Critic Pierre Sprey said the oxygen systems problems can be traced to the… (Airman First Class Courtney )
The U.S. Air Force's F-22 Raptor fighter jets have been cleared for takeoff after a government safety investigation grounded the entire fleet for more than four months.
The Air Force said that all 170 F-22s will be inspected before flight operations resume. The fleet was put out of service May 3 after a dozen incidents since April 2008 in which pilots' oxygen was cut off.
It is the latest issue for the F-22, which cost an estimated $412 million each, according to the U.S. Government Accountability Office's latest report, and have not been used in combat since entering service in 2005.
Air Force Chief of Staff Gen. Norton Schwartz said in a statement that the F-22s are now safe to fly, but he did not specify what went wrong with the plane's oxygen system.
"We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate," he said. "We're managing the risks with our aircrews, and we're continuing to study the F-22's oxygen systems and collect data to improve its performance."
Later this year, the Air Force Scientific Advisory Board will release a more comprehensive report on the suspected oxygen system malfunctions.
The F-22s will undergo an extensive inspection of the life-support systems, with follow-up daily inspections, the Air Force said. Pilots, who haven't been able to fly the planes for 142 days, will have to build up their skills in the cockpit and use additional protective equipment.
"Any time you have a potential problem that can result in inexplicable pilot incapacitation is deeply concerning," said John Noonan, aide to Rep. Howard P. "Buck" McKeon (R-Santa Clarita), chairman of the House Armed Services Committee. "The Air Force believes that the jets are now safe enough to fly. They will continue studying the issue, and the committee will continue to monitor the Raptor's performance."
Pierre Sprey, an aeronautical engineer who helped design the F-16 fighter and A-10 attack jets, and an outspoken critic of the F-22, said the Air Force was rushing the planes back into service.
Sprey said the oxygen system's problems can be traced to the complexity of the aircraft, which is built by Lockheed Martin Corp.
The stealth jet, considered the most advanced fighter in the world, has state-of-art engines with thrust-vectoring nozzles that can move up and down, making the plane exceptionally agile.
The plane can reach supersonic speeds without using afterburners, enabling the plane to fly faster and farther. It's also packed with cutting-edge radar and sensors, allowing a pilot to identify, track and shoot an aircraft before the enemy flier can detect the F-22.
The F-22 takes air from a jet engine's compressor section to supply oxygen to pilots. Previous oxygen systems simply used a separate bottle that fed air to pilots.
Sprey blasted the Air Force for not pinpointing the problem.
"The Air Force said that they have had 12 incidents in three years regarding the oxygen system," he said, "and based on what they've told us there's no reason they won't have another 12 incidents in three years."