SENIOR YEAR / AQUATONE / U-2 / TR-1
Pilot Life Support
The full pressure suit truly stands between life and death for the U-2 aviator. It is the "life vest" of the skies. The U-2 can be a difficult aircraft to fly, and the suit adds one more system that can be a distracter. With decreased visual field of view due to the helmet and aircraft design, landing requires a second U-2 pilot (the mobile officer) to help bring the mission pilot down. Crew coordination [i.e., Crew Resource Management (CRM)] is critical to a successful landing after dealing with the hazards discussed earlier and other mission hazards. A breakdown in teamwork significantly compromises flight safety and can have catastrophic results.
To ensure absolute safety, every screw, bolt, nut, seam, thread, and system gets inspected each time before the aircraft flies. High altitude physiological and life support training associated with the U-2 space suit are vital to protecting the pilot. Every time a Dragon Lady takes off, the life-sustaining physiological equipment enables the pilot to successfully accomplish the mission and come home safely.
As a physical environment, space begins around 125 miles above the earth; but as a physiological environment, it begins at 50,000 feet - the space equivalent zone. Flying in this zone requires the protection of a full pressure suit to protect from the high altitude hazards of hypoxia, decompression sickness, Armstrong's Line, and extreme cold. It is these threats - where regular life support equipment is unable to sustain life - that add a new element to pilot safety. The physiological support equipment the pilot wears creates an environment that minimizes the impact (both physically and physiologically) of flying at extreme altitudes.
While in flight, the pilot's "cocoon" provides 100% oxygen at all times - even during an ejection. The pressure suit prevents hypoxia that would be present at the normal U-2 cabin altitude of 29,500 feet. Hypoxia is caused by a lack of oxygen reaching the bodily tissues. The symptoms of hypoxia include blurred or tunnel vision, dizziness, slow reaction time, as well as poor muscle coordination. Without a full pressure suit to provide supplemental oxygen, the pilot has 30 to 60 seconds before becoming incapacitated.
In addition to preventing hypoxia, the 100% oxygen provided to the pilot at least 1 hour before takeoff as well as during flight decreases the high probability of getting decompression sickness by eliminating most of the nitrogen from the aviator's body. Decompression sickness - or the "bends" - occurs when bubbles of nitrogen develop in a person's blood and tissues. This happens after a rapid reduction in surrounding pressure, is exhibited by pain in the joints, and has the potential of being fatal.
The next threat that the space suit protects pilots from is Armstrong's Line. Water boils at a higher temperature at sea level than it does in the Colorado Rockies, and at 63,000 feet in the sky, water boils at 98.6 degrees Fahrenheit - body temperature. In fact, at FL 630, atmospheric pressure equals the water pressure in hte human. As a result, without a pressure suit to protect the pilot in the event of cabin pressurization loss, the water in the aviator's body would escape as a gas thereby causing damage to tissues and blocking blood flow. In this scenario, the air trapped inside the pressure suit protects the pilot from decompression. Therefore, as the cabin altitude goes from FL 295 to FL 700+, the pressure inside the suit increases to maintain a physiological altitude of 35,000 feet - much better than FL 700.
The last high altitude hazard that the space suit protects against is extreme cold. At operational altitudes, the air temperature is 70 degrees below zero. The suit prevents hypothermia, frostbite, and keeps eyeballs from freezing in the event the pilot ejects or loses cabin heat.
Despite all this protection, flying at extreme altitudes still takes a toll physiologically. Heat build-up in the suit due to physical activity - especially during taxi, pattern work, and landing - can be rapid and incapacitating. Discomfort, profuse sweating, fatigue, dizziness, and decreased situational awareness make flying the U-2 even more "interesting". Dehydration is a constant threat due to breathing dry aviator's oxygen for extended periods of time and the sweating associated with wearing a sealed rubber suit. Since going 9+ hours without drinking also compounds physiological problems, fluid intake is vital. All normal physiological maintenance activities - eating, drinking, urination - are complicated in the suit and can increase the stress and fatigue already associated with flying.
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