Flying a U-2 Mission
High altitude flying is very involved. One day prior to the flight two pilots are selected, # 1 primary pilot and # 2 backup pilot. The mobil officer ( the backup pilot) has two primary functions, saftey mission monitor and if the scheduled pilot can not make the flight the backup pilot flys it. The mission is very well planned. 12 hours prior to the flight both pilots rest and control their diets.
Flight day they both arrive two hours before launch time, receive weather & intelligence reports. A high protein meal (steak & eggs ect.,) that will provide the pilot the necessary energy for a possible 9 hour flight without gastrointestinal problems.
Pilot then receives a physical to ensure that all body parts will endure high altitude flying for an extended period of time The pilot is then intergrated into a full pressurized suit such as an astronaut wears. It is needed as a redundant system. Physiological hazards of high altitude flying dictates this. The pilot breathes 100 percent oxygen for one hour prior to takeoff to avoid what is called the bends because of the high altitude cabin exceeding 30,000 feet & that in the event the pilot is exposed to the atmosphere due to a rapid decompression or ejecting from the aircraft. There are two reasons, Boyles law & Armstrong's line.
Boyle's law is that any amount of gas proportionately with the amount of pressure exerted on it. Humans are used to 14.7 pounds of pressure per square inch (psi) at sea level. Our air has weight. The pounds psi at altitude is less than half a pound.
Armstrong's line is that at an altitude of 63,000 feet pressure altitude conventional liquids will boil at 98 degrees fahrenheit. If a pilot was at 70,000 feet exposed to the atmosphere the body gases would boil & then burst.
The mobile officer performs a preflight inspection of the U2, sets up the cockpit, checks all systems & walks around the aircraft inspecting the structure. It is crucial it be done by a qualified pilot. The pressure suit is bulky & prohibits the mission pilot from doing it. The pilots mobility is limited & could cause heat buildup inside the pressure suit. The mission pilot is now put into the U2 cockpit.