The investigation into why pilots flying Lockheed Martin Corp. (LMT:US)’s F-22 Raptor keep getting dizzy and disoriented is focusing again on whether the plane’s oxygen system works well enough at high altitudes, lawmakers said.
Senator Mark Warner, a Virginia Democrat, and Representative Adam Kinzinger, an Illinois Republican, said today that Honeywell International Inc. (HON:US)’s On-Board Oxygen Generation System “may not provide enough oxygen for pilots operating at higher altitudes while sustaining powerful G- forces.”
Honeywell has said that the system works well, and during a yearlong investigation the Air Force has turned in recent months to other possible causes for the symptoms of hypoxia, or oxygen deprivation, including ill-fitting pressure vests worn by the pilots and the possibility of contaminants in the air.
Citing information they obtained from the Air Force, the lawmakers said an Air Standardization Coordinating Committee “apparently has concluded that the quantity of oxygen required for pilots to perform full F-22 operations may, in fact, be greater than what is supplied” by the oxygen system.
The assertions were made in a letter today to Air Force Secretary Michael Donley in which the lawmakers sought additional answers to the mystery of the F-22’s oxygen-related problems.
A Honeywell Aerospace spokesman, Nathan Drevna, said in a statement that the company’s oxygen system “is performing as designed in accordance with U.S. Air Force specifications.”
“Honeywell continues to support the USAF and the F-22 industry team in understanding the cause for the physiological incidents leading to various F-22 fleet issues,” he said.
Unable to explain episodes of dizziness and other ailments, the Air Force has been looking at a variety of possible causes, from the prosaic -- hoses, masks and the pressure vests -- to the top-secret coatings and adhesives used in the plane’s radar- absorbing stealth skin that makes it harder to track.
The lawmakers suggested on a conference call with reporters today that the Air Force is returning to a lack of sufficient oxygen as the leading theory for the hypoxia problem.
“It seems like we’ve come a bit full-circle back to that,” Warner said.
Kinzinger, urging caution, said, “This may be the leading theory right now, but in the last few times we’ve had a leading theory, we’ve been burned.”
The Air Force focused last month on a pressure vest worn by F-22 pilots that “increases the difficulty of pilot breathing under certain circumstances,” according to a statement from Air Combat Command.
Even after the Air Force instructed pilots to stop wearing the vests, additional hypoxia incidents were reported, most recently on July 6.
At least two dozen pilots and six ground-maintenance workers have reported symptoms associated with a lack of oxygen. There have been at least 11 reported incidents since the plane resumed flying operations last year after a four-month halt because of safety concerns.
Warner and Kinzinger said in the letter that there have been additional hypoxia-related incidents that the Air Force hasn’t disclosed, including a July 6 incident at Joint Base Pearl Harbor in Hawaii, a “restricted airflow” incident in late June at Joint Base Langley-Eustis in Virginia, and a May 31 incident at Tyndall Air Force Base in Florida in which a pilot hit the runway without extending the plane’s landing gear.
Gregory Martin, a retired general who headed a study of the F-22 for the Air Force Scientific Advisory Board, told reporters at a March 29 Pentagon briefing that the plane’s oxygen system “might not produce as much oxygen as it would when it was not under G,” or a high level of acceleration. Still, he said, the oxygen level was “never in an area of concern.”
The assertions by Warner and Kinzinger indicate that the Air Force may be revisiting that assumption.
In May, Defense Secretary Leon Panetta imposed new safety measures that include limiting flight durations and speeding the installation of a back-up oxygen system.
Lockheed Martin, the world’s largest defense contractor, won a $19 million contract in June for the back-up oxygen supply system, which is scheduled to be installed by the end of next year.
Warner and Kinzinger asked the Air Force in their letter to specify whether Lockheed’s new contract was awarded without competition.
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