US limits F-22 flights after pilots' complaints

WASHINGTON - US Defense Secretary Leon Panetta on Tuesday announced new measures to restrict the flight missions by the 5th-generation F-22 Raptor fighters, after pilots continued complaining about hypoxia-like symptoms during flight.

Panetta has directed the US Air Force to take three new measures in order to ensure the safety of F-22 fighter pilots, Pentagon spokesman George Little told reporters at a news briefing.

The measures include the installation of an automatic back-up oxygen system in all F-22 fighters, suspension of long-duration air space control flights by the F-22 fighters, especially in Alaska, and providing a monthly progress report on fixing the problem.

"Secretary Panetta believes the department must do everything possible to ensure pilot safety and minimize flight risks. He will continue to closely monitor the Air Force's efforts to enhance the safety of this very important aircraft," Little said.

Asked why Panetta did not order to ground all F-22 fighter jets until the problem is completely fixed, Little said that "all options remain on the table" as the defense chief will receive regular updates.

But he added that, in terms of the deployment of F-22 fighters in southwest Asia, Washington will not change the plan as "we believe that we can safely continue that deployment given the geography of the region."

Little stressed that, despite the problems reported, the F-22 fighters remain the most advanced US fighter aircraft, whose capabilities are important to maintaining the US air superiority and national security objectives, whether it's protecting the US air space or deploying overseas as part of deterrence and engagement efforts.

Panetta supports the measures taken so far by the Air Force to pursue all plausible hypotheses and determine the root causes of the hypoxia-like symptoms experienced by F-22 pilots, he added.

The US Air Force has been examining a total of 25 reports by F-22 fighter pilots who experienced hypoxia-like symptoms during flight, or oxygen deficiency.

The fleet was grounded in May 2011 for inspection of the complaints, but they were cleared to return to sky after four months, with equipment modifications and new rules including the daily inspection of life-support systems.

However, there have been 11 new complaints from pilots about the same hypoxia-like symptoms since last September, showing that the problem that used to haunt the pilots is still there. Adding to the mystery, some ground maintainers, who sometimes have to do their job inside the cockpit, have also reported hypoxia-like symptoms.

The problem aroused widespread concerns and embarrassed the Air Force when two F-22 fighter pilots from the Virginia Air National Guard went public in early May with their complains about the hypoxia symptoms in an rare interview with the CBS "60 Minutes" TV program.