425

Filed by Southwest Airlines Co.

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12

under the Securities Exchange Act of 1934

Subject Company: AirTran Holdings, Inc.

Commission File No.: 1-15991

On September 27, 2010, Southwest Airlines Co. (“Southwest”) made the following post on its intranet blog, SWALife.

NEW DEAL MEANS GROWTH—INCLUDING MORE PILOTS AND FLIGHT ATTENDANTS

By Mike Van de Ven

I’m sure you all are still buzzing from this morning’s exciting news. I couldn’t be more optimistic about the future of Southwest Airlines and the many opportunities this acquisition brings us. In addition to seeing an opportunity to grow our earnings, an approved deal also presents a number of network opportunities. In order to take advantage of these opportunities, we will be increasing the utilization of our existing fleet in 2011. Naturally, this increase in aircraft utilization means more flights, which requires additional Flight Crews. So, I am happy to say that we are back in the business of hiring Pilots and Flight Attendants!

We are tentatively planning to add 150-200 new Pilots and 250-300 new Flight Attendants next year. Since we haven’t hired Flight Crews since 2008, our hiring Teams will soon begin an aggressive schedule to interview and process qualified candidates. We expect to have 100 Pilots begin New Hire training in first quarter 2011, and start rolling into our system in March. Additional Pilot classes will follow as required. Flight Attendant classes also will begin in first quarter 2011, and will include three classes of approximately 100 each. They will start rolling into our system in April.

Of course, more flights doesn’t just create the need for more Flight Crews. Rest assured, we will be hiring as needed for our other operational groups as well. Stay tuned for more news on this.

I know many of you have been eagerly anticipating growth for our Company, and I’m looking forward to adding to our Family.

Important Information for Investors and Stockholders

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. The proposed acquisition of AirTran Holdings, Inc. (“AirTran”) by Southwest Airlines Co. (“Southwest”) will be submitted to the stockholders of AirTran for their consideration. In connection therewith, Southwest will file a registration statement on Form S-4 with the Securities and Exchange Commission (the “SEC”) that will include a proxy statement of AirTran that also constitutes a prospectus of Southwest. Southwest and AirTran also plan to file other documents with the SEC regarding the proposed transaction. SOUTHWEST URGES INVESTORS AND SECURITY HOLDERS OF AIRTRAN TO READ THE PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS THAT WILL BE FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. Investors and security holders may obtain free copies of the proxy statement/prospectus and other documents containing important information about Southwest and AirTran, once such documents are filed with the SEC, through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by Southwest will be available free of charge on Southwest’s website at www.southwest.com under the tab “Investor Relations” or by contacting Southwest’s Investor Relations Department at (214) 792-4415. Copies of the documents filed with the SEC by


AirTran will be available free of charge on AirTran’s website at www.airtran.com under the tab “Investor Relations” or by contacting AirTran’s Investor Relations Department at (407) 318-5187.

Southwest, AirTran and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of AirTran in connection with the proposed transaction. Information about the directors and executive officers of Southwest is set forth in its proxy statement for its 2010 annual meeting of shareholders, which was filed with the SEC on April 16, 2010. Information about the directors and executive officers of AirTran is set forth in its proxy statement for its 2010 annual meeting of stockholders, which was filed with the SEC on April 2, 2010. These documents can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available.

Cautionary Statement Regarding Forward-Looking Statements

This communication contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These include statements relating to Southwest’s plans and expectations with respect to the acquisition of AirTran and the anticipated impact of the acquisition on Southwest’s operations and AirTran’s Crew Members. Factors include, among others, (i) the possibility that the transaction is delayed or does not close, including due to the inability of Southwest and AirTran to obtain all approvals necessary or the failure of other closing conditions; (ii) Southwest’s ability to successfully integrate AirTran’s business and realize the expected synergies from the transaction; (iii) the impact of the economy on demand for air travel and fluctuations in consumer demand generally for the services to be provided as a result of the transaction; (iv) the impact of fuel prices and economic conditions on Southwest’s business plans and strategies; (v) actions of competitors, including without limitation pricing, scheduling, and capacity decisions, and consolidation and alliance activities; and (vi) the impact of governmental regulations on Southwest’s operations.

Southwest cautions that the foregoing list of factors is not exclusive. Additional information concerning these and other risks is contained in Southwest’s and AirTran’s most recently filed Annual Reports on Form 10-K, subsequent Quarterly Reports on Form 10-Q, recent Current Reports on Form 8-K, and other SEC filings. Southwest undertakes no obligation to publicly update any of these forward-looking statements to reflect events or circumstances that may arise after the date hereof.