 When he retired in 1957, he had flown every aircraft type operated by the USAF, including attack, cargo, trainer, fighter, experimental, bomber, mission trainer, liaison, observation, and general aviation planes and helicopters.From 1947 to 1957, Boyd flew and approved every aircraft type acquired by the USAF.When he retired, he was praised as the "Father of Modern Flight Testing," "World's Number One Test Pilot," "Dean of American Test Pilots" and "Father of USAF Test Pilots."