Airlines Control Program, or ACP, was the operating system developed by IBM in 1969 for processing airline reservations and related data. Most notable about ACP compared to previous airline transcation processing systems was that it was designed to run on most models of the IBM System/360 mainframe computer family instead of each airline having a machine-specific transaction system.
In February 1979, ACP became known as ACP/TPF and then just TPF (Transaction Processing Facility) as the transaction operating system became more widely implemented by businesses other than the major airlines.