AFRL Century Series – Chapter 3: PRESSURE
Flying at altitudes over 25,000 feet allows aircraft to fly above turbulence and enables engines to perform more efficiently, as airframes move through the atmosphere with much less resistance than found in lower altitudes.
For a century, the Air Force Research Laboratory and its predecessor labs have been pioneering the research and development of flight suits, oxygen delivery systems, and pressurized cabins. Without this groundbreaking work to make air travel safe and comfortable, modern flight would have been stranded at low altitudes.