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.
3. As a result of the unconsciousness resulting from anoxia, the
[page 27 of original]
parachute jumper loses all sense of the time which has elapsed since his jump, as was shown in all experiments, so that it is impossible for him, with failing eyesight, to estimate his altitude.