By Adam Levine

Pilots flying the F-22 Raptor reported illness from oxygen deprivation incidents 10 times as often as pilots of other fighter jets, according to Air Force data.

The F-22 has been the focus of an Air Force inquiry because of the oxygen problems.

The new data, released by Sen. Mark Warner, D-Virginia, and Rep. Adam Kinzinger, R-Illinois, shows Raptor pilots have reported 26.43 hypoxia and hypoxia-like incidents per 100,000 flight hours. While that represents a mere fraction of total flight hours, it is far higher than incidents from other Air Force aircraft, including the A-10, the F-15E and the F-16.

Kinzinger, a military pilot himself, said that while low, the numbers are extremely concerning. Kinzinger and Warner have been vocal in pressing the Air Force to investigate the concerns after two pilots came forward about the problem on CBS's "60 Minutes."The problem puts pilots in "a vulnerable situation, because potentially, you have a pilot who at the beginning stages of hypoxia-like symptoms, really can't, you know, think things through, has a hard time making those judgment calls," Kinzinger told CNN's Soledad O'Brien in an interview on the CNN morning show "Starting Point."

"You really do lose your cognitive ability," he said. "So - well, you do this to recognize your symptoms. Everybody has different symptoms. For me, actually, I start finding everything pretty funny. But then you have a hard time."

The Air Force continues to investigate the hypoxia problem. Investigators are looking at whether a compression vest worn as part of the flight suit contributes to the problem, CNN's Mike Mount reported Wednesday. Investigators are focusing on a part of the suit called the Combat Edge, which can hamper breathing and cause oxygen loss when combined with a physiological condition that collapses air sacs in the lungs, according to details of the report that were shared with CNN Security Clearance.

Combat Edge is a vest-like garment that expands and contracts on a pilot's torso to fight the effects of severe G-forces experienced while flying the F-22. What is being looked at is whether the garment may restrict the pilots' breathing beyond what is intended, according to sources familiar with the report.

"In many cases, those vests were actually failing in high-G scenarios," Kinzinger said Friday. "So, at this point, it seems like the most likely place to pursue."

But the problem has proven vexing, especially since there have been incidents of mechanics on the ground having the same symptoms, and some pilots also experiencing hypoxia at lower altitudes.

"The Air Force has explained that these maintainers, you know, had symptoms, but they actually weren't related," Kinzinger said. "I think it's very important that we take a deep look in that, because if they are related, then the high pressure, the upper vest suit, isn't the issue. And I think the other big issue, too, is maintainers and pilots have to feel comfortable to come forward and talk about their concerns."

The fleet was grounded in May 2011 so the service could check the hypoxia reports, but the order was lifted in September under a "return to fly" plan, with equipment modifications and new rules including daily inspections of the life-support systems.

Investigators initially pointed to an onboard oxygen-generating system that feeds pilots' air supply as a possible cause.

Lockheed Martin, the maker of the jet, was given a $19 million contract to install a backup oxygen system in the F-22 last week.

Last month, Defense Secretary Leon Panetta mandated that all F-22 flights "remain within the proximity of potential landing locations" to ensure the ability to recover and land should a pilot run into "unanticipated physiological conditions."