The system that was developed was a compressed air ejection seat which was patented and trialled on the ground by Saab during 1941. Trials showed that a momentary acceleration of 20G "did not cause great discomfort" to the pilot. On 8 Jan 1942 it was trialled successfully with a 80 kg dummy from a Ju 86 at 280 km/h. The dummy passed the tail with a clearance of 4 m. (Unfortunately there are no photographs, since the sequence was initiated too early.)
The compressed air system was large, heavy and complicated, so by the end of 1942 Saab initiated cooperation with Bofors to develop an alternative. By 1943 a gunpowder ejection seat with two guns was tried on the ground. Ejection with the Saab MkI seat was straight up and acceleration 15G.
Ejection sequence was initiated by a handle on the right side of the instrument panel. The canopy was jettisoned and the chair armed. A knive cut radio and oxygen lines. After ejection the seat straps (by this time the only straps were across the waist) were disconnected automatically, but the parachute had to be opened manually.
This chair was tried in the air from a Saab B 17 on 27 Feb 1944, which was after the prototype Saab 21 flew. The dummy plus seat weighed 100 kg, ejection altitude was 1200 m and speed was 405 km/h.
When the first production Saab J 21A on 1 June 1945 it had this ejection seat installed. By this time the seat had been modified by moving the ejection handle to above the left shoulder and shoulder straps had been introduced.
The first emergency in Sweden as on 29 July 1946 when a Saab J 21A collided with a FFVS J 22. First ejection from the jet powered Saab J 21R was on 28 Mar 1948. In all there were 25 ejections from both variants of Saab 21 of which 23 were successful from a total of 302 aircraft during the years 1945-56.
Saab 18 did not have ejection seats fitted from the beginning, but they got it fitted later as a result of the type's bad accident statistics. Out of 244 aircraft 44 were destroyed during 1944-59 and only at four of these crashes were successful emercy escapes made, in spite of ejection seats fitted at least partially as early as 1949.
During the war, some 60 German aircrew lives were saved by ejection seats. The seats were powered by compressed air.
The first British live ejection was 24:th July 1946 from a Gloster Meteor as a test.