The Shuttle Ejection Escape Suit was used from STS-1 (1981) to STS-4 (1982) by a two-man crew used in conjunction with Space Shuttle Columbia's ejection seats. It allowed ejections up to Mach 2.7 and 24.4 km (80,000 ft).[1] The suit was manufactured by the David Clark Company of Worcester, Massachusetts. It was derived from the USAF Model S1030 suit, which at the time, was being worn by SR-71 pilots.[1] The Shuttle was certified as operational for STS-5, at which point the escape suits were replaced with light blue coveralls.[1] The seats themselves were deactivated during STS-5 and removed before STS-9, with the intervening flights conducted by Space Shuttle Challenger, which did not have ejection seats.