March 6, 2012:
Last year the U.S. Air Force decided to extend the life of its U-2 fleet and cut back on the use of large UAVs for strategic reconnaissance. One of the many upgrades U-2s will now receive will be better cockpit pressurization. Currently, pilots operate in a cockpit pressurized to conditions found at 9,600 meters (30,000 feet). This puts more strain on the pilot's body. That, and the fact that they breathe pure oxygen while up there, means they tend to be completely exhausted after returning from a long mission. So pressurizing the cockpit to the level of a lower altitude eliminates a lot of stressful aspects of each flight (like breathing pure oxygen). U-2 missions can be as long as 12 hours and more is being done to make operating the aircraft and the sensors less of a hassle.
The increased use of the U-2s means more pilots will be needed. This is a problem because U-2 pilots are hard to select, train, and retain. Flying the U-2 is very hard on pilots. Because it is a difficult aircraft to fly, only pilots with a lot of previous experience qualify. Even then, most do not last long. In the last 57 years only about three percent of the 900 U-2 pilots have lasted as long as 2,000 hours, and only four pilots have made it to 2,500 hours. The aircraft lasts a lot longer of course. Two of them, both over 40 years old, have been in the air at least 25,000 hours.
With a range of over 11,000 kilometers the 18 ton U-2s typically fly missions 12 hours long. All U-2s have been upgraded to the Block 20 standard and will be receiving more refurbishment and upgrades, so they can be kept in service until the 2020s. The U-2 has been in service since 1955, and only 86 were built.