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                                                                     EXHIBIT 4.5

                               SUBSIDIARY GUARANTY


        THIS SUBSIDIARY GUARANTY (this "Guaranty") is made as of the 31st day of
December, 1999, by AirNet Management, Inc., an Ohio corporation (the "Subsidiary
Guarantor") in favor of the Agent, for the benefit of the Lenders, under the
Credit Agreement referred to below;


                                   WITNESSETH:

        WHEREAS, AirNet Systems, Inc., an Ohio corporation (the "Principal"),
certain Lenders from time to time party thereto and Bank One, Michigan, formerly
known as NBD Bank, as agent for the Lenders (in such capacity, together with any
successor agent, the "Agent") have entered into a certain Credit Agreement dated
as of August 1, 1998, as amended by that certain First Amendment to Credit
Agreement dated as of September 30, 1998, and as further amended by that certain
Second Amendment to Credit Agreement dated of even date herewith (as same may be
amended or modified from time to time, the "Credit Agreement"), providing,
subject to the terms and conditions thereof, for extensions of credit to be made
by the Lenders to the Principal;

        WHEREAS, it is pursuant to Section 5.1(f) of the Credit Agreement that
the Subsidiary Guarantor executes and delivers this Guaranty whereby the
Subsidiary Guarantor shall guarantee the payment when due, subject to Section 9
hereof, of all Guaranteed Obligations, as defined below; and

        WHEREAS, in consideration of the financial and other support that the
Principal has provided, and such financial and other support as the Principal
may in the future provide to the Subsidiary Guarantor, and in order to induce
the Lenders and the Agent to enter into the Credit Agreement, and the Lenders
and their Affiliates to enter into one or more Rate Management Transactions with
the Principal, and because the Subsidiary Guarantor has determined that
executing this Guaranty is in its interest and to its financial benefit, the
Subsidiary Guarantor is willing to guarantee the obligations of the Principal
under the Credit Agreement, any Note, any Rate Management Transaction, and the
other Loan Documents;

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

        SECTION  l.1.  Selected Terms Used Herein.

        "Guaranteed Obligations" is defined in Section 3 below.

        "Rate Management Transaction" means any transaction (including an
agreement with respect thereto) now existing or hereafter entered into between
the Principal and any Lender or Affiliate thereof which is a rate swap, basis
swap, forward rate transaction, commodity swap, commodity option, equity or
equity index swap, equity or equity index option, bond option, interest rate
option, foreign exchange transaction, cap transaction, floor transaction, collar
transaction, forward transaction, currency swap transaction, cross-currency rate
swap transaction, currency option or any other similar transaction (including
any option with respect to any of these transactions) or any combination
thereof, whether linked to one or more interest rates, foreign currencies,
commodity prices, equity prices or other financial measures.

        "Rate Management Obligations" means any and all obligations of the
Principal, whether absolute or contingent and howsoever and whensoever created,
arising, evidenced or acquired (including all renewals, extensions and
modifications thereof and substitutions therefor), under (i) any and all Rate
Management Transactions, and (ii) any and all cancellations, buy backs,
reversals, terminations or assignments of any Rate Management Transactions.

        SECTION 1.2. Terms in Credit Agreement. Other capitalized terms used
herein but not defined herein shall have the meaning set forth in the Credit
Agreement.

        SECTION 2.1. Representations and Warranties. The Subsidiary Guarantor
represents and warrants (which representations and warranties shall be deemed to
have been renewed upon each date an Advance is made under the Credit Agreement)
that:


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               (a) It is a corporation, partnership or limited liability company
duly and properly incorporated or organized, as the case may be, validly
existing and (to the extent such concept applies to such entity) in good
standing under the laws of its jurisdiction of incorporation or organization and
has all requisite authority to conduct its business in each jurisdiction in
which its business is conducted.

               (b) It has the power and authority and legal right to execute and
deliver this Guaranty and to perform its obligations hereunder. The execution
and delivery by it of this Guaranty and the performance of its obligations
hereunder have been duly authorized by proper corporate proceedings, and this
Guaranty constitutes a legal, valid and binding obligation of such Subsidiary
Guarantor enforceable against it in accordance with its terms, except as
enforceability may be limited by bankruptcy, insolvency or similar laws
affecting the enforcement of creditors' rights generally.

               (c) Neither the execution and delivery by it of this Guaranty,
nor the consummation of the transactions herein contemplated, nor compliance
with the provisions hereof will violate (i) any law, rule, regulation, order,
writ, judgment, injunction, decree or award binding on it or any of its
subsidiaries or (ii) its articles or certificate of incorporation, partnership
agreement, certificate of partnership, articles or certificate of organization,
by-laws, or operating or other management agreement, as the case may be, or
(iii) the provisions of any indenture, instrument or agreement to which it or
any of its subsidiaries is a party or is subject, or by which it, or its
property, is bound, or conflict with or constitute a default thereunder, or
result in, or require, the creation or imposition of any Lien in, of or on the
property of such Subsidiary Guarantor or a subsidiary thereof pursuant to the
terms of any such indenture, instrument or agreement. No order, consent,
adjudication, approval, license, authorization, or validation of, or filing,
recording or registration with, or exemption by, or other action in respect of
any governmental or public body or authority, or any subdivision thereof, which
has not been obtained by it or any of its subsidiaries, is required to be
obtained by it or any of its subsidiaries in connection with the execution and
delivery of this Guaranty or the performance by it of its obligations hereunder
or the legality, validity, binding effect or enforceability of this Guaranty.

        SECTION 2.2. Covenants. The Subsidiary Guarantor covenants that, so long
as any Lender has any Commitment outstanding under the Credit Agreement, any
Rate Management Transaction remains in effect or any of the Guaranteed
Obligations shall remain unpaid, that it will, and, if necessary, will enable
the Principal to, fully comply with those covenants and agreements set forth in
the Credit Agreement.

        SECTION 3. The Guaranty. Subject to Section 9 hereof, the Subsidiary
Guarantor hereby absolutely and unconditionally guarantees, as primary obligor
and not as surety, the full and punctual payment (whether at stated maturity,
upon acceleration or early termination or otherwise, and at all times
thereafter) and performance of the Obligations and the Rate Management
Obligations, including without limitation any such Obligations or Rate
Management Obligations incurred or accrued during the pendency of any
bankruptcy, insolvency, receivership or other similar proceeding, whether or not
allowed or allowable in such proceeding (collectively, subject to the provisions
of Section 9 hereof, being referred to as the "Guaranteed Obligations"). Upon
failure by the Principal to pay punctually any such amount, the Subsidiary
Guarantor agrees that it shall forthwith on demand pay to the Agent for the
benefit of the Lenders and, if applicable, their Affiliates, the amount not so
paid at the place and in the manner specified in the Credit Agreement, any Note,
any Rate Management Transaction or the relevant Loan Document, as the case may
be. This Guaranty is a guaranty of payment and not of collection. The Subsidiary
Guarantor waives any right to require the Lender to sue the Principal, any other
guarantor, or any other person obligated for all or any part of the Guaranteed
Obligations, or otherwise to enforce its payment against any collateral securing
all or any part of the Guaranteed Obligations.

        SECTION 4. Guaranty Unconditional. Subject to Section 9 hereof, the
obligations of the Subsidiary Guarantor hereunder shall be unconditional and
absolute and, without limiting the generality of the foregoing, shall not be
released, discharged or otherwise affected by:

        (i) any extension, renewal, settlement, compromise, waiver or release in
        respect of any of the Guaranteed Obligations, by operation of law or
        otherwise, or any obligation of any other guarantor of any of the
        Guaranteed Obligations, or any default, failure or delay, willful or
        otherwise, in the payment or performance of the Guaranteed Obligations;

        (ii) any modification or amendment of or supplement to the Credit
        Agreement, any Note, any Rate Management Transaction or any other Loan
        Document;

        (iii) any release, nonperfection or invalidity of any direct or indirect
        security for any obligation of the Principal under the Credit Agreement,
        any Note, any Rate Management Transaction, any other Loan Document, or
        any obligations of any other guarantor of any of the Guaranteed
        Obligations, or any action or failure to act by the Agent, any Lender or
        any Affiliate of any Lender with respect to any collateral securing all
        or any part of the Guaranteed Obligations;


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        (iv) any change in the corporate existence, structure or ownership of
        the Principal or any other guarantor of any of the Guaranteed
        Obligations, or any insolvency, bankruptcy, reorganization or other
        similar proceeding affecting the Principal, or any other guarantor of
        the Guaranteed Obligations, or its assets or any resulting release or
        discharge of any obligation of the Principal, or any other guarantor of
        any of the Guaranteed Obligations;

        (v) the existence of any claim, setoff or other rights which the
        Subsidiary Guarantor may have at any time against the Principal, any
        other guarantor of any of the Guaranteed Obligations, the Agent, any
        Lender or any other Person, whether in connection herewith or any
        unrelated transactions;

        (vi) any invalidity or unenforceability relating to or against the
        Principal, or any other guarantor of any of the Guaranteed Obligations,
        for any reason related to the Credit Agreement, any Rate Management
        Transaction, any other Loan Document, or any provision of applicable law
        or regulation purporting to prohibit the payment by the Principal, or
        any other guarantor of the Guaranteed Obligations, of the principal of
        or interest on any Note or any other amount payable by the Principal
        under the Credit Agreement, any Note, any Rate Management Transaction or
        any other Loan Document; or

        (vii) any other act or omission to act or delay of any kind by the
        Principal, any other guarantor of the Guaranteed Obligations, the Agent,
        any Lender or any other Person or any other circumstance whatsoever
        which might, but for the provisions of this paragraph, constitute a
        legal or equitable discharge of the Subsidiary Guarantor's obligations
        hereunder.

        SECTION 5. Discharge Only Upon Payment In Full: Reinstatement In Certain
Circumstances. The Subsidiary Guarantor's obligations hereunder shall remain in
full force and effect until all Guaranteed Obligations shall have been
indefeasibly paid in full, the Commitments under the Credit Agreement shall have
terminated or expired and all Rate Management Transactions have terminated or
expired. If at any time any payment of the principal of or interest on any Note
or any other amount payable by the Principal or any other party under the Credit
Agreement, any Rate Management Transaction or any other Loan Document is
rescinded or must be otherwise restored or returned upon the insolvency,
bankruptcy or reorganization of the Principal or otherwise, each of the
Subsidiary Guarantor's obligations hereunder with respect to such payment shall
be reinstated as though such payment had been due but not made at such time.

        SECTION 6. Waivers. The Subsidiary Guarantor irrevocably waives
acceptance hereof, presentment, demand, protest and, to the fullest extent
permitted by law, any notice not provided for herein, as well as any requirement
that at any time any action be taken by any Person against the Principal, any
other guarantor of any of the Guaranteed Obligations, or any other Person.

        SECTION 7. Subrogation. The Subsidiary Guarantor hereby agrees not to
assert any right, claim or cause of action, including, without limitation, a
claim for subrogation, reimbursement, indemnification or otherwise, against the
Principal arising out of or by reason of this Guaranty or the obligations
hereunder, including, without limitation, the payment or securing or purchasing
of any of the Guaranteed Obligations by the Subsidiary Guarantor unless and
until the Guaranteed Obligations are indefeasibly paid in full, any commitment
to lend under the Credit Agreement and any other Loan Documents is terminated
and all Rate Management Transactions have terminated or expired.

        SECTION 8. Stay of Acceleration. If acceleration of the time for payment
of any of the Guaranteed Obligations is stayed upon the insolvency, bankruptcy
or reorganization of the Principal, all such amounts otherwise subject to
acceleration under the terms of the Credit Agreement, any Note, any Rate
Management Transaction or any other Loan Document shall nonetheless be payable
by the Subsidiary Guarantor hereunder forthwith on demand by the Agent made at
the request of the Required Lenders.

        SECTION 9. Limitation on Obligations. (a) The provisions of this
Guaranty are severable, and in any action or proceeding involving any state
corporate law, or any state, federal or foreign bankruptcy, insolvency,
reorganization or other law affecting the rights of creditors generally, if the
obligations of the Subsidiary Guarantor under this Guaranty would otherwise be
held or determined to be avoidable, invalid or unenforceable on account of the
amount of such Subsidiary Guarantor's liability under this Guaranty, then,
notwithstanding any other provision of this Guaranty to the contrary, the amount
of such liability shall, without any further action by the Subsidiary Guarantor,
the Agent or any Lender, be automatically limited and reduced to the highest
amount that is valid and enforceable as determined in such action or proceeding
(such highest amount determined hereunder being the Subsidiary Guarantor's
"Maximum Liability"). This Section 9(a) with respect to the Maximum Liability of
the Subsidiary Guarantor is intended solely to preserve the rights of the Agent
hereunder to the maximum extent not subject to avoidance under applicable law,
and neither the Subsidiary Guarantor nor any other person or entity shall have
any right or claim under this Section 9(a) with respect to the Maximum
Liability, except to the extent necessary so that the obligations of the
Subsidiary Guarantor hereunder shall not be rendered voidable under applicable
law.

        (b) The Subsidiary Guarantor agrees that the Guaranteed Obligations may
at any time and from time to time exceed the Maximum Liability of such
Subsidiary Guarantor, and may exceed the aggregate Maximum Liability of all
other Subsidiary Guarantors, without impairing this Guaranty or affecting the
rights and remedies of the Agent hereunder. Nothing in this Section 9(b) shall
be construed to increase the Subsidiary Guarantor's obligations hereunder beyond
its Maximum Liability.


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        (c) In the event any Subsidiary Guarantor (a "Paying Subsidiary
Guarantor") shall make any payment or payments under this Guaranty or shall
suffer any loss as a result of any realization upon any collateral granted by it
to secure its obligations under this Guaranty, each other Subsidiary Guarantor
(each a "Non-Paying Subsidiary Guarantor") shall contribute to such Paying
Subsidiary Guarantor an amount equal to such Non-Paying Subsidiary Guarantor's
"Pro Rata Share" of such payment or payments made, or losses suffered, by such
Paying Subsidiary Guarantor. For the purposes hereof, each Non-Paying Subsidiary
Guarantor's "Pro Rata Share" with respect to any such payment or loss by a
Paying Subsidiary Guarantor shall be determined as of the date on which such
payment or loss was made by reference to the ratio of (i) such Non-Paying
Subsidiary Guarantor's Maximum Liability as of such date (without giving effect
to any right to receive, or obligation to make, any contribution hereunder) or,
if such Non-Paying Subsidiary Guarantor's Maximum Liability has not been
determined, the aggregate amount of all monies received by such Non-Paying
Subsidiary Guarantor from the Principal after the date hereof (whether by loan,
capital infusion or by other means) to (ii) the aggregate Maximum Liability of
all Subsidiary Guarantors hereunder (including such Paying Subsidiary Guarantor)
as of such date (without giving effect to any right to receive, or obligation to
make, any contribution hereunder), or to the extent that a Maximum Liability has
not been determined for any Subsidiary Guarantors, the aggregate amount of all
monies received by such Subsidiary Guarantors from the Principal after the date
hereof (whether by loan, capital infusion or by other means). Nothing in this
Section 9(c) shall affect any Subsidiary Guarantor's several liability for the
entire amount of the Guaranteed Obligations (up to such Subsidiary Guarantor's
Maximum Liability). Each of the Subsidiary Guarantors covenants and agrees that
its right to receive any contribution under this Guaranty from a Non-Paying
Subsidiary Guarantor shall be subordinate and junior in right of payment to all
the Guaranteed Obligations. The provisions of this Section 9(c) are for the
benefit of both the Agent and the Subsidiary Guarantors and may be enforced by
any one, or more, or all of them in accordance with the terms hereof.

        SECTION 10. Application of Payments. All payments received by the Agent
hereunder shall be applied by the Agent to payment of the Guaranteed Obligations
in the following order unless a court of competent jurisdiction shall otherwise
direct:

               (a) FIRST, to payment of all costs and expenses of the Agent
        incurred in connection with the collection and enforcement of the
        Guaranteed Obligations or of any security interest granted to the Agent
        in connection with any collateral securing the Guaranteed Obligations;

               (b) SECOND, to payment of that portion of the Guaranteed
        Obligations constituting accrued and unpaid interest and fees, pro rata
        among the Lenders and their Affiliates in accordance with the amount of
        such accrued and unpaid interest and fees owing to each of them;

               (c) THIRD, to payment of the principal of the Guaranteed
        Obligations and the net early termination payments and any other Rate
        Management Obligations then due and unpaid from the Borrower to any of
        the Lenders or their Affiliates, pro rata among the Lenders and their
        Affiliates in accordance with the amount of such principal and such net
        early termination payments and other Rate Management Obligations then
        due and unpaid owing to each of them; and

               (d) FOURTH, to payment of any Guaranteed Obligations (other than
        those listed above) pro rata among those parties to whom such Guaranteed
        Obligations are due in accordance with the amounts owing to each of
        them.

        SECTION 11. Notices. All notices, requests and other communications to
any party hereunder shall be given or made by telecopier or other writing and
telecopied, or mailed or delivered to the intended recipient at its address or
telecopier number set forth on the signature pages hereof or such other address
or telecopy number as such party may hereafter specify for such purpose by
notice to the Agent in accordance with the provisions of Article XIII of the
Credit Agreement. Except as otherwise provided in this Guaranty, all such
communications shall be deemed to have been duly given when transmitted by
telecopier, or personally delivered or, in the case of a mailed notice sent by
certified mail return-receipt requested, on the date set forth on the receipt
(provided, that any refusal to accept any such notice shall be deemed to be
notice thereof as of the time of any such refusal), in each case given or
addressed as aforesaid.

        SECTION 12. No Waivers. No failure or delay by the Agent or any Lenders
in exercising any right, power or privilege hereunder shall operate as a waiver
thereof nor shall any single or partial exercise thereof preclude any other or
further exercise thereof or the exercise of any other right, power or privilege.
The rights and remedies provided in this Guaranty, the Credit Agreement, any
Note, any Rate Management Transaction and the other Loan Documents shall be
cumulative and not exclusive of any rights or remedies provided by law.

        SECTION 13. No Duty to Advise. The Subsidiary Guarantor assumes all
responsibility for being and keeping itself informed of the Principal's
financial condition and assets, and of all other circumstances bearing upon the
risk of nonpayment of the Guaranteed Obligations and the nature, scope and
extent of the risks that the Subsidiary Guarantor assumes and incurs under this


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Guaranty, and agrees that neither the Agent nor any Lender has any duty to
advise the Subsidiary Guarantor of information known to it regarding those
circumstances or risks.

        SECTION 14. Successors and Assigns. This Guaranty is for the benefit of
the Agent and the Lenders and their respective successors and permitted assigns
and in the event of an assignment of any amounts payable under the Credit
Agreement, any Note, any Rate Management Transaction, or the other Loan
Documents, the rights hereunder, to the extent applicable to the indebtedness so
assigned, shall be transferred with such indebtedness. This Guaranty shall be
binding upon the Subsidiary Guarantor and its respective successors and
permitted assigns.

        SECTION 15. Changes in Writing. Neither this Guaranty nor any provision
hereof may be changed, waived, discharged or terminated orally, but only in
writing signed by the Subsidiary Guarantor and the Agent with the consent of the
Required Lenders.

        SECTION 16. Costs of Enforcement. The Subsidiary Guarantor agrees to pay
all costs and expenses including, without limitation, all court costs and
attorneys' fees and expenses paid or incurred by the Agent or any Lender or any
Affiliate of any Lender in endeavoring to collect all or any part of the
Guaranteed Obligations from, or in prosecuting any action against, the
Principal, the Subsidiary Guarantor or any other guarantor of all or any part of
the Guaranteed Obligations.

        SECTION 17. GOVERNING LAW; SUBMISSION TO JURISDICTION; WAIVER OF JURY
TRIAL. THIS GUARANTY SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAW OF THE STATE OF MICHIGAN. THE SUBSIDIARY GUARANTOR HEREBY SUBMITS TO THE
NONEXCLUSIVE JURISDICTION OF THE UNITED STATES DISTRICT COURT FOR THE EASTERN
DISTRICT OF MICHIGAN AND OF ANY MICHIGAN STATE COURT SITTING IN DETROIT,
MICHIGAN AND FOR PURPOSES OF ALL LEGAL PROCEEDINGS ARISING OUT OF OR RELATING TO
THIS GUARANTY (INCLUDING, WITHOUT LIMITATION, ANY OF THE OTHER LOAN DOCUMENTS)
OR THE TRANSACTIONS CONTEMPLATED HEREBY. THE SUBSIDIARY GUARANTOR IRREVOCABLY
WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY NOW
OR HEREAFTER HAVE TO THE LAYING OF THE VENUE OF ANY SUCH PROCEEDING BROUGHT IN
SUCH A COURT AND ANY CLAIM THAT ANY SUCH PROCEEDING BROUGHT IN SUCH A COURT HAS
BEEN BROUGHT IN AN INCONVENIENT FORUM. THE SUBSIDIARY GUARANTOR, AND THE AGENT
AND THE LENDERS ACCEPTING THIS GUARANTY, HEREBY IRREVOCABLY WAIVE ANY AND ALL
RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO
THIS GUARANTY OR THE TRANSACTIONS CONTEMPLATED HEREBY.

        SECTION 18. Taxes. etc. All payments required to be made by the
Subsidiary Guarantor hereunder shall be made without setoff or counterclaim and
free and clear of and without deduction or withholding for or on account of, any
present or future taxes, levies, imposts, duties or other charges of whatsoever
nature imposed by any government or any political or taxing authority thereof
(but excluding excluded taxes), provided, however, that if the Subsidiary
Guarantor is required by law to make such deduction or withholding, such
Subsidiary Guarantor shall forthwith (i) pay to the Agent or any Lender, as
applicable, such additional amount as results in the net amount received by the
Agent or any Lender, as applicable, equaling the full amount which would have
been received by the Agent or any Lender, as applicable, had no such deduction
or withholding been made, (ii) pay the full amount deducted to the relevant
authority in accordance with applicable law, and (iii) furnish to the Agent or
any Lender, as applicable, certified copies of official receipts evidencing
payment of such withholding taxes within 30 days after such payment is made.

        IN WITNESS WHEREOF, the Subsidiary Guarantor has caused this Guaranty to
be duly executed, under seal, by its authorized officer as of the day and year
first above written.

                                           AIRNET MANAGEMENT, INC.

                                           By: __________________________

                                           Title: _______________________


                                           Address for Subsidiary Guarantor:
                                           AirNet Management, Inc.
                                           4700 E. Fifth Avenue
                                           Columbus, Ohio  43219

                                           Telecopy No.: (614) 238-1969


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