Space Shuttle Abort Modes - Ejection Escape Systems - Ejection Seat

Ejection Seat

Modified Lockheed SR-71 ejection seats were installed on the first four shuttle flights (all two-man missions aboard Columbia) and removed afterward. Ejection seats were not further developed for the shuttle for several reasons:

• Very difficult to eject seven crew members when three or four were on the middeck (roughly the center of the forward fuselage), surrounded by substantial vehicle structure.
• Limited ejection envelope. Ejection seats only work up to about 3,400 mph (2,692 knots) and 130,000 feet (39,624 m). That constituted a very limited portion of the shuttle's operating envelope, about the first 100 seconds of the 510 seconds powered ascent.
• No help during Columbia-type reentry accident. Ejecting during an atmospheric reentry accident would have been fatal due to the high temperatures and wind blast at high Mach speeds.
• Astronauts were skeptical of the ejector seats' usefulness. STS-1 pilot Robert Crippen stated:

n truth, if you had to use them while the solids were there, I don’t believe you’d—if you popped out and then went down through the fire trail that’s behind the solids, that you would have ever survived, or if you did, you wouldn’t have a parachute, because it would have been burned up in the process. But by the time the solids had burned out, you were up to too high an altitude to use it. ... So I personally didn’t feel that the ejection seats were really going to help us out if we really ran into a contingency.

The Soviet shuttle Buran was planned to be fitted with the crew emergency escape system, which would have included K-36RB (K-36M-11F35) seats and the "Strizh" full-pressure suit, qualified for altitudes up to 30,000 m and speeds up to Mach 3. Buran flew only once in fully automated mode without a crew, thus the seats were never installed and were never tested in real human space flight.