US Air Force grounds F-22 fighters again: officers

The U.S. Air Force has had to ground dozens of F-22 fighter jets for the second time this year after concerns a pilot suffered a lack of oxygen in the cockpit, AFP reported Tuesday, quoting officers in Washington.

An Air Force spokesman said commanders at a base in Virginia and in Alaska ordered a "pause" in flights for the world's most expensive and advanced fighter aircraft as a safety precaution, the report said.

The decision came after an incident last week in which a pilot at Joint Base Langley-Eustis in Virginia suffered "hypoxia-like" symptoms in mid-flight, Lieutenant-Colonel Richard Johnson told AFP.

The announcement came only a month after the Air Force grounded the entire Raptor fleet from May through mid-September to allow engineers to check for possible problems with the plane's oxygen supply.

"Part of our protocol is to allow units to pause operations whenever they need to analyze information collected from flight operations to ensure safety. That is what is happening at Langley at the moment, and we support that decision," Johnson said in an emailed statement, according to AFP. About 30 F-22 Raptors are based at the Langley base in Virginia.

At Joint Base Elmendorf-Richardson in Alaska, senior officers lifted the temporary flight ban on Monday after having ordered the planes grounded last Thursday, he said.

The Air Force has more than 160 F-22 Raptors in its fleet and plans to build a total of 187.