The Stars My Destination: S.T.S-4

For her four test flights—S.T.S-1 (April 1981), S.T.S-2 (November 1981), S.T.S-3 (March 1982), & S.T.S-4 (June-July 1982)—the Columbia OV-102 was equipped with ejection seats derived from those used in the SR-71 Blackbird spy plane. The Enterprise OV-101 had likewise been equipped with ejection seats for the Approach & Landing Tests (February-October 1977). There were only two ejection seats as each of those flights was flown by a crew of two, Commander & Pilot. With the Space Shuttle declared "operational" after S.T.S.-4, crews were set to increase in size. From S.T.S.-5 (November 1982) through S.T.S.-135 (July 2011), no Space Shuttle would fly with a fewer than four astronauts aboard. There was no provision for additional ejection seats for the rest of the crew, but the pilot crews could still have enjoyed the added safety factor of the ejection seats. To their credit, the pilot crews rejected the idea of flying with that added safety factor while their crewmates had to fly without, & so the Columbia's ejection seats were initially disabled (for S.T.S.-5) & eventually removed (for S.T.S.-61-C, January 1986).

The Space Shuttles Challenger OV-099, Discovery OV-103, Atlantis OV-104, & Endeavour OV-105 were never outfitted with ejection seats.