American Airlines said on Thursday that it has signed a 12-year deal with Republic Airways to provide the Fort Worth-based carrier with large regional jet flying.The agreement will give American access to 53 Embraer E-175 jets that have 78 seats, including 12 first class seats. Republic will purchase and operate the aircraft under the American Eagle livery starting in the middle of the year.All 53 aircraft will be in service by the first quarter of 2015, the carrier said."Establishing a large regional jet fleet has long been part of our business plan and this agreement is another example of how we are executing on that plan in a way that benefits our business and our customers," said American vice president of planning Chuck Schubert. "We will offer more flights at the right intervals throughout the day in key markets while providing more opportunities for customers to travel in the First Class cabin to key business markets."Republic's Chautauqua Airlines currently operates regional jet service for American with 15 Embraer E-140 aircraft from Chicago O'Hare airport.