MEDICINE, WARFARE, AND HISTORY — FULTON 437 



disease and under the age of 70, is quite comfortable at an altitude of 

 8,000 feet, even though at that height his night vision may be some- 

 what impaired. But ventilation of the fuselage presents a very real 

 problem because of the accumulation of water vapor and carbon di- 

 oxide ; also in hot weather body odors and fumes from aircraft instru- 

 ments and engines demand rapid change of air at appropriate pres- 

 sure. In a completely sealed cabin a change of air of 2 to 3 cubic 

 feet per minute per person will keep the humidity and the carbon 

 dioxide at a tolerable level, provided there are no exhaust fumes." 

 Leaks in the pressure-cabin equipment are inevitable, however, and 

 with further experience it became evident that a change of at least 

 12 cubic feet per minute per person would be essential for comfortable 

 air travel. This involved installation of larger turbopressurizers and 

 air coolers to make the pressurized air tolerable from a thermal stand- 

 point. Through experience gained during World War II these diffi- 

 culties have now been largely overcome, and essential equipment has 

 now been installed in all long-range, high-flying, pressurized pas- 

 senger aircraft. 



Explosive decoTTipression. — An ever-present hazard in pressurized 

 aircraft, both military and commercial, is that of sudden or explosive 

 decompression. Pressurized aircraft, such as the Constellation, is 

 stressed to withstand a pressure differential of 6.5 pounds per square 

 inch. This would permit flight at 30,000 feet with an internal pres- 

 sure equivalent of 8,000 feet. If a large military aircraft, flying at 

 30,000 feet, were suddenly depressurized by enemy action, the pilot, if 

 he had oxygen available, could carry on, but other crew and passengers 

 without oxygen would retain useful consciousness for about 2 minutes. 

 If no oxygen were available, crew and passengers would become un- 

 conscious within a matter of minutes and death might ensue within 

 a period of 8 to 10 minutes. Hence, commercial planes, in which ex- 

 plosive decompression might occur as a result of the breaking of a 

 window, failure of turbos, or explosion of an observation dome, are not 

 permitted to fly above 22,000 to 24,000 feet, since a large plane cannot 

 descend rapidly enough to insure consciousness of the occupants, 

 especially of the crew. 



With military planes, which ascend to much greater altitudes, the 

 situation is even more critical. For example, if pressurized military 

 aircraft were flying at 52,000 feet and were suddenly decompressed, 

 the pilot would have only 15 to 20 seconds to get himself out of the 

 plane, and, if he did not descend within 3 to 5 minutes through free 

 fall to 20,000 feet, his heart would have stopped. A direct pressure 

 dive might enable the pilot to achieve 15,000-20,000 feet, but he would 



" Spealman, C. R., Aviation toxicology (an introduction to the subject and a 

 handbook of data) , New York, 1953. 



