UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q/A

(Amendment No. 1)

QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

For Quarterly Period Ended September 30, 2010

Commission File Number 000-50368

(Exact name of registrant as specified in its charter)

145 Hunter Drive

Wilmington, Ohio 45177

(Address of Principal Executive Office)

(937) 382-5591

(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    x  Yes    ¨  No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    ¨  Yes    ¨  No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definitions of “large accelerated filer,” “non-accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    ¨  Yes    x  No

As of November 3, 2010, Air Transport Services Group, Inc. had outstanding 63,775,766 shares of common stock, par value $.01.

EXPLANATORY NOTE

Air Transport Services Group, Inc. (the “Company”) is filing this Amendment No. 1 (this “Amendment”) to its Quarterly Report on Form 10-Q (the “Form 10-Q”) for the quarterly period ended September 30, 2010 in response to comments received by the Company from the Securities and Exchange Commission regarding the Company’s request for confidential treatment of certain portions of Exhibit 10.10 filed with the original Form 10-Q. The Company is filing this Amendment for the sole purpose of disclosing a sentence in Exhibit 10.10 to this Amendment that the Company previously redacted from the version of Exhibit 10.10 it filed with the original Form 10-Q pursuant to the Company’s request for confidential treatment.

In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended, new certifications by the Company’s principal executive officer and principal financial officer are filed as exhibits hereto.

Except as described above, this Amendment does not reflect events occurring after the filing of the original Form 10-Q or modify or update those disclosures presented in, or attached as exhibits to, the original Form 10-Q.

The following exhibits are filed as part of, or are incorporated in, the Quarterly Report on Form 10-Q:

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this Amendment No. 1 to Quarterly Report on Form 10-Q to be signed on its behalf by the undersigned thereunto duly authorized:

Date: March 25, 2011

Date: March 25, 2011

INDEX TO EXHIBITS