ABSTRACT
The requirement seems simple and self-evident; to enable the crew to escape from a stricken aircraft and reach ground level uninjured. This was satisfied in early aircraft by supplying a parachute and relying on the crewman's ability to unbuckle the seat harness, clamber from the cockpit, jump, wait till clear and pull the parachute release handle. However, the motion of the aircraft and the force of the windblast, compounded by the likelihood that the crewman would be as incapacitated as the aircraft, made this "bailing out" at best slow. A successful outcome was lucky rather than likely. With the development of enclosed crewstations the crew had also to negotiate their normal means of access and egress, such as a sliding canopy or a series of doors, so the probability of survival declined further. It was then accepted that the crew needed assistance. The requirement has come to mean the provision of facilities that, no matter what the state of the crew or the aircraft, when the need arises the facilities can be triggered to automatically extract the crew from the aircraft, deliver them to ground level, keep them alive and co-operate to ensure their rescue.
