Document:

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                                                                   Exhibit 10.31

                            BAXTER INTERNATIONAL INC.
                     Non-Employee Director Compensation Plan
                               adopted May 6, 2003
                              Terms and Conditions

1.   Purpose

This Non-Employee Director Compensation Plan (the "Plan") is adopted by the
Board of Directors (the "Board") of Baxter International Inc. ("Baxter"). This
Plan is adopted pursuant to the Baxter International Inc. 2003 Incentive
Compensation Program (the "Program"), for the purposes stated in the Program.
Capitalized terms defined in the Program that are used without being defined in
the Plan will have the same meaning as in the Program.

2.   Participants

Each member of the Board who is not an employee of Baxter or any of its
subsidiaries shall participate in the Plan (a "Participant").

3.   Restricted Stock

     3.1  On the date of Baxter's annual meeting of stockholders (the "Annual
          Meeting") in each year beginning with the Annual Meeting on May 6,
          2003, and subject to availability of shares of Common Stock under the
          Program, each Participant upon completion of the Annual Meeting shall,
          automatically and without necessity of any action by the Board or any
          committee thereof, receive the number of shares of Restricted Stock
          equal to the quotient of (A) $60,000 divided by (B) the Fair Market
          Value of a share of Common Stock on the date of grant (rounded to the
          nearest whole number which is a multiple of ten) (the "Annual
          Restricted Stock Grant Amount").

     3.2  Each Participant elected or appointed on a date other than the date of
          an Annual Meeting shall, on the date of such election or appointment
          and automatically and without necessity of any action by the Board or
          any committee thereof, receive the number of shares of Restricted
          Stock equal to the product of (A) the Annual Restricted Stock Grant
          Amount (as defined in Section 3.1, subject to adjustment in accordance
          with the Program) for the Restricted Stock awarded on the date of the
          immediately preceding Annual Meeting, multiplied by (B) the quotient
          of (i) the number of full calendar months before the next Annual
          Meeting divided by (ii) 12 (rounded to the nearest whole number which
          is a multiple of ten). The number of shares of Restricted Stock
          granted under this Section 3.2 shall not exceed the number available
          under the Program on the date of grant.

     3.3  Restricted Stock may not be sold, transferred, assigned, pledged,
          hypothecated or otherwise encumbered or disposed of, whether
          voluntarily,

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          involuntarily or by operation of law, until vested pursuant to the
          terms hereof.

     3.4  Subject to Section 11.10 of the Program and except as expressly
          provided in Sections 3.6 and 3.7, all shares of Restricted Stock shall
          vest on the date of and immediately prior to the next Annual Meeting
          following the date of grant.

     3.5  Except as provided in Sections 3.6 and 3.7, if a Participant ceases
          service as a member of the Board before his or her Restricted Stock
          vests, the Participant will forfeit his or her unvested Restricted
          Stock immediately upon ceasing service as a member of the Board.

     3.6  If a Participant dies while serving as a member of the Board, his or
          her unvested Restricted Stock will not be forfeited and will be fully
          vested immediately.

     3.7  If a Participant becomes disabled and unable to continue service as a
          member of the Board, his or her Restricted Stock will not be forfeited
          and will, when the Participant ceases to serve as member of the Board,
          be fully vested.

     3.8  Each Participant receiving Restricted Stock shall have all of the
          rights of a stockholder with respect to the shares of Restricted Stock
          during any period in which the shares of Restricted Stock are subject
          to forfeiture or restrictions on transfer, including the right to vote
          the shares of Restricted Stock and to receive dividends and other
          distributions thereon, unless and until such shares are forfeited
          pursuant to Section 3.5; provided, however, that a dividend or other
          distribution with respect to Restricted Stock (including, without
          limitation, a stock dividend or stock split), other than a cash
          dividend, shall be delivered to Baxter (and the Participant shall, if
          requested by Baxter, execute and return one or more irrevocable stock
          powers related thereto) and shall be subject to the same restrictions
          as the Restricted Stock with respect to which such dividend or other
          distribution was made. Cash dividends paid on the Restricted Stock
          will be reinvested in shares of Common Stock, unless the Participant
          elects otherwise. Common Stock purchased with reinvested cash
          dividends shall not be restricted.

     3.9  If requested by Baxter, each Participant receiving Restricted Stock
          shall enter into an agreement with Baxter incorporating the terms and
          conditions of this Plan. A stock certificate for the shares of
          Restricted Stock awarded will be issued in the name of each
          Participant and deposited, together with a stock power endorsed in
          blank by Participant, with Baxter. Each such certificate shall bear a
          legend in substantially the following form:

                                        2

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                    The transferability of this certificate and the shares of
                    Common Stock represented by it are subject to the terms and
                    conditions (including conditions of forfeiture) contained in
                    the Baxter International Inc. Non-Employee Director
                    Compensation Plan adopted May 6, 2003. A copy of this Plan
                    is available from the Corporate Secretary of Baxter
                    International Inc.

          Subject to the terms of the Program, after the Restricted Stock vests,
          shares of Common Stock free and clear of all restrictions will be
          delivered to the Participant (or to the Participant's legal
          representative, beneficiary or heir).

4.   Stock Options

     4.1  On the date of Baxter's Annual Meeting in each year beginning with the
          Annual Meeting on May 6, 2003, and subject to availability of shares
          of Common Stock under the Program, upon completion of the Annual
          Meeting each Participant shall be granted Stock Options having a value
          equal to $60,000, to be determined by the Board or the Compensation
          Committee of the Board (the "Committee") based on a Black-Scholes or
          other option valuation model in the discretion of the Board or the
          Committee (rounded to the nearest whole number which is a multiple of
          ten) (the "Annual Stock Option Grant Amount").

     4.2  Each Participant elected or appointed on a date other than the date of
          an Annual Meeting shall, on the date of such election or appointment
          and automatically and without necessity of any action by the Board or
          any committee thereof, be granted a Stock Option to purchase that
          number of shares of Common Stock equal to the product of (A) the
          Annual Stock Option Grant Amount (as defined in Section 4.1, subject
          to adjustment in accordance with the Program) for each Stock Option
          granted on the date of the immediately preceding Annual Meeting,
          multiplied by (B) the quotient of (i) the number of full calendar
          months before the next Annual Meeting divided by (ii) 12 (rounded to
          the nearest whole number which is a multiple of ten). The number of
          shares of Common Stock subject to any Stock Option granted under this
          Section 4.2 shall not exceed the number available under the Program on
          the date of grant.

     4.3  The purchase price for each share of Common Stock subject to a Stock
          Option shall be the Fair Market Value of a share of Common Stock on
          the date of grant. The terms of each Stock Option will be as set forth
          in this Plan and the Program. To the extent that any provision of the
          Plan is inconsistent with the Program, the Program shall control. The
          Stock Options are not intended to qualify as Incentive Stock Options
          within the meaning of Section 422 of the United States Internal
          Revenue Code.

                                        3

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     4.4  Subject to Section 11.10 of the Program and except as expressly
          provided in Sections 4.8, 4.9 and 4.10, Stock Options shall first
          become exercisable on the date of and immediately prior to the next
          Annual Meeting following the date of grant.

     4.5  After a Stock Option becomes exercisable and until it expires, it may
          be exercised in whole or in part, in the manner specified by the
          Company. Under no circumstances may a Stock Option be exercised after
          it has expired. Shares of Common Stock may be used to pay the purchase
          price for shares of Common Stock to be acquired upon exercise of a
          Stock Option or fulfill any tax withholding obligation, subject to any
          requirements or restrictions specified by the Company.

     4.6  Except as provided in Sections 4.8, 4.9 and 4.10, if a Participant
          ceases service as a member of the Board before his or her Stock Option
          becomes exercisable, the Stock Option will expire when the Participant
          ceases service as a member of the Board.

     4.7  If a Participant ceases service as a member of the Board after his or
          her Stock Option becomes exercisable, the Stock Option will not expire
          but will remain exercisable. Subject to Sections 4.8, 4.9, 4.10 and
          4.11, the Stock Option will expire three months after the Participant
          ceases service as a member of the Board, unless the Participant dies
          or becomes disabled during such three month period in which case the
          Stock Option will expire on the first anniversary of the date the
          Participant ceased serving as a member of the Board.

     4.8  If a Participant dies while serving as a member of the Board, his or
          her Stock Option will not expire and will remain, or immediately
          become, fully exercisable, as the case may be. Subject to Sections
          4.10 and 4.11, the Stock Option will expire on the first anniversary
          of the Participant's death.

     4.9  If a Participant becomes disabled and unable to continue service as a
          member of the Board, his or her Stock Option will not expire and will
          remain, or when the Participant ceases to serve as member of the Board
          become, fully exercisable, as the case may be. Subject to Sections
          4.10 and 4.11, the Stock Option will expire on the first anniversary
          of the date the Participant ceases service as a member of the Board.

     4.10 If a Participant who has served as a member of the Board for a
          continuous period of at least ten years or who is at least 72 years of
          age ceases to serve as a member of the Board (including without
          limitation by reason of death or disability), his or her Stock Option
          will not expire and will remain, or when the Participant ceases to
          serve as member of the Board become, fully exercisable, as the case
          may be. Subject to Section 4.11, the Stock Option will expire on the
          fifth anniversary of the date the Participant ceases service as a
          member of the Board.

                                        4

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     4.11 Stock Options that have not previously expired will expire at the
          close of business on the tenth anniversary of the date of grant. If a
          Stock Option would expire on a date that is not a Business Day, it
          will expire at the close of business on the last Business Day
          preceding that date. A "Business Day" is any day on which the Common
          Stock is traded on the New York Stock Exchange.

     4.12 An exercisable Stock Option may only be exercised by the Participant,
          his or her legal representative, or a person to whom the Participant's
          rights in the Stock Option are transferred by will or the laws of
          descent and distribution or in accordance with rules and procedures
          established by the Committee.

5.   Cash Compensation

     5.1  Baxter shall pay each Participant a meeting fee of $1,000 for each
          meeting of the Board or any committee thereof attended, and a
          Participant acting as the chairperson of any meeting of a committee of
          the Board shall receive an additional $1,000 for each meeting chaired
          by him or her. Fees shall be paid quarterly in arrears and are payable
          if the Participant attends in person, by conference telephone, or by
          any other means permitted by the Delaware General Corporation Law and
          Baxter's Bylaws.

     5.2  Baxter shall pay each Participant a total annual cash retainer of
          $45,000 per calendar year ("Annual Cash Retainer"). The Annual Cash
          Retainer shall be paid quarterly in arrears. For purposes of
          determining the amount of such quarterly payment, a Participant must
          be a member of the Board on or prior to the 15th day of a month in
          order to be entitled to receive payment of the Annual Cash Retainer
          with respect to that month.

     5.3  Participants shall be eligible to defer payment of cash compensation
          otherwise payable under this Section 5 pursuant to the terms and
          conditions of the Baxter Non-Employee Director Deferred Compensation
          Plan.

6.   Availability of Shares

     If on any grant date, the number of shares of Common Stock which would
     otherwise be granted in the form of Restricted Stock or subject to Stock
     Options granted under the Plan shall exceed the number of shares of Common
     Stock then remaining available under the Program, the available shares
     shall be allocated among the Stock Options and Restricted Stock to be
     granted Participants in proportion to the number of shares subject to Stock
     Options and shares of Restricted Stock that Participants would otherwise be
     entitled to receive, and allocated evenly between Restricted Stock and
     Stock Options.

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7.   General Provisions

     7.1  Subject to the limitations contained in Section 11.9 of the Program,
          the Board or the Committee may, at any time and in any manner, amend,
          suspend, or terminate the Plan or any Stock Option outstanding under
          the Plan.

     7.2  Participation in the Plan does not give any Participant any right to
          continue as a member of the Board for any period of time or any right
          or claim to any benefit unless such right or claim has specifically
          accrued hereunder.

                                        6<PAGE>
                                                                   Exhibit 10.25

                                 AMENDMENT NO. 1

                                     to the

                                   ZK / UNITED

                    CODE SHARE AND REGULATORY COOPERATION AND

                               MARKETING AGREEMENT

This Amendment No. 1 (this "Amendment"), effective as of July 18, 2003, amends
that certain ZK/United Code Share and Regulatory Cooperation and Marketing
Agreement, which was effective as of May 1, 2001 (United Contract No. 155716)
(the "Agreement" or the "Code Share Agreement") executed by and between United
Air Lines, Inc. ("UA") and Great Lakes Aviation, Ltd. ("ZK").

                                    RECITALS
                                    --------

WHEREAS, UA and ZK engage in code share services pursuant to the Agreement;

WHEREAS, pursuant to the terms of the Agreement, UA places its annotated airline
designator code "UA*" on certain ZK - operated flights, as permitted under
applicable law, regulations and policy; and

WHEREAS, UA and ZK wish to amend the Agreement, as envisioned by the provisions
of that certain Memorandum of Understanding dated July 10, 2003, and
acknowledged in writing by UA and ZK on July 11, 2003 (the "MOU").

                                    AGREEMENT

NOW, THEREFORE, in exchange for valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, UA and ZK agree as follows:

1.   INTRODUCTION
     ------------
     ZK and UA are amending the Agreement in order to (i) provide UA with the
     ability to introduce United Express services in five existing and currently
     exclusive ZK operated code share markets and (ii) to allow ZK commercial
     flexibility to seek other code share partners.

2.   CONSTRUCTION
     ------------
     Capitalized terms used herein shall have the same meanings set forth in the
     Agreement unless otherwise defined herein. In the event of any conflict
     between the terms in this Amendment and the terms in the Agreement, the
     terms in this Amendment shall prevail. Captions appearing in this Amendment
     have been inserted

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     for convenience only and will not control, define, limit, enlarge, or
     affect the meaning of this Amendment, the Agreement, or any of their
     provisions.

3.   EFFECT OF AMENDMENT
     -------------------
     Except as expressly set forth herein, this Amendment shall not by
     implication or otherwise limit, impair, constitute a waiver of, or
     otherwise affect the rights and remedies of either UA or ZK under the
     Agreement, as amended, and shall not alter, modify, amend or in any way
     affect the terms, conditions, obligations, covenants or agreements
     contained in the Agreement, as amended, all of which shall continue in full
     force and effect. This Amendment shall apply and be effective only with
     respect to the provisions of the Agreement specifically referred to herein.
     Except as specifically amended hereby, the Agreement, as amended, shall
     continue in full force and effect in accordance with the provisions thereof
     as in existence on the date hereof. After the date hereof, any reference to
     the Agreement shall mean the Agreement as amended hereby.

4.   COUNTERPARTS
     ------------
     This Amendment may be executed in two or more counterparts, each of which
     shall constitute an original but all of which when taken together shall
     constitute but one contract.

5.   RELEASE OF MARKET EXCLUSIVITY
     -----------------------------
     Effective July 8, 2003, by letter of authority to UA, ZK released market
     exclusivity to operate UA* code share services for flights between Denver,
     Colorado and Casper, Wyoming (the "Casper Release"). The signing of the MOU
     officially recognized this release of market exclusivity.

     In addition to the Casper Release, effective with the execution of this
     Amendment, ZK reaffirms the Casper Release, and additionally hereby
     relinquishes, as of the effective date hereof, UA* code share service
     exclusivity in the following markets:

          a.   Santa Fe, New Mexico
          b.   Telluride, Colorado
          c.   Amarillo, Texas
          d.   Cody, Wyoming

     The existing Section A of Attachment 1 to the Agreement, regarding
     exclusive UA* code share markets, is hereby deleted in its entirety and a
     new Section A regarding the complete listing of exclusive UA* code share
     markets as of the effective date of this Amendment, and in the form of
     Section A of Attachment 1 to this Amendment, shall be substituted as
     Section A of Attachment 1 to the Agreement.

6.   FREQUENT FLYER
     --------------
     A. Section 4.F. of the Agreement is hereby amended in its entirety and
     replaced with the following:
     "The Carriers shall participate in each other's frequent flyer programs.
     This Amendment does not preclude either UA or ZK from participating in
     frequent flyer programs with other transportation companies."

     B. Section 4.F. of the Agreement shall be further amended to add the
     following:

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     "UA will commit to Mileage Plus redemption payments to ZK at ******/1/ per
     Y cabin booking on UA* flights operated by ZK, through April 30, 2004.
     Payment of the Mileage Plus redemptions at the ******/1/ level will be
     subject to further review by UA and ZK for either a possible continuation
     at such level or being replaced by a new Mileage Plus agreement to be
     executed by and between the parties. For the period from the execution of
     this Amendment through April 30, 2004, redemption bookings in XY inventory
     will not be reimbursable to ZK, and UA will not bill ZK for any Mileage
     Plus accruals on UA* flights operated by ZK. Mileage Plus redemption
     credits will only be valid for UA* flight segments and will not be
     applicable for any ZK sold and operated flights. No Mileage Plus redemption
     credits will be allowed for any ZK operated but UA* sold (direct sell)
     flight segments in local markets. Details of the agreed terms for Mileage
     Plus redemption credits are set forth in Attachment 3 to this Amendment,
     which Attachment 3 to this Amendment shall constitute Attachment 8 to the
     Agreement."

7.   ADDITIONAL AMENDMENTS
     ---------------------
     A. Preferential Selling. Section 4.G. of the Agreement is hereby amended in
     its entirety and replaced with the following:
     "The Carriers will make all reasonable efforts to implement procedures in
     their respective reservations sales offices to sell the other Carrier's
     services."

     B. Air Cargo Services. Section 4.I.(6) of the Agreement is hereby amended
     in its entirety and replaced with the following:
     "The Carriers shall review cargo activities to investigate what
     opportunities may exist to offer competitive and cost effective air cargo
     services between points in the United States. Further, ZK and UA shall
     cooperatively endeavor to improve the quality of air cargo transportation
     to the shipping community. The Carriers will make all reasonable efforts to
     implement procedures in their respective sales offices to sell the other
     Carrier's cargo services."

     C. Display Improvement. Section 4.J.(1) of the Agreement is hereby amended
     in its entirety and replaced with the following:
     "To the extent permitted by applicable law and regulations, UA and ZK shall
     make all reasonable efforts to display their connecting flights in their
     respective internal reservation systems and direct access displays provided
     through computerized reservations systems."

     D. Distribution/Preferential Selling. Section 4.J.(3) of the Agreement is
     hereby amended in its entirety and replaced with the following:
     "The Carriers shall make all reasonable efforts to implement procedures in
     their respective reservations sales offices to sell the other Carrier's
     services."

     E. Display Improvement. Section A of Attachment 5 to the Agreement is
     hereby amended in its entirety and replaced with the following:
     "To the extent permitted by applicable law and regulations, UA and ZK shall
     make all reasonable efforts to display their connecting flights in the
     Carrier specific display option or direct access programs either UA or ZK
     has with any other computer reservation systems used by travel agents,
     corporate accounts, or any non-airline staff for the purpose of making
     airline reservations, or internal displays."

                                                                               3

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     F. Preferential Selling/Reservation Sales. Section C of Attachment 5 to the
     Agreement is hereby amended in its entirety and replaced with the
     following: "The Carriers shall make all reasonable efforts to implement
     procedures in their respective reservations sales offices to sell the other
     Carrier's services."

8.   TERM
     ----
     Section 5 of the Agreement is hereby amended in its entirety and replaced
     with the following:
     "This Agreement, as amended, will continue through and expire on December
     31, 2005; provided, however, that if, as of December 31, 2005, ZK is in
     compliance with the terms of this Agreement, as amended, then the term of
     this Agreement, as amended, shall be extended automatically through, and
     expire on, April 30, 2007. This Agreement, as amended, may be terminated
     for convenience, and without default, by either party's election upon
     ninety (90) days' prior written notice."

9.   EXCLUSIVITY
     -----------
     Section 7 of the Agreement is hereby amended in its entirety and replaced
     with the following:
     "This Agreement is non-exclusive and does not preclude either UA or ZK from
     entering into or maintaining existing marketing relationships, including
     code sharing with other Carriers. Notwithstanding the previous provision,
     this Agreement shall be exclusive as related to ZK's right to use the UA*
     code on all flights for the markets described in Section A of Attachment 1
     to this Agreement."

10.  STATION SUPPLIES
     ----------------
     A new Section 4.L., "Station Supplies," shall be added to the Agreement as
     follows:
     "Effective for orders of station supplies placed by ZK on or after July 1,
     2003, ZK will pay for, or reimburse UA for, ***/1/ of the cost of such
     station supplies ordered by ZK to support this code share relationship,
     including, but not limited to, boarding pass stock, baggage tag stock,
     ticket wallets and other passenger related supplies. In the event that the
     order totals for a calendar year for station supplies ordered by ZK exceeds
     ********/1/, ZK will also reimburse UA for ****/1/ of the net amount of
     such annual order totals to the extent such annual order totals are in
     excess of ********/1/, with settlement to be made via the monthly Airline
     Clearing House ("ACH") settlement process. For purposes of calculating the
     calendar year order totals, each calendar year shall commence as of January
     1st of each year; provided, however, that the first calendar year shall
     commence as of July 1, 2003 and end on December 31, 2003, and the second
     calendar year shall commence as of January 1, 2004."

11.  DATA CIRCUITS
     -------------
     A new Section 4.M., "Data Circuits"), shall be added to the Agreement as
     follows:
     "Effective for Quantitude data circuit services utilized by ZK on or after
     July 1, 2003, ZK will pay for the Quantitude data circuits in Denver and
     Cheyenne at the rate of ******/1/ per data circuit per month. In addition,
     effective July 1, 2003, ZK will pay for a maintenance retainer for the
     Quantitude data circuits in the amount of ****/1/ per month. Monthly
     payments by ZK for the Quantitude data circuits and maintenance retainer
     shall be collected by UA through the normal monthly Airline Clearing House
     settlement process."

                                                                               4

<PAGE>

12.  COMPLIANCE WITH GOVERNMENT AND SAFETY REQUIREMENTS
     --------------------------------------------------
     Section 6.C. of the Agreement is hereby replaced in its entirety with the
     following:
     "ZK represents and warrants that it is in compliance with the U.S.
     Department of Defense (DoD) Quality and Safety Requirements and that ZK
     continues to comply with applicable Federal Air Regulations (F.A.R.). ZK
     further warrants that it shall maintain compliance with such requirements
     and regulations for the term of this Agreement. Any failure by ZK to
     maintain compliance shall immediately be brought to UA's attention along
     with a description of the corrective actions already implemented by ZK
     and/or a description or plan of correction actions to be taken by ZK. Any
     failure by ZK to maintain compliance with the above-referenced requirements
     and regulations shall be grounds for immediate termination of this
     Agreement by UA without further liability, but with reservation of all
     other rights and remedies available to UA. Additional safety reviews may be
     required at UA's discretion and ZK shall cooperate with all such reviews;"

13.  TERMINATION FOR CAUSE
     ---------------------
     Section 12.B. of the Agreement is hereby amended in its entirety and
     replaced with the following:
     "If either party (the "Defaulting Party") fails to observe or perform any
     of such party's material obligations (excluding ZK's safety, ACH
     settlements or repayment obligations to UA) under the Code Share Agreement,
     as amended, and if this failure continues for a period of ninety (90) days
     after written notice by the non-defaulting party to the Defaulting Party
     (the "cure period"), then, without prejudice to any other rights or
     remedies the non-defaulting party may have, the non-defaulting party may
     terminate the Code Share Agreement upon the passage of ninety (90) days
     after the expiration of such cure period."

14.  ASSUMPTION OF THE AGREEMENT
     ---------------------------
     Neither the execution or delivery of or entry into this Amendment by either
     party, nor any party's actions taken in support thereof or in accordance
     therewith, shall be deemed to be an assumption or adoption of the
     Agreement, as amended. ZK, its successors, assigns, its officers,
     directors, agents, employees, attorneys, servants, subsidiaries, affiliated
     companies, and parent companies (collectively, "ZK") agree and acknowledge,
     notwithstanding anything expressly or impliedly to the contrary in the
     Agreement, as amended, this Amendment, or under applicable law, (1) that
     the execution of this Amendment shall not alter the pre-petition nature of
     the Agreement, as amended, for the purposes of UA's bankruptcy cases under
     Title 11 of Chapter 11 of the United States Code; (2) that the execution of
     this Amendment will not alter the validity, priority or amount of any
     claims of ZK that may arise under the Agreement, as amended; (3) that any
     claims of ZK against UA arising under the Agreement, as amended, shall not
     be elevated to administrative expense priority by reason of the execution
     or delivery of this Amendment; (4) not to assert or claim at any time that
     the execution of this Amendment operates in any way as an assumption or
     adoption of the Agreement, as amended; and (5) not to assert or claim at
     any time that the execution of this Amendment, or any actions taken in
     accordance therewith, (a) alters in any way the pre-petition nature of the
     Agreement, as amended, or the validity, priority or amount of any claims of
     ZK against UA that may arise under the Agreement, as amended, or (b)
     elevates to administrative expense priority.

                                                                               5

<PAGE>

15.  MODIFICATION OF TERMS
     ---------------------
     UA reserves the right to assume or reject the Code Share Agreement, as
     amended, at any time before confirmation of UA's plan of reorganization by
     the bankruptcy court; provided, however, that UA will not make any
     unilateral requests for changes to the terms of the Code Share Agreement
     between the time the execution of this Amendment and the time that the Code
     Share Agreement, as amended, is either assumed or rejected.

16.  ASSIGNMENT AND CHANGE OF OWNERSHIP
     ----------------------------------
     Section 21.B. of the Agreement is hereby amended in its entirety and
     replaced with the following:
     "Should for any reason whatsoever the ownership of either Carrier change
     such that another air carrier or affiliate of an air carrier acquires a ***
     *******/1/ (***/1/) or more ownership interest in either party, then within
     thirty (30) days of such occurrences either party may request renegotiation
     of this Agreement and, failing unsuccessful renegotiation within sixty (60)
     days of the request to renegotiate, either party may terminate this
     Agreement upon thirty (30) days written notice to the other party.
     Provided, however, that any change of ownership arising out of, resulting
     from, or relating to UA's restructuring process or Chapter 11 case is
     excepted from the operation of this paragraph.

17.  AIRLINE CLEARING HOUSE
     ----------------------
     Both parties agree to abide by Airline Clearing House procedures related to
     interline billing ("ACH procedures"). Upon the second instance of breach of
     such ACH procedures by either party (the defaulting party), the
     non-defaulting party shall have the right to terminate the Agreement, as
     amended, immediately upon written notice to the defaulting party.

18.  PERFORMANCE MEASURES
     --------------------
     The following line set forth in Attachment 6 to the Agreement shall be
     amended as follows: On-time departures as scheduled (zero)         ****%/1/

19.  SIDE LETTERS
     ------------
     The following side letters to the Agreement, which side letters are all
     dated February 1, 2001, are hereby withdrawn and terminated, effective
     immediately:
          a.   Frequent Flyer negotiations
          b.   Exclusivity restrictions on code share partners
          c.   UA* code share commitment at Phoenix, Arizona and Minneapolis,
               Minnesota.

20.  ATTACHMENTS
     -----------
     A. Section A of Attachment 1 "Code Sharing" to this Amendment updates the
     market exclusivity list and hereby replaces Section A of Attachment 1 to
     the Agreement.
     B. Attachment 2 "Agreement Regarding Interline Billing Disputes And Outline
     of Terms of New Prorate Agreement" to this Amendment is hereby added as
     Attachment 7 to the Agreement.

                                                                               6

<PAGE>

     C. Attachment 3 "Settlement of Mileage Plus Accruals and Redemptions And
     Terms of New Mileage Plus Agreement" to this Amendment is hereby added as
     Attachment 8 to the Agreement.

     IN WITNESS WHEREOF, the Carriers hereto have, by their duly authorized
     officers, executed this Amendment as of the dates set forth below to be
     effective as of July 18, 2003.

     GREAT LAKES AVIATION, LTD.

     By: /s/ Charles R. Howell IV
         -------------------------------------------------
     Name:    Charles R. Howell IV
     Title:   Chief Executive Officer

     Date:    July 31, 2003
              -------------------------

     UNITED AIR LINES, INC.

     By: /s/ Graham W. Atkinson
         -------------------------------------------------
     Name:    Graham W. Atkinson
     Title:   Senior Vice President Worldwide Sales & Alliances

     Date:    July 30, 2003
              -------------------------

/1/ Material omitted pursuant to a request for confidential treatment. Omitted
material has been filed separately.

                                                                               7

<PAGE>

                                  ATTACHMENT 1
                                  ------------

                                  CODE SHARING

A.   Exclusive city pairs displayed as UA*
     -------------------------------------

     UA shall exclusively display its UA* designation code on the following
     selected flights operated by ZK, provided, however, that UA may remove, and
     ZK shall stop carrying, the UA* designation code from all such flights,
     upon expiration of the Code Share Agreement:

                           ZK Operated Flights Between
                           ---------------------------
                                   Denver and
                                   ----------

                                  Alamosa, CO
                                  Alliance, NE
                                  Chadron, NE
                                  Cheyenne, WY
                                  Cortez, CO
                                  Dickinson, ND
                                  Dodge City, KS
                                  Farmington, NM
                                  Garden City, KS
                                  Gillette, WY
                                  Grand Island, NE
                                  Hays, KS
                                  Huron, SD
                                  Kearney, NE
                                  Laramie, WY
                                  Liberal, KS
                                  Moab, UT
                                  McCook, NE
                                  Norfolk, NE
                                  North Platte, NE
                                  Page, AZ
                                  Pierre, SD
                                  Pueblo, CO
                                  Riverton, WY
                                  Rock Springs, WY
                                  Salina, KS
                                  Scottsbluff, NE
                                  Sheridan, WY
                                  Vernal, UT
                                  Williston, ND
                                  Worland, WY

                           ZK Operated Flights Between
                           ---------------------------
                                   Phoenix and
                                   -----------

                                  Page, AZ

                                                                               8

<PAGE>

                                  Attachment 2
                                  ------------

                 Agreement Regarding Interline Billing Disputes
                 ----------------------------------------------
                  And Outline of Terms of New Prorate Agreement
                  ---------------------------------------------

The agreed methodology to settle past and current interline pricing/billing
disputes is to review six sample months in detail, August, September, and
November of 2001, and January, March, and April of 2002. The findings from these
months will be applied to all subsequent months in the current ACH process (June
2001 - June 2002), along with remaining months (July 2002 forward) which lead up
to the effective date of a new prorate agreement.

The pricing methodology to be applied to the six sample months referenced is
described in more detail below. All discount percentages are based on published
through and local fares as applicable.

     o    CVA discounts will be split *****/1/ with a maximum discount cap of
          ***./1/ Additional CVA discounts in excess of the ***/1/ cap will be
          absorbed by UA, i.e. a ***/1/ discount would be ***/1/ to ZK and
          ***/1/ to UA. Other "ticket designator" fares will also be included in
          this methodology.
     o    UA will absorb Covia certificates.
     o    UA will absorb "customer relations" and similar certificate discounts
          (cs25, pw50, pw100, dbc, etc.).
     o    Bulk & "zero value" tickets settle @ ***/1/ per coupon.
     o    Private fares will settle at fare collected.
     o    UA will absorb web discounts (Orbitz, United.com and other web fares)
          up to **/1/. Web discounts in excess of **/1/ will be settled on a
          *****/1/ split.
     o    T-fare add-on "mistakes" by UA will be absorbed by UA.
     o    Senior or "Silver Travel Pak" tickets will be honored if within the
          originally specified time frames. Outside those time frames they will
          be priced at the next highest published fare.
     o    ZK or UA pricing errors will be corrected as agreed.

It has been determined that UA has no record of ZK disputing billings for July
2001 and December 2001, though ZK felt that rejection notices had been forwarded
to UA. It is agreed that these two months will be included in the resolution
process as described above.

Once this methodology has been applied to all relevant months, the total amounts
actually collected by ZK for these months will be compared to the amounts that
would have been billed using this methodology. The difference will be added to
or subtracted from the pre-petition operational amounts owed by ZK.

These terms will be incorporated into a new prorate agreement effective July 1,
2003.

/1/ Material omitted pursuant to a request for confidential treatment. Omitted
material has been filed separately.

                                                                               9

<PAGE>

                                  Attachment 3
                                  ------------

               Settlement of Mileage Plus Accruals and Redemptions
               ---------------------------------------------------
                     And Terms of New Mileage Plus Agreement
                     ---------------------------------------

UA and ZK will adopt a Mileage Plus settlement methodology (for the period
ending April 30, 2004, as outlined below. This may be superceded by a new
Mileage Plus agreement.

     o    Mileage Plus accrual and redemption will apply to UA* segments for
          connecting itineraries only.
     o    ZK will not pay for mileage accrual on UA* flight segments
     o    No accrual or redemption will be permitted on flight segments
          reflecting the "ZK" code or the direct sell of UA* in local segment ZK
          markets, i.e. lacking a connecting UA flight in the itinerary:

          o    ORD-UA-DEN-UA*(ZK) CYS          accrual and/or redemption applies
          o    ORD-UA-DEN-ZK-CYS               no accrual or redemption DEN-CYS
          o    DEN-ZK-CYS                      no accrual or redemption on ZK
          o    DEN-UA* (direct sell) CYS       no accrual or redemption on UA*
                                               in a local market

     o    "XY" redemption coupons will settle at "zero value".
     o    Redemption payments by UA to ZK of ***/1/ per coupon for all coupons
          reflecting other than "XY" inventory.

/1/ Material omitted pursuant to a request for confidential treatment. Omitted
material has been filed separately.

                                                                              10

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