Trans World Airlines Inc. President William F. Compton, who is also a pilot for the financially troubled carrier, was promoted to chief executive. He succeeds Gerald Gitner, who remains TWA's chairman. Compton, 51, and Gitner, 53, took over TWA in a 1996 shake-up, and they have since strengthened TWA's operations, improved its on-time performance and upgraded the St. Louis-based airline's fleet. But TWA is still struggling to turn a profit, having lost $121 million on revenue of $3.3 billion last year. Compton became a TWA pilot at age 21, later heading TWA's pilots union before joining management.