Following is the text of the Oct. 6 letter that Mesa Airlines' Chairman and CEO Jonathan Ornstein wrote to Atlantic Coast Airlines (ACA) Chairman and CEO Kerry Skeen regarding Mesa's proposed takeover of ACA.

Dear Kerry,

I tried to reach you this morning to tell you first hand about our intentions. Mesa Air Group, Inc. ("Mesa") believes that a combination with Atlantic Coast Airlines Holdings, Inc. ("ACA" or the "Company") is compelling and in the best interests of both companies, our respective shareholders, employees and customers. While we have reviewed only publicly available data to this point, we are prepared to move forward promptly with a business combination between the two companies.

Accordingly, Mesa is seeking to enter into an agreement with ACA to acquire all the outstanding stock of ACA in a tax-free transaction whereby Mesa would issue 0.9 of a share of its common stock for each ACA share. Based on our closing share price of $12.55 and based on ACA's closing share price of $9.02 on October 3, 2003, our offer represents a premium to your shareholders of 25% over the current value of their shares. This price also represents a premium of 35% over the average closing price of ACA since late July, and we believe shares in the combined company will provide exceptional future value to the ACA shareholders.

There are clear strategic benefits. A combination would form the basis to leverage each company's assets, franchise, partners and management expertise to better position the combined company in today's competitive marketplace. It is clear that such a transaction would enable us to service the needs of our airline partners more efficiently and profitably. If we can realize only a small portion of the potential strategic benefits, we believe our combined earnings could improve by over 25%. Furthermore, our focus will remain in the business of providing cost effective regional feed for our airline partners.

Our proposal will be subject to only customary conditions, including among others, obtaining necessary regulatory approvals, the redemption of the ACA Right's Plan in accordance with its terms, the completion of satisfactory due diligence, negotiation of definitive agreements and necessary shareholder approvals.

Although we are offering a full and fair price to ACA shareholders, we may have flexibility on deal terms and structure if you are willing to work with us towards consummating a transaction. In connection with our proposal, we have retained Cadwalader, Wickersham & Taft LLP as counsel and Merrill Lynch & Co. as financial advisor.

In light of the compelling benefits to our respective shareholders and the materiality of this proposal, we are publicly releasing the text of this letter. Our strong preference would be to work with you to reach a mutually acceptable transaction. I would be happy to meet with you or to meet with your Board at its convenience to discuss in greater detail our thoughts with respect to a possible business combination and the future role that you and your management team would have in the combined entity. I look forward to hearing from you or one of your representatives as soon as possible.

Sincerely,

Jonathan G. Ornstein

Chairman of the Board & Chief Executive Officer

Mesa Airlines

cc: Board of Directors, ACA