<PAGE>   1
                                                                     EXHIBIT 4.8



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

                           REVOLVING CREDIT AGREEMENT
                                    (1999-1G)


                         Dated as of September 21, 1999

                                     between

                            WILMINGTON TRUST COMPANY,

                    not in its individual capacity but solely
                             as Subordination Agent,
                          as agent and trustee for the
                America West Airlines Pass Through Trust 1999-1G

                                   as Borrower

                                       and

                      MORGAN STANLEY CAPITAL SERVICES, INC.

                              as Liquidity Provider

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                                   Relating to

                America West Airlines Pass Through Trust 1999-1G
             7.93% America West Airlines Pass Through Certificates,
                                 Series 1999-1G
<PAGE>   2
                                TABLE OF CONTENTS
                                -----------------

<TABLE>
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                                                                                                                                Page

<S>                                                                                                                             <C>
ARTICLE I  DEFINITIONS ........................................................................................................    1

   SECTION 1.01.  CERTAIN DEFINED TERMS .......................................................................................    1

ARTICLE II  AMOUNT AND TERMS OF THE COMMITMENT ................................................................................    7

   SECTION 2.01.  THE ADVANCES ................................................................................................    7
   SECTION 2.02.  MAKING THE ADVANCES .........................................................................................    8
   SECTION 2.03.  FEES ........................................................................................................   10
   SECTION 2.04.  ADJUSTMENTS OR TERMINATION OF THE MAXIMUM COMMITMENT ........................................................   10
   SECTION 2.05.  REPAYMENTS OF INTEREST ADVANCES OR THE FINAL ADVANCE ........................................................   10
   SECTION 2.06.  REPAYMENTS OF PROVIDER 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 THE EXPIRY DATE; NON-EXTENSION ADVANCE .........................................................   12
   SECTION 3.01.  INCREASED COSTS .............................................................................................   13
   SECTION 3.02.  CAPITAL ADEQUACY ............................................................................................   14
   SECTION 3.03.  PAYMENTS FREE OF DEDUCTIONS .................................................................................   15
   SECTION 3.04.  PAYMENTS ....................................................................................................   16
   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 .....................................................................................   17
   SECTION 3.09.  FUNDING LOSS INDEMNIFICATION ................................................................................   17
   SECTION 3.10.  ILLEGALITY ..................................................................................................   18

ARTICLE IV  CONDITIONS PRECEDENT ..............................................................................................   18

   SECTION 4.01.  CONDITIONS PRECEDENT TO EFFECTIVENESS OF SECTION 2.01 .......................................................   18
   SECTION 4.02.  CONDITIONS PRECEDENT TO BORROWING ...........................................................................   20

ARTICLE V  COVENANTS ..........................................................................................................   20

   SECTION 5.01.  AFFIRMATIVE COVENANTS OF THE BORROWER .......................................................................   20
   SECTION 5.02.  NEGATIVE COVENANTS OF THE BORROWER ..........................................................................   20

ARTICLE VI  LIQUIDITY EVENTS OF DEFAULT .......................................................................................   21

   SECTION 6.01.  LIQUIDITY EVENTS OF DEFAULT .................................................................................   21

ARTICLE VII  MISCELLANEOUS ....................................................................................................   21

   SECTION 7.01.  AMENDMENTS, ETC .............................................................................................   21
   SECTION 7.02.  NOTICES, ETC ................................................................................................   21
   SECTION 7.03.  NO WAIVER; REMEDIES .........................................................................................   22
   SECTION 7.04.  FURTHER ASSURANCES ..........................................................................................   22
   SECTION 7.05.  INDEMNIFICATION; SURVIVAL OF CERTAIN PROVISIONS .............................................................   22
   SECTION 7.06.  LIABILITY OF THE LIQUIDITY PROVIDER .........................................................................   23
   SECTION 7.07.  COSTS, EXPENSES AND TAXES ...................................................................................   23
   SECTION 7.08.  BINDING EFFECT; PARTICIPATIONS ..............................................................................   24
   SECTION 7.09.  SEVERABILITY ................................................................................................   25
   SECTION 7.10.  GOVERNING LAW ...............................................................................................   25
   SECTION 7.11.  SUBMISSION TO JURISDICTION; WAIVER OF JURY TRIAL; WAIVER OF IMMUNITY ........................................   25
   SECTION 7.12.  EXECUTION IN COUNTERPARTS ...................................................................................   26
   SECTION 7.13.  ENTIRETY ....................................................................................................   26
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                                       i
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                                TABLE OF CONTENTS
                                   (CONTINUED)


<TABLE>
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<S>                                                                                                                             <C>
   SECTION 7.14.  HEADINGS ....................................................................................................   26
   SECTION 7.15.  TRANSFER ....................................................................................................   26
   SECTION 7.16.  LIQUIDITY PROVIDER'S OBLIGATION TO MAKE ADVANCES ............................................................   27
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                                       ii
<PAGE>   4
                               TABLE OF CONTENTS
                                  (CONTINUED)





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

EXHIBIT I                Form of Guarantee Agreement



                                      iii
<PAGE>   5
                           REVOLVING CREDIT AGREEMENT

         This REVOLVING CREDIT AGREEMENT dated as of September 21, 1999, between
WILMINGTON TRUST COMPANY, a Delaware banking corporation, 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 G Trust (as defined
below) (the "Borrower"), and MORGAN STANLEY CAPITAL SERVICES, INC., a Delaware
corporation (the "Liquidity Provider").

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

         WHEREAS, pursuant to the Class G Trust Agreement (such term and all
other capitalized terms used in these recitals having the meanings set forth or
referred to in Section 1.01), the Class G Trust is issuing the Class G
Certificates;

         WHEREAS, the Borrower, in order to support the timely payment of a
portion of the interest on the Class G 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; and

         WHEREAS, the Liquidity Provider has requested Morgan Stanley Dean
Witter & Co. (the "Guarantor") to enter into a Guarantee Agreement, providing
for the full and unconditional guarantee of the Liquidity Provider's obligations
under this Agreement (the "Guarantee Agreement").

         NOW, THEREFORE, in consideration of the premises, the parties hereto
agree as follows:


                                    ARTICLE I

                                   DEFINITIONS

         Section 1.01. Certain Defined Terms. (a) Definitions. As used in this
Agreement and unless otherwise expressly indicated, or unless the context
clearly requires otherwise, the following capitalized terms shall have the
following respective meanings for all purposes of this Agreement:

         "Additional Cost" has the meaning assigned to such term in Section
    3.01.

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

         "Applicable Liquidity Rate" has the meaning assigned to such term in
    Section 3.07(f).
<PAGE>   6
                                                                               2


         "Applicable Margin" means (A) with respect to any Unpaid Advance or
    Applied Provider Advance, (x) with respect to any LIBOR Advance, 2.00% and
    (y) with respect to any Base Rate Advance, 2.00%, and (B) with respect to
    any Unapplied Provider Advance, (x) with respect to any LIBOR Advance, .35%
    and (y) with respect to any Base Rate Advance, .35%.

         "Applied Downgrade Advance" has the meaning assigned to such term 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).

         "Assignment and Assumption Agreement" means the Assignment and
    Assumption to be entered into between the Borrower and the trustee of the
    Successor Trust, substantially in the form of Exhibit D to the Class G Trust
    Agreement.

         "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 next
    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 (-1/4 of 1%).

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

         "Borrower" has the meaning assigned to such term in the recital of
    parties to this Agreement.

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

         "Business Day" means any day other than a Saturday or Sunday or a day
    on which commercial banks are required or authorized to close in Phoenix,
    Arizona, New York, New York or, so long as any Class G Certificate is
    outstanding, the city and state in which the Class G Trustee, the Borrower
    or any Loan Trustee maintains its Corporate Trust Office or receives or
    disburses funds, and, if the applicable Business Day relates to any Advance
    or other amount bearing interest based on the LIBOR Rate, on which dealings
    are carried on in the London interbank market.
<PAGE>   7
                                                                               3


         "Deposits" has the meaning assigned to such terms in the Deposit
    Agreement.

         "Depositary" has the meaning assigned to such term in the Deposit
    Agreement.

         "Deposit Agreement" means the Deposit Agreement dated as of the date
    hereof between Wilmington Trust Company, as Escrow Agent and ABN AMRO Bank
    N.V., acting through its Chicago branch, as Depositary, pertaining to the
    Class G Certificates, as the same may be amended, modified or supplemented
    from time to time in accordance with the terms thereof.

         "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) taxes imposed on the overall net income, net
    worth, capital or franchise of the Liquidity Provider or of its Lending
    Office by the jurisdiction where such Liquidity Provider's principal office
    or such Lending Office is located, and (ii) Excluded Withholding Taxes.

         "Excluded Withholding Taxes" means (i) withholding Taxes imposed by the
    United States except (but only in the case of a successor Liquidity Provider
    organized under the laws of a jurisdiction outside the United States) to the
    extent that such United States withholding Taxes are imposed as a result of
    any change in applicable law (excluding from change in applicable law for
    this purpose a change in an applicable treaty or other change in law
    affecting the applicability of a treaty) after the date hereof, or in the
    case of a successor Liquidity Provider (including a transferee of an
    Advance) or Lending Office, after the date on which such successor Liquidity
    Provider obtains its interest or on which the Lending Office is changed, and
    (ii) any withholding Taxes imposed by the United States which are imposed or
    increased as a result of the Liquidity Provider failing to deliver to the
    Borrower any certificate or document (which certificate or document in the
    good faith judgment of the Liquidity Provider it is legally entitled to
    provide) which is reasonably requested by the Borrower to establish that
    payments under this Agreement are exempt from (or entitled to a reduced rate
    of) withholding Tax.

         "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 any Taxes.

         "Expiry Date" means September 18, 2000, initially, or any date to which
    the Expiry Date is extended pursuant to Section 2.10.

         "Final Advance" means an Advance made pursuant to Section 2.02(d).
<PAGE>   8
                                                                               4


         "Guarantee Agreement" has the meaning assigned to such term in the
    preliminary statements of this Agreement.

         "Guarantee Event" has the meaning specified in Section 2.02(c).

         "Guarantor" has the meaning assigned to such term in the preliminary
    statements of this Agreement.

         "Intercreditor Agreement" means the Intercreditor Agreement dated as of
    the date hereof, among the Trustees, the Liquidity Provider, the liquidity
    provider under each Liquidity Facility (other than this Agreement), the
    Policy Provider 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:

          (i)  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 G Cash Collateral Account for the purpose of paying
               interest on the Class G Certificates as contemplated by Section
               2.06(a) hereof and, in either case, ending on the next Regular
               Distribution Date; and

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

    provided, however, that (I) if an Unapplied Provider Advance which is a
    LIBOR Advance becomes an Applied Provider Advance, the Interest Period then
    applicable to such Unapplied Provider Advance shall be applicable to such
    Applied Provider Advance and (II) 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 last day of the Interest Period then applicable to
    such outstanding Advances (in the case of clause (y) above).

         "Lending Office" means the office of the Liquidity Provider in which it
    books this facility presently located at New York, New York, or such other
    office as the Liquidity Provider from time to time shall notify the Borrower
    as its "Lending Office" hereunder in which it books this facility; provided
    that the Liquidity Provider shall not change its Lending Office to a Lending
    Office outside the United States of America except in accordance with
    Section 3.01, 3.02 or 3.03 hereof.
<PAGE>   9
                                                                               5


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

         "LIBOR Rate" means, with respect to any Interest Period,

          (i)  the rate per annum appearing on display page 3750 (British
               Bankers Association-LIBOR) of the Dow Jones Markets Service (or
               any successor or substitute Page of such Service, or any
               successor to or substitute for such Service, providing rate
               quotations comparable to those currently provided on such Page
               applicable to deposits in dollars in the London interbank market)
               at approximately 11:00 A.M. (London time) two Business Days
               before the first day of such Interest Period, as the rate for
               dollar deposits with a maturity comparable to such Interest
               Period, or

          (ii) if the rate calculated pursuant to clause (i) above is not
               available, the average (rounded upwards, if necessary, to the
               next 1/16 of 1%) of the rates per annum at which deposits in
               dollars are offered for the relevant Interest Period by three
               banks of recognized standing selected by the Liquidity Provider
               in the London interbank market at approximately 11:00 A.M.
               (London time) two Business Days before the first day of such
               Interest Period in an amount approximately equal to the principal
               amount of the LIBOR Advance to which such Interest Period is to
               apply and for a period comparable to such Interest Period.

         "Liquidity Event of Default" means the occurrence of either (a) the
    Acceleration of all of the Equipment Notes (provided that, with respect to
    the period prior to the Delivery Period Expiry Date, such Equipment Notes
    have an aggregate outstanding principal balance in excess of $125,000,000)
    or (b) an America West Bankruptcy Event.

         "Liquidity Indemnitee" means (i) the Liquidity Provider, (ii) the
    Guarantor, (iii) the respective directors, officers, employees and agents of
    the Liquidity Provider and the Guarantor, and (iv) the successors and
    permitted assigns of the persons described in clauses (i) and (iii),
    inclusive.

         "Liquidity Provider" has the meaning assigned to such term in the
    recital of parties to this Agreement.

         "Maximum Available Commitment" means, 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 that following a
    Provider Advance or a Final Advance, the Maximum Available Commitment shall
    be zero.

         "Maximum Commitment" means initially $27,794,808.60, as the same may be
    reduced from time to time in accordance with Section 2.04(a).
<PAGE>   10
                                                                               6


         "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.

         "Offering Memorandum" means the Offering Memorandum dated September 14,
    1999 relating to the Certificates, as such Offering Memorandum may be
    amended or supplemented.

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

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

         "Regulatory Change" has the meaning assigned to such term 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 G Certificates, that would be payable on the Class G
    Certificates on each of the three successive semiannual Regular Distribution
    Dates immediately 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 G Certificates on such day and without regard to expected
    future payments of principal on the Class G Certificates. Notwithstanding
    the above, in the event of any Policy Provider Election, the Required Amount
    shall be deemed to be reduced by the amount (if positive) by which (a) the
    then outstanding principal balance of each Series G Equipment Note in
    respect of which such Policy Provider Election has been made shall exceed
    (b) the amount of any policy drawings previously paid by the Policy Provider
    in respect of principal on such Series G Equipment Note.

         "Successor Trust" means America West Airlines Pass Through Trust
    1999-1G-S.

         "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 G Certificates have been paid in
    full (or provision has been made for such payment in accordance with the
    Intercreditor Agreement and the Trust Agreements) 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
<PAGE>   11
                                                                               7


    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 of a Termination Notice from the Liquidity Provider pursuant
    to Section 6.01 hereof; 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.

         "Transferee" has the meaning assigned to such term in Section 7.08(b).

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

         "Unpaid Advance" has the meaning assigned to such term in Section 2.05.

         (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:

     "Acceleration", "Affiliate", "America West", "America West Bankruptcy
     Event", "Certificates", "Class C Certificates", "Class G Cash Collateral
     Account", "Class G Certificates", "Class G Certificateholders", "Class G
     Trust", "Class G Trust Agreement", "Class G Trustee", "Closing Date",
     "Controlling Party", "Corporate Trust Office", "Delivery Period Expiry
     Date", "Distribution Date", "Downgraded Facility", "Equipment Notes", "Fee
     Letter", "Final Legal Distribution Date", "Financing Agreement",
     "Indenture", "Initial Purchasers", "Interest Payment Date", "Investment
     Earnings", "Liquidity Facility", "Liquidity Obligations", "Loan Trustee",
     "Moody's", "Non-Extended Facility", "Note Purchase Agreement", "Operative
     Agreements", "Performing Equipment Note", "Person", "Policy Provider",
     "Policy Provider Election", "Pool Balance", "Purchase Agreement", "Rating
     Agency", "Ratings Confirmation", "Regular Distribution Date", "Replacement
     Liquidity Facility", "Responsible Officer", "Scheduled Payment", "Special
     Payment", "Standard & Poor's", "Stated Interest Rate", "Subordination
     Agent", "Taxes", "Threshold Rating", "Transfer", "Trust Agreements",
     "Trustee", and "Written Notice".



                                   ARTICLE II

                       AMOUNT AND TERMS OF THE COMMITMENT

         Section 2.01. The 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
<PAGE>   12
                                                                               8



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(b)) in an aggregate amount at any time outstanding not to exceed the
Maximum Commitment.

         Section 2.02. Making the Advances. (a) Interest Advances shall be made
in one or more Borrowings by delivery to the Liquidity Provider of one or more
written and completed Notices of Borrowing in substantially the form of Annex I
attached hereto, signed by a Responsible Officer of the Borrower, 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 G 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 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 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) 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 G 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, (i) upon a
downgrading of the Guarantor's short-term unsecured debt rating issued by either
Rating Agency below the applicable Threshold Rating or (ii) if the Guarantee
Agreement ceases to be in full force and effect or becomes invalid or
unenforceable or the Guarantor denies its liability thereunder (any such
occurrence, a "Guarantee Event") (as provided for in Section 3.6(c) of the
Intercreditor Agreement), unless a Replacement Liquidity Facility to replace
this Agreement shall have been previously 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
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 G Cash Collateral Account in accordance with said Section 3.6(c)
and Section 3.6(f) of the Intercreditor Agreement.

         (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 hereof by delivery to the Liquidity Provider of a
written and completed Notice of Borrowing in
<PAGE>   13
                                                                               9


substantially the form of Annex IV 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 G Cash Collateral Account (in
accordance with Section 3.6(i) of the Intercreditor Agreement and Section 3.6(f)
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 10:00 a.m. (New York City 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 make available to
the Borrower, in accordance with its payment instructions, the amount of such
Borrowing in U.S. dollars and immediately available funds, before 12:00 noon.
(New York City time) on such Business Day or on such later Business Day
specified in such Notice of Borrowing. If a Notice of Borrowing is delivered by
the Borrower in respect of any Borrowing after 10:00 a.m. (New York City 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
make available to the Borrower, in accordance with its payment instructions, the
amount of such Borrowing in U.S. dollars and in immediately available funds,
before 12:00 Noon (New York City time) on the first Business Day next 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. Payments of proceeds of a
Borrowing 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.

         (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 12:00 Noon
(New York City 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), (c) or (d) hereof to fund the Class G Cash
Collateral Account, the Liquidity Provider shall have no interest in or rights
to the Class G Cash Collateral Account, such Advance or any other amounts from
time to time on deposit in the Class G Cash Collateral Account; provided 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. 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.
<PAGE>   14
                                                                              10


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

         Section 2.04. Adjustments or Termination of the Maximum Commitment.

         (a) Automatic Adjustments. Promptly following each date on which the
Required Amount is (1) reduced as a result of a reduction in the Pool Balance of
the Class G Certificates or otherwise, (2) increased as a result of an increase
in the Stated Interest Rate or (3) subsequent to such an increase described in
clause (2), reduced pursuant to the definition of "Stated Interest Rate", the
Maximum Commitment shall automatically be reduced or increased, as the case may
be, to an amount equal to the Required Amount (as calculated by the Borrower).
The Borrower shall give notice of any such automatic reduction or increase, as
the case may be, of the Maximum Commitment to the Liquidity Provider within two
Business Days thereof. The failure by the Borrower to furnish any such notice
shall not affect such automatic reduction or increase 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 2.05. Repayments of Interest Advances or the Final Advance.
Subject to Sections 2.06, 2.07 and 2.09 hereof, 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 hereof; provided 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, without
limitation, 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 2.06. Repayments of Provider Advances. (a) Amounts advanced
hereunder in respect of a Provider Advance shall be deposited in the Class G
Cash Collateral Account, invested and withdrawn from the Class G 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
<PAGE>   15
                                                                              11


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 G Cash Collateral Account for the purpose of paying interest on the
Class G 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 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; provided further, however, that if, following the making of a
Provider Advance, the Liquidity Provider delivers a Termination Notice to the
Borrower pursuant to Section 6.01 hereof, 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. Subject to Sections
2.07 and 2.09 hereof, immediately upon the withdrawal of any amounts from the
Class G 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 such reduction, plus interest
on the principal amount prepaid as provided in Section 3.07 hereof.

         (b) At any time when an Applied Provider Advance (or any portion
thereof) is outstanding, upon the deposit in the Class G 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 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 aggregate
outstanding principal amount of all 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 G 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
<PAGE>   16
                                                                              12


by the Liquidity Provider to Liquidity Obligations then due and payable in
accordance with the Intercreditor Agreement or, if not provided for in the
Intercreditor Agreement, then in such manner as the Liquidity Provider shall
deem appropriate.

         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 the amounts
that constitute Scheduled Payments, Special Payments or payments under Section
7.1 or 9.1, as the case may be, of the Participation Agreements and Section 6 of
the 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 will 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, the Intercreditor Agreement or any
Participation Agreement. Amounts on deposit in the Class G 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 the Expiry Date; Non-Extension Advance. The
Expiry Date shall be automatically extended, effective on the 25th day prior to
each Expiry Date (unless such Expiry Date is on or after the date that is 15
days after the Final Legal Distribution Date for the Class G Certificates), for
a period of 364 days after such Expiry Date (unless the obligations of the
Liquidity Provider are earlier terminated in accordance with the terms hereof),
without the necessity of any act on the part of the Borrower or the Liquidity
Provider, unless the Liquidity Provider shall advise the Borrower prior to such
25th day that it does not agree to such extension of such Expiry Date, in which
event (and if the Liquidity Provider shall not have been replaced in accordance
with Section 3.6(e) of the Intercreditor Agreement), the Borrower shall be
entitled on and after such 25th day (but prior to the then effective Expiry
Date) to request a Non-Extension Advance in accordance with Section 2.02(b)
hereof 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
<PAGE>   17
                                                                              13


any increased costs incurred by the Liquidity Provider which are reasonably
attributable to its making or maintaining any LIBOR 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, municipal, or foreign laws or regulations (including Regulation
D of the Board of Governors of the Federal Reserve System applicable to banks
generally), or the adoption or making after the date of this Agreement of any
interpretations, directives, or requirements applying to a class of banks
including the Liquidity Provider under any U.S. federal, state, municipal, or
any foreign laws or regulations (whether or not having the force of law but of
the type with which the Liquidity Provider is accustomed to comply) by any
court, central bank or monetary authority charged with the interpretation or
administration thereof in each case not publicly announced on the date hereof (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 (other than Excluded Taxes); or (2) imposes or modifies any reserve,
special deposit, compulsory loan or similar requirements relating to any
extensions of credit hereunder in respect of LIBOR Advances (including any such
Advances or any deposits referred to in the definition of LIBOR Rate or related
definitions), other than (i) costs which arise as a result of the Liquidity
Provider willfully contravening or exceeding any operating limits or other
restrictions imposed on it by any authority; or (ii) if the increased costs
would not have arisen but for any assignment to another Liquidity Provider or an
alteration in the lending office of the Liquidity Provider. 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 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 will notify the Borrower of any event occurring
after the date of this Agreement that will 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; provided, that if the Liquidity Provider fails to give such
notice within 30 days after it obtains such knowledge, the Liquidity Provider
shall, with respect to any costs resulting from such event, only be entitled to
payment under this Section 3.01 for costs incurred from and after the date 30
days prior to the date the Liquidity Provider does give such notice.
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 compensate the Liquidity Provider in respect of
any Additional Costs, shall be prima facie evidence of the amount owed under
this Section.

         Notwithstanding the preceding two paragraphs, the Liquidity Provider
and the Subordination Agent agree that any permitted assignee or participant of
the initial Liquidity Provider which 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).
<PAGE>   18
                                                                              14

         The Liquidity Provider shall not be entitled to compensation under this
Section 3.01 if (1) it shall not be also seeking compensation (if it should be
so entitled) under other comparable contractual provisions in its other
agreements, (2) if its claim under this Section 3.01 arises through
circumstances peculiar to the Liquidity Provider and which do not affect a
similarly organized commercial banking institution in the same jurisdiction
generally, or (3) the Liquidity Provider is not the initial liquidity provider
and America West did not consent to the transfer of this facility to the
Liquidity Provider, for the amount, if any, payable under this Section 3.01
resulting from events occurring prior to the date the Liquidity Provider
acquired its interests hereunder as shall exceed the amount payable under this
Section 3.01 that would have been due to the Liquidity Provider's transferor had
it continued to be the liquidity provider hereunder.

         Section 3.02. Capital Adequacy. If (1) the adoption, after the date
hereof, of any applicable governmental law, rule or regulation regarding capital
adequacy and not publicly announced on the date hereof, (2) any change, after
the date hereof, in the interpretation or administration of any such law, rule
or regulation by any central bank or other governmental authority charged with
the interpretation or administration thereof and not publicly announced on the
date hereof or (3) compliance by the Liquidity Provider or any corporation
controlling the Liquidity Provider with any applicable guideline or request of
general applicability, issued after the date hereof and not publicly announced
on the date hereof, by any central bank or other governmental authority (whether
or not having the force of law but of the type with which the Liquidity Provider
is accustomed to comply) that constitutes a change of the nature described in
clause (2), has the effect of requiring an increase in the amount of capital
required 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 from time to time such additional
amount or amounts as are necessary to compensate the Liquidity Provider for such
portion of such increase 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 that may thereafter accrue and would not, in the reasonable
judgment of the Liquidity Provider, be otherwise materially disadvantageous to
the Liquidity Provider.

         The Liquidity Provider will notify the Borrower of any event occurring
after the date of this Agreement that will 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; provided that if the Liquidity Provider fails to give such
notice within 30 days after it obtains such knowledge, the Liquidity Provider
shall, with respect of any costs resulting from such event, only be entitled to
payment under this Section 3.02 for costs incurred from and after the date 30
days prior to the date the Liquidity Provider does give such notice.
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
<PAGE>   19
                                                                              15


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.

         Notwithstanding the preceding two paragraphs, the Liquidity Provider
and the Subordination Agent agree that any permitted assignee or participant of
the initial Liquidity Provider which 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).

         The Liquidity Provider shall not be entitled to compensation under this
Section 3.02 if (1) it shall not be also seeking compensation (if it should be
so entitled) under other comparable contractual provisions in its other
agreements, (2) if its claim under this Section 3.02 arises through
circumstances peculiar to the Liquidity Provider and which do not affect a
similarly organized commercial banking institution in the same jurisdiction
generally, or (3) the Liquidity Provider is not the initial liquidity provider
and America West did not consent to the transfer of this facility to the
Liquidity Provider, for the amount, if any, payable under this Section 3.02
resulting from events occurring prior to the date the Liquidity Provider
acquired its interests hereunder as shall exceed the amount payable under this
Section 3.02 that would have been due to the Liquidity Provider's transferor had
it continued to be the liquidity provider hereunder.

         Section 3.03. Payments Free of Deductions. 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 present or future stamp or other taxes,
levies, imposts, duties, deductions or withholdings, of a similar nature other
than Excluded Taxes (collectively, "Non-Excluded Taxes" and, individually, a
"Non-Excluded Tax"). If any Non-Excluded Taxes are required to be withheld from
any amounts payable to the Liquidity Provider under this Agreement, the
Liquidity Provider shall notify the Borrower and America West thereof and from
and after such notice, the amounts so payable to the Liquidity Provider shall be
increased to the extent necessary to yield to the Liquidity Provider (after
payment of all Non-Excluded Taxes) the amount it would have received had no such
deduction or withholding occurred. The Liquidity Provider agrees to use
reasonable efforts (consistent with its 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 shall otherwise take such reasonable steps as are open to
it to mitigate the effects of such circumstances provided that the Liquidity
Provider shall be under no obligation to take any such action if to do so would
have a material adverse effect on its business, operations or financial
condition or result in its rights, interests or position under this Agreement
being prejudiced or involved in any unlawful activity . From time to time upon
the reasonable request of the Borrower, the Liquidity Provider agrees to provide
to the Borrower two original Internal Revenue Service Form W-8BEN or W-8ECI, as
appropriate, or any successor or other form prescribed by the Internal Revenue
Service, certifying that the Liquidity Provider is exempt from or entitled to a
reduced rate of United States withholding tax on payments pursuant to this
Agreement.

                  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. (New
York City time) on the day when due.
<PAGE>   20
                                                                              16


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, New York, ABA#021000089, Account Name:
Morgan Stanley Capital Services, Inc., Account #4072-4601, Reference: America
West Airlines, Inc., 1999-1G.

         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 Rate 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 succeeding 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 succeeding 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 will 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 G Cash Collateral Account
to pay interest on the Class G 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 G 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 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 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 will not reduce the
rate of interest payable pursuant to this Section 3.07 below the maximum rate
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.

         (b) Each Advance will be either a Base Rate Advance or a LIBOR Advance
as provided in this Section. Each such Advance will 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.
<PAGE>   21
                                                                              17


         (c) Each LIBOR Advance shall bear interest during each Interest Period
at a rate per annum equal to the LIBOR Rate 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 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 2% until paid.

         (f) 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. 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
attached hereto (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 incurred by it 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 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 not publicly
announced on the date hereof shall make it unlawful or impossible for the
Liquidity Provider (or its Lending Office) to
<PAGE>   22
                                                                              18


maintain or fund its LIBOR Advances without breaking such law, then upon notice
to the Borrower by the Liquidity Provider, the outstanding principal amount of
the LIBOR Advances shall be converted to Base Rate Advances to the extent
necessary to cure such illegality (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. 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 or cure the aforesaid
illegality.


                                   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, and in the case of each document
     delivered pursuant to paragraphs (i), (ii) and (iii), each 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
          executed and delivered on or before the Closing Date (other than this
          Agreement and the Intercreditor Agreement);

               (iv) A copy of the Offering Memorandum and specimen copies of the
          Class G Certificates;

               (v) An executed copy of each document, instrument, certificate
          and opinion delivered on or before the Closing Date pursuant to the
          Class G Trust Agreement, the Intercreditor Agreement and the other
          Operative Agreements (in the case of each such opinion, other than the
          opinion of counsel for the Initial Purchasers, 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
<PAGE>   23
                                                                              19


          given or taken any notice or other similar action as are necessary or
          in order to establish, perfect, protect and preserve the right, title
          and interest of the Liquidity Provider created by the Operative
          Agreements executed and delivered on or prior to the Closing Date;

               (vii) An agreement from America West, pursuant to which America
          West agrees to provide copies of quarterly financial statements and
          audited annual financial statements to the Liquidity Provider (which
          obligations may be satisfied by the furnishing of America West's Form
          10Q and 10K), in each case, only to the extent that America West is
          obligated to provide such information pursuant to Section 8.2.1 of the
          Leases (related to Leased Aircraft) or the corresponding section of
          the Indentures (related to Owned Aircraft) to the parties thereto; and

               (viii) Such other documents, instruments, opinions and approvals
          pertaining to the transactions contemplated hereby or by the other
          Operative Agreements as the Liquidity Provider shall have reasonably
          requested.

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

          (c) The Liquidity Provider shall have received payment in full of all
     fees and other sums required to be paid to or for 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 Initial Purchasers under the Purchase Agreement
     shall have been satisfied (unless any of such conditions precedent shall
     have been waived by the Initial Purchasers).

          (e) The Borrower shall have received (i) the Guarantee Agreement,
     substantially in the form of Exhibit I hereto, duly executed on behalf of
     each of the parties thereto and (ii) 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 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.
<PAGE>   24
                                                                              20




                                    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 will, unless the Liquidity
Provider shall otherwise consent in writing:

          (a) Performance of This and Other 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, such Operative Agreements entered into after
     the date hereof as from time to time may be reasonably requested by the
     Liquidity Provider.

         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 will not appoint or permit or
suffer to be appointed any successor Borrower without the prior written consent
of the Liquidity Provider, which consent shall not be unreasonably withheld or
delayed.


                                   ARTICLE VI

                           LIQUIDITY EVENTS OF DEFAULT

         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 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, (ii) the Borrower to promptly request, and the Liquidity
Provider to promptly make, a Final Advance in accordance with Section 2.02(d)
hereof 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
<PAGE>   25
                                                                              21


thereon, and (iv) subject to Sections 2.07 and 2.09 hereof, 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 or of a waiver by the
Borrower, 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 telecopier and mailed or delivered or sent by telecopier):

                  Borrower:

                  WILMINGTON TRUST COMPANY
                  Rodney Square North
                  1100 North Market Square
                  Wilmington, DE  19890-0001

                  Attention: Corporate Trust Administration
                  Telephone: 302-651-1000
                  Telecopy: 302-651-8882

                  Liquidity Provider:

                  MORGAN STANLEY CAPITAL SERVICES, INC.
                  1585 Broadway
                  New York, New York  10036

                  Attention:  Keith Amburgey
                  Telephone:  (212) 761-2504
                  Telecopy:  (212) 781-0580

                  With a copy of any Notice of Borrowing to be delivered to:

                  MORGAN STANLEY DEAN WITTER & CO.
                  1585 Broadway
<PAGE>   26
                                                                              22


                  New York, New York  10036
                  Attention:  Aaron Lubowitz and Mark Esparrago
                  Telephone:  (212) 761-2526 and (212) 761-2618
                  Telecopy:  (212) 761-0406

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, and (ii) if given by other means, when
delivered at the address specified above. 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 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 7.1 or 9.1, as the case may be, of the Participation
Agreements and Section 6(c) of the Note Purchase Agreement. The indemnities
contained in Section 7.1 or 9.1, as the case may be, of the Participation
Agreements, and Section 6(c) of the Note Purchase Agreement and the provisions
of Sections 3.01, 3.02, 3.03, 3.09, 7.05 and 7.07 hereof, 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, employees, directors 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; or (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 except as executed by the Liquidity Provider; provided, however, that the
Borrower shall have a claim against the Liquidity Provider, and the 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
<PAGE>   27
                                                                              23


payment hereunder after the delivery to it by the Borrower of a Notice of
Borrowing strictly 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 immediately
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 (including, without limitation, the reasonable fees and
expenses of outside counsel for the Liquidity Provider) 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 and (B)
on demand, all reasonable costs and expenses (including reasonable counsel fees
and expenses) of the Liquidity Provider 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) other than amendments
requested by the Liquidity Provider or a transfer made by the Liquidity Provider
either voluntarily or as a result of the mitigation provisions of Article III or
a Non-Extension Drawing or a Downgrade Drawing 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 Agreement or
otherwise affecting the application of funds in the Class G Cash Collateral
Accounts. 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, other than amendments requested by
the Liquidity Provider or a transfer made by the Liquidity Provider either
voluntarily or as a result of the mitigation provisions of Article III or a
Non-Extension Drawing or a Downgrade Drawing, 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
(except as contemplated by Section 3.08) the Borrower shall have the right to
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 (including, without
<PAGE>   28
                                                                              24


limitation, funded participations and participations in rights to receive
interest payments hereunder) and under the other Operative Agreements to such
Persons (other than America West 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, will
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, additional amounts due pursuant to Section 3.03 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 initial Liquidity Provider, rather than the
participant, had held the interest participated and were a U.S. bank).

         (b) If, pursuant to subsection (a) above, the Liquidity Provider sells
any participation in this Agreement to any bank or other entity (each, a
"Transferee"), then, concurrently with the effectiveness of such participation,
the Transferee 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 will be required to be withheld with
respect to any payments to be made to such Transferee 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-8BEN or Form W-8ECI, as
appropriate, or other applicable form, certificate or document prescribed by the
Internal Revenue Service certifying, in each case, such Transferee'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-8BEN or Form W-8ECI, 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-8ECI or Form
W-8BEN that such Transferee 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) indicating that payments hereunder are not
subject to United States federal withholding tax, the Borrower will withhold
taxes as required by law from such payments at the applicable statutory rate.

         (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
<PAGE>   29
                                                                              25


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 LAW OF THE STATE OF NEW YORK.

         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 nonexclusive 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;

          (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 hereof, 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
<PAGE>   30
                                                                              26


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 counterparts, 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, the Intercreditor Agreement and
the other Operative Agreements to which the Liquidity Provider is a party
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.

         Section 7.15. Transfer. The Liquidity Provider hereby acknowledges and
consents to the Transfer contemplated by the Assignment and Assumption
Agreement.

         Section 7.16. 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.
<PAGE>   31



         IN WITNESS WHEREOF, the parties 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.

                  WILMINGTON TRUST COMPANY,
                    not in its individual capacity but solely as Subordination
                    Agent, as agent and trustee for the Class G Trust, as
                    Borrower



                  By: /s/ James P. Lawler
                     --------------------------------
                     Name: James P. Lawler
                     Title: Vice President


                  MORGAN STANLEY CAPITAL SERVICES, INC.,
                  as Liquidity Provider



                  By:
                     ---------------------------------
                     Name:
                     Title:
<PAGE>   32


        IN WITNESS WHEREOF, the parties 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.

                  WILMINGTON TRUST COMPANY,
                    not in its individual capacity but solely as Subordination
                    Agent, as agent and trustee for the Class G Trust, as
                    Borrower



                  By:
                     --------------------------------
                     Name:
                     Title:


                  MORGAN STANLEY CAPITAL SERVICES, INC.,
                  as Liquidity Provider



                  By: /s/ Elinor L. Hoover
                     ---------------------------------
                     Name: Elinor L. Hoover
                     Title: Vice President
<PAGE>   33
                                                                      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 MORGAN STANLEY CAPITAL SERVICES,
INC. (the "Liquidity Provider"), with reference to the Revolving Credit
Agreement (1999-1G) dated as of September 21, 1999, 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, subject to
     clause (3)(v) below, for the payment of interest on the Class G
     Certificates which was payable on ____________, ____ (the "Distribution
     Date") in accordance with the terms and provisions of the Class G Trust
     Agreement and the Class G Certificates, which Advance is requested to be
     made on the date hereof.

          (3) The amount of the Interest Advance requested hereby (i) is
     $_______________.__, to be applied in respect of the payment of the
     interest which was due and payable on the Class G Certificates on the
     Distribution Date, (ii) does not include any amount with respect to the
     payment of principal of, or premium on, the Class G Certificates or the
     Class C Certificates, or interest on the Class C Certificates, (iii) was
     computed in accordance with the provisions of the Class G Certificates, the
     Class G 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, (v) does not include any
     amount of interest which was due and payable on the Class G Certificates on
     such Distribution Date but which remains unpaid due to the failure of the
     Depositary to pay any amount of accrued interest on the Deposits on such
     Distribution Date and (vi) 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 will 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.

         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

                                      I-1
<PAGE>   34
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 _________, ____.


                            WILMINGTON TRUST COMPANY,
                               not in its individual capacity but solely as
                               Subordination Agent, as Borrower


                            By:_________________________________
                               Name:
                               Title:


                                      I-2
<PAGE>   35
               SCHEDULE I TO INTEREST ADVANCE NOTICE OF BORROWING

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






                                      I-2
<PAGE>   36
         IN WITNESS WHEREOF, the Borrower has executed and delivered this Notice
of Borrowing as of the ____ day of _________, ____.


                            WILMINGTON TRUST COMPANY,
                               not in its individual capacity but solely as
                               Subordination Agent, as Borrower


                            By:_________________________________
                               Name:
                               Title:


                                      II-2
<PAGE>   37
                                                                     Annex II to
                                                      Revolving Credit Agreement

                    NON-EXTENSION ADVANCE NOTICE OF BORROWING

         The undersigned, a duly authorized signatory of the undersigned
subordination agent (the "Borrower"), hereby certifies to MORGAN STANLEY CAPITAL
SERVICES, INC. (the "Liquidity Provider"), with reference to the Revolving
Credit Agreement (1999-1G) dated as of September 21, 1999, 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 G Cash Collateral Account in accordance with Section
     3.6(d) of the Intercreditor Agreement, which Advance is requested to be
     made on __________, ____.

          (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 G 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 premium on, the Class G Certificates, or principal of,
     or interest or premium on, the Class C Certificates, (iii) was computed in
     accordance with the provisions of the Class G Certificates, the Class G
     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 G
     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 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.


                                      II-1
<PAGE>   38
               SCHEDULE I TO INTEREST ADVANCE NOTICE OF BORROWING

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




                                      II-2
<PAGE>   39
                                                                    Annex III to
                                                      Revolving Credit Agreement

                      DOWNGRADE ADVANCE NOTICE OF BORROWING

         The undersigned, a duly authorized signatory of the undersigned
subordination agent (the "Borrower"), hereby certifies to MORGAN STANLEY CAPITAL
SERVICES, INC. (the "Liquidity Provider"), with reference to the Revolving
Credit Agreement (1999-1G) dated as of September 21, 1999, 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 G Cash Collateral Account in accordance with Section
     3.6(c) of the Intercreditor Agreement by reason of (i) the downgrading of
     the short-term unsecured debt rating of the Guarantor issued by either
     Rating Agency below the Threshold Rating, or (ii) the occurrence of a
     Guarantee Event, which Advance is requested to be made on __________, ____.

          (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 G
     Cash Collateral Account in accordance with Section 3.6(c) of the
     Intercreditor Agreement, (ii) does not include any amount with respect to
     the payment of the principal of, or premium on, the Class G Certificates,
     or principal of, or interest or premium on, the Class C Certificates, (iii)
     was computed in accordance with the provisions of the Class G Certificates,
     the Class G 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 G
     Cash Collateral Account and apply the same in accordance with the terms of
     Section 3.6(c) 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 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
<PAGE>   40
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 _________, ____.


                            WILMINGTON TRUST COMPANY,
                               not in its individual capacity but solely as
                               Subordination Agent, as Borrower


                            By:_________________________________
                               Name:
                               Title:
<PAGE>   41
               SCHEDULE I TO DOWNGRADE ADVANCE NOTICE OF BORROWING

     [Insert Copy of computations in accordance with Downgrade Advance Notice of
     Borrowing]
<PAGE>   42
                                                                     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 MORGAN STANLEY CAPITAL SERVICES,
INC. (the "Liquidity Provider"), with reference to the Revolving Credit
Agreement (1999-1G) dated as of September 21, 1999, 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 G 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 G
     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 premium on, the Class G Certificates, or
     principal of, or interest or premium on, the Class C Certificates, (iii)
     was computed in accordance with the provisions of the Class G Certificates,
     the Class G 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 will deposit such amount in the Class G
     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.

         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.

                                      IV-1
<PAGE>   43
                  IN WITNESS WHEREOF, the Borrower has executed and delivered
this Notice of Borrowing as of the ____ day of _________, ____.

                              WILMINGTON TRUST COMPANY,
                                       not in its individual capacity but solely
                                       as Subordination Agent, as Borrower

                              By:_________________________________
                                 Name:
                                 Title:
<PAGE>   44
                 SCHEDULE I TO FINAL ADVANCE NOTICE OF BORROWING

     [Insert Copy of Computations in accordance with Final Advance Notice of
     Borrowing]
<PAGE>   45
                                                                      Annex V to
                                                      Revolving Credit Agreement




                              NOTICE OF TERMINATION



                                     [Date]



Wilmington Trust Company,
  as Subordination Agent, as Borrower
Rodney Square North
1100 North Market Square
Wilmington, DE  19890-0001


Re:  Revolving Credit Agreement dated as of September 21, 1999, between
     Wilmington Trust Company, as Subordination Agent, as agent and trustee for
     the America West Airlines Pass Through Trust, 1999-1G-[O/S], as Borrower,
     and MORGAN STANLEY CAPITAL SERVICES, INC., as the Liquidity Provider (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 the
existence of a Performing 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.



                                      V-1
<PAGE>   46
         THIS NOTICE IS THE "NOTICE OF TERMINATION" PROVIDED FOR UNDER THE
LIQUIDITY AGREEMENT. OUR OBLIGATIONS TO MAKE ADVANCES UNDER THE LIQUIDITY
AGREEMENT WILL TERMINATE ON THE FIFTH BUSINESS DAY AFTER THE DATE ON WHICH YOU
RECEIVE THIS NOTICE.

                                         Very truly yours,

                                         MORGAN STANLEY CAPITAL
                                         SERVICES, INC.,
                                             as Liquidity Provider

                                         By:_________________________________
                                              Name:
                                              Title:


                                         By:_________________________________
                                              Name:
                                              Title:


cc:      WILMINGTON TRUST COMPANY,
           as Class G Trustee


                                      V-2
<PAGE>   47
                                                                     Annex VI to
                                                      Revolving Credit Agreement

                    NOTICE OF REPLACEMENT SUBORDINATION AGENT

[Date]
Attention:


         Revolving Credit Agreement dated as of September 21, 1999, between
         WILMINGTON TRUST COMPANY, as Subordination Agent, as agent and trustee
         for the America West Airlines Pass Through Trust, 1999-1G-[O/S], as
         Borrower, and MORGAN STANLEY CAPITAL SERVICES, INC., as the Liquidity
         Provider (the "Liquidity Agreement")


Ladies and Gentlemen:

         For value received, the undersigned beneficiary hereby irrevocably
transfers to:

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


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

all rights and obligations of the undersigned as Borrower under the Liquidity
Agreement referred to above. The transferee has succeeded the undersigned as
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 under the
Liquidity Agreement are transferred to the transferee and the transferee shall
hereafter have the sole rights and obligations as Borrower thereunder. The
undersigned shall pay any costs and expenses of such transfer, including, but
not limited to, transfer taxes or governmental charges.





                                      VI-1
<PAGE>   48
         We ask that this transfer be effective as of _______________, ____.

                             WILMINGTON TRUST COMPANY,
                                      not in its individual capacity but solely
                                      as Subordination Agent, as Borrower

                             By:_________________________________
                                  Name:
                                  Title:




                                      VI-2
<PAGE>   49
                                                                       EXHIBIT I

                        MORGAN STANLEY DEAN WITTER & CO.
            1221 AVENUE OF THE AMERICAS   NEW YORK, NEW YORK   10020



                                                              September 21, 1999


America West Pass Through Trust 1999-1G


Ladies and Gentlemen:

     In consideration of each of the Revolving Credit Agreement (the
"Agreement") dated as of September 21, 1999 between Morgan Stanley Capital
Services Inc., a Delaware corporation (hereinafter "MSCS") and Wilmington Trust
Company as Subordination Agent, as agent and trustee for the America West Pass
Through Trust 1999-1G ("Counterparty"), Morgan Stanley Dean Witter & Co., a
Delaware corporation (hereinafter "MSDW"), hereby irrevocably and
unconditionally guarantees to Counterparty, with effect from the date of the
Agreement, the due and punctual payment of all amounts payable by MSCS under
the Agreement when the same shall become due and payable, whether on scheduled
payment dates, upon demand, upon declaration of termination or otherwise, in
accordance with the terms of the Agreement and giving effect to any applicable
grace period. Upon failure of MSCS punctually to pay any such amounts, and upon
written demand by Counterparty to MSDW at its address set forth in the
signature block of this Guarantee (or to such other address as MSDW may specify
in writing), MSDW agrees to pay or cause to be paid such amounts; provided that
delay by Counterparty in giving such demand shall in no event affect MSDW's
obligations under this Guarantee.

     MSDW hereby agrees that its obligations hereunder shall be unconditional
and will not be discharged except by complete payment of the amounts payable
under the Agreement, irrespective of any claim as to the Agreement's validity,
regularity or enforceability or the lack of authority of MSCS to execute or
deliver the Agreement; or any change in or amendment to the Agreement; or any
waiver or consent by Counterparty with respect to any provisions thereof; or
the absence of any action to enforce the Agreement or the recovery of any
judgment against MSCS or of any action to enforce a judgement against MSCS
under the Agreement; or any similar circumstance which might otherwise
constitute a legal or equitable discharge or defense of a guarantor generally.
MSDW hereby waives diligence, presentment, demand on MSCS for payment or
otherwise (except as provided hereinabove), filing of claims, requirement of a
prior proceeding against MSCS and protest or notice, except as provided for in
the Agreement with respect to amounts payable by MSCS. If at any time payment
under the Agreement is rescinded or must be otherwise restored or returned by
Counterparty upon the insolvency, bankruptcy or reorganization of MSCS or MSDW
or otherwise, MSDW's obligations hereunder with respect to such payment shall
be reinstated upon such restoration or return being made by Counterparty.

     MSDW represents to Counterparty as of the date hereof, which
representations will be deemed to be repeated by MSDW on each date on which a
Transaction is entered into, that:

     (1)  it is duly organized and validly existing under the laws of the
jurisdiction of its incorporation and has full power and legal right to execute
and deliver this Guarantee and to perform the provisions of this Guarantee on
its part to be performed;
<PAGE>   50
                        MORGAN STANLEY DEAN WITTER & CO.

                                                              September 21, 1999
                                                                          Page 2


     (2)  its execution, delivery and performance of this Guarantee have been
and remain duly authorized by all necessary corporate action and do not
contravene any provision of its certificate of incorporation or by-laws or any
law, regulation or contractual restriction binding on it or its assets;

     (3)  all consents, authorizations, approvals and clearances (including,
without limitation, any necessary exchange control approval) and notifications,
reports and registrations requisite for its due execution, delivery and
performance of this Guarantee have been obtained from or, as the case may be,
filed with the relevant governmental authorities having jurisdiction and remain
in full force and effect and all conditions thereof have been duly complied
with and no other action by, and no notice to or filing with, any governmental
authority having jurisdiction is required for such execution, delivery or
performance; and

     (4)  this Guarantee is its legal, valid and binding obligation enforceable
against it in accordance with its terms except as enforcement hereof may be
limited by applicable bankruptcy, insolvency, reorganization or other similar
laws affecting the enforcement of creditors' rights or by general equity
principles.

     By accepting this Guarantee and entering into the Agreement, Counterparty
agrees that MSDW shall be subrogated to all rights of Counterparty against MSCS
in respect of any amounts paid by MSDW pursuant to this Guarantee, provided
that MSDW shall be entitled to enforce or to receive any payment arising out of
or based upon such right of subrogation only to the extent that it has paid all
amounts payable by MSCS under the Agreement.

     This Guarantee shall be governed by and construed in accordance with the
laws of the State of New York. All capitalized terms not otherwise defined
herein shall have the respective meanings assigned to them in the Agreement.

                                        MORGAN STANLEY DEAN WITTER & CO.


                                        By: /s/ Alexander C. Frank
                                            ---------------------------
                                        Name:  Alexander C. Frank
                                        Title: Treasurer



                                       2
<PAGE>   51
                        MORGAN STANLEY DEAN WITTER & CO.

                            SECRETARY'S CERTIFICATE

     I, Charlene R. Herzer, a duly elected and acting Assistant Secretary of
Morgan Stanley Dean Witter & Co., a corporation organized and existing under the
laws of the State of Delaware (the "Corporation"), certify that (i) Alexander C.
Frank is the duly elected Treasurer and Eileen S. Wallace is a duly elected
Assistant Treasurer of the Corporation; (ii) pursuant to Section 7.01 of the
Bylaws of the Corporation and resolutions adopted by a Unanimous Consent of
Directors in Lieu of a Meeting, dated as of May 31, 1997, both of which are
attached as an exhibit, the Treasurer and the Assistant Treasurers are
authorized to enter into agreements and other instruments on behalf of the
Corporation; and (iii) the signatures of Alexander C. Frank and Eileen S.
Wallace appearing below are copies of their genuine signatures:

                                        /s/ Alexander C. Frank
                                        ----------------------

                                        /s/ Eileen S. Wallace
                                        ----------------------

     IN WITNESS WHEREOF, I have hereunto set my name and affixed the seal of
the Corporation as of the 13th day of September, 1999.

                                        /s/ Charlene R. Herzer
                                        ----------------------
                                        Charlene R. Herzer
                                        Assistant Secretary

[SEAL]
<PAGE>   52
                                                                         EXHIBIT


                        MORGAN STANLEY DEAN WITTER & CO.





SECTION 7.01 OF THE BYLAWS


     SECTION 7.01. CONTRACTS. Except as otherwise required by law, the Amended
and Restated Certificate of Incorporation or these Amended and Restated Bylaws,
any contracts or other instruments may be executed and delivered in the name and
on the behalf of the Corporation by such officer or officers of the Corporation
as the Board of Directors may from time to time direct. Such authority may be
general or confined to specific instances as the Board may determine. Subject to
the control and direction of the Board of Directors, the Chairman of the Board,
the President, the Chief Financial Officer, the Chief Strategic and
Administrative Officer, the Chief Legal Officer and the Treasurer may enter
into, execute, deliver and amend bonds, promissory notes, contracts, agreements,
deeds, leases, guarantees, loans, commitments, obligations, liabilities and
other instruments to be made or executed for or on behalf of the Corporation.
Subject to any restrictions imposed by the Board of Directors, such officers of
the Corporation may delegate such powers to others under his or her
jurisdiction, it being understood, however, that any such delegation of power
shall not relieve such officer of responsibility with respect to the exercise of
such delegated power.

RESOLUTION ADOPTED BY A UNANIMOUS CONSENT OF
DIRECTORS IN LIEU OF A MEETING, DATED AS OF MAY 31, 1997



          RESOLVED FURTHER, that the Treasurer shall have charge and custody of,
     and be responsible for, all funds and securities of the Corporation and
     shall be authorized to deposit all such funds in the name of the
     Corporation in banks or other depositories. In addition, the Treasurer
     shall perform all other necessary acts and duties in connection with the
     financial affairs of the Corporation, shall generally perform all duties
     appertaining to the office of treasurer of a corporation and shall perform
     such other duties and have such other powers as may be prescribed by the
     Board, subject to the supervision of the Chief Financial Officer; and

          RESOLVED FURTHER, that the Assistant Treasurer, if any, or, if there
     shall be more than one, the Assistant Treasurers, shall, under the
     supervision of the Treasurer, perform the duties and exercise the powers of
     an assistant treasurer and, in the absence or disability of the Treasurer,
     perform the duties and exercise the powers of the Treasurer. In addition,
     each Assistant Treasurer is authorized to enter into, execute, deliver and
     amend on behalf of the Corporation any and all letters of credit,
     uncommitted short-term credit obligations and short-term promissory notes
     (as defined by generally accepted accounting principles), such
     authorization to cease automatically upon termination of employment with
     the Corporation.