Other airlines established their own systems. Pan Am launched its PANAMAC system in 1964. Delta Air Lines launched the Delta Automated Travel Account System (DATAS) in 1968. United Airlines and Trans World Airlines followed in 1971 with the Apollo Reservation System and Programmed Airline Reservation System (PARS), respectively. Soon, travel agents began pushing for a system that could automate their side of the process by accessing the various ARSes directly to make reservations. Fearful this would place too much power in the hands of agents, American Airlines executive Robert Crandall proposed creating an industry-wide computer reservation system to be a central clearing house for U.S. travel; other airlines demurred, citing fear of antitrust prosecution.