Aircraft Oxygen-Generating Systems Under Investigation
By DAVE MAJUMDAR
Published: 24 Mar 2011 20:00
The U.S. Air Force is investigating whether the On-Board Oxygen Generating System (OBOGS) found on several U.S. Air Force warplanes, including the F-22 Raptor, might be defective.
"Air Force operational commanders have temporarily restricted F-22 flight operations to an altitude at or below 25,000 feet for routine training missions," said Col. William Nichols, a spokesman for the command, which is responsible for training and equipping the service's combat air forces.
"Air Combat Command is conducting an investigation to assess on-board oxygen generating systems on several platforms, including the F-22," Nichols said.
"The investigation is designed for mishap prevention and is a prudent measure to ensure the OBOGS are operating safely.
"When the investigation is completed, the results will be reviewed and appropriate actions, if warranted, will be taken," he said.
A Lockheed Martin spokesman confirmed that the restriction has been in place ever since an F-22 based at Elmendorf Air Force Base, Alaska, crashed in November. Lockheed is the prime contractor for the F-22, a next-generation stealth fighter jet.
One Air Force source said that an OBOGS malfunction might have been responsible for the incident, which resulted in the death of Capt. Jeffery Haney, an F-22 pilot assigned to the 525th Fighter Squadron.
Despite the restrictions, the Raptor remains fully operational and could carry out combat tasks if needed, he said.
"A standard safety practice with all aircraft is, if there is a known or suspected problem, you take measures to fix it," said Mark Gunzinger, an analyst at the Center for Strategic and Budgetary Assessments, Washington, and a former Air Force pilot.
"It's not something you want to do, but these things happen with complex aircraft."
While the stealth fighter might be restricted in training operations, that does not mean the Raptor would be restricted during wartime missions, Gunzinger said.
"If it's a war, if it's truly a safety-of-flight issue and it's going to hurt pilots and it's going to prevent the mission from being accomplished, then obviously the restriction will stand," he said.
"But if it's something of a temporary nature or there is a work-around in time of war, it may not impact combat operations."
An OBOGS malfunction can be potentially life-threatening, said Hans Weber, who sat on the U.S. Federal Aviation Administration's Research, Engineering and Development Advisory Committee, and is the current president of Tecop International, a San Diego consulting firm.
"It's a big deal if you're at high altitude and you run out of oxygen," Weber said.
At 50,000 feet, a human being has less than 10 seconds of useful consciousness, he said.
The 25,000-foot altitude restriction would allow the pilot to quickly dive below 18,000 feet, where the atmosphere has enough oxygen to ensure prolonged survival in case of an emergency.
"It would take you so long when you're way up high, you may black out before you make it to a safe altitude," Weber said.
Given the nature of the restriction, the problem with the OBOGS is likely to be a reliability issue, Weber said.
While the probability of malfunction is fairly low, it is not something aviators take lightly, he said.
Weber also said that equipment such as the OBOGS is fairly standardized across multiple aircraft types, which means aircraft other than the F-22 likely are also affected, which Air Combat Command acknowledges.
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