promptly distributed shall, to the extent practicable, be invested or
reinvested in Permitted Investments by the Trustee pending distribution of such
Special Payment pursuant to Section 4.02(b). Any
                            ---------------

                                      27
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

                                   ARTICLE V

                                  THE COMPANY

     Section 5.01   Maintenance of Corporate Existence. The Company, at its own
cost and expense, shall 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 necessary or desirable in the conduct of the business of the Company.

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

               (a)  the corporation formed by such consolidation or into which
the Company is merged or the Person that acquires by conveyance, transfer or
lease substantially all of the assets of the Company as an entirety shall be
validly existing under the laws of the United States, any state of the United
States or the District of Columbia.

               (b)  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
a "citizen of the United States" as defined in 49 U.S.C. 40102(a)(15), as
amended, and (ii) hold an air carrier operating certificate issued by the
Secretary of Transportation pursuant to Chapter 447 of Title 49 of the United
States Code, as amended, 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. Section 1110);

               (c)  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 class
a duly authorized, valid, binding and enforceable agreement in form and
substance reasonably satisfactory to the Trustee containing an assumption by
such successor corporation or Person of the due and punctual performance and
observance of each covenant and condition of this Agreement, the Note Purchase
Agreement and any Financing Document to be performed or observed by the Company;

                                      28
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

               (e)  after giving effect to such consolidation or merger, no
Indenture Event of Default shall have occurred and be continuing.

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

                                  ARTICLE VI

                                    DEFAULT

     Section 6.01   Events of Default. (a) Exercise of Remedies. In respect of
                    -----------------      --------------------
the Trusts of any class, upon the occurrence and during the continuation of any
Indenture Default under any related Indenture, the Trustee may, to the extent it
is the Controlling Party at such time (as determined pursuant to the
Intercreditor Agreement), direct the exercise of remedies as provided in the
Intercreditor Agreement.

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

                    (i)  if, as of any date of determination hereof, the then
     Controlling Party is the Trustee for any of the Class A-1 Certificates, the
     Class A-2 Certificates and the Class A-3 Certificates (such Class of
     Certificates, the "Controlling Class" and each of the other two such
     Classes of Certificates, a "Non-Controlling Class"), (x) each
     Certificateholder of the Noncontrolling Class with the then larger amount
     of outstanding Pool Balance shall have the right to purchase all, but not
     less than all, of the Certificates of the Controlling Class and (y) each
     Certificateholder of the Noncontrolling Class with the then smaller amount
     of outstanding Pool Balance shall have the right to purchase all, but not
     less than all, of the Certificates of both the Controlling Class and the
     other Noncontrolling Class (in the case of each of clauses (x) and (y),
     such Noncontrolling Class of such purchasing Certificateholder, the
     "Purchasing Class"), in each case upon

                                      29
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

               (ii)  each Class B Certificateholder shall have the right (which
     shall not expire upon any purchase of the Class A-1 Certificates, the Class
     A-2 Certificates or the Class A-3 Certificates pursuant to clause (i)
     above) to purchase all, but not less than all, of the Class A-1
     Certificates, the Class A-2 Certificates and the Class A-3 Certificates
     upon ten days' written notice to the Trustees for the Class A-1
     Certificates, the Class A-2 Certificates, the Class A-3 Certificates and
     each other Class B Certificateholder, provided that (A) if prior to the end
     of such ten-day period any other Class B Certificateholder notifies such
     purchasing Class B Certificateholder that such other Class B
     Certificateholder wants to participate in such purchase, then such other
     Class B Certificateholder may join with the purchasing Class B
     Certificateholder to purchase all, but not less than all, of the Class A-1
     Certificates, the Class A-2 Certificates and the Class A-3 Certificates pro
     rata based on the Fractional Cumulative Interest held by each such Class B
     Certificateholder and (B) if prior to the end of such ten-day period any
     other Class B Certificateholder fails to notify the purchasing Class B
     Certificateholder of such other Class B Certificateholder's desire to
     participate in such a purchase, then such other Class B Certificateholder
     shall lose its right to purchase the Class A-1 Certificates, the Class A-2
     Certificates and the Class A-3 Certificates pursuant to this Section
                                                                  -------
     6.01(b);
     -------

               (iii) each Class C Certificateholder shall have the right (which
     shall not expire upon any purchase of the Class A-1 Certificates, the Class
     A-2 Certificates, the Class A-3 Certificates or the Class B Certificates
     pursuant to clause (i) or (ii) above) to purchase all, but not less than
     all, of the outstanding Class A-1 Certificates, the Class A-2 Certificates,
     the Class A-3 Certificates and the Class B Certificates upon ten days'
     written notice to the Trustees for the Class A-1 Certificates, the Class A-
     2 Certificates, the Class A-3 Certificates and the Class B Certificates and
     each other Class C Certificateholder, provided that (A) if prior to the end
     of such ten-day period any other Class C Certificateholder notifies such
     purchasing Class C Certificateholder that such other Class C
     Certificateholder wants to participate in such purchase, then such other
     Class C Certificateholder may join with the purchasing Class C
     Certificateholder to purchase all, but not less than all, of the Class A-1
     Certificates, the Class A-2 Certificates, the Class A-3 Certificates and
     the Class B Certificates pro rata based on the Fractional Cumulative
     Interest held by each such Class C Certificateholder and (B) if prior to
     the end of such ten-day period any other Class C Certificateholder fails to
     notify the purchasing Class C

                                      30
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

     Certificateholder of such other Class C Certificateholder's desire to
     participate in such a purchase, then such other Class C Certificateholder
     shall lose its right to purchase such Class A-1 Certificates, Class A-2
     Certificates, Class A-3 Certificates and Class B Certificates pursuant to
     this Section 6.01(b); and
          ---------------

               (iv) each Class D Certificateholder shall have the right (which
     shall not expire upon any purchase of the Class A-1 Certificates, the Class
     A-2 Certificates, the Class A-3 Certificates, the Class B Certificates or
     the Class C Certificates pursuant to clause (i), (ii) or (iii) above) to
     purchase all, but not less than all, of the Class A-1 Certificates, the
     Class A-2 Certificates, the Class A-3 Certificates, the Class B
     Certificates and the Class C Certificates upon ten days' prior written
     notice to the Trustees, for the Class A-1 Certificates, the Class A-2
     Certificates, the Class A-3 Certificates, the Class B Certificates, the
     Class C Certificates and each other Class D Certificateholder, provided
     that (A) if prior to the end of such ten-day period any other Class D
     Certificateholder notifies such purchasing Class D Certificateholder that
     such other Class D Certificateholder wants to participate in such purchase,
     then such other Class D Certificateholder may join with the purchasing
     Class D Certificateholder to purchase all, but not less than all, of the
     Class A-1 Certificates, the Class A-2 Certificates, the Class A-3
     Certificates, the Class B Certificates and the Class C Certificates pro
     rata based on the Fractional Cumulative Interest held by each such Class D
     Certificateholder and (B) if prior to the end of such ten-day period any
     other Class D Certificateholder fails to notify the purchasing Class D
     Certificateholder of such other Class D Certificateholder's desire to
     participate in such a purchase, then such other Class D Certificateholder
     shall lose its right to purchase the Class A-1 Certificates, the Class A-2
     Certificates, the Class A-3 Certificates, the Class B Certificates and the
     Class C Certificates pursuant to this Section 6.01(b).

          The purchase price with respect to the Certificates of any class shall
be equal to the Pool Balance of the Certificates of such class, together with
accrued and unpaid interest thereon to the date of such purchase, without
Additional Payments, but including any other amounts then due and payable to the
Certificateholders of such class under this Agreement, the Intercreditor
Agreement or any other Note Document or on or in respect of the Certificates of
such class; provided, however, that no such purchase of Certificates shall be
            --------  -------
effective unless the purchaser shall certify to the Trustee that
contemporaneously with such purchase, such purchaser is purchasing, pursuant to
the terms of this Agreement, the Certificates of such class that are senior to
the securities held by such purchaser.  Each payment of the purchase price of
the Certificates referred to in the first sentence hereof shall be made to an
account or accounts designated by the Trustee and each such purchase shall be
subject to the terms of this Section 6.01(b).  Each Certificateholder agrees by
                             ---------------
its acceptance of its Certificate that it shall, subject to Section 3.04, upon
                                                            ------------
payment from such Class A-1 Certificateholder(s), Class A-2
Certificateholder(s), Class A-3 Certificateholder(s), Class B
Certificateholder(s), Class C Certificateholder(s) or Class D
Certificateholder(s), as the case may be, of the purchase price set forth in the
first sentence of this paragraph, forthwith sell, assign, transfer and convey to
the purchaser thereof (without recourse, representation or warranty of any kind
except for its own acts), all of the right, title, interest and obligation of
such Certificateholder in this Agreement, the Intercreditor Agreement, the
Liquidity Facilities, in the case of the Class A-1 Certificates, the Class A-2
Certificates, the Class A-3 Certificates, the Class B Certificates and the Class
C

                                      31
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


Certificates, the Note Purchase Agreement, the Note Documents and all
Certificates of the class or classes being purchased held by such
Certificateholder (excluding all right, title and interest under any of the
foregoing to the extent such right, title or interest is with respect to an
obligation not then due and payable as respects any action or inaction or state
of affairs occurring prior to such sale) and the purchaser shall assume all of
such Certificateholder's obligations under this Agreement, the Intercreditor
Agreement, the Liquidity Facilities, the Note Purchase Agreement and the Note
Documents. The Certificates of the class or classes being purchased shall be
deemed to be purchased on the date payment of the purchase price is made
notwithstanding the failure of the applicable Certificateholders to deliver such
Certificates and, upon such a purchase, (i) the only rights of such
Certificateholders shall be to deliver such Certificates to the purchaser and
receive the purchase price for such Certificates and (ii) if the purchaser shall
so request, such Certificateholder shall comply with all the provisions of
Section 3.04 to enable new Certificates of like class to be issued to the
------------
purchaser in such denominations as it shall request.  All charges and expenses
in connection with the issuance of any such new Certificates shall be borne by
the purchaser thereof.

          As used in this Section 6.01(b), the terms "Class," "Class A-1
                          ---------------
Certificateholder," "Class A-2 Certificateholder," "Class A-3
Certificateholder," "Class B Certificateholder," "Class C Certificateholder" and
"Class D Certificateholder" shall have the respective meanings assigned to such
terms in the Intercreditor Agreement.

     Section 6.02   Judicial Proceedings Instituted by Trustee; Trustee May
Bring Suit. If there shall be a failure to make payment of the principal of,
Additional Payments, if any, or interest on any Note, then the Trustee, in its
own name and as trustee of an express trust, as holder of such Notes to the
extent permitted by and in accordance with the terms of the Intercreditor
Agreement and the Financing Documents, 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 Notes 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 6.03   Control by Certificateholders. Subject to Section 6.02 and
                    -----------------------------
the Intercreditor Agreement, the Certificateholders holding Certificates of a
class evidencing Fractional Cumulative Interests aggregating not less than a
majority in interest in the Trusts of the related class 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 Trusts or pursuant to the terms of
the Intercreditor Agreement, or exercising any trust or power conferred on the
Trustee under this Agreement or the Intercreditor Agreement, including any right
of the Trustee as Controlling Party under the Intercreditor Agreement or as
holder of the Notes in the related Trusts, provided 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
     class not taking part in such Direction; and

                                      32
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]

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

     Section 6.04   Waiver of Past Defaults. Subject to the Intercreditor
                    -----------------------
Agreement, the Certificateholders holding Certificates of a class evidencing
Fractional Cumulative Interests aggregating not less than a majority in interest
in the Trusts of such class (i) may on behalf of all of the Certificateholders
of such class waive any past Default or Event of Default hereunder or under the
related Trust Supplements with respect to such class and its consequences or
(ii) if the Trustee is the Controlling Party, may direct the Trustee to instruct
the applicable Indenture Trustee to waive any past Indenture Default under the
related Indenture with respect to such class and its consequences, and thereby
annul any Direction given by such Certificateholders or the Trustee to such
Indenture Trustee with respect thereto, except the following defaults (which may
only be waived upon receipt of the consent of the Certificateholder of each
Outstanding Certificate):

                    (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 such class;
     ------------

                    (2)  in the payment of the principal of, Additional
     Payments, if any, or interest on the Notes held in the Trusts of such
     class; or

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

     Upon any such waiver, such Default shall cease to exist with respect to the
Certificates of such class and any Event of Default arising therefrom shall be
deemed to have been cured for every purpose in respect of such class and any
direction given by the Trustee on behalf of the Certificateholders of such class
to the relevant Indenture 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 of
such class shall vote the Notes issued under the relevant Indenture to waive the
corresponding Indenture Default.

     Section 6.05   Right of Certificateholders to Receive Payments Not to Be
                    ---------------------------------------------------------
Impaired.  Anything in this Agreement to the contrary notwithstanding, including
--------
Section 6.06, but subject to the Intercreditor Agreement, the right of any
------------
Certificateholder to receive distributions of payments required pursuant to
Section 4.02 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 6.06   Certificateholders May Not Bring Suit Except Under Certain
                    ----------------------------------------------------------
Conditions.  A Certificateholder of any class 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:

                                      33
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

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

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

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

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

     Section 6.07   Remedies Cumulative. Every remedy given hereunder to the
                    -------------------
Trustee or to any of the Certificateholders of any class shall not be exclusive
of any other remedy or remedies, and every such remedy shall be cumulative and
in addition to every other remedy given hereunder or now or hereafter given by
statute, law, equity or otherwise.

                                  ARTICLE VII

                                  THE TRUSTEE

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

               (b)  If an Event of Default in respect of any Trust has occurred
and is continuing, the Trustee shall exercise such of the rights and powers
vested in it by this Agreement in respect of such Trust, and use the same degree
of care and skill in their exercise, as a prudent person would exercise or use
under the circumstances in the conduct of its own affairs.

                                      34
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


               (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 wilful misconduct, except that

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

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

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

     Section 7.02   Notice of Defaults. As promptly as practicable after, and in
                    ------------------
any event within 90 days after, the occurrence of any Default hereunder known to
the Trustee, the Trustee shall transmit by mail to the Company, the Indenture
Trustees and the Certificateholders holding Certificates of the related class in
accordance with Section 313(c) of the Trust Indenture Act, notice of such
Default hereunder known to the Trustee, unless such Default shall have been
cured or waived; provided, however, that, except in the case of a Default on the
                 --------  -------
payment of the principal, Additional Payments, if any, or interest on any 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 determine that the
withholding of such notice is in the interests of the Certificateholders of the
related class.

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

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

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

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

                                      35
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

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

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

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

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

     Section 7.04   Not Responsible for Recitals or Issuance of Certificates.
                    --------------------------------------------------------
The recitals contained herein and in the Certificates of each class, 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 or any Trust Supplement, the
Intercreditor Agreement, the Note Purchase Agreement, any Notes, the
Certificates of any class or any other Financing Document, except that the
Trustee hereby represents and warrants that this Basic Agreement has been, and
each Trust Supplement, the Intercreditor Agreement, the Note Purchase Agreement
and each Certificate of each class to which such Trustee is a party shall be,
executed, authenticated and delivered by one of its officers who is duly
authorized to execute, authenticate and deliver such document on its behalf.

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

                                      36
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                                           [2001-1 Pass Through Trust Agreement]


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

     Section 7.07   Compensation and Reimbursement.  The Company agrees:
                    ------------------------------

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

                    (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 or any Trust Supplement (including the reasonable
     compensation and the expenses and disbursements of its agents and counsel),
     except any such expense, disbursement or advance as may be attributable to
     its negligence, willful misconduct or bad faith or as may be incurred due
     to the Trustee's breach of its representations and warranties set forth in
     Section 7.15; and
     ------------

                    (3)  to indemnify, or cause to be indemnified, the Trustee
     pursuant to Section 5(b) of each Participation Agreement.

     The Trustee shall be entitled to reimbursement from, and shall have a lien
prior to the Certificates of each class upon, the Trust Property, with respect
to such class or the related Trusts 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 Trusts (other than any tax attributable
to the Trustee's compensation for serving as such), including any costs and
expenses incurred in contesting the imposition of any such tax.  The Trustee
shall notify the Company of any claim for any tax for which it may seek
reimbursement.  If the Trustee reimburses itself from the Trust Property of such
Trusts for any such tax, it shall mail a brief report within 30 days setting
forth the circumstances thereof to all Certificateholders of such class 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 financial institution unaffiliated
with and independent of the Company, shall be eligible to act as a trustee under
Section 310(a) of the Trust Indenture Act and shall have a combined capital and
surplus of at least $75,000,000 (or a combined capital and surplus in excess of
$5,000,000 and the obligations of which, whether now in existence or hereafter
incurred, are fully and unconditionally guaranteed by a corporation organized
and doing business under the laws of the United States, any state or territory
thereof or of the District of Columbia and having a combined capital and surplus
of at least $75,000,000).  If such corporation publishes reports of conditions
at least annually, pursuant to law or to the requirements of federal, state,
territorial or District of Columbia supervising or examining authority, then for
the purposes of this Section 7.08, the combined capital and surplus of such
                     ------------

                                      37
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                                           [2001-1 Pass Through Trust Agreement]


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.  If the Trustee has or shall acquire a
                        ------------
conflicting interest within the meaning of the Trust Indenture Act, the Trustee
shall either eliminate such interest or resign, to the extent and in the manner
provided by, and subject to the provisions of, the Trust Indenture Act and this
Agreement.

     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 and the Indenture Trustees. If an instrument of acceptance by a successor
Trustee shall not have been delivered to the Company, the Authorized Agents, the
Indenture 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 trustee of the
Trusts of any class by Direction of the Certificateholders of the related class
holding Certificates of such class evidencing Fractional Cumulative Interests
aggregating not less than a majority in interest in such Trusts delivered to the
Trustee and to the Company and the Indenture Trustees.

               (d)  If at any time in respect of the Trusts of any class:

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

                    (ii)  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

                    (iii) 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 class 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
Trusts.

                                      38
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

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

               (g)  The successor Trustee of the Trusts of a class 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 class as their names
and addresses appear in the Register. Each notice shall include the name of such
successor Trustee and the address of its Corporate Trust Office.

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

                                      39
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     If a successor Trustee is appointed with respect to one or more (but not
all) Trusts, the Company, the predecessor Trustee and each successor Trustee
with respect to any Trust shall execute and deliver a supplemental agreement
hereto which shall contain such provisions as shall be deemed necessary or
desirable to confirm that all the rights, powers, trusts and duties of the
predecessor Trustee with respect to the Trusts as to which the predecessor
Trustee is not retiring shall continue to be vested in the predecessor Trustee,
and shall add to or change any of the provisions of this Basic Agreement and the
applicable Trust Supplements as shall be necessary to provide for or facilitate
the administration of the Trusts hereunder by more than one Trustee.

     It is understood that nothing herein or in any supplemental agreement or
Trust Supplement shall constitute any Trustee a co-Trustee of the same Trust and
that each Trustee shall be the Trustee of one or more separate Trusts.

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

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

     Section 7.12   Maintenance of Agencies.  (a)  With respect to each class of
                    -----------------------
Certificates, there shall at all times be maintained an office or agency in the
location set forth in Section 12.03 where Certificates of such class 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 class (e.g., the
                                                                ----
Certificates shall be represented by Definitive Certificates and shall be listed
on a national securities exchange), the Trustee shall 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 the Indenture Trustees (in the case
of any Indenture Trustee, at its address specified in the Note Purchase
Agreement or such other address as may be notified to the Trustee) and the
Certificateholders of such class.  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 class. Each such Authorized
Agent shall be a bank or trust

                                      40
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

               (c)  Any corporation into which any Authorized Agent may be
merged or converted or with which it may be consolidated, or any corporation
resulting from any merger, consolidation or conversion to which any Authorized
Agent shall be a party, or any corporation succeeding to the corporate trust
business of any Authorized Agent, shall be the successor of such Authorized
Agent hereunder, if such successor corporation is otherwise eligible under this
Section 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, and the Indenture
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, and the Indenture Trustees; and in each case the Trustee
shall mail notice of such appointment to all Certificateholders of the related
class as their names and addresses appear on the Register for such class.

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

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

     The Trustee may at any time, for the purpose of obtaining the satisfaction
and discharge of this Agreement or for any other purpose, direct any Paying
Agent to pay to the Trustee all

                                      41
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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 Notes in Name of Subordination Agent. The
                    ----------------------------------------------------
Trustee agrees that all Notes to be purchased by the Trusts of any class shall
be issued in the name of the Subordination Agent or its nominee and held by the
Subordination Agent in trust for the benefit of the Certificateholders of such
class, or, if not so held, the Subordination Agent or its nominee shall be
reflected as the owner of such Notes in the register of the issuer of such
Notes.

     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 Federal laws of the United
States;

               (b)  the Trustee has full power, authority and legal right to
execute, deliver, and perform this Basic Agreement, each Trust Supplement
executed and delivered on the date hereof, each Certificate executed,
authenticated and delivered on the date hereof, the Intercreditor Agreement, the
Note Purchase Agreement and the Participation Agreements and has taken all
necessary action to authorize the execution, delivery and performance by it of
this Basic Agreement, such Trust Supplement, such Certificate, the Intercreditor
Agreement, the Note Purchase Agreement and the Participation Agreements;

               (c)  the execution, delivery and performance by the Trustee of
this Basic Agreement, each Trust Supplement executed and delivered on the date
hereof, each Certificate executed, authenticated and delivered on the date
hereof, the Intercreditor Agreement, the Note Purchase Agreement and the
Participation Agreements (i) shall not violate any provision of United States
federal law or the law of the state of the United States where it is located
governing the banking and trust powers of the Trustee or any order, writ,
judgment, or decree of any court, arbitrator or governmental authority
applicable to the Trustee or any of its assets, (ii) shall not violate any
provision of the articles of association or by-laws of the Trustee, and (iii)
shall not violate any provision of, or constitute, with or without notice or
lapse of time, a default under, or result in the creation or imposition of any
lien on any properties included in the Trust Property of any Trust 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 Basic Agreement, each Trust Supplement executed and delivered on the date
hereof, each Certificate executed, authenticated and delivered on the date
hereof, the Intercreditor Agreement, the Note Purchase Agreement and the
Participation Agreements shall 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

                                      42
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


Trustee; other than the filing of a Statement of Eligibility on Form T-1 in
connection with the registration of any Certificates;

               (e)  this Basic Agreement, each Trust Supplement executed and
delivered on the date hereof, each Certificate executed, authenticated and
delivered on the date hereof, the Intercreditor Agreement, the Note Purchase
Agreement and the Participation Agreements have been duly executed and delivered
by the Trustee and constitute the legal, valid, and binding agreements of the
Trustee, enforceable against it in accordance with their respective terms,
provided 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.

     Section 7.16   Withholding Taxes; Information Reporting. As to the
                    ----------------------------------------
Certificates of any class, the Trustee, as trustee of the related grantor trust
created by this Agreement, shall exclude and withhold from each distribution of
principal, Additional Payments, if any, and interest and other amounts due under
this Agreement or under the Certificates of such class (a "Distribution") any
and all withholding and backup withholding taxes applicable thereto as required
by United States federal, state and local law. The Trustee on behalf of the
Trust shall request, and the Certificateholders shall provide to the Trust, such
forms or certificates as are necessary to establish an exemption from
withholding and backup withholding with respect to each Certificateholder, and
representations and forms as shall reasonably be requested by the Trustee on
behalf of the Trust to assist it in determining the extent of, and in
fulfilling, its withholding and backup withholding tax obligations. 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 class, 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 class, that it shall
file any necessary withholding tax returns or statements when due, and that, as
promptly as possible after the payment thereof, it shall deliver to each such
Certificateholder appropriate documentation showing the payment thereof,
together with such additional documentary evidence as such Certificateholders of
such class 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. To the extent that the Trust is required to withhold and pay over any
amounts to any jurisdiction with respect to Distributions to any
Certificateholder, the amount withheld shall be deemed to be a Distribution in
the amount of the withholding to the Certificateholder. In the event of any
claimed over withholding, Certificateholders shall be limited to an action
against the applicable jurisdiction. If the amount required to be withheld was
not withheld from actual Distributions made, the Trustee on behalf of the Trust
may reduce subsequent Distributions by the amount of such required withholding.

                                      43
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     Section 7.17   Tax Returns and Reports. The Trustee shall prepare (or cause
                    -----------------------
to be prepared), at the Company's expense, and timely file all United States
federal, state and local tax and information returns and reports required to be
filed by or in respect of the Trust. The Trustee shall prepare and furnish (or
cause to be prepared and furnished), in each taxable year of the Trust, to each
Certificateholder all Internal Revenue Service forms and returns required to be
provided by the Trust. The Trustee shall provide the Company with a copy of all
such returns and reports promptly after such filing or furnishing.

     Section 7.18   Trustee's Liens. The Trustee in its individual capacity
                    ---------------
agrees that it shall, in respect of each Trust created by this Agreement, at its
own cost and expense promptly take any action as may be necessary to duly
discharge and satisfy in full any mortgage, pledge, lien, charge, encumbrance,
security interest or claim ("Trustee's Liens") on or with respect to the Trust
Property of such Trust which is attributable to the Trustee either (i) in its
individual capacity and which is unrelated to the transactions contemplated by
this Agreement, the Intercreditor Agreement, the Note Purchase Agreement or the
Note Documents, or (ii) as Trustee hereunder or in its individual capacity and
which arises out of acts or omissions which are not contemplated by this
Agreement.

     Section 7.19   Preferential Collection of Claims. The Trustee shall comply
                    ---------------------------------
with Section 311(a) of the Trust Indenture Act, excluding any creditor
relationship listed in Section 311(b) of the Trust Indenture Act. If the Trustee
shall resign or be removed as Trustee, it shall be subject to Section 311(a) of
the Trust Indenture Act to the extent provided therein.

                                 ARTICLE VIII

               CERTIFICATEHOLDERS' LISTS AND REPORTS BY TRUSTEE

     Section 8.01   The Company to Furnish Trustee with Names and Addresses of
                    ----------------------------------------------------------
Certificateholders.  The Company shall 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 class, 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
--------  -------
class, no such list need be furnished; and provided, further, 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
class 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 class 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.

                                      44
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     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 class of
Certificates, the Trustee shall transmit to the Certificateholders of each
class, as provided in Section 313(c) of the Trust Indenture Act, a brief report
dated as of such May 15, if required by Section 313(a) of the Trust Indenture
Act.

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

               (a)  file with the Trustee, within 30 days after the Company is
required to file the same with the SEC, copies of the annual reports and of the
information, documents and other reports (or copies of such portions of any of
the foregoing as the SEC may from time to time by rules and regulations
prescribe) which the Company is required to file with the SEC pursuant to
Section 13 or Section 15(d) of the Exchange Act; 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 Exchange Act in respect of a security listed and registered on a national
securities exchange as may be prescribed in such rules and regulations;

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

               (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 Sections 8.04(a) and (b) 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 Section 8.04(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 the Certificateholders of any class,
------------------
the Company may (but shall 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

                                      45
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


applicable, to the Intercreditor Agreement, the Note Purchase Agreement or any
Liquidity Facility for any of the following purposes:

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

                    (2)  to evidence the succession of another corporation or
     entity to the Company and the assumption by any such successor of the
     obligations of the Company contained in this Agreement;

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

                    (4)  (a) to correct or supplement any provision in this
     Agreement, the Intercreditor Agreement, the Note Purchase Agreement or any
     Liquidity Facility that may be defective or inconsistent with any other
     provision herein or in any Trust Supplement, (b) to cure any ambiguity or
     correct any mistake or inconsistency contained in this Agreement, the
     Intercreditor Agreement, the Note Purchase Agreement or any Liquidity
     Facility or (c) to modify any other provision with respect to matters or
     questions arising under this Agreement, the Intercreditor Agreement, the
     Note Purchase Agreement or any Liquidity Facility as the Company may deem
     necessary or desirable, provided that any such action in clause (a), (b) or
                                                              ------------------
     (c) shall not materially adversely affect the interests of the
     ---
     Certificateholders of any class;

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

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

                    (7)  to provide the information required under Sections 7.12
                                                                   -------------
     and 12.03 as to the Trustee;
         -----

                    (8)  to provide for the delivery of agreements supplemental
     hereto or the Certificates of any class in or by any means of any
     computerized, electronic or other medium, including by computer diskette;

                                      46
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


                    (9)  to correct or supplement the description of any
     property constituting Trust Property;

                    (10) to make any other amendments or modifications hereto,
     provided that such amendments or modifications shall only apply to
     Certificates of one or more classes to be thereafter issued or shall be
     made to facilitate the issuance of any Certificates in bearer form or to
     facilitate or provide for the issuance of any Certificates in global form
     in addition to or in place of Certificates in certificated form; or

                    (11) 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 class are listed or of any regulatory body;

provided, however, that no such supplemental agreement shall cause any Trust to
become an association taxable as a corporation for United States federal income
tax purposes.

     Section 9.02   Supplemental Agreements with Consent of Certificateholders.
                    ----------------------------------------------------------
With respect to the Trusts of each class and the class of Certificates relating
thereto, with the consent of the Certificateholders holding Certificates
evidencing Fractional Cumulative Interests aggregating not less than a majority
in interest in such Trust, by Direction of said Certificateholders delivered to
the Company and the Trustee, the Company may, 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, the Intercreditor
Agreement, any Liquidity Facility, or the Note Purchase Agreement to the extent
applicable to such Certificateholders or of modifying in any manner the rights
and obligations of such Certificateholders under this Agreement, the
Intercreditor Agreement, any Liquidity Facility, or the Note Purchase Agreement;
provided, however, that no such supplemental 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 Notes held in such Trust
     or distributions that are required to be made herein on any Certificate of
     such class, or change any date of payment on any Certificate of such class,
     or change the place of payment where, or the coin or currency in which, any
     Certificate of such class is payable, or impair the right to institute suit
     for the enforcement of any such payment or distribution on or after the
     Regular Distribution Date or Special Distribution Date applicable thereto;

                    (2)  permit the disposition of any Note included in the
     Trust Property of such Trust except as permitted by this Agreement, any
     Trust Supplement or the Intercreditor Agreement or any Liquidity facility
     or otherwise deprive such Certificateholder of the benefit of the ownership
     of the Notes in such Trust;

                    (3)  reduce the percentage of the aggregate Fractional
     Cumulative Interests of such Trusts that is required for any such
     supplemental agreement, or reduce such percentage required for any waiver
     of compliance with certain provisions of this

                                      47
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     Agreement or PTC Events of Default hereunder and their consequences
     provided for in this Agreement; or

                    (4)  waive, amend or modify Section 2.4, 3.2 or 3.3 of the
     Intercreditor Agreement in a manner that has a material adverse effect on
     the Certificateholders.

     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 has a material adverse effect on 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 upon its request, 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
                    ---------------------------------
supplemental agreement under this Article IX, this Basic Agreement shall be
                                  ----------
modified in accordance therewith, and such supplemental agreement shall form a
part of this Basic Agreement for all purposes; and every Certificateholder of
each class theretofore or thereafter authenticated and delivered hereunder shall
be bound thereby to the extent applicable to such class.

     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 class authenticated and delivered after the execution of
any supplemental agreement applicable to such class 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 class after proper presentation and
demand.

                                   ARTICLE X

                  AMENDMENTS TO INDENTURES AND NOTE DOCUMENTS

     Section 10.01  Amendments and Supplements to Indentures and Other Note
                    -------------------------------------------------------
Documents.  If the Trustee, as holder (or beneficial owner through the
---------
Subordination Agent) of any Note in trust for the benefit of the
Certificateholders of any class or as Controlling Party under the

                                      48
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


Intercreditor Agreement, receives a request pursuant to Section 9.02 or Section
                                                        ------------    -------
6.04 for a consent to any amendment, modification, waiver or supplement under
----
any related Indenture or other related Note Document, the Trustee shall
forthwith send a notice of such proposed amendment, modification, waiver or
supplement to each Certificateholder of such class registered on the Register as
of the date of such notice. The Trustee shall request from the
Certificateholders of such class a Direction as to (a) whether or not to take or
refrain from taking (or direct the Subordination Agent to take or refrain from
taking) any action which a holder of such Note has the option to take or to
direct, (b) whether or not to give or execute (or direct the Subordination Agent
to give or execute) any waivers, consents, amendments, modifications or
supplements as a holder of such Note or a Controlling Party, and (c) how to vote
(or direct the Subordination Agent to vote) the Notes if a vote has been called
for with respect thereto. If 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 such Notes (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 Note in the
same proportion as that of (A) the aggregate face amounts of all Certificates of
such class 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 class evidencing a Fractional Cumulative Interest aggregating not less than
a majority in interest in the related Trusts. For purposes of the preceding
sentence, a Certificate shall have been "actually voted" if the Holder of such
Certificate has delivered to the Trustee an instrument evidencing such Holder's
consent to such Direction prior to two Business Days before the Trustee directs
such action or casts such vote or gives such consent. Notwithstanding the
foregoing, but subject to Section 6.04 and the Intercreditor Agreement, the
                          ------------
Trustee may, with respect to the Certificates of any class, in its own
discretion and at its own direction, consent and notify the relevant Indenture
Trustee of such consent (or direct the Subordination Agent to consent and notify
such Indenture Trustee of such consent) to any amendment, modification, waiver
or supplement under the relevant Indenture or any other Note Document, if an
Event of Default hereunder shall have occurred and be continuing, or if such
amendment, modification, waiver or supplement shall not materially adversely
affect the interests of the Certificateholders of such class.

                                  ARTICLE XI

                             TERMINATION OF TRUSTS

     Section 11.01  Termination of the Trusts.  In respect of the Trusts of each
                    -------------------------
class  created by the Basic Agreement as supplemented by a related Trust
Supplement, the respective obligations and responsibilities of the Company and
the Trustee created under this Agreement and such Trusts created hereby shall
terminate upon the distribution to all Holders of the Certificates of the class
of such Trusts 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 the related class of such Trusts; provided, however, that
                                                        --------  -------
in no event shall such Trusts 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.

                                      49
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     Notice of any termination of the Trusts of a class, specifying the
applicable Regular Distribution Date (or applicable Special Distribution Date,
as the case may be) upon which the Certificateholders of such class 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 class not earlier than the 60th day and not later
than the 26th day 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 class shall be made upon
presentation and surrender of Certificates of such class 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 class 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 class.  Upon presentation and
surrender of the Certificates of such class in accordance with such notice, the
Trustee shall cause to be distributed to Certificateholders of such class such
final payments.

     If all of the Certificateholders of such class 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 class to surrender their
Certificates for cancellation and receive the final distribution with respect
thereto.  No additional interest shall accrue on the Certificates of such class
after the Regular Distribution Date (or Special Distribution Date, as the case
may be) specified in the first written notice.  If any money held by the Trustee
for the payment of distributions on the Certificates of such class 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 Indenture Trustee the appropriate amount
of money relating to such Indenture Trustee and shall give written notice
thereof to the Company.

                                  ARTICLE XII

                           MISCELLANEOUS PROVISIONS

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

     Section 12.02  Certificates Nonassessable and Fully Paid. Except as set
                    -----------------------------------------
forth in the last sentence of this Section 12.02, Certificateholders of each
                                   -------------
class shall not be personally liable for obligations of the related Trusts, the
Fractional Undivided Interests represented by the Certificates of such class
shall be nonassessable for any losses or expenses of such Trust or for any
reason whatsoever, and Certificates of such class, upon authentication thereof
by the Trustee pursuant to Section 3.03, are and shall be deemed fully paid. No
                           ------------
Certificateholder of such class shall have any right (except as expressly
provided herein) to vote or in any manner otherwise

                                      50
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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 class, be
construed so as to constitute the Certificateholders of such class from time to
time as partners or members of an association. Neither the existence of any
Trust nor any provision herein is intended to or shall limit the liability the
Certificateholders of each class would otherwise incur if such
Certificateholders owned the related Trust Property as co-owners, or incurred
any obligations of the related Trust, directly rather than through the related
Trust.

     Section 12.03  Notices. (a) Unless otherwise specifically provided herein
                    -------
or in the applicable Trust Supplement with respect to any Trust, all notices
required under the terms and provisions of this Basic Agreement or such Trust
Supplement with respect to such Trust shall be in English and in writing, and
any such notice may be given by United States mail, courier service or telecopy,
and any such notice shall be effective when delivered or received or, if mailed,
three days after deposit in the United States mail with proper postage for
ordinary mail prepaid,

     if to the Company, to:

     U.S. Mail                  Overnight Delivery Service
     ---------                  --------------------------
     United Air Lines, Inc.     United Air Lines, Inc.
     P.O. Box 66100             1200 East Algonquin Road
     WHQFT                      WHQFT
     Chicago, Illinois 60666    Elk Grove Township, IL 60007
     Attn: Treasurer            Attn: Treasurer
     Telecopy: (847) 700-7117


     if to the Trustee, to:

     State Street Bank and Trust Company
       of Connecticut, National Association
     225 Asylum Street
     Goodwin Square
     Hartford, Connecticut 06103
     Attention:  Corporate Trust Division
     Telephone:  860-244-1844
     Telecopy:   860-244-1881

               (b)  The Company or the Trustee as to any class of Certificates,
by written notice to the other, may designate additional or different addresses
for subsequent notices or communications.

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

                                      51
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


communication shall not affect its sufficiency with respect to other
Certificateholders or Certificate Owners of such class.

               (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. 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.

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

               (f)  The Trustee shall promptly furnish the Company with a copy
of any demand, notice or written communication received by the Trustee hereunder
from any Certificateholder, Certificate Owner or Indenture Trustee.

     Section 12.04  Governing Law. THIS BASIC AGREEMENT, ALL TRUST SUPPLEMENTS
                    -------------
AND ALL CERTIFICATES SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF NEW YORK (WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF
LAWS THEREOF (OTHER THAN SECTION 5-1401 OF THE NEW YORK GENERAL OBLIGATIONS
LAW)) AND THE OBLIGATIONS, RIGHTS AND REMEDIES OF THE PARTIES HEREUNDER AND
THEREUNDER SHALL BE DETERMINED IN ACCORDANCE WITH SUCH LAWS.

     Section 12.05  Severability of Provisions. If any one or more of the
                    --------------------------
covenants, agreements, provisions or terms of this Agreement shall be for any
reason whatsoever held invalid, then such covenants, agreements, provisions, or
terms shall be deemed severable from the remaining covenants, agreements,
provisions or terms of this Agreement and shall in no way affect the validity or
enforceability of the other provisions of this Agreement or any Trust, or of the
Certificates of any class or the rights of the Certificateholders thereof.

     Section 12.06  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.

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

     Section 12.08  Successors and Assigns. All covenants, agreements,
                    ----------------------
representations and warranties in this Agreement by the Trustee and the Company
shall bind and, to the extent permitted hereby, shall inure to the benefit of
and be enforceable by their respective successors and assigns, whether so
expressed or not. Any request, notice, direction, consent, waiver or other
instrument, duly executed or action properly taken by any Certificateholder
shall bind the successors and assigns of such Certificateholder.

     Section 12.09  Benefits of Agreement.  Nothing in this Agreement or in the
                    ---------------------
Certificates of any class, express or implied, shall give to any Person (other
than the parties hereto and their

                                      52
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


successors hereunder, the Certificateholders and the Certificate Owners) any
benefit or any legal or equitable right, remedy or claim under this Agreement.

     Section 12.10  Legal Holidays. In any case where any Regular Distribution
                    --------------
Date or Special Distribution Date relating to any Certificate of any class shall
not be a Business Day with respect to such class, 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
interest shall accrue during the intervening period.

     Section 12.11  Counterparts. For the purpose of facilitating the execution
                    ------------
of this Agreement and for other purposes, this Agreement may be executed
simultaneously in any number of counterparts, each of which counterparts shall
be deemed to be an original, and all of which counterparts shall constitute but
one and the same instrument.

     Section 12.12  Intention of Parties. The parties hereto intend that each
                    --------------------
Trust be classified for U.S. federal income tax purposes as a grantor trust
under Subpart E, Part I of Subchapter J of the Internal Revenue Code of 1986, as
amended, and not as a trust or association taxable as a corporation or as a
partnership. The powers granted and obligations undertaken pursuant to this
Agreement shall be so construed so as to further such intent.

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

                                    *  *  *

                                      53
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


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

                                              UNITED AIR LINES, INC.


                                              By:/s/ Jeffrey T. Kawalsky
                                                 --------------------------
                                                 Name: Jeffrey T. Kawalsky
                                                 Title: Assistant Treasurer

                                              STATE STREET BANK AND TRUST
                                              COMPANY OF CONNECTICUT,
                                              NATIONAL ASSOCIATION, as Trustee


                                              By:/s/ John G. Correia
                                                 --------------------------
                                                 Name: John G. Correia
                                                 Title: Assistant Vice President

                                      54
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


                                  SCHEDULE 1

                                  INDENTURES

     1.   Trust Indenture and Mortgage (2001-1 A319-1) between United Air Lines,
Inc. (the "Owner") and State Street Bank and Trust Company of Connecticut,
National Association, in its individual capacity and as Indenture Trustee.

     2.   Trust Indenture and Mortgage (2001-1 A319-2) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     3.   Trust Indenture and Mortgage (2001-1 A319-3) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     4.   Trust Indenture and Mortgage (2001-1 A319-4) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     5.   Trust Indenture and Mortgage (2001-1 A319-5) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     6.   Trust Indenture and Mortgage (2001-1 A319-6) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     7.   Trust Indenture and Mortgage (2001-1 A319-7) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     8.   Trust Indenture and Mortgage (2001-1 A319-8) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     9.   Trust Indenture and Mortgage (2001-1 A319-9) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     10.  Trust Indenture and Mortgage (2001-1 A319-10) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

                                  Schedule 1
                                    Page 1
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     11.  Trust Indenture and Mortgage (2001-1 A320-1) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     12.  Trust Indenture and Mortgage (2001-1 A320-2) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     13.  Trust Indenture and Mortgage (2001-1 A320-3) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     14.  Trust Indenture and Mortgage (2001-1 A320-4) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     15.  Trust Indenture and Mortgage (2001-1 A320-5) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     16.  Trust Indenture and Mortgage (2001-1 A320-6) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     17.  Trust Indenture and Mortgage (2001-1 747-1) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     18.  Trust Indenture and Mortgage (2001-1 747-2) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     19.  Trust Indenture and Mortgage (2001-1 747-3) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     20.  Trust Indenture and Mortgage (2001-1 747-4) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     21.  Trust Indenture and Mortgage (2001-1 747-5) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     22.  Trust Indenture and Mortgage (2001-1 767-1) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.


                                  Schedule 1
                                    Page 2
<PAGE>

                                           [2001-1 Pass Through Trust Agreement]


     23.  Trust Indenture and Mortgage (2001-1 767-2) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     24.  Trust Indenture and Mortgage (2001-1 767-3) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     25.  Trust Indenture and Mortgage (2001-1 767-4) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     26.  Trust Indenture and Mortgage (2001-1 767-5) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     27.  Trust Indenture and Mortgage (2001-1 777-1) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     28.  Trust Indenture and Mortgage (2001-1 777-2) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     29.  Trust Indenture and Mortgage (2001-1 777-3) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.

     30.  Trust Indenture and Mortgage (2001-1 777-4) between Owner and State
Street Bank and Trust Company of Connecticut, National Association, in its
individual capacity and as Indenture Trustee.


                                  Schedule 1
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