Exhibit 10.6

FIRST AMENDMENT TO SECURITY AGREEMENT

THIS FIRST AMENDMENT TO SECURITY AGREEMENT is entered into as
of March 23, 2007 (this Amendment), by and between Great Lakes Aviation Ltd., as debtor (the Debtor), and Raytheon Aircraft Credit Corporation (the Secured Party).

WITNESSETH:

WHEREAS, Debtor and
Secured Party are parties to a Security Agreement dated as of December 31, 2002 pursuant to which the Debtor granted to the Secured Party a lien on substantially all of its assets (the Security Agreement; capitalized terms used and
not defined herein shall have the meanings ascribed thereto in the Security Agreement);

WHEREAS, Debtor has entered into an Amended and
Restated Restructuring Agreement dated as of March 9, 2007 with the Secured Party (as amended and in effect from time to time, the 2007 Restructuring Agreement) whereby, among other things, the Secured Party has agreed to
restructure certain of its indebtedness owing to RACC;

WHEREAS, the parties intend by this instrument to amend the Security Agreement as
of the date hereof to specifically reflect that the references in the Security Agreement to the Restructuring Agreement are to the 2007 Restructuring Agreement;

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



|1. | The definition of the Restructuring Agreement in the Security Agreement is hereby amended to mean the 2007 Restructuring Agreement, as it may be amended or amended and
restated and in effect from time to time.
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|2. | Except as modified and supplemented hereby, the Security Agreement remains in full force and effect and is hereby ratified and confirmed.
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|3. | THIS AMENDMENT WAS MADE AND ENTERED INTO IN THE STATE OF KANSAS AND THE LAW GOVERNING THIS TRANSACTION SHALL BE THAT OF THE STATE OF KANSAS AS IT MAY FROM TIME TO TIME EXIST. THE
PARTIES AGREE THAT ANY LEGAL PROCEEDING BASED UPON THE PROVISIONS OF THIS AMENDMENT OR THE SECURITY AGREEMENT AS AMENDED HEREBY SHALL BE BROUGHT EXCLUSIVELY IN EITHER THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF KANSAS AT WICHITA, KANSAS, OR
IN THE EIGHTEENTH JUDICIAL DISTRICT COURT OF SEDGWICK COUNTY, KANSAS, TO THE EXCLUSION OF ALL OTHER COURTS AND TRIBUNALS.
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Security Agreement Amendment



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| | NOTWITHSTANDING THE ABOVE, IN THE EVENT AN EVENT OF DEFAULT SHOULD OCCUR, RACC (AT ITS SOLE OPTION) MAY INSTITUTE A LEGAL PROCEEDING IN ANY
JURISDICTION AS MAY BE APPROPRIATE IN ORDER FOR RACC TO OBTAIN POSSESSION OF THE COLLATERAL. THE PARTIES HEREBY CONSENT AND AGREE TO BE SUBJECT TO THE JURISDICTION OF THE AFORESAID COURTS IN SUCH PROCEEDINGS. THE PARTIES EACH IRREVOCABLY WAIVES ANY
OBJECTION, INCLUDING ANY OBJECTION TO THE LAYING OF VENUE OR BASED ON THE GROUNDS OF FORUM NON CONVENIENS, WHICH IT MAY NOW OR HEREAFTER HAVE TO THE BRINGING OF ANY ACTION OR PROCEEDING IN SUCH JURISDICTION IN RESPECT OF THIS AMENDMENT, THE SECURITY
AGREEMENT AS AMENDED HEREBY OR OTHER DOCUMENT RELATED THERETO. THE PARTIES EACH WAIVES PERSONAL SERVICE OF ANY SUMMONS, COMPLAINT OR OTHER PROCESS, WHICH MAY BE MADE BY ANY OTHER MEANS PERMITTED BY THE LAW OF SUCH APPLICABLE STATE.
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|4. | ALL PARTIES TO THIS AMENDMENT HEREBY VOLUNTARILY, KNOWINGLY AND IRREVOCABLY WAIVE ANY CONSTITUTIONAL OR OTHER RIGHT EACH MAY HAVE TO A TRIAL BY JURY IN THE EVENT OF LITIGATION
CONCERNING THIS AMENDMENT OR THE SECURITY AGREEMENT AS AMENDED HEREBY.
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|5. | This Amendment 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.
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Security Agreement Amendment



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Executed as of this 23 day of March, 2007, at Wichita, Kansas.



|                           |  |                                      |  |        |  |                   
|-------------------------- |  | ------------------------------------ |  | ------ |  | ------------------
|GREAT LAKES AVIATION, LTD. |  | RAYTHEON AIRCRAFT CREDIT CORPORATION
|                           |  |                                      | 
|By:                        |  | /s/ Michael Matthews                 |  | By:    |  | /s/ Andrew Mathews
|Name:                      |  | Michael Matthews                     |  | Name:  |  | Andrew Mathews    
|Title:                     |  | Chief Financial Officer              |  | Title: |  | President         



Security Agreement Amendment