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The CIA Museum … Artifacts: U-2 Pilots Protective Assembly

The CIA Museum is home to many interesting artifacts associated with the Central Intelligence Agency’s predecessor, the Office of Strategic Services; foreign intelligence organizations; and the CIA itself. The following article is the fourth in a series that will explore the Agency’s amazing history through the artifacts in the CIA Museum. This article focuses on the U-2 pilots protective assembly.

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U-2 PPA SuitIn the mid-1950s, the creation of the U-2 aircraft signaled the CIA’s entry into the world of overhead reconnaissance. The U-2 flew at an astonishing altitude of 70,000 feet at subsonic speed. With all the amazing innovations of the U-2, it’s easy to overlook another important invention that keeps a U-2 pilot alive at such high altitudes: the pilots protective assembly. It looks like a flight suit, but is actually a six-layer apparatus designed to protect the pilot whether he is flying, ejecting, parachuting, floating in water, or surviving in a harsh land environment. These suits were so effective in protecting pilots during flight that they have become the basis for modern day space suits used by astronauts.


Danger at 70,000 Feet

Cruising at an altitude of 70,000 feet can be physically dangerous to the pilot. The pressure suits must be worn by the pilot at all times as protection against the harsh conditions at such a high altitude. Pilots face many hazards, including:

  • Hypoxia
  • Decompression sickness
  • Armstrong’s limit
  • Extreme cold

The pilots protective assembly helps prevent hypoxia — which occurs when the body is deprived of oxygen — by providing a steady flow of pure oxygen during the flight. This also helps decrease the likeliness of getting decompression sickness or the “bends.”

Armstrong’s limit is another hazard U-2 pilots face. According to this limit, the boiling point of liquids diminishes as pressure is reduced, and above 63,000 feet altitude human blood and other fluids will boil at 98 degrees Fahrenheit. Without the pilots protective assembly, any liquids outside the human body, such as saliva and tears, will boil.

As well as providing adequate pressure to prevent Armstrong’s limit, pressure suits need to protect aircrew from the low temperatures at high altitudes, since they will free fall for two to three minutes after ejecting before their parachutes open, and for 15 minutes after that. The temperature at U-2 mission altitudes is about 70 degrees below zero.

The suit also provides flotation for a water landing and protection for surviving in a harsh land environment.


Parts of the Pilots Protective Assembly

The pilots protective assembly was developed specifically for the U-2 in the mid-1960s to minimize pilot stress and fatigue during the nine-hour flights. It consists of the following layers:

  1. The exterior cover (Figure 1) is the outermost layer. It is made of high-temperature, fire-retardant material, and provides open flame, wind blast, wear and abrasion protection.
  2. The retainer assembly (Figure 2) is a torso harness (Figure 3) integrated with a flotation system (Figure 4). The harness emerges through the exterior cover on the right and left of the chest, where large silver disconnect buckles can be seen, and on the back. The flotation garment is like a pair of water wings, open in front, extending under either arm and going across the back. It can be inflated by pulling a red tab to open CO2 cartridges, or by manually blowing into a tube which is coiled into a pocket on the chest just under the left disconnect buckle.
  3. The next layer down is the restraint layer, consisting of nomex tape and link net, and limits the outward expansion of the gas container/exposure garment.
  4. The gas container/exposure garment (Figure 5) is an inflatable bladder that puts pressure on the pilot’s torso, arms and legs.
  5. The vent duct assembly (Figure 6) consists of a network of channels leading from the ventilation inlet to the neck, hands, and down the legs to approximately two inches below the top of each restraint bladder boot.
  6. The sixth layer down is the liner.

Slide fasteners (zippers) in the restraint layer and gas container/exposure garment extending from the crotch to the back just below shoulder level are closed after the pilot has entered the suit. The fasteners create an airtight seal. If the pilot must get out of the suit by himself, he fastens a lanyard to the double fastener slider that he passes between his legs and over his shoulder, to allow him to pull the slider to its full open position at the top of the middle of his back. The lanyard is stowed until use in a pocket on the left side of the chest.

The air within the helmet (Figure 7) is divided into two regions by the face barrier, made of coated fabric. One region contains the eyes, nose, mouth and chin; the other contains the rest of the head and communicates with the interior of the suit. A face seal fits smoothly to the skin across the forehead, down the face in front of the ears, and under the chin to make an airtight seal between the two regions. The pilot’s exhaust breath passes from one region to the other by means of a one-way exhalation valve near the right cheek. The visor is rotated by the lever down into position in front of the face and then pressed tightly against a gasket on the shell to make an airtight seal. The visor contains a transparent resistive heater to keep the visor clear of condensation. With the visor closed, liquid and paste food can be ingested by the pilot through the feeding port. A lever on the bottom of this part opens and closes the port.

The U-2 pilots protective assembly on display in the CIA Museum’s Directorate of Science and Technology Exhibit dates from 1967.


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Posted: Feb 25, 2010 01:36 PM
Last Updated: Apr 30, 2013 12:35 PM