For practical rescues by parachute jump from the highest and higher
altitudes the experiments yielded the following:
The parachute jump without oxygen with immediate opening of the
parachute is possible up to a jumping altitude of 13 km. [42,700 ft.];
the jump with oxygen equipment can be made at jumping altitudes up to 18
km. [59,100 ft.]. Advice must be given against jumping and immediate
opening of the parachute since there is considerable danger of freezing
and there is no need to pull the rip cord at high altitudes. However the
experimental data give some indication of the chances of the parachute
jumper whose parachute has become unfolded from whatever cause.
The jump with a free fall and opening of the parachute at low altitudes
can be made without oxygen equipment up to altitudes of 20 km. [65,600
ft.], with oxygen up to 21 km. [68,900 ft.], and probably considerably
higher.
In all the experiments at great height, even in experiments with oxygen
breathing, unconsciousness occurred extraordinarily rapidly and was
naturally preceded by loss of control before that. In one unfavorable
case of a subject in the standing position during a descending
experiment with oxygen, jumping from an altitude of 18 km. [59,100 ft.],
unconsciousness occurred after 7 seconds. One may not count on a longer
time than 10 seconds before loss of control occurs at high altitudes
even with the body at rest. So within that time the airplane must be
abandoned or at least one must activate the ejection seat. The technical
solution of this problem must be found through a different approach. It
is certain only that it will be impossible to climb out under one’s own
power, that one must avoid absolutely all bodily exertion, and that the
time must be kept as short as possible. Rescue is still possible from
very great heights; the critical part is the abandoning of the aircraft.
Oxygen equipment is absolutely necessary at these altitudes, since it
assures the most favorable conditions for the jump. In case of failure
of the equipment, loss of the mouthpiece or other mishaps, we still need
not count upon serious disturbances or injuries up to 20 km. [65,600
ft.]. Even jumps from 21 km. [68,900 ft.] will go well if there is
automatic opening of the parachute through barometrical control at 7 to
4 km. [23,000 to 13,100 ft.] altitude.
The automatic opening is also essential for several other reasons:
1. In particular cases the parachute jumper is not able to regain
consciousness at a sufficient altitude above the ground because of
collapse or injury.
2. As a result of cold the jumper may be handicapped by immobility of
his hands, and thus be hindered in pulling the rip cord.