The term 'FORMER FAST FLIERS ABBR.' is an abbreviation for two former supersonic transport aircrafts, the OWNS and the SSTS. The OWNS stands for the Soviet Tupolev Tu-144, which was the first commercial supersonic transport aircraft to enter service in the late 1960s. The SSTS stands for the Anglo-French Concorde, which was the first supersonic airliner to enter commercial service in 1976. Both aircrafts were retired from service in the early 2000s due to high operating costs and environmental concerns.