<PAGE>
                                                                    Exhibit 10.2

                   FOURTH AMENDMENT TO CODE SHARE AND REVENUE
                          SHARING AGREEMENT AND RELEASE

      THIS FOURTH AMENDMENT TO CODE SHARE AND REVENUE SHARING AGREEMENT AND
RELEASE (this "Fourth Amendment") is made and entered as of September 5, 2003
(the "Effective Date"), between AMERICA WEST AIRLINES, INC., a Delaware
corporation ("AWA"), MESA AIRLINES, INC., a Nevada corporation ("Mesa"), AIR
MIDWEST, INC., a Kansas corporation ("AM"), and FREEDOM AIRLINES, INC., a Nevada
corporation ("Freedom").

      RECITALS:

      A. AWA, Mesa, AM and Freedom are parties to that certain Code Share and
Revenue Sharing Agreement, dated to be effective February 1, 2001, as amended by
that certain First Amendment to Code Share and Revenue Sharing Agreement, dated
to be effective April 27, 2001, that certain Second Amendment to Code Share and
Revenue Sharing Agreement, dated to be effective October 24, 2003, and that
certain Third Amendment to Code Share and Revenue Sharing Agreement, dated to be
effective January 29, 2003 (the "Code Share Agreement"). All capitalized terms
used herein, but not otherwise defined herein, shall have the meaning given to
such terms in the Code Share Agreement.

      B. The Code Share Agreement requires Mesa to provide certain Flight
Services and Other Services for AWA, pursuant to the terms and conditions of the
Code Share Agreement.

      C. AWA and Mesa desire to amend the Code Share Agreement pursuant to the
terms and conditions of this Fourth Amendment.

      D. AWA and Mesa, subject to certain exceptions, desire to release the
other from certain amounts owed under the Code Share and Revenue Sharing
Agreement dated July 15, 1998, as amended ("Original Agreement") and the Code
Share Agreement.

      E. In connection with the execution of this Amendment, AWA intends to
compensate Mesa in an amount equal to $[. . . *** . . .] ("Payment Amount"),
which amount shall be offset and paid pursuant to the terms of this Fourth
Amendment.

      NOW, THEREFORE, in consideration of the promises, covenants,
representations and warranties hereinafter set forth, and for other valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, AWA
and Mesa, and Freedom and AM as Affiliated Service Providers under and pursuant
to the Code Share Agreement, agree as set forth below.

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
      AMENDMENTS:

      1.    The Parties agree that the first paragraph of Section 2.1 of the
            Code Share Agreement is amended in its entirety as follows:

            Flight Service. During the term of this Agreement, Mesa (and its
            Affiliated Service Providers) shall operate America West Express air
            transportation services (the "Flight Services"), using the Fleet of
            Aircraft established pursuant to Section 2.2, to and from the cities
            and based upon the schedule established from time to time by AWA
            (the "Schedule") in written notice to Mesa (a "Schedule Notice").
            For purposes of this Agreement, "Flights" means flights operated
            pursuant to the Schedule. AWA may change the Schedule by issuance of
            a Schedule Notice at any time. When creating a Schedule, AWA shall:
            (i) take into account Mesa's (or its Affiliated Service Providers')
            aircraft maintenance requirements; (ii) create a Schedule which will
            permit Mesa (or its Affiliated Service Providers)to schedule flight
            crews in a manner consistent with industry operational practices;
            (iii) schedule block times based on AWA's internal block time
            policy; (iv) provide for the following turn times: (a) in a hub
            location: 20 minutes for Dash 8s and 25 minutes for any Aircraft in
            the CRJ Subfleet; and (b) in other stations: 15 minutes for Dash 8s
            and 20 minutes for any Aircraft in the CRJ Subfleet; (v) take into
            account airport facilities available for Aircraft handling; (vi)
            provide for maintenance as required by Section 2.6.3 and scheduled
            heavy maintenance on Aircraft as required from time to time; and
            (vii) provide for at least 45 days prior notice of any holiday
            cancellations. Mesa (and its Affiliated Service Providers) shall
            implement all changes in the Schedule contained in a Schedule Notice
            in accordance with AWA's scheduling requirements within 60 days
            after Mesa's receipt of a Schedule Notice. Mesa or any of its
            affiliates shall not provide any flight service for any other
            airline for flights that originate in or end in Phoenix, Arizona,
            other than flights approved in advance by AWA, in writing, that are
            scheduled or operated for maintenance requirements only; provided,
            however, that Mesa, until 11:59 p.m. Phoenix time on March 1, 2004,
            may operate [. . . *** . . .] as United Express into Phoenix,
            Arizona [. . . *** . . .].

      2.    The Parties agree that the introductory paragraph of Section 2.2.2
            and Section 2.2.2(a) of the Code Share Agreement are amended in
            their entirety as follows:

            CRJ Fleet Expansion. Pursuant to the Aircraft Contract, Mesa (or its
            Affiliated Service Providers) has the right to acquire additional
            CRJ Model 900 Aircraft, by virtue of firm orders (the "Firm
            Aircraft"), and additional CRJ Models 700 and 900 Aircraft, by
            virtue of options (the "Option Aircraft"), in the number and in the
            months set forth on Exhibit A, attached hereto. The Firm Aircraft
            consist of CRJ Model 900 Aircraft and the Option Aircraft consist of
            CRJ Models 700 and 900

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
            Aircraft as set forth in Exhibit A. For purposes of this Agreement,
            the CRJ Model 200s shall be a "CRJ Subfleet" and the CRJ Model 700s
            and 900s shall be a "CRJ Subfleet". The term "CRJ" is intended to
            refer to CRJ Models 200s, 700s or 900s, as applicable.

            (a)   Each of the Firm Aircraft shall be placed into Flight Services
                  by Mesa (or its Affiliated Service Providers) in the calendar
                  months set forth on Exhibit A (the "Delivery Schedule"). Mesa
                  shall provide AWA with at least 90 days' prior written notice
                  of the week each of the Firm Aircraft will be placed into
                  Flight Service under this Agreement and at least 60 days'
                  prior written notice of the date on which each of the Firm
                  Aircraft will be placed into Flight Service under this
                  Agreement (each, a "Scheduled Delivery Date").

      3.    The Parties agree that Section 2.2.2(c) of the Code Share Agreement
            is amended by: (A) adding the phrase: (i) "or in the calendar month
            in which the Firm Aircraft is to be delivered pursuant to the
            Delivery Schedule, as applicable" after "Scheduled Delivery Date" in
            the first sentence of Section 2.2.2(c); and (ii) "or the calendar
            month in which the Firm Aircraft is to be delivered pursuant to the
            Delivery Schedule, as applicable" after the term "Scheduled Delivery
            Date" is used in the second and third sentences of Section 2.2.2(c);
            and (B) adding the parenthetical "(as initially established by the
            Delivery Notice, as defined in Section 2.2.2(e))" after the term
            "Scheduled Delivery Date" in the Section.

      4.    The Parties agree that the Code Share Agreement is amended by adding
            the following as Section 2.2.2(d):

            Notwithstanding anything contained in Sections 2.2.2(a) and (c) to
            the contrary, Mesa, by providing AWA with written notice (a "Delay
            Notice") at least [. . . *** . . .] prior to the first day of the
            calendar month in which a Firm Aircraft is to be delivered pursuant
            to the Delivery Schedule (the "Scheduled Delivery Month"), may, at
            its sole option and without penalty of any kind, delay the Scheduled
            Delivery Month for a Firm Aircraft by up to [. . . *** . . .] if
            either: (i) Bombardier notifies Mesa, in writing, that Bombardier
            will be unable to deliver the applicable Firm Aircraft on time; or
            (ii) if Mesa, despite using commercially reasonable efforts, is
            unable to obtain financing for the applicable Firm Aircraft, timely
            to deliver the Firm Aircraft in the Scheduled Delivery Month. The
            Delay Notice shall: (i) be accompanied with the Bombardier notice or
            a reasonable description of the efforts made by Mesa to obtain the
            financing and the reason for not obtaining the financing, as
            applicable; and (ii) establish the new Scheduled Delivery Month in
            which the Firm Aircraft being delayed is to be delivered.

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
            Mesa shall only be entitled to extend the Scheduled Delivery Month
            for a Firm Aircraft one time pursuant to this Section 2.2.2(d).

      5.    The Parties agree that the Code Share Agreement is amended by adding
            the following as Section 2.2.2(e):

            Bombardier Delivery Date. Pursuant to Mesa's agreement with
            Bombardier, Bombardier is required to provide Mesa with 90 days'
            written notice of the scheduled delivery week of each Firm Aircraft
            (the "B-90 Notice"). Based on the B-90 Notice, Mesa, at least 60
            days prior to the Scheduled Delivery Date, provides AWA with written
            notice of the Scheduled Delivery Date pursuant to the last sentence
            of Section 2.2.2(a) (the "Delivery Notice") for each Firm Aircraft.
            For purposes of this Section 2.2.2(e), Mesa, based upon a change in
            delivery dates received by Mesa from Bombardier, shall have the
            right to extend the Scheduled Delivery Date to a new date certain
            once for each Firm Aircraft by providing AWA with written notice at
            least 45 days prior to the Scheduled Delivery Date established by
            the applicable Delivery Notice (the "Extension Notice"). If a Firm
            Aircraft is delivered by Mesa to AWA and is ready to be placed into
            Flight Services prior to the Scheduled Delivery Date established by
            the Delivery Notice (as may be extended by an Extension Notice),
            then AWA shall not be obligated to make any payment under this
            Agreement for such Firm Aircraft until the Scheduled Delivery Date
            established by Mesa pursuant to the Delivery Notice (as may be
            extended by an Extension Notice). If a Firm Aircraft is delivered by
            Mesa to AWA and is ready to be placed into Flight Services after the
            Scheduled Delivery Date established by the Delivery Notice (as may
            be extended as a result of an Excusable Delay or an Extension
            Notice), then, notwithstanding anything in Section 2.2.2(c) to the
            contrary, Mesa, within 30 days after receipt of written demand from
            AWA, shall pay to AWA an amount equal to $[. . . *** . . .] for each
            day following the fifth day after the Scheduled Delivery Date that
            the Firm Aircraft is not delivered until the date that the Firm
            Aircraft is available to AWA to be placed into Flight Services under
            this Agreement ("Delay Amount"), not to exceed for any Firm Aircraft
            the greater of (i) $[. . . *** . . .] or (ii) the amount paid by
            Bombardier to Mesa as damages for the late delivery of such Firm
            Aircraft. An "Excusable Delay" shall be defined to include delays
            commencing after the date of the Delivery Notice and before the
            Scheduled Delivery Date (as may be extended by an Extension Notice)
            and occasioned by the following causes:

                  i.    acts of God;

                  ii.   war, warlike operations, act of the enemy, armed
                        aggression, civil commotion, insurrection, riot or
                        embargo;

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                  iii.  fire, explosion, earthquake, lightning, flood, drought,
                        windstorm or other action of the elements or other
                        catastrophic or serious accidents;

                  iv.   epidemic or quarantine restrictions;

                  v.    any change in legislation, acts, orders, directives or
                        regulations of any governmental or other duly
                        constituted authority (other than CRJ Regulatory Changes
                        and CRJ Airworthiness Directives) once the applicable
                        Aircraft type has been certified by the FAA; or

                  vi.   strikes, lock-out, walk-out, and/or other labor
                        troubles, in each case, with respect to employees of
                        Bombardier causing cessation of work;.

            If an Excusable Delay occurs, then the Scheduled Delivery Date for
            purposes of this Section 2.2.2(e) shall be extended for the number
            of days of Excusable Delay ("Excusable Delay Period"), and the Delay
            Amount shall not begin to accrue until the fifth day after the
            Scheduled Delivery Date, as extended by the Excusable Delay Period.
            The terms of this Section 2.2.2(e) are in addition to, and not in
            lieu of, the terms of Sections 2.2.2(c) and 2.2.2(d).

      6.    The Parties agree that the Code Share Agreement is amended by adding
            the following as Section 2.2.2(f):

            [. . . *** . . .]

      7.    The Parties agree that the Code Share Agreement is amended by adding
            the following as Section 2.2.2(g):

            [. . . *** . . .]

      8.    The Parties agree that Section 2.2.3 of the Code Share Agreement is
            amended by adding the following:

            Elimination of CRJ Model 700s. In addition to the terms of Sections
            2.2.4 and 2.2.5(d), (i) in recognition of the total of four (4) CRJ
            Model 900s to be delivered pursuant to the Delivery Schedule in
            October 2003, November 2003 and December 2003, Mesa shall remove, or
            cause Freedom to remove, from the CRJ Subfleet one (1) CRJ Model 700
            at 11:59 p.m. Phoenix time on each of the following dates: November
            24, 2003; December 1, 2003; December 2, 2003; and December 24, 2003;
            and (ii) on each date that a CRJ Model 900 is placed into Flight
            Services pursuant to the terms of this Agreement, commencing with
            the CRJ Model 900 to be delivered in January 2004, Mesa shall
            remove, or shall cause Freedom to remove, from the CRJ Subfleet a
            CRJ Model 700 for each CRJ Model 900 placed into Flight Services,
            until the number of CRJ Model 700s in the CRJ Subfleet is reduced to
            zero, which, pursuant to the Delivery Schedule, is

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
            scheduled to occur upon the delivery of the March 2004 CRJ Model
            900. AWA shall reimburse Mesa for the actual, out-of-pocket costs or
            expenses incurred by Mesa (or Freedom as applicable) as a direct
            result of the painting (including the days out of service for
            painting) of each CRJ Model 700 removed pursuant to this Section
            2.2.3 within thirty (30) days after receipt of an invoice from Mesa
            together with commercially reasonable evidence of such costs or
            expenses.

      9.    The Parties agree that Section 2.2.4 of the Code Share Agreement is
            amended in its entirety as follows:

            Additional CRJ Fleet Reduction. In addition to the terms of Sections
            2.2.3 and 2.2.5, upon 180 days' prior written notice from AWA to
            Mesa given from time to time during the Term, AWA, subject to
            limitations set forth in the next sentence, may require Mesa to
            reduce, or require Mesa to cause Freedom to reduce, the number of
            Aircraft in the combined CRJ Subfleets. AWA shall not require Mesa
            to reduce, or require Mesa to cause Freedom to reduce, the number of
            Aircraft: (i) in the CRJ Model 200 CRJ Subfleet prior to January 1,
            2007; (ii) in the CRJ Model 900s (and CRJ Model 700s if any CRJ
            Model 900s are replaced pursuant to Section 2.2.2(g)) CRJ Subfleet
            prior to: (1) January 1, 2007, if Mesa does not induct any of the
            Put CRJ 900s pursuant to Section 2.2.2(f) (as may be replaced
            pursuant to Section 2.2.2(g) with CRJ Model 700s), or (2) July 1,
            2006, if Mesa inducts one or more of the Put CRJ 900s pursuant to
            Section 2.2.2(f) (as may be replaced pursuant to Section 2.2.2(g)
            with CRJ Model 700s); and (iii) in the combined CRJ Subfleets by
            more than one Aircraft in any Six Calendar Month Period;
            notwithstanding such limitation, during the two (2) Six Calendar
            Month Periods commencing January 1, 2007 and July 1, 2007, AWA may
            reduce the combined CRJ Subfleets by either: (i) up to two (2) CRJ
            Model 200 Aircraft; or (ii) one (1) CRJ Model 900 or CRJ Model 700
            Aircraft and one (1) CRJ Model 200 Aircraft, in each such Six
            Calendar Month Periods. For purposes of this Agreement, "Six
            Calendar Month Period" means each period during the Term (as defined
            below) commencing on January 1 and ending on June 30 and commencing
            on July 1 and ending on December 31.

      10.   The Parties agree that Section 2.2.5 of the Code Share Agreement is
            amended in its entirety as follows:

            Additional Aircraft Reduction.

            (a)   Effective July 1, 2003, the Subfleet of Beech 1900s was
                  reduced to zero. From and after July 1, 2003, Mesa shall no
                  longer provide any Flight Services using Beech 1900s and AWA
                  shall have no payment or other obligations under this
                  Agreement accruing or arising after July 1, 2003 in regards to
                  any

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                  Beech 1900s. All references to the Beech 1900s and the
                  subcontracting of services relating to the Beech 1900s shall
                  be eliminated from the Agreement effective as of July 1, 2003.

            (b)   Mesa, on July 1, 2003, removed one (1) Dash 8 Aircraft from
                  the Dash 8 Subfleet and on September 3, 2003, will remove two
                  (2) Dash 8 Aircraft from the Dash 8 Subfleet. At any time
                  during the Term after August 25, 2007, AWA may require Mesa to
                  reduce the Subfleet of Dash 8s to zero by providing Mesa with
                  at least 180 days' prior written notice of AWA's election to
                  eliminate the Dash 8s on or after such date (the "Dash 8
                  Elimination Notice"). The Dash 8 Elimination Notice may be
                  given at any time during the Term on or after February 27,
                  2007.

            (c)   Mesa removed one (1) CRJ Model 200 from the CRJ Subfleet (for
                  a total of five (5) CRJ Model 200s) on each of the following
                  dates:

                  April 27, 2003
                  June 4, 2003
                  June 22, 2003
                  June 27, 2003
                  July 2, 2003

                  reducing the CRJ Model 200 CRJ Subfleet to 18 Aircraft.

            (d)   Mesa removed two (2) CRJ Model 700s from the CRJ Subfleet at
                  11:59 p.m. Phoenix time on September 2, 2003. Mesa shall
                  remove, or cause Freedom to remove, (or not place into Flight
                  Services, as applicable) one (1) CRJ Model 700 at 11:59 p.m.
                  Phoenix time on September 14, 2003, and two (2) CRJ Model 700s
                  at 11:59 p.m. Phoenix time on September 21, 2003 from the CRJ
                  Subfleet, reducing the CRJ Model 700s in the applicable CRJ
                  Subfleet to 10.

            (e)   On or before October 31, 2003, AWA, by written notice to Mesa,
                  shall have the right to cause the 12 CRJ Model 900s scheduled
                  to be delivered into Flight Services from April, 2005 to
                  November, 2005 (the "Rejectable CRJs"), pursuant to the
                  Delivery Schedule, not to be added to the CRJ Subfleet and not
                  to be placed into Flight Services (the "900 Election Notice").
                  If AWA does not issue the 900 Election Notice, timely, and
                  such failure to issue the 900 Election Notice, timely,
                  continues for 15 days after AWA's receipt of written notice
                  from Mesa stating that AWA failed to issue the 900 Election
                  Notice, then AWA shall have no further right to issue a 900
                  Election Notice and reject the Rejectable CRJs. If AWA issues
                  the Election Notice as provided by this Section 2.2.5(e), then
                  none of the Rejectable CRJs shall be

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                  added to the CRJ Subfleet or placed into Flight Services under
                  this Agreement.

            (f)   Neither Mesa, AM nor Freedom shall operate any Aircraft
                  removed from Flight Services for itself or any other airline
                  while the Aircraft are marked with AWA's livery

            (g)   From and after the date each Aircraft was or is removed from
                  Flight Services pursuant to any section of this Agreement, AWA
                  had and shall have no further payment or other obligation
                  under this Agreement for such Aircraft.

      11.   The Parties agree that Section 2.2.6 is amended in its entirety as
            follows:

            Spares. Mesa shall have available 1 spare CRJ Model 200, 700 or 900
            Aircraft for Flight Services under this Agreement at any time there
            are 25 or more Aircraft in the combined CRJ Subfleets in Flight
            Services under this Agreement and 2 spare CRJ Model 200, 700 or 900
            Aircraft available for Flight Services under this Agreement at any
            time there are 65 or more Aircraft in the combined CRJ Subfleets in
            Flight Services under this Agreement. AWA shall pay the Actual
            Costs, Guaranteed Non-Maintenance Costs (other than overhead) and
            Guaranteed Maintenance Costs actually incurred by or payable to Mesa
            for each spare Aircraft as provided in Section 7.

      12.   The Parties agree that the Code Share Agreement is amended by adding
            the following as Section 2.2.8:

            Affiliated Service Provider Aircraft. Mesa, with at least 30 days'
            prior written notice to AWA, may substitute any Aircraft operated by
            Mesa or Freedom under or pursuant to this Agreement with an aircraft
            of the same model, capacity, configuration and meeting the other
            requirements of this Agreement, operated by an Affiliated Service
            Provider (each, a "Substituted Aircraft"); provided that Mesa and
            such Affiliated Service Provider have complied with the provisions
            of Section 2.1 and all other provisions relating to Affiliated
            Service Providers. Upon each substitution, each Substituted Aircraft
            shall become an Aircraft for all purposes of this Agreement. Mesa
            shall reimburse AWA for any out-of-pocket costs or expenses incurred
            by AWA as a result of the substitution of Aircraft under this
            Section 2.2.8 within thirty (30) days after receipt of an invoice
            from AWA together with commercially reasonable evidence of the
            out-of-pocket costs or expenses actually incurred by AWA.

      13.   The Parties agree that the Code Share Agreement is amended by
            deleting Section 7.1.8.

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
      14.   The parties agree that the Code Share Agreement is amended by adding
            the following as a new Section 7.10:

            Station Costs. AWA shall reimburse to Mesa the costs and expenses
            incurred by Mesa at stations maintained by Mesa in the amounts and
            at the rates set forth in Exhibit B, attached hereto (the "Station
            Costs"). Mesa shall invoice, as part of the "Estimated Costs", and
            AWA shall pay the Station Costs on a monthly basis in accordance
            with Section 7.5.1 of this Agreement. Pursuant to Section 7.5.2 of
            this Agreement, Mesa shall include in each Incurred Costs Statement
            the final amount of the Station Costs payable by AWA to Mesa for
            each applicable calendar month, all as calculated in accordance with
            Exhibit B, attached hereto. Underpayments and overpayments of
            Station Costs shall be reconciled in the manner set forth in Section
            7.5.2 for "Incurred Costs". The terms of Section 7.5.4 shall be
            applicable to the Station Costs included or not included in each
            applicable Incurred Costs Statement; provided, however, that if any
            landlord or operator of any station is entitled to retroactively
            adjust station rents, then the applicable station rent shall be
            adjusted by Mesa as soon as reasonably practicable after such
            adjustment and shall be paid by or reimbursed to AWA within 30 days
            after Mesa provides AWA with notice of such adjustment and
            recalculation. All of the terms contained in Sections 7.8 and 7.9
            shall apply to the invoicing, paying, collecting and auditing of
            Station Costs.

            AWA and Mesa intend for the Station Costs to be effective
            retroactive to January 1, 2003. As soon as practicable and in no
            event later than 90 days after the Effective Date of the Fourth
            Amendment, Mesa shall submit to AWA a reconciliation of the Station
            Costs (the "Reconciliation") since January 1, 2003 calculated in
            accordance with Exhibit F. To the extent the Reconciliation
            discloses that sums are due from AWA to Mesa, AWA shall pay such
            sums to Mesa.

      15.   The Parties agree that Section 8.1 of the Code Share Agreement is
            amended as follows:

            Term. The term of this Agreement (the "Term") commences on the
            Effective Date retroactive to the Contract Date (the "Commencement
            Date") and shall expire at 11:59 p.m., Phoenix time, on June 30,
            2012 ("Expiration Date"), unless earlier terminated as provided in
            this Agreement. Notwithstanding the foregoing to the contrary, if
            the 900 Election Notice is not issued by AWA to Mesa as required by
            Section 2.2.5(e) and the Rejectable CRJs are added to the CRJ
            Subfleet, then the Expiration Date shall be extended to 11:59 p.m.,
            Phoenix time, on November 30, 2013. AWA, by written notice to Mesa
            at

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
            least 180 days prior to the Expiration Date, may extend the
            Expiration Date for two years, expiring at 11:59 p.m., Phoenix time,
            on June 30, 2014 or November 30, 2015, as applicable.

      16.   The Parties agree that Exhibit A to the Code Share Agreement is
            amended in its entirety as set forth in Attachment 1 to this Fourth
            Amendment, and Exhibit B to the Code Share Agreement is amended in
            its entirety as set forth in Attachment 2 to this Fourth Amendment.

      17.   Reserved.

            AGREEMENTS:

      18.   Release.

            (a)   Except as provided in Section 17(c), below, AWA fully and
                  finally releases, acquits and forever discharges Mesa and its
                  parent companies and subsidiaries from any and all claims or
                  demands for any amounts owed, accrued, payable, incurred,
                  billed or invoiced pursuant to the Code Share Agreement or the
                  Original Agreement for matters, services, actions, events,
                  activities or other items provided or occurring on or before,
                  or related to the period expiring on, December 31, 2002.

            (b)   Except as provided in Section 17(c), below, Mesa, AM and
                  Freedom fully and finally release, acquit and forever
                  discharge AWA and its parent companies and subsidiaries from
                  any and all claims or demands for any amounts owed, accrued,
                  payable, incurred, billed or invoiced pursuant to the Code
                  Share Agreement or the Original Agreement for matters,
                  services, actions, events, activities or other items provided
                  or occurring on or before, or related to the period expiring
                  on, December 31, 2002.

            (c)   Notwithstanding the foregoing, the parties agree that the
                  releases set forth in subsections (a) and (b) above shall not
                  apply to (i) any amounts accruing or payable under the Code
                  Share Agreement after December 31, 2002 for services, actions,
                  events, activities or other items occurring after December 31,
                  2002; (ii) any amounts owed by Mesa pursuant to Section 5 of
                  the Code Share Agreement (provided, however, that AWA shall
                  not use its right of offset for these amounts until payment by
                  AWA of any amounts owing pursuant to the Reconciliation,
                  unless Mesa has not provided AWA with the Reconciliation
                  pursuant to Section 7.10 within 90 days of the Effective Date
                  of this Fourth Amendment in which case AWA may exercise its
                  offset rights for these amounts at any time after the 90th day
                  after the Effective Date of this

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                  Fourth Amendment); (iii) any Transition Reimbursement owed by
                  AWA pursuant to Section 2.2.7 of the Code Share Agreement;
                  (iv) any amounts to be paid by AWA pursuant to paragraph 18
                  below; (v) any amount payable by AWA to Mesa for the closure
                  of the maintenance base in Columbus, Ohio pursuant to Section
                  2.6.3 of the Code Share Agreement; (vi) any amounts owed by
                  Mesa to AWA as reimbursement for overpayment of landing fees
                  by AWA to Mesa; or (vii) any amounts payable by Mesa to AWA as
                  reimbursement for Aviation Security Infrastructure Fees.

            Payment Obligation. On the Effective Date, AWA shall be obligated to
            pay to Mesa the Payment Amount, [. . . *** . . .]

      19.   Withdrawal of Notice. AWA withdraws all notices that it provided to
            Mesa for the cancellation of three (3) CRJ Model 700s and agrees and
            acknowledges that, as of the Effective Date of this Fourth
            Amendment, the number of CRJ Model 700s in the CRJ Subfleet (and
            committed to be added to the CRJ Subfleet) is, in the aggregate,
            fifteen (15).

      20.   CRJ Model 200s. As of the Effective Date of this Fourth Amendment,
            the number of CRJ Model 200s in the CRJ Subfleet is eighteen (18).

      21.   Effect. Except as set forth in this Fourth Amendment, all of the
            terms and conditions of the Code Share Agreement remain in full
            force and effect.

      22.   Counterparts. This Fourth Amendment may be executed in counterparts,
            all of which when taken together shall be one and the same document.

      23.   Entire Agreement. This Fourth Amendment constitutes the entire
            agreement between the parties with respect to the subject matter
            hereof and supersedes all prior understandings with respect thereto.

                                        AMERICA WEST AIRLINES, INC.


                                        By:    /s/ J. Scott Kirby
                                               ---------------------------------
                                        Name:  J. Scott Kirby
                                               ---------------------------------
                                        Title: EVP - Sales and Marketing
                                               ---------------------------------

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                                        MESA AIRLINES, INC.


                                        By:    /s/ Jonathan Ornstein
                                               ---------------------------------
                                        Name:  Jonathan Ornstein
                                               ---------------------------------
                                        Title: Chief Executive Officer
                                               ---------------------------------

                                        AIR MIDWEST, INC.


                                        By:    /s/ George Murnane
                                               ---------------------------------
                                        Name:  George Murnane
                                               ---------------------------------
                                        Title:
                                               ---------------------------------

                                        FREEDOM AIRLINES, INC.


                                        By:    /s/ Michael Lotz
                                               ---------------------------------
                                        Name:  Michael Lotz
                                               ---------------------------------
                                        Title:
                                               ---------------------------------

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                                    EXHIBIT A
                                   CRJ-700/900
                                DELIVERY SCHEDULE

<TABLE>
<CAPTION>
                CURRENT                                    NEW                                                         TOTAL
                CRJ-900             CRJ-700              CRJ-900                                                     CRJ-7/900
               DELIVERIES         REDUCTIONS            DELIVERIES           CRJ-700            CRJ-900                FLEET
               ----------         ----------            ----------           -------            -------                -----
<S>        <C>                <C>                 <C>                 <C>                <C>                   <C>
9/2/03     [. . . *** . . .]  [. . . *** . . .]   [. . . *** . . .]   [. . . *** . . .]  [. . . *** . . .]     [. . . *** . . .]
Sep-03
Oct-03
Nov-03
Dec-03

Jan-04
Feb-04
Mar-04
Apr-04
May-04
Jun-04
Jul-04
Aug-04
Sep-04
Oct-04
Nov-04
Dec-04

Jan-05
Feb-05
Mar-05
Apr-05
May-05
Jun-05
Jul-05
Aug-05
Sep-05
Oct-05
Nov-05

Incremental Aircraft          [. . . *** . . .]   [. . . *** . . .]
</TABLE>

Note:

[. . . *** . . .]

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                                    EXHIBIT A
                               OPTION CRJ-700/900
                                DELIVERY SCHEDULE

<TABLE>
<CAPTION>
          DELIVERY                                       OPTION
           MONTH                                        CRJ-7/900
           -----                                        ---------
<S>                                                 <C>
          Jan-04                                    [. . . *** . . .]
          Feb-04
          Mar-04
          Apr-04
          May-04
          Jun-04
          Jul-04
          Aug-04
          Sep-04
          Oct-04
          Nov-04
          Dec-04
Each calendar month
thereafter through Oct-07                           [. . . *** . . .]
                                                    [. . . *** . . .]
</TABLE>

Note:

[. . . *** . . .]

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.
<PAGE>
                                    EXHIBIT B

<TABLE>
<CAPTION>
                                                  Cost per
                                                 Departure >3            Cost/                B19, DH8 and CRJ 200
                           Monthly Cost         Departures per         Departure          Markets Covered by Model (as of
Aircraft Type              Per Station              Day                 PHX Hub                    12/31/02)
-------------              -----------              ---                 -------                    ---------
<S>                     <C>                   <C>                  <C>                    <C>

B19                     [. . . *** . . .]     [. . . *** . . .]    [. . . *** . . .]           [. . . *** . . .]
DH8
CRJ 200
CRJ 700
CRJ 900
Mexico Stations
GDL (CRJ 200)           [. . . *** . . .]
</TABLE>

Each month, overall station cost reimbursement (exclusive of station rent) will
be determined by the sume of:

[. . . *** . . .]

Notes

[ . . . *** . . .]

[. . . *** . . .] Portions hereof have been omitted and filed separately with
the Commission pursuant to a request for confidential treatment in accordance
with Rule 24b-2 under the Securities Exchange Act of 1934, as amended.