Document:

<PAGE>

                                                                    Exhibit 10.5

                              EMPLOYMENT CONTRACT

THIS AGREEMENT made as of the 22 day of March 2000.  Between NANOWORLD PROJECTS
CORPORATION, a corporation incorporated under the laws of the state of Delaware,
and having its principal place of business at 1175 North Creek, Parkway South,
Suite 10, in the City of Bothell, State of Washington ("Employer") and Jean
Beliveau, of __________________ ("Employee");

     WHEREAS the Employer desires to obtain the benefit of the services of the
Employee, and the Employee desires to render such services on the terms and
conditions set forth.

     IN CONSIDERATION of the promises and other good and valuable consideration
set forth, the parties agree as follows:

1.  EMPLOYMENT

1.1  Commencing April 1st, 2000, the Employer hereby agrees to employ the
     Employee, subject to the terms of this agreement, in the capacity of Chief
     of Chemistry, responsible for advising the Employer with respect to
     research and development related to the field of chemistry, and the
     exploitation and improvement of intellectual property owned by the Employer
     or its subsidiaries, or co-venturers, and the acquisition of new
     intellectual property for the Employer.  The Employee's duties may be
     reasonably modified at the Company's discretion from time to time.  In
     fulfillment of these responsibilities, the Employee shall perform such
     duties and exercise such specific responsibilities as are assigned from
     time to time by the Board of Directors or Officers of the Employer.  In
     carrying out these duties and responsibilities, the Employee shall comply
     with all written policies, procedures, rules and regulations, as are
     announced by the Employer from time to time and carry out said duties in
     and responsibilities in a diligent, faithful and honest manner.

1.2  The Employee will devote full time, attention, and energies to the business
     of the Company, and, during this employment, will not engage in any other
     business activity, regardless of whether such activity is pursued for
     profit, gain, or other pecuniary advantage, save and except with the
     written permission of the Employer.  Employee is not prohibited from making
     personal investments in any other businesses provided those investments do
     not require active involvement in the operation of said companies.

1.3  The parties agree that there are no statements or representations, oral or
     otherwise, express or implied, with respect to the employment opportunity
     offered to the Employee, which form part of this agreement, other than
     those which are set forth expressly in this agreement.  This agreement
     supersedes any prior representations, statements or agreements with respect
     to the subject matter hereof and the employment opportunity offered to the
     Employee.  The parties agree that any such prior representations,
     statements or agreements, if made, were not material to the execution of
     this agreement, or to the decisions of either party to enter into this
     agreement.
<PAGE>

2.   Compensation

2.1  As full compensation for all services provided herein, the Employer shall
     pay or cause to be paid, to the Employee, and the Employee shall accept a
     salary, at an annual rate of $65,000.00 (U.S.D.) commencing April 1st, 2000
     to be paid in regular installments in accordance with the Employer's usual
     paying practices, but not less frequently than monthly.

2.2  Such payments shall be subject to such deductions by the Employer as the
     Employer is from time to time required to make pursuant to law, government
     regulation or order or by agreement with, or consent of, the Employee.

2.3  The Employer is in the process of arranging an employee and consultant
     incentive program, which shall include provisions respecting the granting
     of options to acquire common stock of the Employer from the Employer
     ("Incentive Program").  The Employee shall have the right to participate in
     the Incentive Program, once initiated on reasonable terms as the parties
     may agree.  For greater clarity, the parties agree that the Employee shall
     not be denied participation in the incentive plan once initiated by the
     Employer.  The Employer understands that participation by the Employee in
     the Incentive Program is a material inducement to the Employee to enter
     this agreement.

3.   Expenses

3.1  It is understood and agreed that the Employee will incur expenses in
     connection with his duties under this agreement.  Therefore, the Employer
     agrees to reimburse the Employee for all reasonable expenses provided the
     Employee provides to the Employer an itemized written account and receipts
     acceptable to the Employer within thirty days after they have been
     incurred.  The Employee will not be reimbursed for any item in excess of
     $1,000.00 U.S. dollars unless approved in advance by the Employer.

4.   Vacation

4.1  The Employee shall be entitled to vacations in the amount of 3 weeks per
     annum, and in addition to the period of December 23rd to January 5th, June
     24th,  and such other statutory holidays as are provided for by law.

5.   Assignment of Intellectual Property Created by the Employee

5.1  The Employer and Employee agree that in consideration of the transaction
     giving rise to this agreement and the Employment provided hereunder, the
     Employee hereby assigns to the Employer all interest in any intellectual
     property created by the Employee, including additions, alterations,
     improvements and modifications to existing or acquired property of the
     Employer ("Created Property").
<PAGE>

5.2  The parties agree that the Employee shall be entitled to no compensation in
     addition to the consideration herein provided for the creation of Created
     Property relating to the business of the Employer, including nano-
     technology, nano-particles, and assembly of nano-particles (the "Core
     Technology")

5.3  The Employer shall be able to waive its assignment of any Created Property
     in which case the Employee shall be free to exploit such Created Property
     at his sole discretion.

5.4  The parties shall negotiate a separate agreement providing for reasonable
     compensation for Created Property other than Core Technology that the
     Employer may elect to exploit, which shall provide that the Employee shall
     receive not less than 3% of any net profits accruing to the Employer from
     the exploitation of such property, unless the parties otherwise agree.

6.  Confidential Materials and Information

6.1  The Employee acknowledges that in the course of employment with the
     Employer, the Employee will acquire and be exposed to information about
     certain matters which are confidential to the Employer and not known to the
     public, or the scientific community, or to competitors (the "Confidential
     and Proprietary Materials and Information"), and which Confidential and
     Proprietary Materials and Information are the exclusive property of the
     Employer, and includes:

     (a)  confidential methods of operation, which includes all information
          relating to the Employer's intellectual property owned by subsidiaries
          of the Employer, unique marketing programs, unique products, unique
          methods, unique service systems, unique security information and
          systems, and trade secrets;

     (b)  all information regarding the Employer's existing customers and
          client, including customer lists, contracts, prices, invoices,
          computer printouts, and other similar information;

     (c)  all information concerning the Employer's potential customers and
          clients, including mailing lists, prospect cards, and other similar
          information; any information about the business of the Employer that
          is not known to the public or competitors, or any other information
          which gives the Employer an opportunity to obtain an advantage over
          competitors who do not know of such information;

     (d)  financial information, including the Employer's costs, sales, income,
          profits and other similar information; business opportunities,
          including all ventures considered by the Employer, whether or not such
          ventures are pursued;

     (e)  personnel information, including the names of employees and applicable
          remuneration and benefit policies, and computer programs and
          procedures relating to the Employer's business, including related data
          input procedures or techniques, and similar information;
<PAGE>

     (f)  intellectual property assigned to the Employer pursuant to paragraph
          5.1 herein.

6.2  The Employee acknowledges that the Confidential and Proprietary Materials
     and Information referred to herein could be used to the detriment of the
     Employer.  Accordingly, throughout the time of the Employee's employment
     with the Employer, the Employee undertakes not to disclose to any third
     party and to treat in strict confidence all Confidential and Proprietary
     Materials and Information, except where disclosure is made with the prior
     written permission of an Officer of the Employer, or required by law.
     Further, after the termination of the Employee's employment with the
     Employer, regardless of how that termination should occur, the Employee
     undertakes, without time limitation, not to disclose to any third party and
     to treat in strict confidence all Confidential and Proprietary Materials
     and Information, except where disclosure is made with the prior written
     permission of the President of the Employer, or required by law.  For
     greater clarity, the parties agree that the Employee is under no
     restriction with respect to information relating to the Employer or its
     business affairs that are generally known to the public, or scientific
     community.  The Employer undertakes to provide a list of persons to whom
     the Employee is authorized to disclose Confidential and Proprietary
     Materials and Information, and to update or alter that list from time to
     time.  Any list provided pursuant to this undertaking shall constitute
     written permission if signed by the President of the Employer.

6.3  The Employee understands and agrees that the restrictions and covenants
     contained in paragraph 6.2 constitute a material inducement to the Employer
     to enter into this agreement and to employ the Employee, and that the
     Employer would not enter into this agreement absent such inducement.  The
     Employee agrees that such restrictions and covenants shall be construed
     independent of any other provision of this agreement, and the existence of
     any claim or cause of action by the Employee against the Employer, whether
     predicated under this agreement or otherwise, shall not constitute a
     defense to the enforcement by the Employer of the said restrictions and
     covenants.

6.4  The Employee acknowledges that all items of any and every nature or kind
     created by the Employee pursuant to the Employee's employment under this
     agreement, or used by the Employee pursuant to the Employee's employment
     under this agreement, or furnished by the Employer to the Employee, and all
     equipment, automobiles, credit cards, books, records, reports, files,
     manuals, literature, and Confidential Materials and Information shall
     remain and be considered the exclusive property of the Employer at all
     times and shall be surrendered to the Employer, in good condition, on
     demand, and in any event, promptly on the termination of the Employee's
     employment irrespective of the time, manner or cause of the termination.

6.5  The Employee acknowledges, agrees, and understands that, without prejudice
     to any and all remedies available to the Employer, an injunction is the
     only effective remedy for any breach of the Employee's covenants under
     paragraph 6.2, and that the Employer would suffer irreparable harm and
     injury in the event of any such breach.  Accordingly, the Employee hereby
     agrees that the Employer may apply for and have injunctive relief,
<PAGE>

     including an interim or interlocutory injunction, in any court of competent
     jurisdiction, to enforce paragraph 6.2 upon the breach or threatened breach
     thereof.  The Employee further agrees that the Employer may apply for and
     is entitled to said injunctive relief without having to prove damages, and
     is entitled to all costs and expenses, including reasonable legal costs.

7.   Non-Competition

7.1  The Employer and Employee agree that in consideration of the transaction
     giving rise to this agreement and the Employment provided hereunder, the
     Employee shall not, during the term of this agreement, or 5 years from the
     date on which the Employee ceases to be employed by the Employer ("Post-
     Termination Non-Competition Period") alone or in partnership with any other
     person, firm or corporation, as principal, agent, shareholder or in any
     other manner, carry on or be engaged in or concerned with or interested in,
     directly or indirectly, or advise, be employed by, or permit his name or
     any part thereof to be used by any person, firm or corporation engaged in
     or interested in any enterprise which is competitive to the Employer's
     business, solicit or attempt to solicit the business of any customer of the
     Employer who has been a customer of the Employer at any time in the thirty-
     six months preceding the date of termination or expiry of this agreement,
     or request or influence any employee of the Employer to terminate his
     employment.  The Employee acknowledges and confirms that the scope of this
     covenant is in all respects no more than reasonable to protect the
     Employer.

7.2  The Employee acknowledges, agrees, and understands that, without prejudice
     to any and all remedies available to the Employer, an injunction is the
     only effective remedy for any breach of the Employee's covenants under
     paragraph 6.1 and that the Employer would suffer irreparable harm and
     injury in the event of any such breach.  Accordingly, the Employee hereby
     agrees that the Employer may apply for and have injunctive relief,
     including an interim or interlocutory injunction, in any court of competent
     jurisdiction, to enforce any of the provisions of paragraph 6.1 upon the
     breach or threatened breach thereof.  The Employee further agrees that the
     Employer may apply for and is entitled to said injunctive relief without
     having to prove damages, and is entitled to all costs and expenses,
     including reasonable legal costs.

7.3  The Employee understands and agrees that the restrictions and covenants
     contained in paragraph 6.1 constitute a material inducement to the Employer
     to enter into this agreement and to employ the Employee, and that the
     Employer would not enter into this agreement absent such inducement.  The
     Employee agrees that the restrictions and covenants contained in this
     paragraph shall be construed independent of any other provisions of this
     agreement, and the existence of any claim or cause of action by the
     Employee against the Employer, whether predicated under this agreement or
     otherwise, shall not constitute a defense to the enforcement by the
     Employer of said restrictions and covenants contained in this paragraph.
     Further, any clause or provisions of this paragraph that may be found
     unenforceable shall be considered to be severable from the rest of this
     paragraph, which remaining portions shall continue in full force and effect
     in accordance with the terms of this paragraph and agreement.
<PAGE>

7.4  On the cessation of his employment with the Employer, otherwise than by
     reason of the liquidation of the Employer, or by reason of dismissal from
     the Employer for misconduct or serious breach of contractual obligations,
     the Employer agrees that should the Employee in good faith be offered a
     position, acceptance of which would cause him to be in breach of the
     obligations contained in paragraph 6.1, the Employer will pay to him the
     lesser of his base salary until the end of the Post-Termination Non-
     Competition Period or the amount of the financial loss that would be
     suffered by the Employee by declining the offer, provided that the Employee
     has made written application to the company within 7 days of the offer to
     be released from the provisions of paragraph 6.1, and the Employer has
     refused to release him.

8.   Termination

8.1  This agreement may be terminated in the following manner:

     (a)  By the Employee on the giving of 12 weeks' notice to the Employer.
          The Employer may waive the notice, in whole or in part.

     (b)  By the Employer on the giving of one months' notice to the Employee
          for each year of service pursuant to this agreement, or payment in
          lieu thereof ("Notice Period"), in which case the Employee shall be
          free to seek other employment.  Should the Employee obtain other
          employment prior to the end of the Notice Period, the Employer's
          obligations shall cease as at the date other employment is obtained.

     (c)  By the Employer, at its option, for cause including: a material breach
          of the provisions of this agreement, and conviction of the Employee of
          a criminal offense punishable by indictment.

9.   Entire Agreement

9.1  The written provisions of this agreement shall constitute the full extent
     of the employment contract between the Employer and the Employee regardless
     of any oral agreements or understandings that may presently or hereafter
     exist between the Employer and the Employee.  No waiver or modification of
     any provision of this agreement shall be valid unless in writing and duly
     executed by both the Employer and the Employee.

10.  Waiver and Modification

10.1 No amendments to this agreement shall be valid or binding unless set forth
     in writing and duly executed by both of the parties hereto. No waiver of
     any breach of any term or provision of this agreement shall be effective or
     binding unless made in writing and signed by the party purporting to give
     the same and, unless otherwise provided in the written waiver, shall be
     limited to the specific breach waived.
<PAGE>

10.2 The parties agree that in the event that any provision, clause or article
     herein, or part thereof, shall be deemed void, involved, or unenforceable
     by a court of competent jurisdiction, the remaining provisions, clauses or
     articles, or part thereof, shall be and remain in full force and effect.

11.  Assignment

11.1 This agreement is personal to the Employee and is not assignable by him and
     shall not enure to the benefit of his heirs, executors or personal
     representatives. The Employer shall be fully assignable by the Employer at
     its sole discretion.

12.  Independent Legal Advice

12.1 The Employee acknowledges that he has read and understands this agreement,
     and acknowledges that he has had the opportunity to obtain independent
     legal advice with respect to it.

13.  Choice of Law

13.  This Agreement shall be construed and enforced in accordance with the laws
     of the Province of British Columbia.

     IN WITNESS WHEREOF the Employer has caused this agreement to be executed by
its duly authorized officers and the Employee has hereunto set his hand as of
the date first above written.

     SIGNED, SEALED AND DELIVERED in the presence of:

Jean Beliveau            Nanoworld Projects Corporation

/s/ Jean Beliveau          /s/ Alnoor Kassam
-----------------          -----------------
                           per:
                           President        c/s

/s/ Fornero Battistino
-----------------------
[Signature of witness]<PAGE>

                                                                     Exhibit 4.1

________________________________________________________________________________

                          REVOLVING CREDIT AGREEMENT

                           Dated as of July 31, 2000

                                    between

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

                            as Subordination Agent,
                         as agent and trustee for the
                 United Airlines 2000-1A-1 Pass Through Trust,

                                  as Borrower

                                      and

                   LANDESBANK HESSEN-THURINGEN GIROZENTRALE,

                             as Liquidity Provider

________________________________________________________________________________

                                  Relating to

                 United Airlines 2000-1A-1 Pass Through Trust
     United Airlines Enhanced Pass Through Certificates, Series 2000-1A-1
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<S>                                                                                                            <C>
                                             ARTICLE I      DEFINITIONS
Section 1.01   Certain Defined Terms.........................................................................  1

                                             ARTICLE II     AMOUNT AND TERMS OF THE COMMITMENT

Section 2.01   Advances......................................................................................  7
Section 2.02   Making the Advances...........................................................................  7
Section 2.03   Fees..........................................................................................  9
Section 2.04   Automatic Reductions and Termination of the Maximum Commitment. ..............................  9
Section 2.05   Repayments of Interest Advances or the Final Advance.......................................... 10
Section 2.06   Repayments of Downgrade Advances.............................................................. 10
Section 2.07   Payments to the Liquidity Provider Under the Intercreditor Agreement.......................... 11
Section 2.08   Book Entries.................................................................................. 12
Section 2.09   Payments from Available Funds Only............................................................ 12
Section 2.10   Extension of Expiry Date. .................................................................... 12

                                             ARTICLE III    OBLIGATIONS OF THE BORROWER

Section 3.01   Increased Costs............................................................................... 13
Section 3.02   Capital Adequacy.............................................................................. 14
Section 3.03   Payments Free of Deductions................................................................... 14
Section 3.04   Payments...................................................................................... 15
Section 3.05   Computations.................................................................................. 16
Section 3.06   Payment on Non-Business Days.................................................................. 16
Section 3.07   Interest...................................................................................... 16
Section 3.08   Replacement of Borrower....................................................................... 18
Section 3.09   Funding Loss Indemnification.................................................................. 18
Section 3.10   Illegality.................................................................................... 18
</TABLE>

                                       i
<PAGE>

<TABLE>
<S>                                                                                                           <C>
                                              ARTICLE IV    CONDITIONS PRECEDENT

Section 4.01   Conditions Precedent to Effectiveness ........................................................ 21
Section 4.02   Conditions Precedent to Borrowing............................................................. 21

                                              ARTICLE V     COVENANTS

Section 5.01   Affirmative Covenants of the Borrower......................................................... 21
Section 5.02   Negative Covenants of the Borrower............................................................ 22

                                              ARTICLE VI    LIQUIDITY EVENTS OF DEFAULT

Section 6.01   Liquidity Events of Default................................................................... 22

                                              ARTICLE VII   MISCELLANEOUS

Section 7.01   Amendments, Etc............................................................................... 22
Section 7.02   Notices, Etc.................................................................................. 22
Section 7.03   No Waiver; Remedies........................................................................... 23
Section 7.04   Further Assurances............................................................................ 23
Section 7.05   Indemnification; Survival of Certain Provisions............................................... 23
Section 7.06   Liability of the Liquidity Provider........................................................... 24
Section 7.07   Costs, Expenses and Taxes..................................................................... 24
Section 7.08   Binding Effect; Participations................................................................ 25
Section 7.09   Severability.................................................................................. 26
Section 7.10   GOVERNING LAW................................................................................. 27
Section 7.11   Submission to Jurisdiction; Waiver of Jury Trial.............................................. 27
Section 7.12   Execution in Counterparts..................................................................... 28
Section 7.13   Entirety...................................................................................... 28
Section 7.14   Headings...................................................................................... 28
Section 7.15   LIQUIDITY PROVIDER'S OBLIGATION TO MAKE ADVANCES.............................................. 28
</TABLE>

                                      ii
<PAGE>

Annex I     Interest Advance Notice of Borrowing
Annex II    Non-Extension Advance Notice of Borrowing
Annex III   Downgrade Advance Notice of Borrowing
Annex IV    Final Advance Notice of Borrowing
Annex V     Notice of Termination
Annex VI    Notice of Replacement Subordination Agent

                                      iii

<PAGE>

                          REVOLVING CREDIT AGREEMENT

          This REVOLVING CREDIT AGREEMENT, dated as of July 31, 2000 (as it may
be amended, supplemented or otherwise modified from time to time in accordance
with the terms hereof, this "Agreement"), between STATE STREET BANK AND TRUST
                             ---------
COMPANY OF CONNECTICUT, NATIONAL ASSOCIATION, a national banking association,
not in its individual capacity but solely as Subordination Agent under the
Intercreditor Agreement (each as defined below), as agent and trustee for the
Class A-1 Trust (as defined below) (the "Borrower"), and LANDESBANK HESSEN-
                                         --------
THURINGEN GIROZENTRALE, a public-law banking institution organized under the
laws of Germany ("Liquidity Provider").
                  ------------------

                              W I T N E S S E T H
                              -------------------

          WHEREAS, pursuant to the Class A-1 Trust Agreement (as defined below),
the Class A-1 Trust is issuing the Class A-1 Certificates; and

          WHEREAS, the Borrower, in order to support the timely payment of a
portion of the interest on the Class A-1 Certificates in accordance with their
terms, has requested the Liquidity Provider to enter into this Agreement,
providing in part for the Borrower to request in specified circumstances that
Advances be made hereunder.

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

                                   ARTICLE I

                                  DEFINITIONS

          Section 1.01  Certain Defined Terms.  (a)  For all purposes of this
                        ---------------------
Agreement, except as otherwise expressly provided or unless the context
otherwise requires:

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

     (2)  all references in this Agreement to designated "Articles," "Sections"
and other subdivisions are to the designated Articles, Sections and other
subdivisions of this Agreement;
<PAGE>

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

     (4)  the term "including" means "including without limitation".

          "747 Leased Aircraft Participation Agreement" means, with respect to
           -------------------------------------------
the Equipment Note Indenture pertaining to the 747 Leased Aircraft, the
"Participation Agreement" referred to therein.

          "Additional Costs" has the meaning specified in Section 3.01.
           ----------------                               ------------

          "Advance" means an Interest Advance, a Final Advance, a Provider
           -------
Advance or an Applied Provider Advance, as the case may be.

          "Applicable Liquidity Rate" has the meaning specified in Section 3.0
           -------------------------                               -----------
7(g).
----

          "Applicable Margin" means (w) with respect to any Unpaid Advance or
           -----------------
Applied Provider Advance, 1.5% and (x) with respect to any Unapplied Provider
Advance, 0.28% per annum.

          "Applied Downgrade Advance" has the meaning specified in Section
           -------------------------                               -------
2.06(a).
-------
          "Applied Non-Extension Advance" has the meaning assigned to such term
           -----------------------------
in Section 2.06(a).
   ---------------

          "Applied Provider Advance" has the meaning assigned to such term in
           ------------------------
Section 2.06(a).
---------------

          "Base Rate" means a fluctuating interest rate per annum in effect from
           ---------
time to time, which rate per annum shall at all times be equal to (a) the
weighted average of the rates on overnight Federal funds transactions with
members of the Federal Reserve System arranged by Federal funds brokers, as
published for such day (or, if such day is not a Business Day, for the preceding
Business Day) by the Federal Reserve Bank of New York, or if such rate is not so
published for any day that is a Business Day, the average of the quotations for
such day for such transactions received by the Liquidity Provider from three
Federal funds brokers of recognized standing selected by it, plus (b) one-
quarter of one percent (.25)%.

          "Base Rate Advance" means an Advance that bears interest at a rate
           -----------------
based upon the Base Rate.

                                       2
<PAGE>

          "Borrower" has the meaning specified in the recitals to this
           --------
Agreement.

          "Borrowing" means the making of Advances requested by delivery of a
           ---------
Notice of Borrowing.

          "Business Day" means any day (x) other than a Saturday or Sunday or a
           ------------
day on which commercial banks are authorized or required by law to close in
Chicago, Illinois, New York, New York or the city and state in which the Class
A-1 Trustee, the Subordination Agent or any Indenture Trustee maintains its
corporate trust office or receives and disburses funds, and (y) if the
applicable Business Day relates to any Advance or amount bearing interest based
on LIBOR, on which dealings are carried on in the London interbank market.

          "Consent Period" has the meaning specified in Section 2.10.
           --------------                               ------------

          "Downgrade Advance" means an Advance made pursuant to Section 2.02(c).
           -----------------                                    ---------------

          "Effective Date" has the meaning specified in Section 4.01. The
           --------------                               ------------
delivery of the certificate of the Liquidity Provider contemplated by Section
                                                                      -------
4.01(e) shall be conclusive evidence that the Effective Date has occurred.
-------

          "Excluded Taxes" means (i) any Taxes imposed on, based on, or measured
           --------------
by the overall net income, capital, franchises, or receipts (other than Taxes
which are or are in the nature of sales or use Taxes or value added Taxes) of
the Liquidity Provider or any of its Lending Offices, (ii) withholding Taxes
imposed under laws in effect on the date hereof by the United States on payments
to a recipient in the jurisdiction in which the Liquidity Provider's initial
Lending Office is located, and (iii) withholding Taxes imposed by the United
States on payments to a recipient in any other jurisdiction to which such
Lending Office is moved if, under the laws in effect at the time of such move,
such laws would require greater withholding of Taxes on payments to such
Liquidity Provider acting from an office in such jurisdiction than would be
required on payments to such Liquidity Provider acting from an office in the
jurisdiction from which such Lending Office was moved.

          "Expenses" means liabilities, obligations, damages, settlements,
           --------
penalties, claims, actions, suits, costs, expenses, and disbursements
(including, without limitation, reasonable fees and disbursements of legal
counsel and costs of investigation), provided that Expenses shall not include
                                     --------
Taxes.

          "Expiry Date" means July 29, 2001, initially, or any date to which the
           -----------
Expiry Date is extended pursuant to Section 2.10.
                                    ------------

                                       3
<PAGE>

          "Final Advance" means an Advance made pursuant to Section 2.02(c).
           -------------                                    ---------------

          "Indenture Trustee" means, with respect to any Equipment Note
           -----------------
Indenture, the Indenture Trustee thereunder.

          "Intercreditor Agreement" means the Intercreditor Agreement, dated as
           -----------------------
of July 31, 2000 between the Trustee, the Liquidity Provider, the liquidity
provider under each Liquidity Facility (other than this Agreement) and the
Subordination Agent, as the same may be amended, supplemented or otherwise
modified from time to time in accordance with its terms.

          "Interest Advance" means an Advance made pursuant to Section 2.02(a).
           ----------------                                    ---------------

          "Interest Period" means, with respect to any LIBOR Advance, each of
           ---------------
the following periods:

          (1)  the period beginning on the third Business Day following either
     (x) the Liquidity Provider's receipt of the Notice of Borrowing for such
     LIBOR Advance or (y) the withdrawal of funds from the Class A-1 Cash
     Collateral Account for the purpose of paying interest on the Class A-1
     Certificates as contemplated by Section 2.06(a) hereof and, in either case,
                                     ---------------
     ending on the next Regular Distribution Date; and

          (2)  each subsequent period commencing on the last day of the
     preceding Interest Period and ending on the next Regular Distribution Date;

provided, however, that if (x) the Final Advance shall have been made, or (y)
--------  -------
other outstanding Advances shall have been converted into the Final Advance,
then the Interest Periods shall be successive periods of one month beginning on
the third Business Day following the Liquidity Provider's receipt of the Notice
of Borrowing for such Final Advance (in the case of clause (x) above) or the
                                                    ----------
Regular Distribution Date following such conversion (in the case of clause (y)
                                                                    ----------
above).

          "Leased Aircraft Participation Agreement" means, with respect to the
           ---------------------------------------
Equipment Note Indenture pertaining to each Leased Aircraft, the "Participation
Agreement" referred to therein.

          "Lending Office" means the lending office of the Liquidity Provider,
           --------------
presently located at Frankfurt am Main, Germany, or such other lending office as
the Liquidity Provider from time to time shall notify the Borrower as its
lending office hereunder.

          "LIBOR" means, with respect to any Interest Period, the interest rate
           -----
per annum (calculated on the basis of a 360-day year and actual days elapsed) at
which deposits in United States dollars are offered to prime banks in the London
interbank market as indicated on display page 3750 (British Bankers Association-
LIBOR) of the Dow Jones Markets Service (or such other page as may

                                       4
<PAGE>

replace such display page 3750 for the purpose of displaying London interbank
offered rates for United States dollar deposits) or, if not so indicated, the
average (rounded upwards to the nearest 1/100%), as determined by the Liquidity
Provider, of such rates as indicated on the Reuters Screen LIBO Page (or such
other page as may replace such Reuters Screen LIBO Page for the purpose of
displaying London interbank offered rates for United States dollar deposits) or,
if neither such alternative is indicated, the average (rounded upwards to the
nearest 1/100%), as determined by the Liquidity Provider, of such rates offered
by the London Reference Banks to prime banks in the London interbank market, in
each case at or about 11:00 a.m. (London time) on the day two LIBOR Business
Days prior to the first day of such Interest Period for deposits of a duration
equal to such Interest Period (or such other period most nearly corresponding to
such period) in an amount substantially equal to the principal amount of the
applicable LIBOR Advance as of the first day of such Interest Period. The
Liquidity Provider will, if necessary, request that each of the London Reference
Banks provide a quotation of its rate. If at least two such quotations are
provided, the rate will be the average of the quotations (rounded upwards to the
nearest 1/100%). If no such quotation can be obtained, the rate will be Base
Rate.

          "LIBOR Advance" means an Advance bearing interest at a rate based upon
           -------------
LIBOR.

          "Liquidity Event of Default" means the occurrence of either (a) the
           --------------------------
Acceleration of all of the Equipment Notes or (b) a United Bankruptcy Event.

          "Liquidity Indemnitee" means (i) the Liquidity Provider, (ii) each
           --------------------
Affiliate of the Liquidity Provider, (iii) the directors, officers, employees,
servants and agents of the Liquidity Provider and its Affiliates, and (iv) the
successors and permitted assigns of the persons described in clauses (i) through
(iii), inclusive.

          "Liquidity Provider" has the meaning specified in the recital of
           ------------------
parties to this Agreement.

          "London Reference Banks" means the principal London offices of
           ----------------------
National Westminster Bank PLC, the Mitsubishi Trust and Banking Corporation and
ABN AMRO Bank N.V., or such other bank or banks as may from time to time be
agreed to by United and the Liquidity Provider.

          "Maximum Available Commitment" shall mean, subject to the proviso
           ----------------------------
contained in the third sentence of Section 2.02(a), at any time of
                                   ---------------
determination, (a) the Maximum Commitment at such time, less (b) the aggregate
                                                        ----
amount of each Interest Advance outstanding at such time; provided, however,
                                                          --------  -------
that following a Provider Advance or a Final Advance, the Maximum Available
Commitment shall be zero.

                                       5
<PAGE>

          "Maximum Commitment" means initially $32,174,805, as the same may be
           ------------------
reduced from time to time in accordance with Section 2.04(a).
                                             ---------------

          "Non-Excluded Tax" has the meaning specified in Section 3.03.
           ----------------                               ------------

          "Non-Extension Advance" means an Advance made pursuant to Section
           ---------------------                                    -------
2.02(b).
-------

          "Notice of Borrowing" has the meaning specified in Section 2.02(e).
           -------------------                               ---------------

          "Notice of Replacement Subordination Agent" has the meaning specified
           -----------------------------------------
in Section 3.08.
   ------------

          "Owned Aircraft Participation Agreement" means, with respect to the
           --------------------------------------
Equipment Note Indenture pertaining to each Owned Aircraft, the "Participation
Agreement" referred to therein.

          "Participating Institution" has the meaning specified in Section
           -------------------------                               -------
7.08(b).
-------

          "Performing Equipment Note Deficiency" means any time that less than
           ------------------------------------
65% of the then aggregate outstanding principal amount of all Equipment Notes
are Performing Equipment Notes.

          "Prospectus Supplement" means the Prospectus Supplement dated July 19,
           ---------------------
2000 relating to the Certificates, as such Prospectus Supplement may be amended
or supplemented.

          "Provider Advance" means a Downgrade Advance or a Non-Extension
           ----------------
Advance.

          "Regulatory Change" has the meaning specified in Section 3.01.
           -----------------                               ------------

          "Replenishment Amount" has the meaning assigned to such term in
           --------------------
Section 2.06(b).
---------------

          "Required Amount" means, for any day, the sum of the aggregate amount
           ---------------
of interest, calculated at the rate per annum equal to the Stated Interest Rate
for the Class A-1 Certificates on the basis of a 360-day year comprised of
twelve 30-day months, that would be payable on the Class A-1 Certificates on
each of the three successive semiannual Regular Distribution Dates following
such day or, if such day is a Regular Distribution Date, on such day and the
succeeding two semiannual Regular Distribution Dates, in each case calculated on
the basis of the Pool Balance of the Class A-1 Certificates on such day and
without regard to expected future payments of principal on the Class A-1
Certificates.

                                       6
<PAGE>

          "Termination Date" means the earliest to occur of the following: (i)
           ----------------
the Expiry Date; (ii) the date on which the Borrower delivers to the Liquidity
Provider a certificate, signed by a Responsible Officer of the Borrower,
certifying that all of the Class A-1 Certificates have been paid in full (or
provision has been made for such payment in accordance with the Intercreditor
Agreement and the Trust Agreement) or are otherwise no longer entitled to the
benefits of this Agreement; (iii) the date on which the Borrower delivers to the
Liquidity Provider a certificate, signed by a Responsible Officer of the
Borrower, certifying that a Replacement Liquidity Facility has been substituted
for this Agreement in full pursuant to Section 3.6(e) of the Intercreditor
Agreement; (iv) the fifth Business Day following the receipt by the Borrower and
United of a Termination Notice from the Liquidity Provider pursuant to Section
                                                                       -------
6.01; and (v) the date on which no Advance is or may (including by reason of
----
reinstatement as herein provided) become available for a Borrowing hereunder.

          "Termination Notice" means the Notice of Termination substantially in
           ------------------
the form of Annex V to this Agreement.
            -------

          "Unapplied Downgrade Advance" means any Downgrade Advance other than
           ---------------------------
an Applied Downgrade Advance.

          "Unapplied Non-Extension Advance" means any Non-Extension Advance
           -------------------------------
other than an Applied Non-Extension Advance.

          "Unapplied Provider Advance" means any Provider Advance other than an
           --------------------------
Applied Provider Advance.

          "Unpaid Advance" has the meaning specified in Section 2.05.
           --------------                               ------------

          "Withdrawal Notice" has the meaning specified in Section 2.10.
           -----------------                               ------------

          (b)  Terms Defined in the Intercreditor Agreement.  For all purposes
               --------------------------------------------
of this Agreement, the following terms shall have the respective meanings
assigned to such terms in the Intercreditor Agreement:

     "747 Leased Aircraft," "Acceleration," "Additional Payments," "Affiliate,"
      -------------------    ------------    -------------------    ---------
     "Certificates," "Class A-1 Cash Collateral Account,""Class A-1
      ------------    ---------------------------------   ---------
     Certificates," "Class A-1 Trust ," "Class A-1 Trust Agreement," "Class A-1
     ------------    ---------------     -------------------------    ---------
     Trustee," "Class A-2 Certificates," "Class B Certificates," "Class C-1
     -------    ----------------------    --------------------    ---------
     Certificates," "Class C-2 Certificates," "Closing Date," "Controlling
     ------------    ----------------------    ------------    -----------
     Party," "Distribution Date," "Downgraded Facility," "Equipment Note
     -----    -----------------    -------------------    --------------
     Indenture," "Equipment Notes," "Fee Letter," "Final Maturity Date,"
     ---------    ---------------    ----------    -------------------
     "Indenture," "Investment Earnings," "Leased Aircraft", "Liquidity
      ---------    -------------------    ---------------    ---------
     Facility," "Liquidity Obligations," "Moody's," "Non-Extended Facility,"
     --------    ---------------------    -------    ---------------------

                                       7
<PAGE>

     "Note Purchase Agreements," "Operative Agreements," "Owned Aircraft",
      ------------------------    --------------------    --------------
     "Participation Agreements," "Performing Equipment Note," "Person," "Pool
      ------------------------    -------------------------    ------    ----
     Balance," "Rating Agency," "Regular Distribution Date," "Replacement
     -------    -------------    --------------------------   -----------
     Liquidity Facility," "Responsible Officer," "Scheduled Payment," "Special
     ------------------    -------------------    -----------------    -------
     Payment," "Standard & Poor's," "Stated Interest Rate," "Subordination
     -------    -----------------    --------------------    -------------
     Agent," "Taxes," "Threshold Rating," "Triggering Event," "Trust Agreement,
     -----    -----    ----------------    ---------- -----    ---------------
     "Trustee," "Underwriter," "Underwriting Agreement," "United," "United
      -------    -----------    ----------------------    ------    ------
     Bankruptcy Event" and "Written Notice."
     ----------------       --------------

                                  ARTICLE II

                      AMOUNT AND TERMS OF THE COMMITMENT

          Section 2.01   Advances. The Liquidity Provider hereby irrevocably
                         --------
agrees, on the terms and conditions hereinafter set forth, to make Advances to
the Borrower from time to time on any Business Day during the period from the
Effective Date until 12:00 noon (New York City time) on the Expiry Date (unless
the obligations of the Liquidity Provider shall be earlier terminated in
accordance with the terms of Section 2.04) in an aggregate amount at any time
                             ------------
outstanding not to exceed the Maximum Commitment.

          Section 2.02   Making the Advances. (a) Each "Interest Advance" shall
                         -------------------            ----------------
be made in a single Borrowing by delivery to the Liquidity Provider of a written
and completed Notice of Borrowing in substantially the form of Annex I, signed
                                                               -------
by a Responsible Officer of the Borrower, such Interest Advance in an amount not
exceeding the Maximum Available Commitment at such time and shall be used solely
for the payment when due of interest on the Class A-1 Certificates at the Stated
Interest Rate therefor in accordance with Section 3.6(a) of the Intercreditor
Agreement. Each Interest Advance made hereunder shall automatically reduce the
Maximum Available Commitment and the amount available to be borrowed hereunder
by subsequent Advances by the amount of such Interest Advance (subject to
reinstatement as provided in the next sentence). Upon repayment to the Liquidity
Provider in full of the amount of any Interest Advance made pursuant to this
Section 2.02(a), together with accrued interest thereon (as provided herein),
---------------
the Maximum Available Commitment shall be reinstated by the amount of such
repaid Interest Advance, but not to exceed the Maximum Commitment; provided,
                                                                   --------
however, that the Maximum Available Commitment shall not be so reinstated at any
-------
time if (i) a Liquidity Event of Default shall have occurred and be continuing
and (ii) there is a Performing Equipment Note Deficiency.

          (b)  A Non-Extension Advance shall be made in a single Borrowing if
this Agreement is not extended in accordance with Section 3.6(d) of the
Intercreditor Agreement (unless a Replacement Liquidity Facility to replace this
Agreement shall have been delivered to the Borrower as contemplated by said
Section 3.6(d) within the time period specified in such Section)

                                       8
<PAGE>

by delivery to the Liquidity Provider of a written and completed Notice of
Borrowing in substantially the form of Annex II attached hereto, signed by a
                                       --------
Responsible Officer of the Borrower, in an amount equal to the Maximum Available
Commitment at such time, and shall be used to fund the Class A-1 Cash Collateral
Account in accordance with said Section 3.6(d) and Section 3.6(f) of the
Intercreditor Agreement.

          (c)  A "Downgrade Advance" shall be made in a single Borrowing upon a
                  -----------------
downgrading of the Liquidity Provider's relevant debt rating issued by either
Rating Agency below the applicable Threshold Rating (as provided for in Section
3.6(c) of the Intercreditor Agreement) unless a Replacement Liquidity Facility
shall have been delivered to the Borrower in accordance with said Section
3.6(c), by delivery to the Liquidity Provider of a written and completed Notice
of Borrowing in substantially the form of Annex III, signed by a Responsible
                                          ---------
Officer of the Borrower, in an amount equal to the Maximum Available Commitment
at such time, and shall be used to fund the Class A-1 Cash Collateral Account in
accordance with said Section 3.6(c) and Section 3.6(f). Upon such downgrading,
the Liquidity Provider shall promptly deliver notice thereof to the Borrower,
the Trustee and United.

          (d)  A "Final Advance" shall be made in a single Borrowing upon the
                  -------------
receipt by the Borrower of a Termination Notice from the Liquidity Provider
pursuant to Section 6.01, by delivery to the Liquidity Provider of a written and
            ------------
completed Notice of Borrowing in substantially the form of Annex IV, signed by a
                                                           --------
Responsible Officer of the Borrower, in an amount equal to the Maximum Available
Commitment at such time, and shall be used to fund the Class A-1 Cash Collateral
Account (in accordance with Section 3.6(f) and Section 3.6(i) of the
Intercreditor Agreement).

          (e)  Each Borrowing shall be made on notice in writing (a "Notice of
                                                                     ---------
Borrowing") in substantially the form required by Section 2.02(a), 2.02(b),
---------                                         ---------------  -------
2.02(c) or 2.02(d), as the case may be, given by the Borrower to the Liquidity
-------    -------
Provider. If a Notice of Borrowing is delivered by the Borrower in respect of
any Borrowing no later than 11:00 a.m. (Chicago time) on a Business Day, upon
satisfaction of the conditions precedent set forth in Section 4.02 with respect
                                                      ------------
to a requested Borrowing, the Liquidity Provider shall, before 4:00 p.m.
(Chicago time) on the date of such Borrowing or on such later Business Day
specified by the Borrower in such Notice of Borrowing, make available for the
account of its Lending Office, in U.S. dollars and in immediately available
funds, the amount of such Borrowing to be paid to the Borrower in accordance
with its payment instructions. If a Notice of Borrowing is delivered by the
Borrower in respect of any Borrowing after 11:00 a.m. (Chicago time) on a
Business Day, the Liquidity Provider shall, before 11:00 a.m. (Chicago time) on
the first Business Day following the day of receipt of such Notice of Borrowing
or on such later Business Day specified by the Borrower in such Notice of
Borrowing, make available to the Borrower, in accordance with its payment
instructions, in U.S. dollars and in immediately available funds, the amount of
such Borrowing. Payments of proceeds of a Borrowing

                                       9
<PAGE>

shall be made by wire transfer of immediately available funds to the Borrower in
accordance with such wire transfer instructions as the Borrower shall furnish
from time to time to the Liquidity Provider for such purpose. Each Notice of
Borrowing shall be irrevocable and binding on the Borrower. Each Notice of
Borrowing shall be effective upon delivery of a copy thereof to the Liquidity
Provider's New York Branch at the address specified in Section 7.02.
                                                       ------------

          (f)  Upon the making of any Advance requested pursuant to a Notice of
Borrowing in accordance with the Borrower's payment instructions, the Liquidity
Provider shall be fully discharged of its obligation hereunder with respect to
such Notice of Borrowing, and the Liquidity Provider shall not thereafter be
obligated to make any further Advances hereunder in respect of such Notice of
Borrowing to the Borrower or to any other Person. If the Liquidity Provider
makes an Advance requested pursuant to a Notice of Borrowing before 11:00 a.m.
(Chicago time) on the second Business Day after the date of payment specified in
said Section 2.02(e), the Liquidity Provider shall have fully discharged its
obligations hereunder with respect to such Advance and an event of default shall
not have occurred hereunder. Following the making of any Advance pursuant to
Section 2.02(b), Section 2.02(c) or Section 2.02(d) to fund the Class A-1 Cash
---------------  ---------------    ---------------
Collateral Account, the Liquidity Provider shall have no interest in or rights
to the Class A-1 Cash Collateral Account, such Advance or any other amounts from
time to time on deposit in the Class A-1 Cash Collateral Account; provided,
                                                                  --------
however, that the foregoing shall not affect or impair the obligations of the
-------
Subordination Agent to make the distributions contemplated by Section 3.6(e) or
(f) of the Intercreditor Agreement and provided further, that the foregoing
                                       -------- -------
shall not affect or impair the rights of the Liquidity Provider to provide
written instructions with respect to the investment and reinvestment of the Cash
Collateral Accounts to the extent provided in Section 2.2(b) of the
Intercreditor Agreement. By paying to the Borrower proceeds of Advances
requested by the Borrower in accordance with the provisions of this Agreement,
the Liquidity Provider makes no representation as to, and assumes no
responsibility for, the correctness or sufficiency for any purpose of the amount
of the Advances so made and requested.

          Section 2.03   Fees.  The Borrower agrees to pay to the Liquidity
                         ----
Provider the fees set forth in the Fee Letter.

          Section 2.04   Automatic Reductions and Termination of the Maximum
                         ---------------------------------------------------
Commitment.
----------

          (a)  Automatic Reductions. Promptly following each date on which the
               --------------------
Required Amount is reduced as a result of a reduction in the Pool Balance of the
Class A-1 Certificates or otherwise, the Maximum Commitment shall automatically
be reduced to an amount equal to such reduced Required Amount (as calculated by
the Borrower). The Borrower shall give notice of any such automatic reduction of
the Maximum Commitment to the Liquidity Provider within two

                                       10
<PAGE>

Business Days thereof. The failure by the Borrower to furnish any such notice
shall not affect such automatic reduction of the Maximum Commitment.

          (b)  Termination. Upon the making of any Provider Advance or Final
               -----------
Advance hereunder or the occurrence of the Termination Date, the obligation of
the Liquidity Provider to make further Advances hereunder shall automatically
and irrevocably terminate, and the Borrower shall not be entitled to request any
further Borrowing hereunder.

          Section  1.6   Repayments of Interest Advances or the Final Advance.
                         ----------------------------------------------------
Subject to Sections 2.06, 2.07 and 2.09, the Borrower hereby agrees, without
           -------------  ----     ----
notice of an Advance or demand for repayment from the Liquidity Provider (which
notice and demand are hereby waived by the Borrower), to pay, or to cause to be
paid, to the Liquidity Provider on each date on which the Liquidity Provider
shall make an Interest Advance or the Final Advance, an amount equal to (a) the
amount of such Advance (any such Advance, until repaid, is referred to herein as
an "Unpaid Advance"), plus (b) interest on the amount of each such Unpaid
    --------------
Advance as provided in Section 3.07; provided, however, that if (i) the
                       ------------  --------  -------
Liquidity Provider shall make a Provider Advance at any time after making one or
more Interest Advances which shall not have been repaid in accordance with this
Section 2.05 or (ii) this Liquidity Facility shall become a Downgraded Facility
------------
or Non-Extended Facility at any time when unreimbursed Interest Advances have
reduced the Maximum Available Commitment to zero, then such Interest Advances
shall cease to constitute Unpaid Advances and shall be deemed to have been
changed into an Applied Downgrade Advance or an Applied Non-Extension Advance,
as the case may be, for all purposes of this Agreement (including, for the
purpose of determining when such Interest Advance is required to be repaid to
the Liquidity Provider in accordance with Section 2.06 and for the purposes of
                                          ------------
Section 2.06(b)). The Borrower and the Liquidity Provider agree that the
----------------
repayment in full of each Interest Advance and Final Advance on the date such
Advance is made is intended to be a contemporaneous exchange for new value given
to the Borrower by the Liquidity Provider.

          Section 1.7    Repayments of Provider Advances. (a) Amounts advanced
                         -------------------------------
hereunder in respect of a Provider Advance shall be deposited in the Class A-1
Cash Collateral Account, invested and withdrawn from the Class A-1 Cash
Collateral Account as set forth in Sections 3.6(c), (d) and (f) of the
Intercreditor Agreement. The Borrower agrees to pay to the Liquidity Provider,
on each Regular Distribution Date, commencing on the first Regular Distribution
Date after the making of a Provider Advance, interest on the principal amount of
any such Provider Advance as provided in Section 3.07; provided, however, that
                                         ------------  --------  -------
amounts in respect of a Provider Advance withdrawn from the Class A-1 Cash
Collateral Account for the purpose of paying interest on the Class A-1
Certificates in accordance with Section 3.6(f) of the Intercreditor Agreement
(the amount of any such withdrawal being (y) in the case of a Downgrade Advance,
an "Applied Downgrade Advance" and (z) in the case of a Non-Extension Advance,
    -------------------------
an "Applied Non-Extension Advance" and, together with an Applied Downgrade
    -----------------------------
Advance, an "Applied Provider Advance") shall thereafter (subject to
             ------------------------

                                       11
<PAGE>

Section 2.06(b)) be treated as an Interest Advance under this Agreement for
----------------
purposes of determining the Applicable Liquidity Rate for interest payable
thereon; and provided, further, that if, following the making of a Provider
             --------  -------
Advance, the Liquidity Provider delivers a Termination Notice to the Borrower
pursuant to Section 6.01, such Provider Advance shall thereafter be treated as a
            ------------
Final Advance under this Agreement for purposes of determining the Applicable
Liquidity Rate for interest payable thereon and the obligation for repayment
thereof. Subject to Sections 2.07 and 2.09 hereof, immediately upon the
                    ------------      ----
withdrawal of any amounts from the Class A-1 Cash Collateral Account on account
of a reduction in the Required Amount, the Borrower shall repay to the Liquidity
Provider a portion of the Provider Advances in a principal amount equal to the
amount of such reduction, plus interest on the principal amount prepaid as
provided in Section 3.07.
            ------------

          (b)  At any time when an Applied Provider Advance (or any portion
thereof) is outstanding, upon the deposit in the Class A-1 Cash Collateral
Account of any amount pursuant to clause third of Section 2.4(b) of the
                                         -----
Intercreditor Agreement, clause third of Section 3.2 of the Intercreditor
                                -----
Agreement or clause fourth of Section 3.3 of the Intercreditor Agreement (any
                    ------
such amount being a "Replenishment Amount") for the purpose of replenishing or
                     --------------------
increasing the balance thereof up to the amount of the Required Amount at such
time, (i) the aggregate outstanding principal amount of all Applied Provider
Advances (and of Provider Advances treated as an Interest Advance for purposes
of determining the Applicable Liquidity Rate for interest payable thereon) shall
be automatically reduced by the amount of such Replenishment Amount and (ii) the
principal amount of all outstanding Unapplied Provider Advances shall be
automatically increased by the amount of such Replenishment Amount.

          (c)  Upon the provision of a Replacement Liquidity Facility in
replacement of this Agreement in accordance with Section 3.6(e) of the
Intercreditor Agreement, amounts remaining on deposit in the Class A-1 Cash
Collateral Account after giving effect to any Applied Provider Advance on the
date of such replacement shall be reimbursed to the Liquidity Provider, but only
to the extent such amounts are necessary to repay in full to the Liquidity
Provider all amounts owing to it hereunder.

          Section 2.07   Payments to the Liquidity Provider Under the
                         --------------------------------------------
Intercreditor Agreement. In order to provide for payment or repayment to the
-----------------------
Liquidity Provider of any amounts hereunder, the Intercreditor Agreement
provides that amounts available and referred to in Articles II and III of the
Intercreditor Agreement, to the extent payable to the Liquidity Provider
pursuant to the terms of the Intercreditor Agreement (including, without
limitation, Section 3.6(f) of the Intercreditor Agreement), shall be paid to the
Liquidity Provider in accordance with the terms thereof. Amounts so paid to the
Liquidity Provider shall be applied by the Liquidity Provider to Liquidity
Obligations then due and payable in the order of priority required by the
applicable provisions of Articles II and III of the Intercreditor Agreement or,
if not provided for in the Intercreditor Agreement, then in such manner as the
Liquidity Provider shall deem appropriate.

                                       12
<PAGE>

          Section 2.08   Book Entries. The Liquidity Provider shall maintain in
                         ------------
accordance with its usual practice an account or accounts evidencing the
indebtedness of the Borrower resulting from Advances made from time to time and
the amounts of principal and interest payable hereunder and paid from time to
time in respect thereof; provided, however, that the failure by the Liquidity
                         --------  -------
Provider to maintain such account or accounts shall not affect the obligations
of the Borrower in respect of Advances.

          Section 2.09   Payments from Available Funds Only. All payments to be
                         ----------------------------------
made by the Borrower under this Agreement shall be made only from amounts
received by it that constitute Scheduled Payments or Special Payments or
payments under Sections 7(b) and 7(c) of the Leased Aircraft Participation
Agreement, Section 7(c) of the 747 Leased Aircraft Participation Agreement,
Section 5(b) of the Owned Aircraft Participation Agreement and Section 7 of the
747 Leased Equipment Note Purchase Agreement, Sections 5(i), 7 and 9 of the AFE
Note Purchase Agreement and Sections 4(i) and 7 of the United Equipment Note
Purchase Agreement, and only to the extent that the Borrower shall have
sufficient income or proceeds therefrom to enable the Borrower to make payments
in accordance with the terms hereof after giving effect to the priority of
payments provisions set forth in the Intercreditor Agreement. The Liquidity
Provider agrees that it shall look solely to such amounts to the extent
available for distribution to it as provided in the Intercreditor Agreement and
this Agreement and that the Borrower, in its individual capacity, is not
personally liable to it for any amounts payable or liability under this
Agreement except as expressly provided in this Agreement or the Intercreditor
Agreement. Amounts on deposit in the Class A-1 Cash Collateral Account shall be
available to the Borrower to make payments under this Agreement only to the
extent and for the purposes expressly contemplated in Section 3.6(f) of the
Intercreditor Agreement.

          Section 2.10   Extension of Expiry Date. No earlier than the 60th day
                         ------------------------
and no later than the 40th day prior to the then effective Expiry Date (unless
such Expiry Date is on or after the date that is 15 days after the Final
Maturity Date for the Class A-1 Certificates), the Borrower shall request that
the Liquidity Provider extend the Expiry Date to the earlier of (i) the date
that is 15 days after the Final Maturity Date for the Class A-1 Certificates and
(ii) the date that is the day immediately preceding the 364th day occurring
after the last day of the Consent Period (as hereinafter defined). Whether or
not the Borrower has made such request, the Liquidity Provider shall advise the
Borrower, no earlier than the 40th day (or, if earlier, the date of the
Liquidity Provider's receipt of such request, if any, from the Borrower) and no
later than the 25th day prior to the then effective Expiry Date (such period the
"Consent Period"), whether, in its sole discretion, it agrees to so extend the
 --------------
Expiry Date. If the Liquidity Provider advises the Borrower on or before the
date on which the Consent Period ends that such Expiry Date shall not be so
extended, or fails to irrevocably and unconditionally advise the Borrower on or
before the date on which the Consent Period ends that such Expiry Date shall be
so extended (and, in each case, if the Liquidity Provider shall not have

                                       13
<PAGE>

been replaced in accordance with Section 3.6(e) of the Intercreditor Agreement),
the Borrower shall be entitled on and after the date on which the Consent Period
ends (but prior to the then effective Expiry Date) to request a Non-Extension
Advance in accordance with Section 2.02(b) and Section 3.6(d) of the
                           ---------------
Intercreditor Agreement.

                                  ARTICLE III

                          OBLIGATIONS OF THE BORROWER

     Section 3.01 Increased Costs. The Borrower shall pay to the Liquidity
                  ---------------
Provider from time to time such amounts as may be necessary to compensate the
Liquidity Provider for any costs incurred by the Liquidity Provider which are
attributable to its making or maintaining any Advances hereunder or its
obligation to make any such Advances hereunder, or any reduction in any amount
receivable by the Liquidity Provider under this Agreement or the Intercreditor
Agreement in respect of any such Advances or such obligation (such increases in
costs and reductions in amounts receivable being herein called "Additional
                                                                ----------
Costs"), resulting from any change after the date of this Agreement in U.S.
-----
federal, state, or municipal, or any foreign laws or regulations, or the
adoption or making after such date of any interpretation, regulation, directive,
guideline, requirement or request whether or not having the force of law, by any
court or governmental or monetary authority charged with the interpretation or
administration thereof (a "Regulatory Change"), which: (1) changes the basis of
                           -----------------
taxation of any amounts payable to the Liquidity Provider under this Agreement
in respect of any such Advances or such obligation (other than Excluded Taxes or
any Non-Excluded Taxes; or (2) imposes or modifies any reserve, special deposit,
compulsory loan or similar requirements relating to any extensions of credit or
other assets of, or any deposits with other liabilities of, the Liquidity
Provider (including any such Advances or such obligation or any deposits
referred to in the definition of LIBOR or related definitions). The Liquidity
Provider agrees to use reasonable efforts (consistent with its internal policy
and applicable legal and regulatory restrictions) to change the jurisdiction of
its Lending Office if making such change would avoid the need for, or reduce the
amount of, any amount payable under this Section 3.01 that may thereafter accrue
                                         ------------
and would not, in the reasonable judgment of the Liquidity Provider, be
otherwise disadvantageous to the Liquidity Provider.

     The Liquidity Provider shall notify the Borrower of any event occurring
after the date of this Agreement that shall entitle the Liquidity Provider to
compensation pursuant to this Section 3.01 as promptly as practicable after it
                              ------------
obtains knowledge thereof and determines to request such compensation, which
notice shall describe in reasonable detail the calculation of the amounts owed
under this Section 3.01. Determinations by the Liquidity Provider for purposes
           ------------
of this Section 3.01 of the effect of any Regulatory Change on its costs of
        ------------
making or maintaining Advances or on amounts receivable by it in respect of
Advances, and of the additional amounts required to

                                       14
<PAGE>

compensate the Liquidity Provider in respect of any Additional Costs, shall be
prima facie evidence of the amount owed under this Section 3.01.
                                                   ------------

     Notwithstanding the preceding two paragraphs, the Liquidity Provider and
the Subordination Agent agree that any permitted assignee or participant of the
initial Liquidity Provider that is not a bank shall not be entitled to the
benefits of the preceding two paragraphs (but without limiting the provisions of
Section 7.08 hereof).
------------

     Section 3.02 Capital Adequacy. If (1) compliance with any judicial,
                  ----------------
administrative or other governmental interpretation of any law or regulation or
(2) compliance by the Liquidity Provider or any corporation controlling the
Liquidity Provider with any guideline or request from any central bank or other
governmental authority (whether or not having the force of law) has the effect
of requiring an increase in the amount of capital required or expected to be
maintained by the Liquidity Provider or any corporation controlling the
Liquidity Provider, and such increase is based upon the Liquidity Provider's
obligations hereunder and other similar obligations, the Borrower shall pay to
the Liquidity Provider such additional amount as shall be reasonably allocable
to the Liquidity Provider's obligations to the Borrower hereunder. The Liquidity
Provider agrees to use reasonable efforts (consistent with applicable legal and
regulatory restrictions) to change the jurisdiction of its Lending Office if
making such change would avoid the need for, or reduce the amount of, any amount
payable under this Section 3.02 that may thereafter accrue and would not, in the
                   ------------
reasonable judgment of the Liquidity Provider, be otherwise disadvantageous to
the Liquidity Provider.

     The Liquidity Provider shall notify the Borrower of any event occurring
after the date of this Agreement that shall entitle the Liquidity Provider to
compensation pursuant to this Section 3.02 as promptly as practicable after it
                              ------------
obtains knowledge thereof and determines to request such compensation, which
notice shall describe in reasonable detail the calculation of the amounts owed
under this Section 3.02. Determinations by the Liquidity Provider for purposes
           ------------
of this Section 3.02 of the effect of any increase in the amount of capital
        ------------
required to be maintained by the Liquidity Provider and of the amount allocable
to the Liquidity Provider's obligations to the Borrower hereunder shall be prima
facie evidence of the amounts owed under this Section 3.02.
                                              ------------

     Notwithstanding the preceding two paragraphs, the Liquidity Provider and
the Subordination Agent agree that any permitted assignee or participant of the
initial Liquidity Provider that is not a bank shall not be entitled to the
benefits of the preceding two paragraphs (but without limiting the provisions of
Section 7.08 hereof).
------------

     Section 3.03 Payments Free of Deductions. (a) All payments made by the
                  ---------------------------
Borrower under this Agreement shall be made free and clear of, and without
reduction for or on account of, any Taxes, excluding Excluded Taxes (such non-
excluded taxes being referred to herein, collectively, as "Non-Excluded Taxes").
                                                           ------------------
If any Non-Excluded Taxes are required to be withheld or deducted from any
amounts payable to the Liquidity Provider under this Agreement, the Borrower

                                       15
<PAGE>

shall (i) within the time prescribed therefor by applicable law pay to the
appropriate governmental or taxing authority the full amount of any such Non-
Excluded Taxes (and any additional Non-Excluded Taxes in respect of the payment
required under clause (ii) below) and make such reports or returns in connection
               -----------
therewith at the time or times and in the manner prescribed by applicable law,
and (ii) pay to the Liquidity Provider an additional amount which (after
deduction of all such Non-Excluded Taxes) shall be sufficient to yield to the
Liquidity Provider the full amount which would have been received by it had no
such withholding or deduction been made. Within 30 days after the date of each
payment hereunder, the Borrower shall furnish to the Liquidity Provider the
original or a certified copy of (or other documentary evidence of) the payment
of the Non-Excluded Taxes applicable to such payment. The Liquidity Provider
agrees to use reasonable efforts (consistent with applicable legal and
regulatory restrictions) to change the jurisdiction of its Lending Office if
making such change would avoid the need for, or reduce the amount of, any such
additional amounts that may thereafter accrue and would not, in the reasonable
judgment of the Liquidity Provider, be otherwise materially disadvantageous to
the Liquidity Provider or require the Liquidity Provider to incur any cost or
expenses for which it is not indemnified by the Borrower. The Liquidity Provider
shall deliver to the Borrower such certificates and documents as may be
reasonably requested by the Borrower and required by applicable law to establish
that payments hereunder are exempt from (or entitled to a reduced rate of)
withholding Tax.

                  (b) All payments (including, without limitation, Advances)
made by the Liquidity Provider under this Agreement shall be made free and clear
of, and without reduction for or on account of, any Taxes. If any Taxes are
required to be withheld or deducted from any amounts payable to the Borrower
under this Agreement, the Liquidity Provider shall (i) within the time
prescribed therefor by applicable law pay to the appropriate governmental or
taxing authority the full amount of any such Taxes (and any additional Taxes in
respect of the additional amounts payable under clause (ii) hereof) and make
                                                -----------
such reports or returns in connection therewith at the time or times and in the
manner prescribed by applicable law, and (ii) pay to the Borrower an additional
amount which (after deduction of all such Taxes) shall be sufficient to yield to
the Borrower the full amount which would have been received by it had no such
withholding or deduction been made. Within 30 days after the date of each
payment hereunder, the Liquidity Provider shall furnish to the Borrower the
original or a certified copy of (or other documentary evidence of) the payment
of the Taxes applicable to such payment.

                  (c) If any exemption from, or reduction in the rate of, any
Taxes is reasonably available to the Borrower to establish that payments under
this Agreement are exempt from (or entitled to a reduced rate of) tax, the
Borrower shall deliver to the Liquidity Provider such form or forms and such
other evidence of the eligibility of the Borrower for such exemption or
reduction as the Liquidity Provider may reasonably identify to the Borrower as
being required as a condition to exemption from, or reduction in the rate of,
any Taxes.

                                       16
<PAGE>

                  Section 3.04  Payments. The Borrower shall make or cause to
                                --------
be made each payment to the Liquidity Provider under this Agreement so as to
cause the same to be received by the Liquidity Provider not later than 1:00 P.M.
(Chicago time) on the day when due. The Borrower shall make all such payments in
lawful money of the United States of America, to the Liquidity Provider in
immediately available funds, by wire transfer to Citibank, N.A., New York, ABA
No. 021000089, for credit to Helaba, account no. 10920118, ref: United Airlines
2000-1A-1 account 4111290.

                  Section 3.05  Computations. All computations of interest based
                                ------------
on the Base Rate shall be made on the basis of a year of 365 or 366 days, as the
case may be, and all computations of interest based on the LIBOR shall be made
on the basis of a year of 360 days, in each case for the actual number of days
(including the first day but excluding the last day) occurring in the period for
which such interest is payable.

                  Section 3.06  Payment on Non-Business Days. Whenever any
                                ----------------------------
payment to be made hereunder shall be stated to be due on a day other than a
Business Day, such payment shall be made on the next Business Day and no
additional interest shall be due as a result (and if so made, shall be deemed to
have been made when due). If any payment in respect of interest on an Advance is
so deferred to the next Business Day, such deferral shall not delay the
commencement of the next Interest Period for such Advance (if such Advance is a
LIBOR Advance) or reduce the number of days for which interest shall be payable
on such Advance on the next interest payment date for such Advance.

                  Section 3.07  Interest. (a) Subject to Section 2.09, the
                                --------                 ------------
Borrower shall pay, or shall cause to be paid, without duplication, interest on
(i) the unpaid principal amount of each Advance from and including the date of
such Advance (or, in the case of an Applied Provider Advance, from and including
the date on which the amount thereof was withdrawn from the Class A-1 Cash
Collateral Account to pay interest on the Class A-1 Certificates) to but
excluding the date such principal amount shall be paid in full (or, in the case
of an Applied Provider Advance, the date on which the Class A-1 Cash Collateral
Account is fully replenished in respect of such Advance) and (ii) any other
amount due hereunder (whether fees, commissions, expenses or other amounts or to
the extent permitted by applicable law, installments of interest on Advances or
any such other amount) which is not paid when due (whether at stated maturity,
by acceleration or otherwise) from and including the due date thereof to but
excluding the date such amount is paid in full, in each such case, at a
fluctuating interest rate per annum for each day equal to the Applicable
Liquidity Rate (as defined below) for such Advance or such other amount as in
effect for such day, but in no event at a rate per annum greater than the
maximum rate permitted by applicable law; provided, however, that, if at any
                                          --------  -------
time the otherwise applicable interest rate as set forth in this Section 3.07
                                                                 ------------
shall exceed the maximum rate permitted by applicable law, then any subsequent
reduction in such interest rate shall not reduce the rate of interest payable
pursuant to this Section 3.07 below the maximum rate
                 ------------

                                       17
<PAGE>

permitted by applicable law until the total amount of interest accrued equals
the amount of interest that would have accrued if such otherwise applicable
interest rate as set forth in this Section 3.07 had at all times been in effect.
                                   ------------
Nothing contained in this Section 3.07 shall require the Borrower to pay any
                          ------------
amount under this Section 3.07 other than to the extent the Borrower shall have
                  ------------
funds available therefor.

          (b)  Except as provided in Section 3.07(e), each Advance shall be
                                     ---------------
either a Base Rate Advance or a LIBOR Advance as provided in this Section or
                                                                  -------
Section 3.10. Each such Advance shall be a Base Rate Advance for the period from
------------
the date of its borrowing to (but excluding) the third Business Day following
the Liquidity Provider's receipt of the Notice of Borrowing for such Advance.
Thereafter, such Advance shall be a LIBOR Advance; provided, however, that the
                                                   --------  -------
Borrower (at the direction of the Controlling Party, so long as the Liquidity
Provider is not the Controlling Party) may (x) convert the Final Advance into a
Base Rate Advance on the last day of an Interest Period for such Advance by
giving the Liquidity Provider no less than four Business Days' prior written
notice of such election or (y) elect to maintain the Final Advance as a Base
Rate Advance by not requesting a conversion of the Final Advance to a LIBOR
Advance under Clause (5) of the applicable Notice of Borrowing (or, if such
Final Advance is deemed to have been made, without delivery of a Notice of
Borrowing pursuant to Section 2.06, by requesting, prior to 11:00 A.M. (New York
                      ------------
time) on the first Business Day following the Borrower's receipt of the
applicable Termination Notice, that such Final Advance not be converted from a
Base Rate Advance to a LIBOR Advance).

          (c)  Each LIBOR Advance shall bear interest during each Interest
Period at a rate per annum equal to LIBOR for such Interest Period plus the
Applicable Margin for such LIBOR Advance, payable in arrears on the last day of
such Interest Period and, in the event of the payment of principal of such LIBOR
Advance on a day other than such last day, on the date of such payment (to the
extent of interest accrued on the amount of principal repaid).

          (d)  Each Base Rate Advance shall bear interest at a rate per annum
equal to the Base Rate plus the Applicable Margin for such Base Rate Advance,
payable in arrears on each Regular Distribution Date and, in the event of the
payment of principal of such Base Rate Advance on a day other than a Regular
Distribution Date, on the date of such payment (to the extent of interest
accrued on the amount of principal repaid).

          (e)  Each outstanding Unapplied Non-Extension Advance shall bear
interest in an amount equal to the Investment Earnings on amounts on deposit in
the Class A-1 Cash Collateral Account plus the Applicable Margin for such
period, payable in arrears on each Regular Distribution Date.

                                       18
<PAGE>

                  (f) Each amount not paid when due hereunder (whether fees,
commissions, expenses or other amounts or, to the extent permitted by applicable
law, installments of interest on Advances but excluding Advances) shall bear
interest at a rate per annum equal to the Base Rate plus 1.00% per annum.

                  (g) Each change in the Base Rate shall become effective
immediately. The rates of interest specified in this Section 3.07 with respect
                                                     ------------
to any Advance or other amount shall be referred to as the "Applicable Liquidity
                                                            --------------------
Rate."
----

                  Section 3.08 Replacement of Borrower. Subject to Section 5.02,
                               -----------------------             ------------
from time to time and subject to the successor Borrower's meeting the
eligibility requirements set forth in Section 6.9 of the Intercreditor Agreement
applicable to the Subordination Agent, upon the effective date and time
specified in a written and completed Notice of Replacement Subordination Agent
in substantially the form of Annex VI (a "Notice of Replacement Subordination
                             --------     ------------------------------------
Agent") delivered to the Liquidity Provider by the then Borrower, the successor
-----
Borrower designated therein shall be substituted for as the Borrower for all
purposes hereunder.

                  Section 3.09 Funding Loss Indemnification.  The Borrower shall
                               ----------------------------
pay to the Liquidity Provider, upon the request of the Liquidity Provider, such
amount or amounts as shall be sufficient (in the reasonable opinion of the
Liquidity Provider) to compensate it for any loss, cost, or expense incurred by
reason of the liquidation or redeployment of deposits or other funds acquired by
the Liquidity Provider to fund or maintain any LIBOR Advance (but excluding loss
of anticipated profits) incurred as a result of:

                  (1) Any repayment of a LIBOR Advance, any conversion of a
         LIBOR Advance to a Base Rate Advance or a conversion of a LIBOR Advance
         to an Advance bearing interest in accordance with Section 3.07(e), in
                                                           ---------------
         any case on a date other than the last day of the Interest Period for
         such Advance; or

                  (2) Any failure by the Borrower to borrow a LIBOR Advance on
         the date for borrowing specified in the relevant notice under Section
                                                                       -------
         2.02.
         ----

                  Section 3.10 Illegality.  Notwithstanding any other provision
                               ----------
in this Agreement, if any change in any applicable law, rule or regulation, or
any change in the interpretation or administration thereof by any governmental
authority, central bank or comparable agency charged with the interpretation or
administration thereof, or compliance by the Liquidity Provider (or its Lending
Office) with any request or directive (whether or not having the force of law)
of any such authority, central bank or comparable agency shall make it unlawful
or impossible for the Liquidity Provider (or its Lending Office) to maintain or
fund its LIBOR Advances, then upon notice to the Borrower by the Liquidity
Provider, the outstanding principal amount of the LIBOR Advances shall

                                       19
<PAGE>

be converted to Base Rate Advances (a) immediately upon demand of the Liquidity
Provider, if such change or compliance with such request, in the judgment of the
Liquidity Provider, requires immediate repayment; or (b) at the expiration of
the last Interest Period to expire before the effective date of any such change
or request.

                                  ARTICLE IV

                             CONDITIONS PRECEDENT

                  Section 4.01 Conditions Precedent to Effectiveness of Section
                               ------------------------------------------------
2.01. Section 2.01 of this Agreement shall become effective on and as of the
----  ------------
first date (the "Effective Date") on which the following conditions precedent
                 --------------
have been satisfied or waived:

                  (a) The Liquidity Provider shall have received on or before
         the Closing Date each of the following, each dated such date, and in
         the case of each document delivered pursuant to paragraphs (i), (ii)
                                                         ---------- ---  ---
         and (iii), in form and substance satisfactory to the Liquidity
             -----
         Provider:

         (i)      This Agreement duly executed on behalf of the Borrower;

         (ii)     The Intercreditor Agreement duly executed on behalf of each of
the parties thereto;

         (iii)    Fully executed copies of each of the Operative Agreements
(other than this Agreement and the Intercreditor Agreement);

         (iv)     A copy of the Prospectus Supplement and specimen copies of the
Class A-1 Certificates;

         (v)      An executed copy of each opinion, document, instrument and
certificate delivered pursuant to the Class A-1 Trust Agreement, the
Intercreditor Agreement, the Note Purchase Agreements and the other Operative
Agreements (together with, in the case of each such opinion, other than the
opinion of counsel for the Underwriters, either addressed to the Liquidity
Provider or accompanied by a letter from the counsel rendering such opinion to
the effect that the Liquidity Provider is entitled to rely on such opinion as of
its date as if it were addressed to the Liquidity Provider);

         (vi)     Evidence that there shall have been made and shall be in full
force and effect, all filings, recordings and/or registrations, and there shall
have been given or taken any notice or other similar action as may be reasonably
necessary or, to the extent reasonably requested by the Liquidity Provider,
reasonably advisable, in order to establish, perfect, protect and preserve the
right, title and

                                       20
<PAGE>

interest, remedies, powers, privileges, liens and security interests of, or for
the benefit of, the Trustee and the Liquidity Provider created by the Operative
Agreements;

         (vii)  An agreement from United, pursuant to which United agrees to
provide copies of its Quarterly Reports on Form 10-Q and Annual Reports on Form
10-K to the Liquidity Provider promptly after becoming publicly available; and

         (viii) Such other documents, instruments, opinions and approvals as the
Liquidity Provider shall have reasonably requested.

                (b)  The following statements shall be true on and as of the
Effective Date:

         (i)    The representations and warranties in the Note Purchase
Agreements and each of the Participation Agreements are true and correct on and
as of the Effective Date as though made on and as of the Effective Date;

         (ii)   No event has occurred and is continuing, or would result from
the entering into of this Agreement or the making of any Advance, which
constitutes a Liquidity Event of Default; and

         (iii)  There has been no material adverse change in the financial
condition or results of operations of United and its subsidiaries taken as a
whole since December 31, 1999.

                (c)  The Liquidity Provider shall have received payment in full
         of all fees and other sums required to be paid to or for the account of
         the Liquidity Provider on or prior to the Effective Date.

                (d)  All conditions precedent to the issuance of the
         Certificates under the Trust Agreements shall have been satisfied or
         waived, all conditions precedent to the effectiveness of the other
         Liquidity Facilities shall have been satisfied or waived, and all
         conditions precedent to the purchase of the Certificates by the
         Underwriter under the Underwriting Agreement shall have been satisfied
         (unless any of such conditions precedent shall have been waived by the
         Underwriter).

                (e) The Borrower shall have received a certificate, dated the
         date hereof, signed by a duly authorized representative of the
         Liquidity Provider, certifying that all conditions precedent to the
         effectiveness of Section 2.01 have been satisfied or waived.
                          ------------

                Section 4.02 Conditions Precedent to Borrowing. The obligation
                             ---------------------------------
of the Liquidity Provider to make an Advance on the occasion of each Borrowing
shall be subject to the conditions precedent that the Effective Date shall have
occurred and, prior to the date of such Borrowing, the Borrower shall have
delivered a Notice of Borrowing which conforms to the terms and conditions

                                       21
<PAGE>

of this Agreement and has been completed as may be required by the relevant form
of the Notice of Borrowing for the type of Advances requested.

                                   ARTICLE V

                                   COVENANTS

                  Section 5.01 Affirmative Covenants of the Borrower. So long as
                               -------------------------------------
any Advance shall remain unpaid or the Liquidity Provider shall have any Maximum
Commitment hereunder or the Borrower shall have any obligation to pay any amount
to the Liquidity Provider hereunder, the Borrower shall, unless the Liquidity
Provider shall otherwise consent in writing:

                  (a) Performance of Agreements. Punctually pay or cause to be
                      -------------------------
paid all amounts payable by it under this Agreement and the other Operative
Agreements and observe and perform in all material respects the conditions,
covenants and requirements applicable to it contained in this Agreement and the
other Operative Agreements.

                  (b) Reporting Requirements. Furnish to the Liquidity Provider
                      ----------------------
with reasonable promptness, such other information and data with respect to the
transactions contemplated by the Operative Agreements as from time to time may
be reasonably requested by the Liquidity Provider; and permit the Liquidity
Provider, upon reasonable notice, to inspect the Borrower's books and records
with respect to such transactions and to meet with officers and employees of the
Borrower to discuss such transactions.

                  (c) Certain Operative Agreements. Furnish to the Liquidity
                      ----------------------------
Provider with reasonable promptness any Operative Agreement entered into after
the date hereof.

                  Section 5.02 Negative Covenants of the Borrower. So long as
                               ----------------------------------
any Advance shall remain unpaid or the Liquidity Provider shall have any Maximum
Commitment hereunder or the Borrower shall have any obligation to pay any amount
to the Liquidity Provider hereunder, the Borrower shall not appoint or permit or
suffer to be appointed any successor Borrower without the written consent of the
Liquidity Provider, which consent shall not be unreasonably withheld or delayed.

                                  ARTICLE VI

                          LIQUIDITY EVENTS OF DEFAULT

                                       22
<PAGE>

                  Section 6.01 Liquidity Events of Default. If (a) any Liquidity
                               ---------------------------
Event of Default has occurred and is continuing and (b) there is a Performing
Equipment Note Deficiency, the Liquidity Provider may, in its discretion,
deliver to the Borrower a Termination Notice, the effect of which shall be to
cause (i) the obligation of the Liquidity Provider to make Advances hereunder to
expire on the fifth Business Day after the date on which such Termination Notice
is received by the Borrower and United, (ii) the Borrower to promptly request,
and the Liquidity Provider to promptly make, a Final Advance in accordance with
Section 2.02(d) and Section 3.6(i) of the Intercreditor Agreement, (iii) all
---------------
other outstanding Advances to be automatically converted into Final Advances for
purposes of determining the Applicable Liquidity Rate for interest payable
thereon, and (iv) subject to Sections 2.07 and 2.09, all Advances (including,
                             -------------     ----
without limitation, any Provider Advance and Applied Provider Advance), any
accrued interest thereon and any other amounts outstanding hereunder to become
immediately due and payable to the Liquidity Provider.

                                  ARTICLE VII

                                 MISCELLANEOUS

                  Section 7.01 Amendments, Etc. No amendment or waiver of any
                               ---------------
provision of this Agreement, nor consent to any departure by the Borrower
therefrom, shall in any event be effective unless the same shall be in writing
and signed by the Liquidity Provider, and, in the case of an amendment, the
Borrower, and then such waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given.

                  Section 7.02 Notices, Etc. Except as otherwise expressly
                               ------------
provided herein, all notices and other communications provided for hereunder
shall be in writing (including sent by telecopier):

                  Borrower:  State Street Bank and Trust Company of Connecticut,
                             National Association
                             225 Asylum Street
                             Hartford, Connecticut 06103
                             Attention: Corporate Trust Division

                             Telephone: 860-244-1844
                             Telecopy: 860-244-1881

                                       23
<PAGE>

                  Liquidity
                  Provider:           Landesbank Hessen-Thuringen Girozentrale
                                      Main Tower
                                      Neue Mainzer Str. 52 - 58
                                      60311 Frankfurt am Main
                                      Germany
                                      Attention: Asset Finance

                                      Telephone: 49699132-4882
                                      Telecopy: 49699132-4392

with a copy of any Notice of Borrowing to:

                                      Landesbank Hessen-Thuringen
                                      420 Fifth Avenue, 24/th/ Floor
                                      New York, NY 10018
                                      Attention: Project Finance, Michael Novack
                                      Telephone: 212-703-5224
                                      Telecopy:  212-703-5256

or, as to each of the foregoing, at such other address as shall be designated by
such Person in a Written Notice to the others. All such notices and
communications shall be effective (i) if given by telecopier, when transmitted
to the telecopier number specified above with receipt confirmed, (ii) if given
by mail, when deposited in the mails addressed as specified above, and (iii) if
given by other means, when delivered at the address specified above, except that
Written Notices to the Liquidity Provider pursuant to the provisions of Articles
                                                                        --------
II and III shall not be effective until received by the Liquidity Provider,
--     ---
subject to the last sentence of Section 2.02(e). A copy of all notices delivered
                                ---------------
hereunder to either party shall in addition be delivered to each of the parties
to the Participation Agreements at their respective addresses set forth therein.

                  Section 7.03 No Waiver; Remedies. No failure on the part of
                               -------------------
the Liquidity Provider to exercise, and no delay in exercising, any right under
this Agreement shall operate as a waiver thereof; nor shall any single or
partial exercise of any right under this Agreement preclude any other or further
exercise thereof or the exercise of any other right. The remedies herein
provided are cumulative and not exclusive of any remedies provided by law.

                  Section 7.04 Further Assurances. The Borrower agrees to do
                               ------------------
such further acts and things and to execute and deliver to the Liquidity
Provider such additional assignments, agreements, powers and instruments as the
Liquidity Provider may reasonably require or deem advisable to carry into effect
the purposes of this Agreement and the other Operative Agreements or to better
assure

                                       24
<PAGE>

and  confirm  unto the  Liquidity  Provider  its  rights,  powers  and  remedies
hereunder and under the other Operative Agreements.

                  Section 7.05 Indemnification; Survival of Certain Provisions.
                               -----------------------------------------------
The Liquidity Provider shall be indemnified hereunder to the extent and in the
manner described in Section 7 of the AFE Note Purchase Agreement, Sections 7(b)
and 7(c) of the Leased Aircraft Participation Agreement, Section 7(c) of the 747
Leased Aircraft Participation Agreement and Section 5(b) of the Owned Aircraft
Participation Agreement. In addition, the Borrower agrees to indemnify, protect,
defend and hold harmless the Liquidity Provider from, against and in respect of,
and shall pay on demand, all Expenses (including the expenses set forth in
Section 7 of the 747 Leased Equipment Note Purchase Agreement, Section 9 of the
AFE Note Purchase Agreement and Section 7 of the United Equipment Note Purchase
Agreement) of any kind or nature whatsoever (other than any Expenses of the
nature described in Section 3.01, 3.02 or 7.07 hereof or in the Fee Letter
                    ------------  ----    ----
(regardless of whether indemnified against pursuant to said Sections or in such
Fee Letter)) that may be imposed, incurred by or asserted against any Liquidity
Indemnitee, in any way relating to, resulting from, or arising out of or in
connection with any action, suit or proceeding by any third party against such
Liquidity Indemnitee and relating to this Agreement, the Intercreditor
Agreement, the Fee Letter or any Participation Agreement; provided, however,
                                                          --------  -------
that the Borrower shall not be required to indemnify, protect, defend and hold
harmless any Liquidity Indemnitee in respect of any Expense of such Liquidity
Indemnitee to the extent such Expense is (i) attributable to the gross
negligence or willful misconduct of such Liquidity Indemnitee or any other
Liquidity Indemnitee, (ii) ordinary and usual operating overhead expense or
(iii) attributable to the failure by such Liquidity Indemnitee or any other
Liquidity Indemnitee to perform or observe any agreement, covenant or condition
on its part to be performed or observed in this Agreement, the Intercreditor
Agreement, the Fee Letter or any other Operative Agreement to which it is a
party. The indemnities and cost provisions contained in Section 7 of the AFE
Note Purchase Agreement, Section 5(i) of the 747 Leased Equipment Note Purchase
Agreement, Section 4(i) of the United Equipment Note Purchase Agreement,
Sections 7(b) and 7(c) of the Leased Aircraft Participation Agreement, Section
7(c) of the 747 Leased Aircraft Participation Agreement, and Section 5(b) of the
Owned Aircraft Participation Agreement and the provisions of Sections 3.01,
                                                             -------------
3.02, 3.03, 3.09 7.05 and 7.07 shall survive the termination of this Agreement.
----  ----  ---- ----     ----

                  Section 7.06 Liability of the Liquidity Provider. (a) Neither
                               -----------------------------------
the Liquidity Provider nor any of its officers, directors, employees or
affiliates shall be liable or responsible for: (i) the use which may be made of
the Advances or any acts or omissions of the Borrower or any beneficiary or
transferee in connection therewith; (ii) the validity, sufficiency or
genuineness of documents, or of any endorsement thereon, even if such documents
should prove to be in any or all respects invalid, insufficient, fraudulent or
forged; or (iii) the making of Advances by the Liquidity Provider against
delivery of a Notice of Borrowing and other documents which do not comply with
the terms hereof; provided, however, that the Borrower shall have a claim
                  --------  -------
against the Liquidity Provider, and the

                                       25
<PAGE>

Liquidity Provider shall be liable to the Borrower, to the extent of any damages
suffered by the Borrower which were the result of (A) the Liquidity Provider's
willful misconduct or negligence in determining whether documents presented
hereunder comply with the terms hereof, or (B) any breach by the Liquidity
Provider of any of the terms of this Agreement, including, but not limited to,
the Liquidity Provider's failure to make lawful payment hereunder after the
delivery to it by the Borrower of a Notice of Borrowing complying with the terms
and conditions hereof.

                  (b) Neither the Liquidity Provider nor any of its officers,
employees, directors or Affiliates shall be liable or responsible in any respect
for (i) any error, omission, interruption or delay in transmission, dispatch or
delivery of any message or advice, however transmitted, in connection with this
Agreement or any Notice of Borrowing delivered hereunder, or (ii) any action,
inaction or omission which may be taken by it in good faith, absent willful
misconduct or negligence (in which event the extent of the Liquidity Provider's
potential liability to the Borrower shall be limited as set forth in the
preceding paragraph), in connection with this Agreement or any Notice of
Borrowing.

                  Section 7.07 Costs, Expenses and Taxes. The Borrower agrees to
                               -------------------------
pay, or cause to be paid (A) on the Effective Date and on such later date or
dates on which the Liquidity Provider shall make demand, all reasonable out-of-
pocket costs and expenses of the Liquidity Provider in connection with the
preparation, negotiation, execution, delivery, filing and recording of this
Agreement, any other Operative Agreement and any other documents which may be
delivered in connection with this Agreement, including, without limitation, the
reasonable fees and expenses of outside counsel for the Liquidity Provider and
(B) on demand, all reasonable costs and expenses of the Liquidity Provider
(including reasonable counsel fees and expenses) in connection with (i) the
enforcement of this Agreement or any other Operative Agreement, (ii) the
modification or amendment of, or supplement to, this Agreement or any other
Operative Agreement or such other documents which may be delivered in connection
herewith or therewith (whether or not the same shall become effective) or (iii)
any action or proceeding relating to any order, injunction, or other process or
decree restraining or seeking to restrain the Liquidity Provider from paying any
amount under this Agreement, the Intercreditor Agreement or any other Operative
Document or otherwise affecting the application of funds in the Class A-1 Cash
Collateral Account. In addition, the Borrower shall pay any and all recording,
stamp and other similar taxes and fees payable or determined to be payable in
connection with the execution, delivery, filing and recording of this Agreement
any other Operative Agreement and such other documents, and agrees to save the
Liquidity Provider harmless from and against any and all liabilities with
respect to or resulting from any delay in paying or omission to pay such taxes
or fees.

                  Section 7.08 Binding Effect; Participations. (a) This
                               ------------------------------
Agreement shall be binding upon and inure to the benefit of the Borrower and the
Liquidity Provider and their respective successors and assigns, except that
neither the Liquidity Provider (except as otherwise provided in this Section
                                                                     -------
7.08) nor the Borrower (except as contemplated by Section 3.08) shall have the
----                                              ------------
right to

                                       26
<PAGE>

assign its rights or obligations hereunder or any interest herein without the
prior written consent of the other party, subject to the requirements of Section
                                                                         -------
7.08(b). The Liquidity Provider may grant participations herein or in any of its
-------
rights hereunder and under the other Operative Agreements to such Persons (other
than United or any of its Affiliates) as the Liquidity Provider may in its sole
discretion select, subject to the requirements of Section 7.08(b). No such
                                                  ---------------
participation by the Liquidity Provider, however, shall relieve the Liquidity
Provider of its obligations hereunder. In connection with any participation or
any proposed participation, the Liquidity Provider may disclose to the
participant or the proposed participant any information that the Borrower is
required to deliver or to disclose to the Liquidity Provider pursuant to this
Agreement. The Borrower acknowledges and agrees that the Liquidity Provider's
source of funds may derive in part from its participants. Accordingly,
references in this Agreement and the other Operative Agreements to
determinations, reserve and capital adequacy requirements, increased costs,
reduced receipts and the like as they pertain to the Liquidity Provider shall be
deemed also to include those of each of its participants that are banks
(subject, in each case, to the maximum amount that would have been incurred by
or attributable to the Liquidity Provider directly if the Liquidity Provider,
rather than the participant, had held the interest participated other than a
result of a change in law following the date of any participation).

         (b) If, pursuant to Section 7.08(a) above, the Liquidity Provider sells
                             ---------------
any participation in this Agreement to any bank or other entity (each, a
"Participating Institution"), then, concurrently with the effectiveness of such
 -------------------------
participation, the Participating Institution shall (i) represent to the
Liquidity Provider (for the benefit of the Liquidity Provider and the Borrower)
either (A) that it is incorporated under the laws of the United States or a
state thereof or (B) that under applicable law and treaties, no taxes shall be
required to be withheld by the Borrower or the Liquidity Provider with respect
to any payments to be made to such Participating Institution in respect of this
Agreement, (ii) furnish to the Liquidity Provider and the Borrower either (x) a
statement that it is incorporated under the laws of the United States or a state
thereof or (y) if it is not so incorporated, two copies of a properly completed
United States Internal Revenue Service Form W-8ECI or Form W-8BEN, as
appropriate, or other applicable form, certificate or document prescribed by the
Internal Revenue Service certifying, in each case, such Participating
Institution's entitlement to a complete exemption from United States federal
withholding tax in respect to any and all payments to be made hereunder, and
(iii) agree (for the benefit of the Liquidity Provider and the Borrower) to
provide the Liquidity Provider and the Borrower a new Form W-8ECI or Form W-
8BEN, as appropriate, (A) on or before the date that any such form expires or
becomes obsolete or (B) after the occurrence of any event requiring a change in
the most recent form previously delivered by it and prior to the immediately
following due date of any payment by the Borrower hereunder, certifying in the
case of a Form W- 8BEN or Form W-8ECI that such Participating Institution is
entitled to a complete exemption from United States federal withholding tax on
payments under this Agreement. Unless the Borrower has received forms or other
documents reasonably satisfactory to it (and required by applicable law) from
the Participating Institution indicating that payments hereunder are not subject
to United States

                                       27
<PAGE>

federal withholding tax, the Borrower shall withhold taxes as required by law
from such payments at the applicable statutory rate without any obligation to
make additional payments under Section 3.03.
                               ------------

                  (c) Notwithstanding the other provisions of this Section 7.08,
the Liquidity Provider may assign and pledge all or any portion of the Advances
owing to it to any Federal Reserve Bank or the United States Treasury as
collateral security pursuant to Regulation A of the Board of Governors of the
Federal Reserve System and any Operating Circular issued by such Federal Reserve
Bank, provided that any payment in respect of such assigned Advances made by the
Borrower to the Liquidity Provider in accordance with the terms of this
Agreement shall satisfy the Borrower's obligations hereunder in respect of such
assigned Advance to the extent of such payment. No such assignment shall release
the Liquidity Provider from its obligations hereunder.

                  Section 7.09  Severability.  Any  provision of this  Agreement
                                ------------
which is prohibited,  unenforceable or not authorized in any jurisdiction shall,
as to such  jurisdiction,  be  ineffective  to the  extent of such  prohibition,
unenforceability  or   non-authorization   without  invalidating  the  remaining
provisions hereof or affecting the validity,  enforceability or legality of such
provision in any other jurisdiction.

                  Section 7.10 GOVERNING LAW. THIS AGREEMENT 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 UNDER THIS AGREEMENT SHALL BE DETERMINED IN ACCORDANCE
WITH SUCH LAWS.

                  Section 7.11 Submission to Jurisdiction; Waiver of Jury Trial;
                               -------------------------------------------------
Waiver of Immunity.
------------------

                  (a)  Each of the parties hereto hereby irrevocably and
         unconditionally:

                  (i)  submits for itself and its property in any legal action
         or proceeding relating to this Agreement or any other Operative
         Agreement, or for recognition and enforcement of any judgment in
         respect hereof or thereof, to the non-exclusive general jurisdiction of
         the courts of the State of New York, the courts of the United States of
         America for the Southern District of New York, and the appellate courts
         from any thereof;

                  (ii) consents that any such action or proceeding may be
         brought in such courts, and waives any objection that it may now or
         hereafter have to the venue of any such action or proceeding in any
         such court or that such action or proceeding was brought in an
         inconvenient court and agrees not to plead or claim the same;

                                       28
<PAGE>

                  (iii) agrees that service of process in any such action or
         proceeding may be effected by mailing a copy thereof by registered or
         certified mail (or any substantially similar form of mail), postage
         prepaid, to each party hereto at its address set forth in Section 7.02,
         or at such other address of which the Liquidity Provider shall have
         been notified pursuant thereto; and

                  (iv)  agrees that nothing herein shall affect the right to
         effect service of process in any other manner permitted by law or shall
         limit the right to sue in any other jurisdiction.

                  (b)   THE BORROWER AND THE LIQUIDITY PROVIDER EACH HEREBY
AGREE TO WAIVE THEIR RESPECTIVE RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF
ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT OR ANY DEALINGS BETWEEN THEM
RELATING TO THE SUBJECT MATTER OF THIS AGREEMENT AND THE RELATIONSHIP THAT IS
BEING ESTABLISHED, including, without limitation, contract claims, tort claims,
breach of duty claims and all other common law and statutory claims. The
Borrower and the Liquidity Provider each warrant and represent that it has
reviewed this waiver with its legal counsel, and that it knowingly and
voluntarily waives its jury trial rights following consultation with such legal
counsel. THIS WAIVER IS IRREVOCABLE, AND CANNOT BE MODIFIED EITHER ORALLY OR IN
WRITING, AND THIS WAIVER SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS, RENEWALS,
SUPPLEMENTS OR MODIFICATIONS TO THIS AGREEMENT.

                  (c)   The Liquidity Provider hereby waives any immunity it may
have from the jurisdiction of the courts of the United States or of any State
and waives any immunity any of its properties located in the United States may
have from attachment or execution upon a judgment entered by any such court
under the United States Foreign Sovereign Immunities Act of 1976 or any similar
successor legislation.

                  Section 7.12 Execution in Counterparts. This Agreement may be
                               -------------------------
executed in any number of counterparts and by different parties hereto on
separate counterparts, each of which counterpart, when so executed and
delivered, shall be deemed to be an original and all of which counterparts,
taken together, shall constitute but one and the same Agreement.

                  Section 7.13 Entirety. This Agreement and the other Operative
                               --------
Agreements constitute the entire agreement of the parties hereto with respect to
the subject matter hereof and supersedes all prior understandings and agreements
of such parties.

                  Section 7.14 Headings. Section headings in this Agreement are
                               --------
included herein for convenience of reference only and shall not constitute a
part of this Agreement for any other purpose.

                                       29
<PAGE>

                  Section 7.15 LIQUIDITY PROVIDER'S OBLIGATION TO MAKE ADVANCES.
                               ------------------------------------------------
EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, THE OBLIGATIONS OF THE
LIQUIDITY PROVIDER TO MAKE ADVANCES HEREUNDER, AND THE BORROWER'S RIGHTS TO
DELIVER NOTICES OF BORROWING REQUESTING THE MAKING OF ADVANCES HEREUNDER, SHALL
BE UNCONDITIONAL AND IRREVOCABLE, AND SHALL BE PAID OR PERFORMED, IN EACH CASE
STRICTLY IN ACCORDANCE WITH THE TERMS OF THIS AGREEMENT.

                                       30
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and delivered by their respective officers thereunto duly
authorized as of the date first set forth above.

                                         STATE STREET BANK AND TRUST
                                         COMPANY OF CONNECTICUT,
                                         NATIONAL ASSOCIATION, not
                                         in its individual capacity
                                         but solely as Subordination
                                         Agent and Trustee, as
                                         Borrower

                                         By:____________________________________
                                            Name:
                                            Title:

                              S-1
<PAGE>

                                         LANDESBANK HESSEN-THURINGEN
                                         GIROZENTRALE,
                                          as Liquidity Provider

                                         By:____________________________________
                                            Name:
                                            Title:

                                      S-2
<PAGE>

                                                                      Annex I to
                                                      Revolving Credit Agreement

                     INTEREST ADVANCE NOTICE OF BORROWING

         The undersigned, a duly authorized signatory of the undersigned
borrower (the "Borrower"), hereby certifies to Landesbank Hessen-Thuringen
               --------
Girozentrale (the "Liquidity Provider"), with reference to the Revolving Credit
                   ------------------
Agreement, dated as of July 31, 2000, between the Borrower and the Liquidity
Provider (the "Liquidity Agreement"; the terms defined therein and not otherwise
               -------------------
defined herein being used herein as therein defined or referenced), that:

                  (1)   The Borrower is the Subordination Agent under the
         Intercreditor Agreement.

                  (2)   The Borrower is delivering this Notice of Borrowing
         for the making of an Interest Advance by the Liquidity Provider to be
         used for the payment of interest on the Class A-1 Certificates which
         was payable on _____________________ in accordance with the terms and
         provisions of the Class A-1 Trust Agreement and the Class A-1
         Certificates, which Advance is requested to be made on _______________.
         The Interest Advance should be transferred to account __________.

                  (3)   The amount of the Interest Advance requested hereby (i)
         is $__________, to be applied in respect of the payment of interest
         which was due and payable on the Class A-1 Certificates on such
         Distribution Date, (ii) does not include any amount with respect to the
         payment of principal of, or Additional Payments on, the Class A-1
         Certificates, the Class A-2 Certificates, the Class B Certificates, the
         Class C-1 Certificates or the Class C-2 Certificates, or interest on
         the Class A-2 Certificates, the Class B Certificates, the Class C-1
         Certificates or the Class C-2 Certificates, (iii) was computed in
         accordance with the provisions of the Class A-1 Certificates, the Class
         A-1 Trust Agreement and the Intercreditor Agreement (a copy of which
         computation is attached hereto as Schedule I), (iv) does not exceed the
                                           ----------
         Maximum Available Commitment on the date hereof, and (v) has not been
         and is not the subject of a prior or contemporaneous Notice of
         Borrowing.

                  (4)   Upon receipt by or on behalf of the Borrower of the
         amount requested hereby, (a) the Borrower shall apply the same in
         accordance with the terms of Section 3.6(b) of the Intercreditor
         Agreement, (b) no portion of such amount shall be applied by the
         Borrower for any other purpose and (c) no portion of such amount until
         so applied shall be commingled with other funds held by the Borrower.

                                      I-1
<PAGE>

         The Borrower hereby acknowledges that, pursuant to the Liquidity
Agreement, the making of the Interest Advance as requested by this Notice of
Borrowing shall automatically reduce, subject to reinstatement in accordance
with the terms of the Liquidity Agreement, the Maximum Available Commitment by
an amount equal to the amount of the Interest Advance requested to be made
hereby as set forth in clause (i) of paragraph (3) of this Notice of Borrowing
and such reduction shall automatically result in corresponding reductions in the
amounts available to be borrowed pursuant to a subsequent Advance.

         IN WITNESS WHEREOF, the Borrower has executed and delivered this Notice
of Borrowing as of the ____ day of ____________, ___.

                                            STATE STREET BANK AND TRUST
                                            COMPANY OF CONNECTICUT,
                                            NATIONAL ASSOCIATION,
                                            not in its individual capacity but
                                            solely as Subordination Agent, as
                                            Borrower

                                            By:_________________________________
                                               Name:
                                               Title:

                                      I-2
<PAGE>

              SCHEDULE I TO INTEREST ADVANCE NOTICE OF BORROWING

[Insert Copy of Computations in accordance with Interest Advance Notice of
Borrowing]

                                      I-3
<PAGE>

                                                                     Annex II to
                                                      Revolving Credit Agreement

                   NON-EXTENSION ADVANCE NOTICE OF BORROWING

                  The undersigned, a duly authorized signatory of the
undersigned borrower (the "Borrower"), hereby certifies to Landesbank Hessen-
                           --------
Thuringen Girozentrale (the "Liquidity Provider"), with reference to the
                             ------------------
Revolving Credit Agreement, dated as of July 31, 2000, between the Borrower and
the Liquidity Provider (the "Liquidity Agreement"; the terms defined therein and
                             -------------------
not otherwise defined herein being used herein as therein defined or
referenced), that:

                  (1)   The Borrower is the Subordination Agent under the
         Intercreditor Agreement.

                  (2)   The Borrower is delivering this Notice of Borrowing for
         the making of the Non-Extension Advance by the Liquidity Provider to be
         used for the funding of the Class A-1 Cash Collateral Account in
         accordance with Section 3.6(d) of the Intercreditor Agreement, which
         Advance is requested to be made on __________, ____. The Non- Extension
         Advance should be transferred to ____________.

                  (3)   The amount of the Non-Extension Advance requested hereby
         (i) is $_______________.__, which equals the Maximum Available
         Commitment on the date hereof and is to be applied in respect of the
         funding of the Class A-1 Cash Collateral Account in accordance with
         Section 3.6(d) of the Intercreditor Agreement, (ii) does not include
         any amount with respect to the payment of the principal of, or
         Additional Payments on, the Class A-1 Certificates, the Class A-2
         Certificates, the Class B Certificates, the Class C-1 Certificates or
         the Class C-2 Certificates, or interest on the Class A-2 Certificates,
         the Class B Certificates, the Class C-1 Certificates or the Class C-2
         Certificates, (iii) was computed in accordance with the provisions of
         the Class A-1 Certificates, the Class A-1 Trust Agreement and the
         Intercreditor Agreement (a copy of which computation is attached hereto
         as Schedule I), and (iv) has not been and is not the subject of a prior
         or contemporaneous Notice of Borrowing under the Liquidity Agreement.

                  (4)   Upon receipt by or on behalf of the Borrower of the
         amount requested hereby, (a) the Borrower will deposit such amount in
         the Class A-1 Cash Collateral Account and apply the same in accordance
         with the terms of Section 3.6(d) of the Intercreditor Agreement, (b) no
         portion of such amount shall be applied by the Borrower for any other
         purpose and (c) no portion of such amount until so applied shall be
         commingled with other funds held by the Borrower.

                  The Borrower hereby acknowledges that, pursuant to the
Liquidity Agreement, (A) the making of the Non-Extension Advance as requested by
this Notice of Borrowing shall
                                     II-1
<PAGE>

automatically and irrevocably terminate the obligation of the Liquidity Provider
to make further Advances under the Liquidity Agreement; and (B) following the
making by the Liquidity Provider of the Non-Extension Advance requested by this
Notice of Borrowing, the Borrower shall not be entitled to request any further
Advances under the Liquidity Agreement.

                  IN WITNESS WHEREOF, the Borrower has executed and delivered
this Notice of Borrowing as of the ____ day of _________, ____.

                                         STATE STREET BANK AND TRUST
                                         COMPANY OF CONNECTICUT,
                                         NATIONAL ASSOCIATION,
                                         not in its individual capacity but
                                         solely as Subordination Agent, as
                                         Borrower

                                         By:____________________________________
                                             Name:
                                             Title:

                                     II-2
<PAGE>

                      SCHEDULE I TO NON-EXTENSION ADVANCE
                              NOTICE OF BORROWING
                [Insert copy of computations in accordance with
                  Non-Extension Advance Notice of Borrowing]

                                     II-3
<PAGE>

                                                                    Annex III to
                                                      Revolving Credit Agreement

                     DOWNGRADE ADVANCE NOTICE OF BORROWING

         The undersigned, a duly authorized signatory of the undersigned
borrower (the "Borrower"), hereby certifies to Landesbank Hessen-Thuringen
               --------
Girozentrale (the "Liquidity Provider"), with reference to the Revolving Credit
                   ------------------
Agreement dated as of July 31, 2000, between the Borrower and the Liquidity
Provider (the "Liquidity Agreement"; the terms defined therein and not otherwise
               -------------------
defined herein being used herein as therein defined or referenced), that:

                  (1)   The Borrower is the Subordination Agent under the
         Intercreditor Agreement.

                  (2)   The Borrower is delivering this Notice of Borrowing for
         the making of the Downgrade Advance by the Liquidity Provider to be
         used for the funding of the Class A-1 Cash Collateral Account in
         accordance with Section 3.6(c) of the Intercreditor Agreement by reason
         of the downgrading of the relevant rating of the Liquidity Provider
         issued by either Rating Agency below the Threshold Rating, which
         Advance is requested to be made on ______________. The Downgrade
         Advance should be transferred to __________.

                  (3)   The amount of the Downgrade Advance requested hereby (i)
         is $________, which equals the Maximum Available Commitment on the date
         hereof and is to be applied in respect of the funding of the Class A-1
         Cash Collateral Account in accordance with Section 3.6(d) of the
         Intercreditor Agreement, (ii) does not include any amount with respect
         to the payment of principal of, or Additional Payments on, the Class A-
         1 Certificates, the Class A-2 Certificates, the Class B Certificates,
         the Class C-1 Certificates or the Class C-2 Certificates or interest on
         the Class A-2 Certificates, the Class B Certificates, the Class C-1
         Certificates or the Class C-2 Certificates, (iii) was computed in
         accordance with the provisions of the Class A-1 Certificates, the Class
         A-1 Trust Agreement and the Intercreditor Agreement (a copy of which
         computation is attached hereto as Schedule 1), and (iv) has not been
         and is not the subject of a prior or contemporaneous Notice of
         Borrowing under the Liquidity Agreement.

                  (4)   Upon receipt by or on behalf of the Borrower of the
         amount requested hereby, (a) the Borrower shall deposit such amount in
         the Class A-1 Cash Collateral Account and apply the same in accordance
         with the terms of Section 3.6(d) of the Intercreditor Agreement, (b) no
         portion of such amount shall be applied by the Borrower for any other
         purpose and (c) no portion of such amount until so applied shall be
         commingled with other funds held by the Borrower.

                                     III-1
<PAGE>

                  The Borrower hereby acknowledges that, pursuant to the
Liquidity Agreement, (A) the making of the Downgrade Advance as requested by
this Notice of Borrowing shall automatically and irrevocably terminate the
obligation of the Liquidity Provider to make further Advances under the
Liquidity Agreement; and (B) following the making by the Liquidity Provider of
the Downgrade Advance requested by this Notice of Borrowing, the Borrower shall
not be entitled to request any further Advances under the Liquidity Agreement.

                  IN WITNESS WHEREOF, the Borrower has executed and delivered
this Notice of Borrowing as of the _____ day of _________, _____.

                                         STATE STREET BANK AND TRUST COMPANY
                                         CONNECTICUT, NATIONAL ASSOCIATION,
                                         not in its individual capacity but
                                         solely as Subordination Agent, as
                                         Borrower

                                         By:____________________________________
                                            Name:
                                            Title:

                                     III-2
<PAGE>

              SCHEDULE I TO DOWNGRADE ADVANCE NOTICE OF BORROWING

                [Insert Copy of Computations in accordance with
                    Downgrade Advance Notice of Borrowing]

                                     III-3
<PAGE>

                                                                     Annex IV to
                                                      Revolving Credit Agreement

                       FINAL ADVANCE NOTICE OF BORROWING

                  The undersigned, a duly authorized signatory of the
undersigned borrower (the "Borrower"), hereby certifies to Landesbank Hessen-
                           --------
Thuringen Girozentrale (the "Liquidity Provider"), with reference to the
                             ------------------
Revolving Credit Agreement, dated as of July 31, 2000, between the Borrower and
the Liquidity Provider (the "Liquidity Agreement"); the terms defined therein
                             -------------------
and not otherwise defined herein being used herein as therein defined or
referenced), that:

                  (1)   The Borrower is the Subordination Agent under the
         Intercreditor Agreement.

                  (2)   The Borrower is delivering this Notice of Borrowing for
         the making of the Final Advance by the Liquidity Provider to be used
         for the funding of the Class A-1 Cash Collateral Account in accordance
         with Section 3.6(i) of the Intercreditor Agreement by reason of the
         receipt by the Borrower of a Termination Notice from the Liquidity
         Provider with respect to the Liquidity Agreement, which Advance is
         requested to be made on ________________.

                  (3)   The amount of the Final Advance requested hereby (i) is
         $_____________, which equals the Maximum Available Commitment on the
         date hereof and is to be applied in respect of the funding of the Class
         A-1 Cash Collateral Account in accordance with Section 3.6(i) of the
         Intercreditor Agreement, (ii) does not include any amount with respect
         to the payment of principal of, or Additional Payments on the Class A-1
         Certificates, the Class A-2 Certificates, the Class B Certificates, the
         Class C-1 Certificates or the Class C-2 Certificates, or interest on
         the Class A-2 Certificates, the Class B Certificates, the Class C-1
         Certificates or the Class C-2 Certificates, (iii) was computed in
         accordance with the provisions of the Class A-1 Certificates, the Class
         A-1 Trust Agreement and the Intercreditor Agreement (a copy of which
         computation is attached hereto as Schedule I), and (iv) has not been
         and is not the subject of a prior or contemporaneous Notice of
         Borrowing.

                  (4)   Upon receipt by or on behalf of the Borrower of the
         amount requested hereby, (a) the Borrower shall deposit such amount in
         the Class A-1 Cash Collateral Account and apply the same in accordance
         with the terms of Section 3.6(i) of the Intercreditor Agreement, (b) no
         portion of such amount shall be applied by the Borrower for any other
         purpose and (c) no portion of such amount until so applied shall be
         commingled with other funds held by the Borrower.
<PAGE>

                  (5)   The Borrower hereby requests that the Advance requested
         hereby be a Base Rate Advance [and that such Base Rate Advance be
         converted into a LIBOR Advance on the third Business Day following your
         receipt of this notice.]/1/

                  The Borrower hereby acknowledges that, pursuant to the
Liquidity Agreement, (A) the making of the Final Advance as requested by this
Notice of Borrowing shall automatically and irrevocably terminate the obligation
of the Liquidity Provider to make further Advances under the Liquidity
Agreement; and (B) following the making by the Liquidity Provider of the Final
Advance requested by this Notice of Borrowing, the Borrower shall not be
entitled to request any further Advances under the Liquidity Agreement.

                  IN WITNESS WHEREOF, the Borrower has executed and delivered
this Notice of Borrowing as of the _____ day of ___________, _____.

                                         STATE STREET BANK AND TRUST
                                         not in its individual capacity but
                                         solely as Subordination Agent, as
                                         Borrower

                                         By:____________________________________
                                            Name:
                                            Title:

______________________________
/1// Bracketed language may be included at Borrower's option.
 -
<PAGE>

                SCHEDULE I TO FINAL ADVANCE NOTICE OF BORROWING

                [Insert Copy of Computations in accordance with
                      Final Advance Notice of Borrowing]
<PAGE>

                                                                      Annex V to
                                                      Revolving Credit Agreement

                             NOTICE OF TERMINATION

                                    [Date]

State Street Bank and Trust Company
of Connecticut, National Association,
  as Subordination Agent, as Borrower
225 Asylum Street
Goodwin Square
Hartford, Connecticut 06103

Attention: Corporate Trust Administration

Re:      Revolving Credit Agreement, dated as of July 31, 2000, between State
         Street Bank and Trust Company of Connecticut, National Association, as
         Subordination Agent, as agent and trustee for the United Airlines 2000-
         1A-1 Pass Through Trust, as Borrower, and Landesbank Hessen-Thuringen
         Girozentrale (the "Liquidity Agreement")
                            -------------------

Ladies and Gentlemen:

                  You are hereby notified that pursuant to Section 6.01 of the
Liquidity Agreement, by reason of the occurrence of a Liquidity Event of Default
and a Performing Equipment Note Deficiency (each as defined therein), we are
giving this notice to you in order to cause (i) our obligations to make Advances
(as defined therein) under such Liquidity Agreement to terminate on the fifth
Business Day after the date on which you receive this notice and (ii) you to
request a Final Advance under the Liquidity Agreement pursuant to Section 3.6(i)
of the Intercreditor Agreement (as defined in the Liquidity Agreement) as a
consequence of your receipt of this notice.

                  THIS NOTICE IS THE "NOTICE OF TERMINATION" PROVIDED FOR UNDER
THE LIQUIDITY AGREEMENT. OUR OBLIGATIONS TO MAKE ADVANCES UNDER THE LIQUIDITY
AGREEMENT SHALL TERMINATE ON THE FIFTH BUSINESS DAY AFTER THE DATE ON WHICH YOU
RECEIVE THIS NOTICE.
<PAGE>

                                         Very truly yours,

                                         LANDESBANK HESSEN-THURINGEN
                                         GIROZENTRALE,
                                         as Liquidity Provider

                                         By:____________________________________
                                            Name:
                                            Title:

cc:      State Street Bank and Trust Company
         of Connecticut, National Association, as Trustee
<PAGE>

                                                                     Annex VI to
                                                      Revolving Credit Agreement

                   NOTICE OF REPLACEMENT SUBORDINATION AGENT

                                    [Date]

Attention:

Re:      Revolving Credit Agreement, dated as of July 31, 2000, between State
         Street Bank and Trust Company of Connecticut, National Association, as
         Subordination Agent, as agent and trustee for the United Airlines 2000-
         1A-1 Pass Through Trust, as Borrower, and Landesbank Hessen-Thuringen
         Girozentrale (the "Liquidity Agreement")
                            -------------------

Ladies and Gentlemen:

For value received, the undersigned hereby irrevocably transfers to:

                                 --------------------------------
                                        [Name of Transferee]

                                 --------------------------------
                                      [Address of Transferee]

all rights and obligations of the undersigned as Borrower and Subordination
Agent under the Liquidity Agreement referred to above. The transferee has
succeeded the undersigned as Borrower and Subordination Agent under the
Intercreditor Agreement referred to in the first paragraph of the Liquidity
Agreement, pursuant to the terms of Section 8.1 of the Intercreditor Agreement.

     By this transfer, all rights of the undersigned as Borrower and
Subordination Agent under the Liquidity Agreement are transferred to the
transferee and the transferee shall hereafter have the sole rights and
obligations as Borrower and Subordination Agent thereunder. The undersigned
shall pay any costs and expenses of such transfer, including, but not limited
to, transfer taxes or governmental charges.
<PAGE>

We ask that this transfer be effective as of ____________, ____.

                                         STATE STREET BANK AND TRUST COMPANY OF
                                         CONNECTICUT, NATIONAL ASSOCIATION
                                         not in its individual capacity but
                                         solely as Subordination Agent, as
                                         Borrower

                                         By:____________________________________
                                            Name:
                                            Title:

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