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                                                                       Exhibit 4

                              MESA AIR GROUP, INC.

                      OUTSIDE DIRECTORS' STOCK OPTION PLAN


1.       PURPOSE OF THE PLAN; TYPE OF PLAN

         (a) Attract and Retain Talented Outside Directors. The purpose of the
Mesa Air Group, Inc. Outside Directors' Stock Option Plan (the "Plan") is to
attract and retain independent directors ("Qualified Directors") who are and
will be responsible for the restructuring, growth and success of Mesa Air Group,
Inc., a Nevada corporation (the "Company"), and its subsidiaries by providing an
incentive-based form of compensation to the Qualified Directors and encouraging
such Qualified Directors to invest in shares of the Company's Common Stock to
increase the Qualified Directors' personal interest in the success of the
Company. The Plan is also intended to reduce the cash compensation necessary to
attract Qualified Directors.

         (b) Designation of Stock Options as Non-Qualified Stock Options. Stock
options granted under the Plan (the "Options") shall not be treated as incentive
stock options under Section 422 of the Internal Revenue Code of 1986, as amended
(the "Code").

         (c) Exemption from Short-Swing Liability. Options granted to Qualified
Directors of the Company pursuant to this Plan shall be exempt from Section
16(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act").

         (d) Administration. This Plan may be administered by the Board of
Directors of the Company (the "Board") or by any person or persons chosen by a
majority of the Board.

2.       STOCK AND MAXIMUM NUMBER OF SHARES SUBJECT TO PLAN

         (a) Description of Stock and Maximum Shares Allocated. The stock
subject to the provisions of this Plan and issuable upon exercise of the Options
are shares of the Company's Common Stock, no par value, which may be either
unissued or treasury shares, as the Board may from time to time determine.
Subject to adjustment as provided in Section 6, the aggregate number of shares
of Common Stock covered by the Plan issuable upon exercise of all Options shall
be 150,000 shares, which shares shall be reserved for use upon the exercise of
the Options. (The shares available for Options and all other shares of Common
Stock of the Company shall be referred to as the "Shares.")

         (b) Restoration of Unpurchased Shares. If an Option expires or
terminates for any reason prior to the exercise in full before the term of the
Plan expires, the Shares subject to, but not issued under, such Option shall
again be available for other Options hereafter granted.
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3.       FORMULA AND OPERATION OF THE PLAN

         (a) Eligible Persons. Options will automatically be granted to all
present and future directors of the Company who are not employees of the Company
or of any subsidiary of the Company ("Qualified Directors").

         (b) Date of Grants; Allocation. Each Qualified Director serving on the
Board of Directors as of April 1, 1998, shall receive (i) 3,000 options to
purchase 3,000 shares of Common Stock, no par value, plus (ii) the number of
options to purchase Common Stock equivalent to a cash value of $13,000 as
calculated pursuant to the Black-Scholes valuation method at a risk-free rate of
a ten-year zero coupon bond (collectively referred to herein as the "Formula
Amount") effective as of April 1, 1998. (For example, if the Black-Scholes
valuation method results in a value of $6.50 per option, each Qualified Director
would receive 2,000 options plus the fixed allocation of 3,000 options, or a
total of 5,000 options at the exercise price as set forth below in Section
3(c).) Each Qualified Director shall receive an additional Formula Amount on
each April 1st thereafter or if at any time there is an insufficient number of
options to make the full Formula Amount allocation, a pro-rata amount of the
remaining options available under the Plan shall be granted to each Qualified
Director.

Any Qualified Director who was not serving as a director as of April 1, 1998,
upon the first business day after being appointed as a director, shall be
granted a pro rata portion of the Formula Amount ("Pro Rata Options") and
Options shall be granted to such Qualified Director on each succeeding April 1
in the Formula Amount. The amount of Pro Rata Options to be granted to each new
Qualified Director shall be calculated by dividing the number of days prior to
April 1 by the number of days in the calendar year and multiplying the quotient
by the Formula Amount.

         Any Qualified Director who is serving as the Chairman of the Board of
Directors shall receive an annual grant of the number of options equal to a
value of $10,000 calculated in accordance with the Black-Scholes method as
specified above (the "Chairman's Options") on each April 1st which shall be in
addition to any other options granted to him as a director pursuant to this
Section 3(b). (Each of the dates upon which Options are granted shall be
referred to herein as the "Grant Date.")

         (c) Price. The Option price per Share shall not be less than the fair
market value of the Shares, as defined below, on the Grant Date.

         (d) Fair Market Value. The fair market value of a Share on any
particular day shall be determined as follows:

                  (i) If the Shares are listed or admitted to trading on any
         security exchange, the fair market value shall be the average sales
         price on such day on the New York Stock Exchange, or if the Shares have
         not been listed or admitted to trading on the New York Stock Exchange,
         on such other securities exchange on which such stock is then listed or
         admitted to trading, or if no sale takes place on such day on any such
         exchange, the

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         average of the closing bid and asked price on such day as officially
         quoted on any such exchange;

                  (ii) If the Shares are not then listed or admitted to trading
         on any securities exchange, the fair market value shall be the average
         sales price on such day or, if no sale takes place on such day, the
         average of the reported closing bid and asked price on such date, in
         the over-the-counter market as furnished by the National Association of
         Securities Dealers Automated Quotation ("NASDAQ"), or if NASDAQ at the
         time is not engaged in the business of reporting such prices, as
         furnished by any similar firm then engaged in such business and
         selected by the Board; or

                  (iii) If the Shares are not then listed or admitted to trading
         in the over-the-counter market, the fair market value shall be the
         amount determined by the Board in a manner consistent with Treasury
         Regulation Section 20-2031-2 promulgated under the Code or in such
         other manner prescribed by the Secretary of the Treasury or the
         Internal Revenue Service.

         (e) Duration of Plan; Term of Option. The term of the Plan, unless
  previously terminated by the Board, is ten (10) years commencing on the date
  of adoption of the Plan by the Board. No Option shall be granted under the
  Plan unless granted within ten (10) years of the adoption of the Plan by the
  Board, but Options outstanding on that date shall not be terminated or
  otherwise affected by virtue of the Plan's expiration. Except as otherwise
  indicated in Section 5, all Options automatically expire ten (10) years from
  the date of grant.

         (f) Vesting of the Options. Options granted to the Qualified Directors
serving as of April 1, 1998 shall fully vest and become exercisable immediately
upon shareholder approval (as required by Section 4(a) of the Plan) or, with
respect to Options granted after shareholders approve the Plan, immediately upon
the Grant Date. Options granted to Qualified Directors who are not serving as
directors as of April 1, 1998, shall vest in full and become exercisable six (6)
months after the Grant Date.

         (g) Additional Restrictions on Option Exercise. A Qualified Director
may only exercise Options during the period commencing three (3) business days
following the release for publication of quarterly or annual financial
information regarding the Company and ending two (2) weeks prior to the end of
the then current fiscal quarter of the Company (the "Release Period").

         A "release for publication" shall be deemed to be satisfied if the
specified financial data appears:

                  (i)      On a wire service;

                  (ii)     A financial news service;

                  (iii)    In a newspaper of general circulation; or

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                  (iv) Is otherwise made publicly available.

         Notwithstanding any provision to the contrary contained
herein, a Qualified Director may exercise Options only so long as such exercise
does not violate the law or any rule or regulation adopted by the appropriate
governmental authority.

4.       TERMS AND CONDITIONS OF OPTIONS

         (a) Approval by Shareholders. The Plan shall be submitted to the
shareholders of the Company for their approval at a meeting to be held within
twelve (12) months after the adoption of the Plan by the Board. Shareholder
approval shall be evidenced by the affirmative vote of the holders of a majority
of the Shares of Common Stock present in person or by proxy and voting at the
meeting. If the shareholders decline to approve the Plan at such meeting or if
the Plan is not approved by the shareholders within twelve (12) months after its
adoption by the Board, the Plan and all Options and rights granted hereunder
shall automatically terminate to the same extent and with the same effect as
though the Plan had never been adopted.

         (b) Amendments to Plan. Without the approval of the shareholders of the
Company, the Board shall not (i) increase the aggregate number of shares of
Common Stock subject to the Plan; (ii) change the class of persons eligible to
receive Options; (iii) modify the period within which Options may be granted,
the exercise price or the terms upon which Options may be exercised; (iv) change
the exercise price of the Options except as provided in Section 6; or (v)
increase the material benefits accruing to participants under the Plan. An
amendment to permit the assignment of options other than as specified in Section
5(b) shall not be considered a Material Amendment. (Collectively, each of these
changes in the Plan are referred to herein as "Material Amendments.") The Board
may suspend or terminate the Plan at any time.

         (c) Individual Agreements. Options granted under the Plan shall be
evidenced by agreements in such form as the Board from time to time approves,
which agreements shall substantially comply with and be subject to the terms of
the Plan.

         (d) No Fractional Shares. Options shall be granted and exercisable only
for whole shares; no fractional shares will be issuable upon exercise of any
Option granted under the Plan.

         (e) Method of Exercising Options. Options shall be exercised by written
notice to the Company, addressed to the Company at its principal place of
business. Such notice shall state the election to exercise the option and the
number of shares with respect to which it is being exercised, and shall be
signed by the person exercising the option. Such notice shall be accompanied by
payment in full of the exercise price for the number of Shares being purchased.
Payment may be made in cash or by bank cashier's check or by tendering duly
endorsed certificates for shares of the Company's Common Stock then owned by the
optionholder. The Company shall deliver a certificate or certificates
representing the Option Shares to the purchaser as soon as practicable after
payment for those Shares has been received. If an Option is exercised by any
person other than the optionholder, such notice shall be accompanied by
appropriate proof of the right of such person to exercise the Option. All Shares
that are purchased and paid for in full upon the exercise of an Option shall be
fully paid and non-

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assessable. The Board may determine that payment upon the exercise of an Option
may be made with Shares owned by the Qualified Director having a fair market
value on the exercise date equivalent to the amount of payment, or any
combination of cash and such Shares equal to such amount.

         (f) No Rights of a Shareholder. An Optionholder shall have no rights as
a shareholder with respect to shares covered by an Option. No adjustment will be
made for cash dividends for which the record date is prior to the date a stock
certificate is issued upon exercise of an Option. Upon such exercise of an
Option, the holder of the Shares of Common Stock so received shall have all the
rights of a shareholder of the Company as of the date of issuance.

5.       TERMINATION OF DIRECTORSHIP; ASSIGNABILITY; DEATH

         (a) Termination of Directorship. If any Optionholder ceases to be a
Director of the Company other than by reason of death, disability or discharge
for cause, such holder (or its successors in the case of the holder's death
which results in the termination of directorship) may, within three months after
the date of termination, but in no event after the stated expiration date,
purchase some or all of the Shares with respect to which such Optionholder was
entitled to exercise such Option, on the date such directorship terminated;
provided, that if after directorship is terminated, the holder commits acts
detrimental to the Company's interests as determined by a two-thirds vote of the
members of the Board, then the Option shall thereafter be void for all purposes.

         (b) Assignability. No Option or the privileges conferred thereby shall
be assignable or transferable by a holder other than by will or the laws of
descent and distribution.

         (c) Disability. If the Optionholder is removed as a director due to
disability, the Optionholder may exercise the Options, in whole or in part, to
the extent they were exercisable on the date when the Optionholder's
directorship terminated, at any time prior to the expiration date of the Options
or within one (1) year of the date of removal, whichever is earlier.

         (d) Discharge for Cause. If an Optionholder is removed as a director of
the Company for cause, the Options shall terminate upon receipt by the
Optionholder of a notice of such removal or on the effective date of the
removal, whichever is earlier. The Board shall have the right to determine
whether the optionholder has been discharged for cause for purposes of the Plan
and the date of such discharge.

         (e) Death of Holder. If Optionholder dies while serving as a director,
an Option shall be exercisable until the stated expiration date thereof by the
person or persons ("successors") to whom the holder's rights pass under will or
by the laws of descent and distribution, but only to the extent that the holder
was entitled to exercise the Option at the date of death. An Option may be
exercised (and payment of the option price made in full) by the successors only
after written notice to the Company, specifying the number of shares to be
purchased. Such notice shall comply with the provisions of Section 4(e).

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6.       CERTAIN ADJUSTMENTS

         (a) Capital Adjustments. Except as limited by Section 422 of the Code,
the aggregate number of Shares subject to the Plan, the number of Shares covered
by outstanding Options, and the price per share stated in such Options shall be
proportionately adjusted for any increase or decrease in the number of
outstanding Shares of Common Stock of the Company resulting from a subdivision
or consolidation of shares or any other capital adjustment or the payment of a
stock dividend or any other increase or decrease in the number of such shares
effected without receipt by the Company of consideration therefor in money,
services or property.

         (b) Mergers, Etc. Except as limited by the provisions of Section 422 of
the Code, if the Company is the surviving corporation in any merger or
consolidation, any Option granted under the Plan shall pertain to and apply to
the securities to which a holder of the number of Shares subject to the Option
would have been entitled. A dissolution or liquidation of the Company shall
cause every Option outstanding hereunder to terminate, unless specifically
provided otherwise by the Board. A merger or consolidation in which the Company
is not the surviving corporation shall also cause every Option outstanding
hereunder to terminate, unless specifically provided otherwise by the Board, but
each holder shall have the right immediately prior to a merger or consolidation
in which the Company is not the surviving corporation, to exercise such Option
in whole or in part without regard to any installment provisions contained in
the Option agreement.

7.       COMPLIANCE WITH LEGAL REQUIREMENTS

         (a) For Investment Only. If, at the time of exercise of this Option,
there is not in effect as to the Option Shares being purchased a registration
statement under the Securities Act of 1933, as amended (or any successor
statute) (collectively the "1933 Act"), then the exercise of this option shall
be effective only upon receipt by the Company from the Director (or his legal
representatives or heirs) of a written representation that the Option Shares are
being purchased for investment and not for distribution.

         (b) Registration Statement Preparation. Each Qualified Director hereby
agrees to supply the Company with such information and to cooperate with the
Company, as the Company may reasonably request, in connection with the
preparation and filing of the registration statements and amendments thereto
under the Securities Act of 1933 and applicable state statutes and regulations
applicable to the Option Shares. The Company shall not be liable for failure to
issue any such Option Shares where such opinion of counsel cannot be obtained
within the period specified for the exercise of the Option, or where such
registration is required in the opinion of counsel. If shares of Common Stock of
the Company are, at the time of the exercise of this Option, listed upon a
securities exchange, the exercise of this Option shall be contingent upon
completion of the necessary steps to list the Option Shares being purchased upon
such securities exchange.

         (c) Compliance with Law. No Shares shall be issued or transferred upon
the exercise of any Option unless and until the following occurs:

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                  (i) All legal requirements applicable to the issuance or
         transfer of Shares have been complied with; and

                  (ii) All requirements of any national securities exchange or
         association upon which the Shares are listed, traded or quoted have
         been met, in each case to the satisfaction of the Board. The Board
         shall have the right to condition the issuance of any Shares made to
         any person hereunder on such person's undertaking in writing to comply
         with such restrictions on his or her subsequent disposition of such
         Shares as the Board shall deem necessary or advisable as a result of
         any applicable law, regulation or official interpretation thereof, and
         certificates representing such shares may contain a legend to reflect
         any such restriction.

8.       MISCELLANEOUS

         (a) No Funding. This Plan shall be unfunded. The Company shall not be
required to establish any special or separate fund or to make any other
segregation of assets to assure any payment under the Plan.

         (b) Nevada Law. The Plan and the Options shall be governed by the laws
of the State of Nevada.

         (c) Modification of Grant, Vesting Date. Should April 1 in any given
year fall on a day on which trading in the Shares is closed, the action which
would have taken place on April 1 shall be delayed until the first day after
April 1 that trading in the Shares commences.

         DATED as of the 1st day of June, 1998 and effective as of April 1,
1998.

MESA AIR GROUP, INC.


By:
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--------------------------------

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ATTESTED BY:


By:
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     Gary E. Risley
     Secretary


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