USAF Grounds F-22s

F-22 RAPTORS TAXI April 10 during an operational readiness inspection at Joint Base Langley-Eustis, Va. The commander of the 1st Fighter Wing made the decision to ground the Langley-based F-22s. (U.S. Air Force)

U.S. Air Force F-22 Raptors at the 1st Fighter Wing, Joint Base Langley-Eustis, Va., have once again been grounded, service officials confirmed Oct. 21.

Air Force spokesman Maj. Chad Steffey said that the grounding decision is limited to the Virginia base. A spokesman for Air Combat Command confirmed that the wing's commander, Col. Kevin Robbins, made the decision after an incident.

While details were not immediately available, Air Force officials confirmed that one of the wing's pilots appeared to have suffered an oxygen-related problem.

The Air Force's Raptor fleet was only cleared to resume flight operations last month after a four-and-a-half month grounding. The stealthy fifth-generation fighter was originally grounded May 3 after about a dozen pilots suffered "hypoxia-like" symptoms.

The Air Force is still investigating the problem with the F-22's oxygen system, but had cleared the aircraft to fly because service officials felt that the risk factors had been mitigated. However, the Air Force has not determined what is causing the problem with the jet's oxygen systems.

"There is no conclusive cause or group of causes that has been established for the incidents that prompted the stand-down earlier this year," spokesman Scott Knuteson said in an emailed statement. "We've therefore made the decision to resume operations while implementing improvements to the aircraft's life support systems and carefully collecting and analyzing operational, maintenance and physiological data for all Raptor flights - more than 1,300 missions since the return to flight."

However, as a condition to allowing flights to resume, Air Force leaders have enabled operational commanders to suspend operations as needed.

"Part of our protocol is to allow units to pause operations whenever they need to analyze information collected from flight operations to ensure safety," Knuteson said. "That is what is happening at Langley at the moment, and we support that decision."

One precaution the service took when returning the jets to service was to add carbon filters to the pilot's oxygen supply, one source said. Additionally, pilots were required to give blood samples to use as a baseline to measure against in case of future incidents and are now required to wear a device called a pulse oximeter. The device is supposed to alert the pilot if there is a physiological problem.

However, numerous sources had voiced their misgivings about the return to flight arrangements.

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