I. Introduction and Statement of the Problem

Berlin, Adlershof, 28 July 1942.

Rf 401/20

[page 2 of original]

It is theoretically possible for man to reach as high altitude as he may wish in an aircraft with a pressure cabin. However, the question must be settled as to what results or effects the destruction of the pressure cabin will have upon the human being, who in such cases is exposed in a few seconds to the low air pressure and thereby to the lack of oxygen, which is characteristic of high altitude. Of particular practical interest is the question from what altitudes and by what means the safest rescue of the crew can be made. In the work at hand, a report is presented on experiments in which the various possibilities of rescue were studied under special experimental conditions. Since the urgency of the solution of the problem was evident, it was necessary, especially under the given conditions of the experiment, to forego for the time being the thorough clearing up of purely scientific questions.

II. Procedure of the Experiment

The experiments were carried on in a portable low-pressure chamber with equipment for explosive decompression. The performance of this apparatus limited the highest altitude attainable to about 21,000 meters [68,900 feet].

In this experimental series, which was to clarify the possibilities of rescue from high altitudes, the experiments, simulating actual conditions, were carried out in such a way that rescue with parachute unfolded (designated as descending experiments) and with parachute folded (designated as falling experiments) were studied sometimes with and sometimes without oxygen breathing. Since the altitude or posture of the body is of essential significance for the demands made by the lack of O₂ on the circulation, the experiments were carried out in sitting and prone positions; and, in descending experiments, in a suspended

position in a parachute harness corresponding to the actual position. For purposes of demonstration certain of the experiments were recorded on film. Electrocardiograms were made of several experiments in the experimental series. Oxygen was breathed out of the customary low-pressure apparatus with continuous flow at altitudes over 10 km. [32,800 ft.]. The following experimental sequence was chosen:

The sinking and falling times which were used in the experiments are tabulated in figures 1 and 2. [Figure 2 not reproduced.]

III. Results of the Experiments

Since a thoroughly dependable parachute oxygen apparatus is not yet generally available, experimental tests were made to determine from what altitudes a rescue with open parachute without oxygen is possible. Therefore, sinking experiments were carried out in which the mask was taken off after ascent with O₂ (for speed of ascent of the chamber see fig. 1), and, after a waiting period of 10 seconds the sinking was begun.

In the experiment no altitude sickness occurred at 9 km. [29,500 ft.] as was expected.

In the sinking experiments, from 10 km. [32,800 ft.] altitude, typical altitude sickness occurred after about 2 minutes, i. e., at an altitude of about 8.6 km. [28,200 ft.], which was indicated by a very pronounced scrawling in the writing test. However, no loss of consciousness occurred. (Kloos’ writing test.)

The experiments from 12 to 15 km. altitude were made partly during suspension in a parachute harness, partly in a sitting position, and partly in a prone position. These experiments show that the body attitude has a very essential influence on the tolerance for a high degree of lack of oxygen. Since, besides this, every bodily exertion is of great importance, in one portion of the experiments six knee bends were made by the subject during the waiting period before beginning the descent. These six knee bends consisted of three knee bends while breathing oxygen followed by deep inhaling and holding of the breath, and then three more knee bends without oxygen breathing. This procedure was chosen in order not to neglect the bodily work involved in an actual parachute jump. The descending experiments from 12 km. [39,400 ft.] altitude yielded the following average times:

It is to be noted in connection with the stated time and altitude values that the beginning of unconsciousness, or of the recovery, was calculated from the withdrawal of oxygen, while in most experiments the sinking or free fall was begun at the expiration of the 10-second waiting period. Since in addition to this the stages of altitude were read off at the moment of unconsciousness, small variations from the times given in figs. 2 and 3 [not reproduced] are possible

since, especially in the falling experiments, variations occurred because of the somewhat crude valve control. These variations, however, are small and may be overlooked since in any case the fall and sinking time under practical conditions are dependent on the flying attitude at the moment of the leap from the catapult seat. In addition to this, the calculated fall and sinking time are influenced to a high degree under actual conditions by weight and air resistance.

It should be kept in mind in regard to the experiments conducted in the sitting position that the subjects fell over at the beginning of unconsciousness and so passed the critical time of greatest load on the circulatory system in a prone position, while those suspended in the parachute harness remained throughout the experiment in a vertical position, the most unfavorable position for loading the circulatory system.

Figure 1. Speed of ascent in the portable low-pressure chamber.

In the writing test shown above [not reproduced] the occurrence of altitude sickness in a sinking experiment for 12 km. [39,400 ft.] altitude is shown in this manner: For example, after 1 minute and 20 seconds at 11 km. [36,100 ft.] altitude, the writing is interrupted because of sudden altitude sickness with unconsciousness, and is resumed after 4½ minutes at an altitude of 8.8 km. [28,870 ft.], with erroneous writing. At 8.3 km. [27,230 ft.] altitude the writing becomes free of errors. This is worthy of special attention because in this case a person has fully recovered mentally at an altitude of 8.3 km. [27,230 ft.], after 3 minutes of the most severe lack of oxygen, while in altitude endurance experiments at this altitude severe altitude sickness sets in after about 3 minutes. Here we are dealing with a process which in any case is very favorable but which is not yet entirely clear and which was already observed in earlier experiments of parachute jumps from great altitudes. Still, it appears from this that a rather long oxygen lack at altitudes up to 13 km. does not present any great strain in

the sense of using the last reserves, but, on the contrary, the human organism seems to react to this loading with a certain increase in resistance to altitude.

In descending experiments from 13 km. [42,700 ft.] altitude the waiting time of 10 seconds was retained, but on the other hand exertion in the form of knee bends was omitted since technical difficulties interfered with this procedure.

The experiments involving suspension could be done only in the large low-pressure chamber, since suspension was impossible in the small low-pressure chamber for reasons of space. Therefore, the ascent to 13 km. [42,700 ft.] altitude was carried out slowly in the main chamber (without explosive decompression) so that when 13 km. [42,700 ft.] was reached a certain oxygen lack existed. With this oxygen lack the knee bends would have presented a great burden which would have falsified too greatly the results of the experiment. The same conditions were also given in further experiments at higher altitudes in the main chamber. For this reason, the 13 km. [42,700 ft.] descending experiments were carried out partly in the sitting position, partly in the sitting position strapped in, and partly suspended. They yielded the following average data:

Since in unfavorable cases in these experiments, namely while suspended, recovery of consciousness did not occur until 1.6 km. [5,250 ft.] altitude, it had to be concluded that in jumps from altitudes over 13 km. [42,700 ft.], recovery of consciousness would follow only after 0 km., which would mean that in an actual situation the landing would be made in an unconscious condition. This raised the question of a safe means of rescue.

Descending experiments were made in larger numbers from 15 km. altitude, since it became evident that at this altitude the approximate limits for what was possible in emergencies had already been reached or essentially surpassed. After an ascent made as rapidly as possible, using oxygen apparatus with free flow, the mask was removed immediately upon attaining 15 km. [49,200 ft.] altitude and the descent was begun. Since the results of these descending experiments were very typical and especially impressive it is necessary to present one of these experiments in detail. The record of an experiment is represented as follows:

The events of the descending experiments from 15 km., as shown here through this example, repeated themselves in a similar way in all the rest of the experiments. The average data from 20 experiments with 15 different subjects are as follows:

Unconsciousness after discontinuation of oxygen occurs following a short motor restlessness with severe altitude sickness, whereupon light spasmodic and then very severe tonic convulsions follow in a condition of complete unconsciousness. These tonic convulsions lasting virtually a minute are followed rather suddenly by a phase of complete

flacidity with a drop in breathing rate and transition to convulsive breathing with 3 to 4 breaths per minute until complete cessation of breathing of 45 seconds duration (post-hypoxemic pseudo-death—Lutz). Then follows a period of improvement in breathing, until the first subconsciousness movements announce the gradual recovery of consciousness, during which, nevertheless, the higher mental functions are temporarily entirely absent. Further recovery proceeds slowly during the course of the following ½ to 1½ hours as may be seen from the above case record. During the time of complete unconsciousness, there was defecation and urination in the case of most subjects, increased salivation and, in some cases, vomiting.

Here we obviously have the conditions which Lutz and Wendt in their animal experimentation which is referred to in greater detail later found in falling experimentation with O₂ breathing and designated as “post-hypoxemic twilight state” (“Posthypoxaemischen Daemmerzustand”) since we are dealing with a slow recovery of consciousness, especially also in view of the mental behavior of the experimental subjects. The post hypoxemic pseudo-death observed by Wendt and Lutz was not found in any experiments in the form which they had observed. The severe condition described above we could designate as hypoxemic pseudo-death only because it was limited to the period of the most severe O₂ lack (on the average, between 13.3 and 12.3 km.).

In spite of the relatively large number of experiments, the actual cause of the severe mental disturbances and bodily failures (paralysis, blindness, etc.) attendant upon post-hypoxemic twilight state remains something of a riddle. It appeared often as though the phenomena of pressure drop sickness had combined with the results of severe oxygen lack. In this connection, the subjective accounts made by the authors in two experiments each were interesting. In the case of Ro. during a half hour stay at 12 km. [39,400 ft.] with oxygen,

only the usual pains attendant with bends occurred. In a further experiment with a stay of 40 minutes duration at an altitude of between 13 [42,650 ft.] and 13.5 km. [44,290 ft.] there developed very gradually a condition of weakness, combined with a peculiar headache, which then led to a considerable slackening of strength in the arms and hands. As a result of this, Ro. could no longer hold the breathing mouthpiece (for special reasons in these experiments, Ro. had to breathe with a mouthpiece and nose clamp) so that it slid out of his mouth. All these phenomena were still clearly observed by Ro. Ra. returned the mouthpiece to Ro. However at this point Ro. failed rather suddenly with paleness, strong cyanosis of the lips and complete unconsciousness. After Ro. had regained clear consciousness through descent and sufficient O₂ breathing, he determined the existence in himself of a complete paralysis of the legs, weakness of the arms and severe disturbances of vision. These serious disturbances developed although the time of oxygen lack and unconsciousness had lasted only about 5 seconds. Following descent soon after this to 0 km., the paralysis of the legs continued for about 5 minutes more and the very severe visual disturbances only cleared up after 2 hours. While this episode of Ro.’s occurred in an experiment at a special altitude, the disturbances occurred in Ra. at an altitude of between 12 [39,400 ft.] and 13 km. [42,700 ft.] while he was breathing sufficient oxygen with a mask and continuous flow into the circuit. After 10 minutes stay at this altitude, pains began on the right side with a spastic paralytic condition of the right leg which increased continually as though Ra.’s whole right side were being crushed between two presses. At the same time there were most severe headaches as though the skull were being burst apart. The pains became continually more severe so that at last the discontinuation of the experiment became necessary. The pains disappeared when ground level was reached while the disturbances of the right leg continued about 5 minutes more. Shortly before the

second experiment, Ra. took two tablets of “Antineuralgica” (a coal tar derivative) and two tablets of pervitin. In the course of the experiments there occurred only light pains in the right arm and leg, moderate headaches, but a very severe uncontrollable urge to cough, actually less severe difficulties than in the foregoing experiment, although this one was made at 1,000 m. [3,280 ft.] higher.

Ro. experienced disturbances which in quality resembled the severe disturbances in the 15 km. [49,200 ft.] sinking experiment, although the degree of oxygen lack in this experiment was negligible in comparison to the 15 km. [49,200 ft.] experiment, so that the idea of a combination of pressure drop phenomena with the phenomena of oxygen lack is definitely suggested.

Since obviously the utmost limits of these experiments had been reached with the descending experiments from 15 km. [49,200 ft.] without oxygen breathing, descending experiments with oxygen breathing were conducted from greater heights.

In the experiments, the following experimental procedure was chosen: ascent to 8 km. [26,300 ft.], remaining there 5 to 10 minutes with oxygen breathing; then turning on the oxygen blower explosive decompression to a predetermined altitude; 10 seconds waiting time (experiments from 17 [55,800 ft.] and 18 km. [59,100 ft.], altitude without waiting time) and descent at sinking speed. In order to imitate the perpendicular body position as occurs in suspension in a parachute harness, the experimental subjects had to stand during the experiments since suspension was not possible in the small decompression chamber.

In the descending experiments from 15 km. [49,200 ft.] altitude there was no altitude sickness or only a slight temporary kind. In the further descending experiments, the following results were obtained (Table 4):

Thus it was shown that unconsciousness developed relatively early in spite of oxygen breathing, while the following convulsive stage ran its course in a much less severe form than in the experiments without oxygen breathing. Primarily spasmodic convulsions with only occasionally light tonic convulsions developed. Breathing paralysis never set in and upon recovery of consciousness the experimental subjects were again completely in control of themselves. The markedly quick development of unconsciousness was caused by the fact that the subjects were standing during the experiments (to be considered in comparison with the corresponding times in the falling experiments with oxygen breathing). Descending experiments from still greater altitudes were not undertaken, since in practice there is no need to escape from such altitudes with open parachute and thus to expose oneself to the danger of severe freezing.

Since the results of falling experiments from 12 km. altitude were known from earlier experimentation and indeed descending experiments up to 15 km. [49,200 ft.] without oxygen had been conducted within the scope of this work, falling experiments were begun at an altitude of 14 km. [45,900 ft.], in order not to increase unnecessarily the number of experiments.

The ascent preceded by explosive decompression from 8 to 14 and 15 km. altitude, in which the ascent to 8 km. was made with oxygen and the explosive decompression with continuous flow, followed after 5 to 10 minutes waiting time. After the removal of the oxygen mask directly in connection with the explosive decompression, five knee bends were made during the waiting period of 10 seconds, then descent at free fall speed. During the explosive decompression the oxygen supply was interrupted from the outside. The results of these experiments were (Table 5):

The further experiments up to 20 km. [65,600 ft.] altitude were made with the same procedure as those up to 15 km. [49,200 ft.], although without knee bends during the waiting period of 10 seconds, since unconsciousness would have occurred too soon as a result of the knee bends and the experimenters had become convinced that rescue from these altitudes would have to be brought about by abandonment of the aircraft without bodily exertion (catapult seat).

From 21 km. [68,900 ft.] altitude only one experiment was made in this series, just as in the falling experiments, with oxygen breathing since the pumps achieved the evacuation of the main chamber necessary for a pressure drop to 21 km. altitude only after hours of overloading and the fact that the mercury barometer used in these experiments had its limit of measurement at this altitude. The two experiments were considered only as an orientation on the behavior of the human organism at this altitude at which the ebullition point of the blood had already been far surpassed. A systematic working over of these altitudes must be carried on with perfected measuring instruments and a two-stage pump aggregate in a new experimental series.

The result of this falling experiment from 21 km. altitude was made unreliable through the fact that the subject experienced a paralysis of breathing from 11 to 7 km., through which his recovery was doubtless greatly delayed. However, no permanent damage occurred.

Falling experiments with oxygen breathing were undertaken only in small numbers for crude orientation for the following reasons: The altitude

was limited by the available equipment to a maximum of 21 km. [68,900 ft.], but indeed from this altitude falling experiments without oxygen breathing had already been profitably carried out. It is self-evident that oxygen breathing during parachute jumps from such extreme altitudes greatly increases in any case the chances of success of the jump and, therefore, is to be unconditionally demanded. For that reason it devolved upon the experimenters only to determine to what degree the results of the experiments are influenced by oxygen breathing, especially in regard to the recovery of consciousness, which, of course, followed without oxygen only at relatively low altitudes. As was to be expected, these experiments showed clearly the favorable effect of oxygen breathing. (Table 6):

The astonishing value of 60 seconds = 12.9 km. [42,320 ft.] for the recovery of consciousness in the 21 km. [68,900 ft.] experiment is explained on the basis that this value was obtained from a single experiment with one subject, who had shown himself in numerous other experiments to be especially resistant to altitude. On the other hand the 20 km. [65,600 ft.] values are the average of a series of experiments.

IV. Discussion of the Results

The descending experiments without oxygen show that the limit for a safe escape with an open parachute lies approximately at a jumping altitude of 13 km. [42,700 ft.], since in a jump from 13 km. [42,700 ft.] recovery of consciousness occurred only at an altitude of 1.6 km. [5,250 ft.], and so one must already consider the possibilities of landing in an unconscious condition with all the attendant dangers. This still does not take into account the heavy demands made on the body by the cold and the consequent risk. The great effect of the body position during the experiment makes it obvious how severe is the effect of every additional demand. While, for example, in the 13 km. [42,700 ft.], experiment upon a seated subject, recovery of consciousness took place after 8 minutes 12 seconds at an altitude of 7.2 km. [23,620 ft.], the suspended subjects recovered consciousness only after 19 minutes at 1.6 km. [5,250 ft.] altitude. Correspondingly also, unconsciousness occurred in the suspended subjects much more rapidly than in those who were seated. The same observation was made in the 15 km. [49,200 ft.] experiments, and indeed those who went through the experiment lying down could already state name and birth date immediately upon reaching ground level although they were paralyzed, while those who had been suspended did not respond at all to speech within this time. Except for one mentally very sluggish subject, the return of normal condition occurred much earlier to those who were lying down, namely within 15 minutes. The descending experiments extended to 18 km. [59,100 ft.] altitude with oxygen breathing showed that, except for the danger of cold, escape with an open parachute is possible from these altitudes even though, practically, no need exists for it.

Before we go into a discussion on the falling experiments it seems essential for us to cite the work of Lutz and Wendt on “Animal Experiments on Parachute Jumping from High-Pressure Cabins.” Unfortunately this work was not available to us during these experiments so that we could not build upon the valuable results contained in it and derived from numerous animal experiments, or upon the experience of the authors. Although both authors approach with necessary scepticism the problem of “reaching decisions through animal experimentation upon questions in

which, in the final analysis, the behavior of the human being in identical situations is of exclusive interest,” they could, and had to depend upon the previously proved experience that no fundamental qualitative differences in the manner of reaction to oxygen lack is to be expected between animals and human beings although there are considerable quantitative differences which, in this case, mean temporal differences. However, the results of our experiments show that to some extent quantitative as well as qualitative differences are present to the extent that the above animal experiments must lead to great fallacies which are significant to future developments. This appears especially in a comparison of results obtained with animals with the collective results of human experimentation upon escape from high altitudes through free fall without oxygen. On the basis of animal experiments, Lutz and Wendt were forced to the conclusion that if oxygen is breathed before the pressure drop “jumps from 14 km. [45,900 ft.] altitude can theoretically be survived—at any rate, that is the maximum altitude * * *,” whereas we were able to carry out human experiments up to 21 km. [68,900 ft.] altitude without any harm whatever. In all experiments at 20 km. [65,600 ft.] the subjects recovered clear consciousness with spontaneous control above 3 km. [9,800 ft.], and so within a sufficient altitude for actual parachute jumping. As instructed before the experiment, the subject rang a cowbell hung up in the chamber by pulling a handle (the equivalent of pulling the rip cord) without a new order to do so, so that under actual conditions they would certainly have also pulled the rip cord at the right time.

Experiments with a pressure drop from 4 km. [13,100 ft.] without previous breathing in of oxygen were not carried out by us because we proceeded from the viewpoint that when contact with the enemy is possible, pressure cabin machines fly with a pressure corresponding to 8 km. [26,200 ft.] altitude and, therefore, the crews would already be breathing oxygen in case of a possible pressure drop as a result of damage to the cabin.

Since the falling experiments without oxygen had already given such good results, falling experiments were begun only at 20 km. [65,600 ft.] altitude, and, because of the limitations described above, could be carried out only to 21 km. [68,900 ft.]. In these the results obtained by Lutz and Wendt were fully corroborated in this respect, that jumps from above 21 km. [68,900 ft.] can probably be made without danger, and that ebullition of the blood does not yet take place up to 21 km. [68,900 ft.] altitude. On the other hand in a falling experiment with human beings, neither a post-hypoxemic pseudo-death nor a post-hypoxemic twilight sleep were ever observed (Lutz).

In conclusion, we must make it particularly clear that, in view of the extreme experimental conditions in this whole experimental series, no fatality and no lasting injury due to oxygen lack occurred.

V. Conclusions from the Results

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.

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.

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.

On the other hand it is desirable, on the basis of the reason adduced under number 3 above, that the opening of the parachute at altitudes above 7 km. [23,000 ft.] be prevented, since very often the parachute jumper would pull the rip cord immediately after recovering from his altitude sickness, which may be too soon and at too high an altitude.

The best conditions for explosive decompression itself and for the seconds elapsing until the appearance of altitude sickness are provided if flying is done at a cabin pressure corresponding to 8 km. [26,300 ft.] and with oxygen breathing.

Since it may become necessary to abandon the aircraft for reasons other than damage to the pressure cabin, the pressure equalization at a predetermined rate must be made possible by means of a valve.

In case abandonment does not appear necessary in spite of the loss of cabin pressure the danger of oxygen lack is still less with the automatic diving control mechanism than in a parachute jump, since the dive may be made with considerably greater rate of descent.

VI. Summary

Experiments were instituted upon the possibility of rescue from altitudes up to 21 km. [68,900 ft.].

Without parachute oxygen equipment, rescue in descending experiments is still possible from 13 km. [42,700 ft.], with equipment, from 18 km. [59,100 ft.]. The danger arising from cold must be considered.

In falling experiments, rescue from 21 km. [68,900 ft.] altitude with and without oxygen was proved possible. Automatic parachute opening is necessary. Ebullition of the blood does not yet occur at 21 km. [68,900 ft.] altitude.

Oxygen must be breathed before explosive decompression. Abandonment must be by means of the ejection seat. The dive to safe altitude offers good possibilities of rescue if abandonment of the plane is not necessary after loss of the cabin pressure.

Bibliography

Lutz and Wendt—“Animal Experiments on Parachute Jumping from High-Pressure Cabins.” Communications in the Field of Aviation Medicine, Research Report 5/42.

Romberg—“The Parachute Jump from Great Heights.” German Aviation Research, Research Report No. 1416.

1.	Descending experiments without	O₂ breathing.
2.	Descending experiments with	O₂ breathing.
3.	Falling experiments without	O₂ breathing.
4.	Falling experiments with	O₂ breathing.

Descending experiment	Unconsciousness	Recovery of consciousness
from 12 km. [39,400 ft.]	after—	after—

Sitting without knee bends	1′39″ = 10.85 km.	6′38″ = 7.45 km.
	[35,600 ft.].	[24,440 ft.].
Sitting after 6 knee bends	55″ = 11.4 km.	6′55″ = 7.25 km.
	[37,400 ft.].	[23,786 ft.].
Suspended in parachute harness	37″ = 11.65 km.	7′40″ = 6.77 km.
	[38,220 ft.].	[22,212 ft.].

Descending experiment	Unconsciousness	Recovery of consciousness
from 13 km. [42,700 ft.]	after—	after—

Seated (lying during unconsciousness)	50″ = 12.4 km.	8′ 12″ = 7.2 km.
	[40,672 ft.].	[23,620 ft.].
Seated strapped in	35″ = 12.6 km.	10′ 30″ = 5.85 km.
	[41,340 ft.].	[19,190 ft.].
Suspended	20″ = 12.8 km.	19′ = 1.6 km.
	[41,980 ft.].	[5,250 ft.].

15 km. [49,200 ft.]	Lets the mask fall, severe altitude sickness, clonic convulsions.
14.5 km. [47,560 ft.] 30 sec.	Opisthotonus.
14.3 km. [46,900 ft.] 45 sec.	Arms stretched stiffly forward; sits up like a dog (“Pfoetchenstellung”), legs spread stiffly apart.
13.7 km. [44,950 ft.] 1 min. 20 sec.	Suspended in opisthotonus.
13.2 km. [43,310 ft.] 1 min. 50 sec.	Agonal convulsive breathing.
12.2 km. [40,030 ft.] 3 min.	Dyspnea, hangs limp.
7.2 km. [23,620 ft.] 10 min.	Uncoordinated movements with the extremities.
6 km. [19,690 ft.] 12 min.	Clonic convulsions, groaning.
5.5 km. [18,040 ft.] 13 min.	Yells loudly.

2.9 km. [9,520 ft.] 18 min.	Still yelling, convulses arms and legs, head sinks forward.
2-0 km. [6,560-0 ft.] 20-24.5 min.	Yells spasmodically, grimaces, bites his tongue.
0 km.	Does not respond to speech, gives the impression of someone who is completely out of his mind.
5 min. (after reaching ground level).	Reacts for the first time to vocal stimulation.
7 min.	Attempts upon command to arise, says in stereotyped manner: “No, please”.
9 min.	Stands up on command; severe ataxia; answers to all questions: “Just a minute”. Tries spasmodically to recall his birth date.
10 min.	Typical stereotypes of attitude and movement (catatonia); mumbles number to himself.
11 min.	Holds his head turned convulsively to the right; tries repeatedly to answer the first question concerning his birth date.
12 min.	Questions of the subject: “May I slice something?” (Note: In civilian work he was a delicatessen clerk.) “May I pant, will it be all right if I inhale?” Breathes deeply, then says, “All right, thank you very much.”
15 min.	On being ordered to walk, steps forward and says: “All right, thank you very much”.
17 min.	Gives his name; says he was born in 1928 (born 1 November 1908). Experimenter asks: “Where?” “Something 1928” “Profession?” “28—1928”.
18 min.	“May I inhale?” “Yes.” “I am content with that.”
25 min.	Still the question continues: “Pant?”
28 min.	Sees nothing; runs against open window sash upon which the sun is shining, so that large lump is formed on his forehead; says: “Excuse me please.” No expression of pain.

30 min.	Knows his name and place of birth. Upon being asked for the day’s date: “1 November 1928”. Shivering of the legs; stupor continues; cannot be frightened by the report of a shot. Dark objects are still not discerned; subject bumps against them. Is aware of bright light; knows his profession; spacially disoriented.
37 min.	Reacts to pain stimuli.
40 min.	Begins to observe differences. Falls continually into his previous speech stereotypes.
50 min.	Spacially oriented.
75 min.	Still disoriented in time; retrogressive amnesia over 3 days.
24 hours	Normal condition again attained; has no recollection of the experiment itself.

			Clear
15 km.	Unconsciousness	Subconscious awakening	consciousness
[47,200 ft.]	after—	movements	at 0 km.

Suspended	16″ = 14.7 km.	20½′ = 1.8 km.
	[48,220 ft.].	[5,910 ft.].	18′-90′

Lying	20″ = 14.6 km.	14′ = 5 km.	15′-80′
	[47,890 ft.].	[16,400 ft.]

Unconsciousness	From—	Recovery of
after—		consciousness after—

23 sec. = 15.75 km.	16 km. [52,500 ft.]	2 min. 35 sec. = 13.55 km.
[51,660 ft.]		[44,460 ft.]
10 sec. = 16.8 km.	17 km. [55,800 ft.]	3 min. 50 sec. = 13 km.
[55,120 ft.]		[42,700 ft.]
7 sec. = 17.9 km.	18 km. [59,100 ft.]	10 min. 35 sec. = 8.5 km.
[58,740 ft.]		[27,890 ft.]