AirTran Airways launched twice-daily flights to Tampa International Airport and San Juan on Tuesday.Tampa becomes the fourth U.S. city, after Atlanta, Baltimore and Orlando, with nonstop AirTran service to the Puerto Rican capitol city.The flights depart Tampa at 7:30 a.m. and 1:44 p.m. and arrive in San Juan almost three hours later. Return flights land at Tampa at 2:05 p.m. and 8:19 p.m.