**EXHIBIT 4.51****AMENDED AND RESTATED NOTE**   $15,000,000.00 March 29, 2007               AirNet Systems, Inc., an Ohio corporation (the “Borrower”), promises to pay to the order ofThe Huntington National Bank (the “Lender”) the aggregate unpaid principal amount of all RevolvingLoans made by Lender to the Borrower pursuant to Article II of the Agreement (as hereinafterdefined), in immediately available funds at the main office of Lender, together with interestthereon at the rate or rates set forth in the Agreement. The Borrower shall pay the principal ofand accrued and unpaid interest on such Loans as set forth in the Agreement.     Lender shall, and is hereby authorized to, record by entries made by Lender into itselectronic data processing system and/or internal memoranda maintained by Lender, or to otherwiserecord in accordance with its usual practice, the date and amount of each such Loan and the dateand amount of each principal and interest payment hereunder. The Borrower agrees that the sum orsums shown on such schedule, the most recent printout from Lender’s electronic data processingsystem and/or such memoranda shall be rebuttably presumptive evidence of the amount of theoutstanding principal, interest or any other amount due under this Note; *provided, however*, thatthe failure of Lender to make any such entry(s) shall not affect the obligation of the Borrower torepay outstanding principal, interest or any other amount due under this Note in accordance withthe terms hereof.     This Note is issued pursuant to, and is entitled to the benefits of, the Second Amended andRestated Credit Agreement dated as of March 29, 2007 (which, as it may be amended, modified,supplemented, extended, restated and/or replaced from time to time, is herein called the“Agreement”), between the Borrower and Lender, which was given as an amendment and restatement tothe First Amended and Restated Credit Agreement, to which Agreement reference is hereby made for astatement of the terms and conditions governing this Note, including the terms and conditions underwhich this Note may be prepaid or its maturity date accelerated. Capitalized terms used herein andnot otherwise defined herein are used with the meanings attributed to them in the Agreement.     This Note is given as an amendment and restatement for and as evidence of the indebtednesspreviously evidenced by that certain (i) Note dated May 28, 2004 given by Borrower in favor ofLender in the face amount of $18,750,000.00 (as amended from time to time, the “HNB Note”), and(ii) Note dated May 28, 2004 given by Borrower in favor of JPMorgan Chase Bank, a national bankingassociation (“JPM”) formerly known as Bank One, N.A. (Columbus) in the face amount of$11,250,000.00 (as amended from time to time, the “JPM Note”), the outstanding principalindebtedness, as of the date hereof, of (i) the HNB Note being Zero Dollars ($0), and (ii) the JPMNote being Zero Dollars ($0); with said JPM Note having been assigned by JPM to Lender pursuant tothe Assignment Agreement dated of even date herewith by and between Lender and JPM, as Assignee andAssignor, respectively. The HNB Note and the JPM Note were executed and delivered by Borrowerpursuant to the First Amended and Restated Credit Agreement. The maximum principal amountavailable under the “Commitment” (as defined in the First Amended and Restated Credit Agreement)and under the HNB Note and the JPM Note has been reduced from time to time, and, ultimately,pursuant to that certain Fifth Change in Terms Agreement dated November 10, 2006, by and amongBorrower, Lender in its capacity as Administrative Agent for the benefit of the “Lenders” (as suchterm is defined thereunder), and such “Lenders” (inclusive of JPM and Lender), the maximumoutstanding principal indebtedness available under (i) said “Commitment” was reduced to$15,000,000.00, (ii) the HNB Note was reduced to $9,375,000.00, and (iii) the JMP Note was reducedto $5,625,000.00.     Further, this Note does not constitute a novation of the HNB Note or the JPM Note or arefinance of the “Commitment” referenced above or the outstanding principal balance of the HNB Noteor the JPM Note, and the Agreement does not constitute or represent a novation of the First Amendedand Restated Credit Agreement, and this Note and the obligations and liabilities under theAgreement and all other Loan Documents shall remain secured by all mortgage liens, securityinterests, pledges, and other interests given, by Borrower, each Guarantor and any other Person, tosecure the HNB Note and/or the JPM Note, this Note and/or the obligations under the Agreement andthe other Loan Documents.     The Borrower hereby irrevocably authorizes any attorney-at-law, including any attorney-at-lawemployed or retained by Lender, to appear for it in any action on this Note at any time after thesame becomes due as herein provided in any court of record situated in the county where thiswarrant was signed (being Franklin County, Ohio), or in the county where the Borrower then residesor can be found, to waive the issuing and service of process, and confess a judgment in favor ofthe holder of this Note against the Borrower, for the amount that may then be due, with interest atthe rate(s) provided for herein, together with the costs of suit, and to waive and release allerrors in said proceedings and the right to appeal from the judgment rendered. The Borrowerconsents to the jurisdiction and venue of such court. The Borrower waives any conflict of interestthat any attorney-at-law employed or retained by
 

 
Lender may have in confessing judgment hereunder and consents to the payment of a legal fee to anyattorney-at-law confessing judgment hereunder.
 

 
      AIRNET SYSTEMS, INC.