Document:

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                                                                   EXHIBIT 10.15
                               SECURITY AGREEMENT

        SECURITY AGREEMENT, dated as of December 31, 2002 (this "Agreement"),
between Great Lakes Aviation, Ltd., an Iowa corporation (the "Company"), and
Raytheon Aircraft Credit Corporation, a Kansas corporation (hereinafter,
"RACC").

        WHEREAS, the Company has entered into a Restructuring Agreement dated as
of the date hereof (as amended and in effect from time to time, the
"Restructuring Agreement") with RACC, pursuant to which RACC, subject to the
terms and conditions contained therein, has agreed to accept the return of
certain aircraft and provide certain related financing, to restructure its
financing of certain existing aircraft and reduce lease payments on certain
aircraft; and

        WHEREAS, it is a condition precedent to RACC's restructuring any loan or
otherwise extending credit to the Company under the Restructuring Agreement that
the Company execute and deliver to RACC a security agreement in substantially
the form hereof; and

        WHEREAS, the Company wishes to grant a security interest in favor of
RACC as herein provided;

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

        1.      Definitions. All capitalized terms used herein without
definitions shall have the respective meanings provided therefor in the
Restructuring Agreement. The term "State", as used herein, means the State of
Kansas. All terms defined in the Uniform Commercial Code of the State and used
herein shall have the same definitions herein as specified therein. However, if
a term is defined in Article 9 of the Uniform Commercial Code of the State
differently than in another Article of the Uniform Commercial Code of the State,
the term has the meaning specified in Article 9.

        2.      Grant of Security Interest. The Company hereby grants to RACC,
to secure the payment and performance in full of all of the Obligations, a
security interest in and pledges and assigns to RACC the following properties,
assets and rights of the Company, wherever located, whether now owned or
hereafter acquired or arising, and all proceeds and products thereof (all of the
same being hereinafter called the "Collateral"): all personal and fixture
property of every kind and nature including without limitation all goods
(including inventory, equipment and any accessions thereto), instruments
(including promissory notes), documents, accounts (including
health-care-insurance receivables), chattel paper (whether tangible or
electronic), deposit accounts, letter-of-credit rights (whether or not the
letter of

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                                       -2-

credit is evidenced by a writing), commercial tort claims, securities and all
other investment property, supporting obligations, any other contract rights or
rights to the payment of money, insurance claims and proceeds, and all general
intangibles (including all payment intangibles). RACC acknowledges that the
attachment of its security interest in any commercial tort claim as original
collateral is subject to the Company's compliance with Section 4.7.

        3.      Authorization to File Financing Statements. The Company hereby
irrevocably authorizes RACC at any time and from time to time to file in any
filing office in any Uniform Commercial Code jurisdiction any initial financing
statements and amendments thereto that (a) indicate the Collateral (i) as all
assets of the Company or words of similar effect, regardless of whether any
particular asset comprised in the Collateral falls within the scope of Article 9
of the Uniform Commercial Code of the State or such jurisdiction, or (ii) as
being of an equal or lesser scope or with greater detail, and (b) provide any
other information required by part 5 of Article 9 of the Uniform Commercial Code
of the State or such other jurisdiction for the sufficiency or filing office
acceptance of any financing statement or amendment, including (i) whether the
Company is an organization, the type of organization and any organizational
identification number issued to the Company and, (ii) in the case of a financing
statement filed as a fixture filing or indicating Collateral as as-extracted
collateral or timber to be cut, a sufficient description of real property to
which the Collateral relates. The Company agrees to furnish any such information
to RACC promptly upon RACC's request. The Company also ratifies its
authorization for RACC to have filed in any Uniform Commercial Code jurisdiction
any like initial financing statements or amendments thereto if filed prior to
the date hereof.

        4.      Other Actions. Further to insure the attachment, perfection and
first priority of, and the ability of RACC to enforce, RACC's security interest
in the Collateral, the Company agrees, in each case at the Company's expense, to
take the following actions with respect to the following Collateral and without
limitation on the Company's other obligations contained in this Agreement:

                4.1.    Promissory Notes and Tangible Chattel Paper. If the
        Company shall, now or at any time hereafter, hold or acquire any
        promissory notes or tangible chattel paper, the Company shall forthwith
        endorse, assign and deliver the same to RACC, accompanied by such
        instruments of transfer or assignment duly executed in blank as RACC may
        from time to time specify.

                4.2.    Deposit Accounts. For each deposit account that the
        Company, now or at any time hereafter, opens or maintains, the Company
        shall, at RACC's request and option, pursuant to an agreement in form
        and substance satisfactory to RACC, either (a) cause the depositary bank
        to agree to comply, without further consent of the Company, at any time
        with instructions from RACC to such depositary bank directing the
        disposition of funds from time to

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                                       -3-

        time credited to such deposit account, or (b) arrange for RACC to become
        the customer of the depositary bank with respect to the deposit account,
        with the Company being permitted, only with the consent of RACC, to
        exercise rights to withdraw funds from such deposit account. RACC agrees
        with the Company that RACC shall not give any such instructions or
        withhold any withdrawal rights from the Company, unless an Event of
        Default has occurred and is continuing, or, if effect were given to any
        withdrawal not otherwise permitted by the Transaction Documents, would
        occur. The provisions of this paragraph shall not apply to (i) any
        deposit account for which the Company, the depositary bank and RACC have
        entered into a cash collateral agreement specially negotiated among the
        Company, the depositary bank and RACC for the specific purpose set forth
        therein and (ii) any deposit accounts specially and exclusively used for
        payroll, payroll taxes and other employee wage and benefit payments to
        or for the benefit of the Company's employees.

                4.3.    Investment Property. If the Company shall, now or at any
        time hereafter, hold or acquire any certificated securities, the Company
        shall forthwith endorse, assign and deliver the same to RACC,
        accompanied by such instruments of transfer or assignment duly executed
        in blank as RACC may from time to time specify. If any securities now or
        hereafter acquired by the Company are uncertificated and are issued to
        the Company or its nominee directly by the issuer thereof, the Company
        shall immediately notify RACC thereof and, at RACC's request and option,
        pursuant to an agreement in form and substance satisfactory to RACC,
        either (a) cause the issuer to agree to comply, without further consent
        of the Company or such nominee, at any time with instructions from RACC
        as to such securities, or (b) arrange for RACC to become the registered
        owner of the securities. If any securities, whether certificated or
        uncertificated, or other investment property now or hereafter acquired
        by the Company are held by the Company or its nominee through a
        securities intermediary or commodity intermediary, the Company shall
        immediately notify RACC thereof and, at RACC's request and option,
        pursuant to an agreement in form and substance satisfactory to RACC,
        either (i) cause such securities intermediary or (as the case may be)
        commodity intermediary to agree to comply, in each case without further
        consent of the Company or such nominee, at any time, with entitlement
        orders or other instructions from RACC to such securities intermediary
        as to such securities or other investment property, or (as the case may
        be) to apply any value distributed on account of any commodity contract
        as directed by RACC to such commodity intermediary, or (ii) in the case
        of financial assets or other investment property held through a
        securities intermediary, arrange for RACC to become the entitlement
        holder with respect to such investment property, with the Company being
        permitted, only with the consent of RACC, to exercise rights to withdraw
        or otherwise deal with such investment property. RACC agrees with the
        Company that RACC shall not give any

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                                       -4-

        such entitlement orders or instructions or directions to any such
        issuer, securities intermediary or commodity intermediary, and shall not
        withhold its consent to the exercise of any withdrawal or dealing rights
        by the Company, unless an Event of Default has occurred and is
        continuing, or, after giving effect to any such investment and
        withdrawal rights not otherwise permitted by the Transaction Documents,
        would occur. The provisions of this paragraph shall not apply to any
        financial assets credited to a securities account for which RACC is the
        securities intermediary.

                4.4.    Collateral in the Possession of a Bailee. If any
        Collateral is, now or at any time hereafter, in the possession of a
        bailee, the Company shall promptly notify RACC thereof and, at RACC's
        request and option, shall promptly obtain an acknowledgement from the
        bailee, in form and substance satisfactory to RACC, that the bailee
        holds such Collateral for the benefit of RACC and such bailee's
        agreement to comply without further consent of the Company, at any time
        with instructions of RACC as to such Collateral. RACC agrees with the
        Company that RACC shall not give any such instructions unless an Event
        of Default has occurred and is continuing or would occur after taking
        into account any action by the Company with respect to the bailee.

                4.5.    Electronic Chattel Paper and Transferable Records. If
        the Company, now or at any time hereafter, holds or acquires an interest
        in any electronic chattel paper or any "transferable record," as that
        term is defined in Section 201 of the federal Electronic Signatures in
        Global and National Commerce Act, or in Section 16 of the Uniform
        Electronic Transactions Act as in effect in any relevant jurisdiction,
        the Company shall promptly notify RACC thereof and, at the request and
        option of RACC, shall take such action as RACC may reasonably request to
        vest in RACC control, under Section 9-105 of the Uniform Commercial
        Code, of such electronic chattel paper or control under Section 201 of
        the federal Electronic Signatures in Global and National Commerce Act
        or, as the case may be, Section 16 of the Uniform Electronic
        Transactions Act, as so in effect in such jurisdiction, of such
        transferable record. RACC agrees with the Company that RACC will
        arrange, pursuant to procedures satisfactory to RACC and so long as such
        procedures will not result in RACC's loss of control, for the Company to
        make alterations to the electronic chattel paper or transferable record
        permitted under UCC Section 9-105 or, as the case may be, Section 201 of
        the federal Electronic Signatures in Global and National Commerce Act or
        Section 16 of the Uniform Electronic Transactions Act for a party in
        control to make without loss of control, unless an Event of Default has
        occurred and is continuing or would occur after taking into account any
        action by the Company with respect to such electronic chattel paper or
        transferable record.

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                                       -5-

                4.6.    Letter-of-Credit Rights. If the Company is, now or at
        any time hereafter, a beneficiary under a letter of credit now or
        hereafter, the Company shall promptly notify RACC thereof and, at the
        request and option of RACC, the Company shall, pursuant to an agreement
        in form and substance satisfactory to RACC, either (a) arrange for the
        issuer and any confirmer or other nominated person of such letter of
        credit to consent to an assignment to RACC of the proceeds of the letter
        of credit or (b) arrange for RACC to become the transferee beneficiary
        of the letter of credit, with RACC agreeing, in each case, that the
        proceeds of the letter of credit are to be applied as provided in
        Section 11(C) of the Restructuring Agreement.

                4.7.    Commercial Tort Claims. If the Company shall, now or at
        any time hereafter, hold or acquire a commercial tort claim, the Company
        shall immediately notify RACC in a writing signed by the Company of the
        particulars thereof and grant to RACC in such writing a security
        interest therein and in the proceeds thereof, all upon the terms of this
        Agreement, with such writing to be in form and substance satisfactory to
        RACC.

                4.8.    Other Actions as to any and all Collateral. The Company
        further agrees, upon request of RACC and at RACC's option, to take any
        and all other actions as RACC may determine to be necessary or useful
        for the attachment, perfection and first priority of, and the ability of
        RACC to enforce, RACC's security interest in any and all of the
        Collateral, including, without limitation, (a) executing, delivering
        and, where appropriate, filing financing statements and amendments
        relating thereto under the Uniform Commercial Code, to the extent, if
        any, that the Company's signature thereon is required therefor, (b)
        causing RACC's name to be noted as secured party on any certificate of
        title for a titled good if such notation is a condition to attachment,
        perfection or priority of, or ability of RACC to enforce, RACC's
        security interest in such Collateral, (c) complying with any provision
        of any statute, regulation or treaty of the United States as to any
        Collateral if compliance with such provision is a condition to
        attachment, perfection or priority of, or ability of RACC to enforce,
        RACC's security interest in such Collateral, (d) obtaining governmental
        and other third party waivers, consents and approvals in form and
        substance satisfactory to RACC, including, without limitation, any
        consent of any licensor, lessor or other person obligated on Collateral,
        (e) obtaining waivers from mortgagees and landlords in form and
        substance satisfactory to RACC and (f) taking all actions under any
        earlier versions of the Uniform Commercial Code or under any other law,
        as reasonably determined by RACC to be applicable in any relevant
        Uniform Commercial Code or other jurisdiction, including any foreign
        jurisdiction.

        5.      Representations and Warranties. The Company represents,
and warrants as follows:

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                                       -6-

                (a)     The Company has previously delivered to RACC a
        certificate signed by the Company and entitled "Perfection Certificate"
        (the "Perfection Certificate"). The Company represents and warrants to
        RACC as follows: (i) the Company's exact legal name is that indicated on
        the Perfection Certificate and on the signature page hereof, (ii) the
        Company is an organization of the type, and is organized in the
        jurisdiction, set forth in the Perfection Certificate, (iii) the
        Perfection Certificate accurately sets forth the Company's
        organizational identification number or accurately states that the
        Company has none, (iv) the Perfection Certificate accurately sets forth
        the Company's place of business or, if more than one, its chief
        executive office, as well as the Company's mailing address, if
        different, (v) all other information set forth on the Perfection
        Certificate pertaining to the Company is accurate and complete, and (vi)
        there has been no change in any of such information since the date on
        which the Perfection Certificate was signed by the Company.

                (b)     All filings, registrations and recordings necessary to
        create, preserve, protect and perfect the security interest granted by
        the Company to RACC hereby in respect of the Collateral of the Company
        have been accomplished, and the security interest granted to RACC
        pursuant to this Agreement in and to the Collateral of the Company will
        constitute, a perfected security interest therein prior to the rights of
        all other persons therein and subject to no other liens other than liens
        granted to RACC pursuant to the Transaction Documents and liens set
        forth on Schedule 5(b) (collectively, "Permitted Liens").

                (c)     The Company is, and as to Collateral acquired by it from
        time to time after the date hereof the Company will be, the holder of
        all Collateral granted by it free from any lien (other than Permitted
        Liens). The Company shall defend the Collateral against any and all
        claims and demands of all persons at any time claiming any interest
        therein adverse to RACC (other than Permitted Liens).

                (d)     There is no financing statement (or similar statement or
        instrument of registration under the law of any jurisdiction intended to
        provide notice of a lien) covering or purporting to cover any interest
        of any kind in the Collateral of the Company (other than financing
        statements that relate to transactions for which all secured obligations
        have been paid in full and there is no commitment on the part of any
        person to advance funds or perform any obligation that would be secured
        by the collateral described in such financing statements) and other than
        the Permitted Liens, and so long as the Restructuring Agreement has not
        been terminated or any of the Obligations remain unpaid, the Company
        shall not execute or authorize to be filed in any public office any
        financing statement (or similar statement or instrument of registration
        under the law of any jurisdiction intended to

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                                       -7-

        provide notice of a lien) relating to the Collateral of the Company,
        except financing statements filed or to be filed in respect of and
        covering the security interests granted hereby by the Company.

                (e)     As of the date hereof, the Company has no (i) agreements
        providing the Company with the right to use, operate or occupy space in
        any airport in the United States ("Gate Agreements"), (ii) route
        authorities ("Routes"), or (iii) rights and operational authority
        acquired or held by the Company in and to the operating authority
        granted by the Federal Aviation Administration (the "FAA") pursuant to
        Title 14 to conduct one Instrument Flight Rule (as defined under the
        federal aviation regulations) landing or takeoff operating in a
        specified time period ("Slots") that it has the right to pledge as
        Collateral under this Agreement.

                (f)     The Company is a Citizen of the United States and a
        Certificated Air Carrier. All licenses, permits, authorizations,
        certificates of compliance, certificates of public convenience and
        necessity and other certificates (including, without limitation, air
        carrier operating certificates and operations specifications issued by
        the FAA pursuant to 14 C.F.R. Part 121) which are required by the DOT or
        the FAA and which are necessary for the conduct of the business of the
        Company are in full force and duly issued to the Company. There are no
        license fees owed on the Company's DOT or FAA licenses, certificates or
        authorizations. The Company is in compliance with all material
        requirements of the certificates and. authorizations issued to it by the
        DOT or the FAA.

                (f)     The Company has full corporate power and authority and
        legal right to pledge all the Collateral pursuant to this Agreement.

                (g)     No consent of any other party (including, without
        limitation, stockholders or creditors of the Company), and no consent,
        authorization, approval, or other action by, and (except in connection
        with the perfection of the liens created hereby) no notice to or filing
        with, any governmental authority or other person is required either (x)
        for the pledge by the Company of the Collateral of the Company pursuant
        to this Agreement or for the execution, delivery or performance of this
        Agreement or (y) for the exercise by RACC of the rights provided for in
        this Agreement or the remedies in respect of the Collateral pursuant to
        this Agreement.

                (h)     The Company is the owner of or has other rights in or
        power to transfer the Collateral, free from any right or claim of any
        person or any adverse lien, security interest or other encumbrance,
        except for the security interest created by this Agreement and other
        Permitted Liens.

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                                       -8-

                (i)     None of the Collateral constitutes, or is the proceeds
        of, "farm products" as defined in Section 9-102(a)(34) of the Uniform
        Commercial Code of the State.

                (j)     None of the account debtors or other persons obligated
        on any of the Collateral is a governmental authority covered by the
        Federal Assignment of Claims Act or like federal, state or local statute
        or rule in respect of such Collateral.

                (k)     The Company holds no commercial tort claim except as
        indicated on the Perfection Certificate.

                (l)     The Company has at all times operated its business in
        compliance with all applicable provisions of the federal Fair Labor
        Standards Act, as amended, and with all applicable provisions of
        federal, state and local statutes and ordinances dealing with the
        control, shipment, storage or disposal of hazardous materials or
        substances.

        6.      Covenants Concerning Company's Legal Status. The Company
covenants with RACC as follows: (a) without providing at least thirty (30) days
prior written notice to RACC, the Company will not change its name, its place of
business or, if more than one, chief executive office, or its mailing address or
organizational identification number if it has one, (b) if the Company does not
have an organizational identification number and later obtains one, the Company
will forthwith notify RACC of such organizational identification number, and (c)
the Company will not change its type of organization, jurisdiction of
organization or other legal structure.

        7.      Covenants Concerning Collateral, Etc. The Company further
covenants with RACC as follows:

                (a)     The Collateral, to the extent not delivered to RACC
        pursuant to Section 4, will be kept at those locations listed on the
        Perfection Certificate and the Company will not remove the Collateral
        from such locations, without providing at least thirty (30) days prior
        written notice to RACC.

                (b)     Except for the security interest herein granted and
        Permitted Liens, the Company shall be the owner of or have other rights
        in the Collateral free from any right or claim of any other person or
        any lien, security interest or other encumbrance, and the Company shall
        defend the same against all claims and demands of all persons at any
        time claiming the same or any interests therein adverse to RACC.

                (c)     The Company shall not pledge, mortgage or create, or
        suffer to exist any right of any person in or claim by any person to the
        Collateral, or

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                                       -9-

        any security interest, lien or other encumbrance in the Collateral in
        favor of any person, other than RACC except for Permitted Liens.

                (d)     The Company will keep the Collateral in good order and
        repair and will not use the same in violation of law or any policy of
        insurance thereon.

                (e)     The Company will permit RACC, or its designee, to
        inspect the Collateral at any reasonable time, wherever located.

                (f)     The Company will pay promptly when due all taxes,
        assessments, governmental charges and levies upon the Collateral or
        incurred in connection with the use or operation of the Collateral or
        incurred in connection with this Agreement.

                (g)     The Company will continue to operate, its business in
        compliance with all applicable provisions of the federal Fair Labor
        Standards Act, as amended, and with all applicable provisions of
        federal, state and local statutes and ordinances dealing with the
        control, shipment, storage or disposal of hazardous materials or
        substances.

                (h)     The Company will not sell or otherwise dispose, or offer
        to sell or otherwise dispose, of the Collateral or any interest therein
        except that for sales of inventory so long as no Event of Default has
        occurred and is continuing, sales or other dispositions of obsolescent
        items of equipment consistent with past practices and dispositions
        permitted by the Restructuring Agreement shall be permitted.

                (i)     If at any time in the future the Company acquires any
        Gate Agreements, Routes or Slots that are capable of being pledged to
        RACC as Collateral, the Company shall provide prompt written notice to
        RACC and take all action and sign all documents reasonably requested by
        RACC to create and maintain a first-priority security interest in any
        such Gate Agreements, Routes or Slots at such time or at any time
        thereafter.

        8.      Insurance.

                8.1.    Maintenance of Insurance. In addition to any other
        insurance required to be maintained in connection with the other
        Transaction Documents, the Company will maintain with financially sound
        and reputable insurers insurance with respect to its properties and
        business against such casualties and contingencies as shall be in
        accordance with general practices of businesses engaged in similar
        activities in similar geographic areas. Such insurance shall be in such
        minimum amounts that the Company will not be deemed a co-insurer under
        applicable insurance laws, regulations and policies and otherwise shall
        be in such amounts, contain such terms, be in

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                                      -10-

        such forms and be for such periods as may be reasonably satisfactory to
        RACC. In addition, all such insurance shall be payable to RACC as loss
        payee under a "standard" loss payee clause. Without limiting the
        foregoing, the Company will (a) keep all of its physical property
        insured with casualty or physical hazard insurance on an "all risks"
        basis, with a full replacement cost endorsement and an "agreed amount"
        clause in an amount equal to 100% of the full replacement cost of such
        property, (b) maintain all such workers' compensation or similar
        insurance as may be required by law and (c) maintain, in amounts and
        with deductibles equal to those generally maintained by businesses
        engaged in similar activities in similar geographic areas, general
        public liability insurance against claims of bodily injury, death or
        property damage occurring, on, in or about the properties of the
        Company; business interruption insurance; and product liability
        insurance.

                8.2.    Insurance Proceeds. Except as otherwise specifically
        provided in any of the other Transaction Documents, the proceeds of any
        casualty insurance in respect of any casualty loss of any of the
        Collateral shall, subject to the rights, if any, of other parties with
        an interest having priority in the property covered thereby, (a) so long
        as no Default or Event of Default has occurred and is continuing and to
        the extent that the amount of such proceeds is less than $50,000, be
        disbursed to the Company for direct application by the Company solely to
        the repair or replacement of the Company's property so damaged or
        destroyed and (b) in all other circumstances, be held by RACC as cash
        collateral for the Obligations. RACC may, at its sole option, disburse
        from time to time all or any part of such proceeds so held as cash
        collateral, upon such terms and conditions as RACC may reasonably
        prescribe, for direct application by the Company solely to the repair or
        replacement of the Company's property so damaged or destroyed, or RACC
        may apply all or any part of such proceeds to the Obligations.

                8.3.    Continuation of Insurance. Except as otherwise
        specifically provided in any of the other Transaction Documents, all
        policies of insurance shall provide for at least thirty (30) days prior
        written cancellation notice to RACC. In the event of failure by the
        Company to provide and maintain insurance as herein provided, RACC may,
        at its option, provide such insurance and charge the amount thereof to
        the Company. The Company shall furnish RACC with certificates of
        insurance and policies evidencing compliance with the foregoing
        insurance provision.

        9.      Collateral Protection Expenses; Preservation of Collateral.

                9.1.    Expenses Incurred by Lender. In RACC's discretion, if
        the Company fails to do so, RACC may discharge taxes and other
        encumbrances at any time levied or placed on any of the Collateral, make
        repairs thereto and pay any necessary filing fees or insurance premiums.
        The Company

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                                      -11-

        agrees to reimburse RACC on demand for all expenditures so made. RACC
        shall have no obligation to the Company to make any such expenditures,
        nor shall the making thereof be construed as a waiver or cure of any
        Default or Event of Default.

                9.2.    Lender's Obligations and Duties. Anything herein to the
        contrary notwithstanding, the Company shall remain obligated and liable
        under each contract or agreement comprised in the Collateral to be
        observed or performed by the Company thereunder. RACC shall not have any
        obligation or liability under any such contract or agreement by reason
        of or arising out of this Agreement or the receipt by RACC of any
        payment relating to any of the Collateral, nor shall RACC be obligated
        in any manner to perform any of the obligations of the Company under or
        pursuant to any such contract or agreement, to make inquiry as to the
        nature or sufficiency of any payment received by RACC in respect of the
        Collateral or as to the sufficiency of any performance by any party
        under any such contract or agreement, to present or file any claim, to
        take any action to enforce any performance or to collect the payment of
        any amounts which may have been assigned to RACC or to which RACC may be
        entitled at any time or times. RACC's sole duty with respect to the
        custody, safe keeping and physical preservation of the Collateral in its
        possession, under Section 9-207 of the Uniform Commercial Code of the
        State or otherwise, shall be to deal with such Collateral in the same
        manner as RACC deals with similar property for its own account.

        10.     Securities and Deposits. RACC may at any time following and
during the continuance of Event of Default, at its option, transfer to itself or
any nominee any securities constituting Collateral, receive any income thereon
and hold such income as additional Collateral or apply it to the Obligations.
Whether or not any Obligations are due, RACC may following and during the
continuance of an Event of Default demand, sue for, collect, or make any
settlement or compromise which it deems desirable with respect to the
Collateral. Regardless of the adequacy of Collateral or any other security for
the Obligations, any deposits or other sums at any time credited by or due from
RACC to the Company may at any time be applied to or set off against any of the
Obligations.

        11.     Notification to Account Debtors and Other Persons Obligated on
Collateral. If an Event of Default shall have occurred and be continuing, the
Company shall, at the request and option of RACC, notify account debtors and
other persons obligated on any of the Collateral of the security interest of
RACC in any account, chattel paper, general intangible, instrument or other
Collateral and that payment thereof is to be made directly to RACC or to any
financial institution designated by RACC as RACC's agent therefor, and RACC may
itself, if Event of Default shall have occurred and be continuing, without
notice to or demand upon the Company, so notify account debtors and other
persons obligated on Collateral. After the making of such a request or the
giving of any such notification, the

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                                      -12-

Company shall hold any proceeds of collection of accounts, chattel paper,
general intangibles, instruments and other Collateral received by the Company as
trustee for RACC without commingling the same with other funds of the Company
and shall turn the same over to RACC in the identical form received, together
with any necessary endorsements or assignments. RACC shall apply the proceeds of
collection of accounts, chattel paper, general intangibles, instruments and
other Collateral received by RACC to the Obligations, such proceeds to be
immediately credited after final payment in cash or other immediately available
funds of the items giving rise to them.

        12.     Power of Attorney.

                12.1.   Appointment and Powers of Lender. The Company hereby
        irrevocably constitutes and appoints RACC and any officer or agent
        thereof, with full power of substitution, as its true and lawful
        attorneys-in-fact with full irrevocable power and authority in the place
        and stead of the Company or in RACC's own name, for the purpose of
        carrying out the terms of this Agreement, to take any and all
        appropriate action and to execute any and all documents and instruments
        that may be necessary or useful to accomplish the purposes of this
        Agreement and, without limiting the generality of the foregoing, hereby
        gives said attorneys the power and right, on behalf of the Company,
        without notice to or assent by the Company, to do the following:

                        (a)     upon the occurrence and during the continuance
                of an Event of Default, generally to sell, transfer, pledge,
                make any agreement with respect to or otherwise dispose of or
                deal with any of the Collateral in such manner as is consistent
                with the Uniform Commercial Code of the State and as fully and
                completely as though RACC were the absolute owner thereof for
                all purposes, and to do, at the Company's expense, at any time,
                or from time to time, all acts and things which RACC deems
                necessary or useful to protect, preserve or realize upon the
                Collateral and RACC's security interest therein, in order to
                effect the intent of this Agreement, all no less fully and
                effectively as the Company might do, including, without
                limitation, (i) the filing and prosecuting of registration and
                transfer applications with the appropriate federal, state or
                local agencies or authorities with respect to trademarks,
                copyrights and patentable inventions and processes, (ii) upon
                written notice to the Company, the exercise of voting rights
                with respect to voting securities, which rights may be
                exercised, if RACC so elects, with a view to causing the
                liquidation of assets of the issuer of any such securities and
                (iii) the execution, delivery and recording, in connection with
                any sale or other disposition of any Collateral, of the
                endorsements, assignments or other instruments of conveyance or
                transfer with respect to such Collateral; and

<PAGE>

                                      -13-

                        (b)     to the extent that the Company's authorization
                given in Section 3 is not sufficient, to file such financing
                statements with respect hereto, with or without the Company's
                signature, or a photocopy of this Agreement in substitution for
                a financing statement, as RACC may deem appropriate and to
                execute in the Company's name such financing statements and
                amendments thereto and continuation statements which may require
                the Company's signature.

                12.2.   Ratification by Company. To the extent permitted by law,
        the Company hereby ratifies all that said attorneys shall lawfully do or
        cause to be done by virtue hereof. This power of attorney is a power
        coupled with an interest and is irrevocable.

                12.3.   No Duty on RACC. The powers conferred on RACC hereunder
        are solely to protect its interests in the Collateral and shall not
        impose any duty upon it to exercise any such powers. RACC shall be
        accountable only for the amounts that it actually receives as a result
        of the exercise of such powers, and neither it nor any of its officers,
        directors, employees or agents shall be responsible to the Company for
        any act or failure to act, except for RACC's own gross negligence or
        willful misconduct.

        13.     Rights and Remedies. RACC, without any notice or demand upon the
Company, may from time to time exercise in respect of the Collateral, in
addition to other rights and remedies provided for herein, or otherwise
available to and to the extent not in violation of applicable law, including the
Federal Aviation Act, and if required, subject to the approval of the DOT and/or
the FAA or their respective successors or nominee, all the rights and remedies
of a secured party on default under the UCC in effect in all relevant
jurisdictions at the time of an Event of Default, including, without limitation,
the right to take possession of the Collateral, and for that purpose, RACC may,
so far as the Company can give authority therefor, enter upon any premises on
which the Collateral may be situated and remove the same therefrom. RACC may in
its discretion require the Company to assemble all or any part of the Collateral
at such location or locations within the jurisdiction(s) of the Company's
principal office(s) or at such other locations as RACC may reasonably designate.
RACC may also in its sole discretion, without notice except as specified below,
sell the Collateral or any part thereof in one or more parcels at public or
private sale, at any exchange, broker's board or at any of the RACC's offices or
elsewhere, for cash, on credit or for future delivery, and at such price or
prices and upon such other terms as RACC may deem commercially reasonable. To
the extent not inconsistent with the Federal Aviation Act, the DOT and the FAA
requirements, RACC may be the purchaser of any or all of the Collateral at any
such sale and shall be entitled, for the purpose of bidding and making
settlement or payment of the purchase price for all or any portion of the
Collateral sold at such sale, to use and apply any of the Obligations as a
credit on account of the purchase price of any Collateral payable by such person
at such sale.

<PAGE>

                                      -14-

Each purchaser at any such sale shall acquire the property sold absolutely free
from any claim or right on the purchase of the Company, and the Company hereby
waives, to the fullest extent permitted by law, all right of redemption, stay or
appraisal which it now has or may at any time in the future have under rule of
law or statute now existing or hereafter enacted. Unless the Collateral is
perishable or threatens to decline speedily in value or is of a type customarily
sold on a recognized market, RACC shall give the Company at least five (5)
business days prior written notice of the time and place of any public sale of
Collateral or of the time after which any private sale or any other intended
disposition is to be made. The Company hereby acknowledges that five (5)
business days prior written notice of such sale or sales shall be reasonable
notice. RACC shall not be obligated to make any sale of Collateral regardless of
notice of sale having been given. RACC may adjourn public or private sale from
time to time by announcement at the time and place fixed therefore and such sale
may, without further notice, be made at the time and place to which it was so
adjourned. The Company hereby waives, to the full extent permitted by law, any
claims against the RACC arising by reason of the fact that the price at which
any Collateral may have been sold at such a private sale was less than the price
which might have been obtained at a public sale. In addition, the Company waives
any and all rights that it may have to a judicial hearing in advance of the
enforcement of any of RACC's rights and remedies hereunder, including, without
limitation, its right following an Event of Default to take immediate possession
of the Collateral and to exercise its rights and remedies with respect thereto.

        14.     Standards for Exercising Rights and Remedies. To the extent that
applicable law imposes duties on RACC to exercise remedies in a commercially
reasonable manner, the Company acknowledges and agrees that it is not
commercially unreasonable for RACC (a) to fail to incur expenses reasonably
deemed significant by RACC to prepare Collateral for disposition or otherwise to
fail to complete raw material or work in process into finished goods or other
finished products for disposition, (b) to fail to obtain third party consents
for access to Collateral to be disposed of, or to obtain or, if not required by
other law, to fail to obtain governmental or third party consents for the
collection or disposition of Collateral to be collected or disposed of, (c) to
fail to exercise collection remedies against account debtors or other persons
obligated on Collateral or to fail to remove liens or encumbrances on or any
adverse claims against Collateral, (d) to exercise collection remedies against
account debtors and other persons obligated on Collateral directly or through
the use of collection agencies and other collection specialists, (e) to
advertise dispositions of Collateral through publications or media of general
circulation, whether or not the Collateral is of a specialized nature, (f) to
contact other persons, whether or not in the same business as the Company, for
expressions of interest in acquiring all or any portion of the Collateral, (g)
to hire one or more professional auctioneers to assist in the disposition of
Collateral, whether or not the collateral is of a specialized nature, (h) to
dispose of Collateral by utilizing Internet sites that provide for the auction
of assets of the types included in

<PAGE>

                                      -15-

the Collateral or that have the reasonable capability of doing so, or that match
buyers and sellers of assets, (i) to dispose of assets in wholesale rather than
retail markets, (j) to disclaim disposition warranties, (k) to purchase
insurance or credit enhancements to insure RACC against risks of loss,
collection or disposition of Collateral or to provide to RACC a guaranteed
return from the collection or disposition of Collateral, or (l) to the extent
deemed appropriate by RACC, to obtain the services of brokers, investment
bankers, consultants and other professionals to assist RACC in the collection or
disposition of any of the Collateral. The Company acknowledges that the purpose
of this Section 14 is to provide non-exhaustive indications of what actions or
omissions by RACC would fulfill RACC's duties under the Uniform Commercial Code
of the State or any other relevant jurisdiction in RACC's exercise of remedies
against the Collateral and that other actions or omissions by RACC shall not be
deemed to fail to fulfill such duties solely on account of not being indicated
in this Section 14. Without limitation upon the foregoing, nothing contained in
this Section 14 shall be construed to grant any rights to the Company or to
impose any duties on RACC that would not have been granted or imposed by this
Agreement or by applicable law in the absence of this Section 14.

        15.     No Waiver by Lender, etc. RACC shall not be deemed to have
waived any of its rights and remedies in respect of the Obligations or the
Collateral unless such waiver shall be in writing and signed by RACC. No delay
or omission on the part of RACC in exercising any right or remedy shall operate
as a waiver of such right or remedy or any other right or remedy. A waiver on
any one occasion shall not be construed as a bar to or waiver of any right or
remedy on any future occasion. All rights and remedies of RACC with respect to
the Obligations or the Collateral, whether evidenced hereby or by any other
instrument or papers, shall be cumulative and may be exercised singularly,
alternatively, successively or concurrently at such time or at such times as
RACC deems expedient.

        16.     Suretyship Waivers by Company. The Company waives demand,
notice, protest, notice of acceptance of this Agreement, notice of loans made,
credit extended, Collateral received or delivered or other action taken in
reliance hereon and all other demands and notices of any description. With
respect to both the Obligations and the Collateral, the Company assents to any
extension or postponement of the time of payment or any other indulgence, to any
substitution, exchange or release of or failure to perfect any security interest
in any Collateral, to the addition or release of any party or person primarily
or secondarily liable, to the acceptance of partial payment thereon and the
settlement, compromising or adjusting of any thereof, all in such manner and at
such time or times as RACC may deem advisable. RACC shall have no duty as to the
collection or protection of the Collateral or any income therefrom, the
preservation of rights against prior parties, or the preservation of any rights
pertaining thereto beyond the safe custody thereof as set forth in Section 9.2.
The Company further waives any and all other suretyship defenses.

<PAGE>

                                      -16-

        17.     Marshalling. RACC shall not be required to marshal any present
or future collateral security (including but not limited to the Collateral) for,
or other assurances of payment of, the Obligations or any of them or to resort
to such collateral security or other assurances of payment in any particular
order, and all of its rights and remedies hereunder and in respect of such
collateral security and other assurances of payment shall be cumulative and in
addition to all other rights and remedies, however existing or arising. To the
extent that it lawfully may, the Company hereby agrees that it will not invoke
any law relating to the marshalling of collateral which might cause delay in or
impede the enforcement of RACC's rights and remedies under this Agreement or
under any other instrument creating or evidencing any of the Obligations or
under which any of the Obligations is outstanding or by which any of the
Obligations is secured or payment thereof is otherwise assured, and, to the
extent that it lawfully may, the Company hereby irrevocably waives the benefits
of all such laws.

        18.     Proceeds of Dispositions; Expenses. The Company shall pay to
RACC on demand any and all expenses, including reasonable attorneys' fees and
disbursements, incurred or paid by RACC in protecting, preserving or enforcing
RACC's rights and remedies under or in respect of any of the Obligations or any
of the Collateral. After deducting all of said expenses, the residue of any
proceeds of collection or sale or other disposition of Collateral shall, to the
extent actually received in cash, be applied to the payment of the Obligations
in such order or preference as RACC may determine, proper allowance and
provision being made for any Obligations not then due. Upon the final payment
and satisfaction in full of all of the Obligations and after making any payments
required by Sections 9-608(a)(1)(C) or 9-615(a)(3) of the Uniform Commercial
Code of the State, any excess shall be returned to the Company. In the absence
of final payment and satisfaction in full of all of the Obligations, the Company
shall remain liable for any deficiency.

        19.     Overdue Amounts. Until paid, all amounts due and payable by the
Company hereunder shall be a debt secured by the Collateral and shall bear,
whether before or after judgment, interest at the Default Interest Rate set
forth in the Restructuring Agreement.

        20.     Governing Law; Consent to Jurisdiction. THIS AGREEMENT IS
INTENDED TO TAKE EFFECT AS A SEALED INSTRUMENT AND SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE. The Company agrees that any
action or claim arising out of any dispute in connection with this Agreement,
any rights or obligations hereunder or the performance or enforcement of such
rights or obligations may be brought in the courts of the State or any federal
court sitting therein and consents to the non-exclusive jurisdiction of such
court and to service of process in any such suit being made upon the Company by
mail at the address specified in of the Restructuring Agreement. The Company
hereby waives any objection that it may now or

<PAGE>

                                      -17-

hereafter have to the venue of any such suit or any such court or that such suit
is brought in an inconvenient court.

        21.     Waiver of Jury Trial. THE COMPANY WAIVES ITS RIGHT TO A JURY
TRIAL WITH RESPECT TO ANY ACTION OR CLAIM ARISING OUT OF ANY DISPUTE IN
CONNECTION WITH THIS AGREEMENT, ANY RIGHTS OR OBLIGATIONS HEREUNDER OR THE
PERFORMANCE OR ENFORCEMENT OF ANY SUCH RIGHTS OR OBLIGATIONS. Except as
prohibited by law, the Company waives any right which it may have to claim or
recover in any litigation referred to in the preceding sentence any special,
exemplary, punitive or consequential damages or any damages other than, or in
addition to, actual damages. The Company (a) certifies that neither RACC nor any
representative, agent or attorney of RACC has represented, expressly or
otherwise, that RACC would not, in the event of litigation, seek to enforce the
foregoing waivers or other waivers contained in this Agreement and (b)
acknowledges that, in entering into the Restructuring Agreement and the other
Transaction Documents to which RACC is a party, RACC is relying upon, among
other things, the waivers and certifications contained in this Section 21.

        22.     Successors and Assigns. This Agreement shall be binding upon and
shall inure to the benefit of the parties hereto and their respective successors
and assigns permitted by the Restructuring Agreement; provided that the Company
may not transfer or assign any or all of its rights or obligations hereunder
without the prior written consent of RACC.

        23.     Miscellaneous. The headings of each section of this Agreement
are for convenience only and shall not define or limit the provisions thereof.
If any term of this Agreement shall be held to be invalid, illegal or
unenforceable, the validity of all other terms hereof shall in no way be
affected thereby, and this Agreement shall be construed and be enforceable as if
such invalid, illegal or unenforceable term had not been included herein. The
Company acknowledges receipt of a copy of this Agreement. This Agreement may be
executed in one or more counterparts, each of which shall be deemed an original,
but all of which together shall constitute one and the same instrument.

            [The remainder of this page is intentionally left blank.]

<PAGE>

                                      -18-

        IN WITNESS WHEREOF, intending to be legally bound, the Company has
caused this Agreement to be duly executed as of the date first above written.

                                                 GREAT LAKES AVIATION, LTD.

                                                 By: /s/ Charles R. Howell IV
                                                     ------------------------
                                                      Title: CEO
                                                             ----------------

Accepted:

RAYTHEON AIRCRAFT CREDIT
CORPORATION

By: /s/ Andrew A. Mathews
    ---------------------
    Title: President
           --------------

<PAGE>

                                      -19-

List of Schedules

Schedule 5(b) Existing Liens on Collateral

<PAGE>

                                  SCHEDULE 5(b)

                        EXISTING LIENS ON COLLATERAL/1//

                       DEBTOR: GREAT LAKES AVIATION, LTD.

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                               <C>               <C>              <C>
Iowa Secretary of State   CIT Group/Equipment Financing,    K663105           7-11-95          Embraer model EMB-120ER bearing
                          Inc. ("CIT")                                                         United States registration number
                                                                                               N299UX and manufacturer's serial
                                                                                               number 120.299; two Pratt and
                                                                                               Whitney model PW-118A engines
                                                                                               having serial numbers PCE-115679
                                                                                               and PCE-115680; two Hamilton
                                                                                               Standard model 14RF-9 propellers
                                                                                               having serial numbers MFG-950302
                                                                                               and MFG-950402; any Replacement
                                                                                               Engine or Propeller
                                                            K950755           9-28-98          Release of engine PCE-115679
                                                            K954957           10-15-98         Amendment of Debtor's address
                                                            P084757           2-25-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
                          CIT                               K682978           10-19-95         Embraer model EMB-120RT Brasilia
                                                                                               aircraft bearing United States
                                                                                               registration number N451UE and
                                                                                               manufacturer's serial number
                                                                                               120.108; two Pratt and Whitney
                                                                                               model PW-118 engines having serial
                                                                                               numbers PCE-115078 and PCE-115436;
                                                                                               two Hamilton Standard model 14RF-9
                                                                                               propellers having serial numbers
                                                                                               MFG-789 and MFG-1066; any
                                                                                               Replacement Engine or Propeller
                                                            P019578           6-1-99           Amendment of Debtor's address
                                                            P107619           5-30-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

----------------
        /1//Does not include liens naming Coast Business Credit as secured
party, which are to be terminated pursuant to Section 12(B)(22) of the
Restructuring Agreement.

<PAGE>

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                               <C>               <C>              <C>
                          CIT                               K688414           11-13-95         One Embraer model EMB-120RT
                                                                                               Brasilia aircraft (including
                                                                                               accessories and attachments)
                                                                                               bearing United States registration
                                                                                               number N452UE and manufacturer's
                                                                                               serial number 120.096; two Pratt
                                                                                               and Whitney model PW-118 engines
                                                                                               having serial numbers PCE-115434
                                                                                               and PCE-115440; two Hamilton
                                                                                               Standard model 14RF-9 propellers
                                                                                               having serial numbers MFG-567 and
                                                                                               MFG-1674; any Replacement Engine or
                                                                                               Propeller
                                                            K950754           9-28-98          Release of Engine PCE-115434
                                                            K950756           9-28-98          Amendment of Debtor's address
                                                            P107620           5-30-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
                          CIT                               P301264           7-13-2001        One Embraer model EMB-120RT
                                                                                               Brasilia aircraft (including
                                                                                               accessories and attachments)
                                                                                               bearing United States registration
                                                                                               number N299UX and manufacturer's
                                                                                               serial number 120.299; two Pratt
                                                                                               and Whitney model PW-118A engines
                                                                                               having serial numbers PCE-115679
                                                                                               and PCE-115680; two Hamilton
                                                                                               Standard model 14RF-9 propellers
                                                                                               having serial numbers MFG-950302
                                                                                               and MFG-950402; any Replacement
                                                                                               Engine or Propeller
                                                            P304152           7-31-2001        Release of engine PCE-115679; add
                                                                                               engine PCE-115668 to collateral
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                               <C>               <C>              <C>
                          CIT                               P301265           7-13-2001        One Embraer model EMB-120RT
                                                                                               Brasilia aircraft (including
                                                                                               accessories and attachments)
                                                                                               bearing United States registration
                                                                                               number N452UE and manufacturer's
                                                                                               serial number 120.096; two Pratt
                                                                                               and Whitney model PW-118 engines
                                                                                               having serial numbers PCE-115620
                                                                                               and PCE-115440; two Hamilton
                                                                                               Standard model 14RF-9 propellers
                                                                                               having serial numbers MFG-567 and
                                                                                               MFG-1674; any Replacement Engine or
                                                                                               Propeller
----------------------------------------------------------------------------------------------------------------------------------
                          CIT                               P301266           7-13-2001        Embraer model EMB-120RT Brasilia
                                                                                               aircraft bearing United States
                                                                                               registration number N451UE and
                                                                                               manufacturer's serial number
                                                                                               120.108; two Pratt and Whitney
                                                                                               model PW-118 engines having serial
                                                                                               numbers PCE-115078 and PCE-115436;
                                                                                               two Hamilton Standard model 14RF-9
                                                                                               propellers having serial numbers
                                                                                               MFG-789 and MFG-1066; any
                                                                                               Replacement Engine or Propeller
----------------------------------------------------------------------------------------------------------------------------------
                          Davco Industries, LLC             K974504           12-21-98         Davco 400-60-28 Ground Power Unit
                          (assignee: Soris, a division of
                          Case Credit Corporation)
----------------------------------------------------------------------------------------------------------------------------------
                          Steelcase Financial Services,     P079704           2-4-2000         All furniture and equipment
                          Inc.                                                                 leased or financed from Steelcase
                                                                                               Financial Services, Inc.
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                               <C>               <C>              <C>
Minnesota Secretary of    CIT                               1775173           7-12-95          One Embraer model EMB-120RT
State                                                                                          Brasilia aircraft (including
                                                                                               accessories and attachments)
                                                                                               bearing United States registration
                                                                                               number N299UX and manufacturer's
                                                                                               serial number 120.299; two Pratt
                                                                                               and Whitney model PW-118A engines
                                                                                               having serial numbers PCE-115679
                                                                                               and PCE-115680; two Hamilton
                                                                                               Standard model 14RF-9 propellers
                                                                                               having serial numbers MFG-950302
                                                                                               and MFG-950402; any Replacement
                                                                                               Engine or Propeller
                                                            2071826           9-29-98          Release of Engine PCE-115679
                                                            2071827           9-29-98          Amend Debtor's address and add an
                                                                                               engine to the collateral
                                                            2204973           2-25-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
                          CIT                               1797535           10-19-95         Embraer model EMB-120RT Brasilia
                                                                                               aircraft bearing United States
                                                                                               registration number N451UE and
                                                                                               manufacturer's serial number
                                                                                               120.108; two Pratt and Whitney
                                                                                               model PW-118 engines having
                                                                                               serial numbers PCE-115078 and
                                                                                               PCE-115436; two Hamilton Standard
                                                                                               model 14RF-9 propellers having
                                                                                               serial numbers MFG-789 and
                                                                                               MFG-1066; any Replacement Engine
                                                                                               or Propeller
                                                            21362401          6-2-99           Amendment of Debtor's address
                                                            2232182           5-30-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                               <C>               <C>              <C>
                          CIT                               1803588           11-14-95         One Embraer model EMB-120RT Brasilia
                                                                                               aircraft (including accessories and
                                                                                               attachments) bearing United States
                                                                                               registration number N452UE and
                                                                                               manufacturer's serial number
                                                                                               120.096; two Pratt and Whitney
                                                                                               model PW-118 engines having serial
                                                                                               numbers PCE-115434 and PCE-115440;
                                                                                               two Hamilton Standard model 14RF-9
                                                                                               propellers having serial numbers
                                                                                               MFG-567 and MFG-1674; any
                                                                                               Replacement Engine or Propeller
                                                            2071828           9-29-98          Release of Engine PCE-115434
                                                            2071829           9-29-98          Amendment of Debtor's address and
                                                                                               add engine to collateral
                                                                                               description
                                                            2232181           5-30-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
                          Finova Capital Corporation        1824525           2-12-96          One Airframe: Embraer Model
                          ("Finova")                                                           EMB-120, FAA Registration Number
                                                                                               N279UE and Manufacturer's Serial
                                                                                               No. 120.085 Two Pratt & Whitney
                                                                                               model PW-118 engines with
                                                                                               Manufacturer's serial numbers
                                                                                               PCE-115497 and PCE-115330 Two
                                                                                               Hamilton Standard Model 14RF-9
                                                                                               propellers bearing serial numbers
                                                                                               866 and 1293
                                                            2261034           9-25-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
                          Finova                            1824526           2-12-96          One Airframe: Embraer Model
                                                                                               EMB-120, FAA Registration Number
                                                                                               N281UE and Manufacturer's Serial
                                                                                               No. 120.092 Two Pratt & Whitney model
                                                                                               PW-118 engines with Manufacturer's
                                                                                               serial numbers PCE-115347 and
                                                                                               PCE-115189; Two Hamilton Standard
                                                                                               Model 14RF-9 propellers bearing
                                                                                               serial numbers 1829 and 626
                                                            2261033           9-25-2000        Continuation
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
JURISDICTION              SECURED PARTY                     FILE NUMBER       DATE FILED       COLLATERAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                          <C>                            <C>               <C>              <C>
WY, Laramie County           Steelcase Financial Services,  U-588931          2-18-2000        All furniture and equipment
                                                      Inc.  105707155                          leased from Steelcase.Lease No.
                                                                                               13702.
----------------------------------------------------------------------------------------------------------------------------------
</TABLE><PAGE>

                                                                   EXHIBIT 10.16

                     FOURTH AMENDMENT TO SECURITY AGREEMENT
                          [Great Lakes Aviation, Ltd.]

        THIS FOURTH AMENDMENT TO SECURITY AGREEMENT [Great Lakes Aviation, Ltd.]
is entered into as of December 31, 2002 (the "Agreement"), by and between Great
Lakes Aviation Ltd., as debtor (the "Debtor"), and Raytheon Aircraft Credit
Corporation (the "Secured Party").

                              W I T N E S S E T H :

        WHEREAS, Debtor and Secured Party are parties to an existing security
agreement as previously amended from time to time that is described and defined
on Exhibit A attached hereto and referred to as the "Security Agreement"
(capitalized terms used and not defined herein shall have the meanings ascribed
thereto in the Security Agreement);

        WHEREAS, the Security Agreement encumbers various aircraft parts and
other collateral collectively described herein as the "Collateral";

        WHEREAS, as of this date, Debtor has entered into a Restructuring
Agreement with the Secured Party (as amended and in effect from time to time,
the "Restructuring Agreement") whereby, among other things, the Secured Party
has agreed to accept the return of certain aircraft and provide certain related
financing, to restructure its financing of certain aircraft and to reduce lease
payments on certain aircraft;

        WHEREAS, as part of such Restructuring Agreement, Debtor has issued
thirty-three (33) Notes in favor of the Secured Party (collectively, the "New
Notes");

        WHEREAS, the parties intend by this instrument to amend the Security
Agreement as of December 31, 2002, to specifically reflect that the Security
Agreement secures payments of the Debtor's obligations under the Restructuring
Agreement and the New Notes in addition to any and all other indebtedness owed
by Debtor to Secured Party (whether now existing or hereinafter arising), as
well as any renewals, extensions or changes in the form of said obligations or
indebtedness;

        WHEREAS, the parties, by this amendment, intend to include a updated
listing of all Collateral relating to Debtor's obligations under the
Restructuring Agreement and the New Notes as well as any and all other
indebtedness owed by Debtor to the Secured Party;

        NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is acknowledged, the parties hereto agree as follows:

<PAGE>

1.      Debtor acknowledges and confirms that the security interest granted
        pursuant to Section 1 of the Security Agreement secures payment of all
        indebtedness, obligations and liabilities of Debtor to Secured Party,
        now existing or arising hereafter, direct or indirect, joint or several,
        absolute or contingent, matured or unmatured, liquidated or
        unliquidated, secured or unsecured, arising by contract, operation of
        law or otherwise, arising or incurred under the Restructuring Agreement,
        the Notes (as defined in the Restructuring Agreement) and the other
        Transaction Documents (as defined in the Restructuring Agreement),
        including, without limitation, all such indebtedness, obligations and
        liabilities that would become due but for the operation of the automatic
        stay pursuant to section 362(a) of the Federal Bankruptcy Code and the
        operation of sections 502(b) and 506(b) of the Federal Bankruptcy Code
        and including, without limitation, post-petition interest;

2.      Exhibit A to the Security Agreement is hereby amended in its entirety by
        substituting in its place Exhibit A-1 hereto, and all locations
        previously subject to the Security Agreement, and not described on
        Exhibit A-1 hereto, are hereby released from the terms thereof.

3.      Exhibit B to the Security Agreement is hereby amended in its entirety by
        substituting in its place Exhibit B-1 hereto, and all engines previously
        subject to the Security Agreement, and not described on Exhibit B-1
        hereto, are hereby released from the terms thereof.

4.      Debtor hereby grants to Secured Party a security interest in all of the
        Collateral described on Exhibit A-1 and Exhibit B-1 attached hereto.
        Except as modified and supplemented hereby, the Security Agreement
        remains in full force and effect and is hereby ratified and confirmed.

5.      Debtor hereby covenants and agrees that it is a certificated air carrier
        holding a certificate issued under 40 U.S.C. Section 44705.

<PAGE>

        THIS FOURTH AMENDMENT TO SECURITY AGREEMENT [Great Lakes Aviation, Ltd.]
may be executed and delivered by the parties hereto in separate counterparts,
each of which when executed and delivered, shall be an original, but all such
counterparts shall together constitute but one and the same instrument.

GREAT LAKES AVIATION, LTD.           RAYTHEON AIRCRAFT CREDIT CORPORATION

By: /s/ Charles R. Howell IV         By: /s/ Andrew A. Mathews
    ------------------------            ------------------------
Name:  Charles R. Howell IV          Name:  Andrew A. Mathews
      ----------------------              ----------------------
Title: CEO                           Title: President
      ----------------------               ---------------------

<PAGE>

                                    EXHIBIT A

                               SECURITY AGREEMENT

Security Agreement and Encumbrance Against Air Carrier Aircraft Engines,
Propellers, Appliances and Spare Parts dated August 21, 1997 by and between
Great Lakes Aviation, Ltd., as debtor, and Raytheon Aircraft Credit Corporation,
as secured party, recorded by the Federal Aviation Administration Aircraft
Registry on October 1, 1997 as Conveyance Number XX008998 amended by the
Amendment dated as of December 1, 2000, recorded October 4, 2001, as Conveyance
No. NN022610, amended by Second Amendment and Supplement to Security Agreement
dated as of June 29, 2001, recorded October 4, 2001, as Conveyance No. NN022612,
and amended by Third Amendment to Security Agreement dated as of July 2, 2001,
recorded October 5, 2001, as Conveyance No. NN022613.

<PAGE>

                                   EXHIBIT A-1

                           GREAT LAKES AVIATION, LTD.
                              SPARE PARTS LOCATIONS

                          GREAT LAKES AVIATION
                          1022 AIRPORT PARKWAY
                          CHEYENNE WY. 82001

                          CERTIFIED REPAIR STATION
                          1204 AIRPORT PARKWAY
                          CHEYENNE, WY 82001

                          GREAT LAKES AVIATION
                          3851 N. SKY PARK ROAD
                          GRAND ISLAND, NE 68801

                          GREAT LAKES AVIATION
                          HURON REGIONAL A/P
                          1501 COLORADO AVENUE N.W.
                          HURON, SD 57350

                          GREAT LAKES AVIATION
                          8900 PENA BLVD., A-52
                          DENVER, CO 80249

<PAGE>

                                   EXHIBIT B-1

                           GREAT LAKES AVIATION, LTD.
                                  SPARE ENGINES

                 Engine Model                     Engine Serial #
                 ------------------------------------------------

                   PT6A-67D                           114179

                   PT6A-67D                           PS0090

                   PT6A-67D                           PS0082

                   PT6A-67D                           PS0069

                   PT6A-67D                           PS0059

                   PT6A-67D                           PS0084

                   PT6A-67D                           114267

                   PT6A-67D                           PS0072

                   PT6A-67D                           114218

                   PT6A-67D                           PS0017

                   PT6A-67D                           114277

                   PT6A-67D                           PS0056

                   PT6A-67D                           PS0001

                   PT6A-67D                           114305

                   PT6A-65B                           32358

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00050-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00050-of-00352.parquet"}]]