The Air Force's fleet of 170 F-22 stealth fighters will return to service Wednesday, Air Force officials said.
The fleet was put on stand-down in May over concerns about the system that delivered oxygen to pilots aboard the jets.
That order came after 12 pilots reported hypoxia-like symptoms since 2008. Hypoxia is when the body does not receive enough oxygen.
The Air Force didn't explain exactly what has changed to clear the fleet.
"We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate," Air Force Chief of Staff Gen. Norton Schwartz said in a statement. "We're managing the risks with our aircrews, and we're continuing to study the F-22's oxygen systems and collect data to improve its performance."
An Air Force spokeswoman could not elaborate.
However, the Air Force said the planes will be subject to "rigorous inspections, training on life support systems, and continued data collection," according to the statement.
Officials at Joint Base Elmendorf-Richardson said Tuesday that the entire fleet has been cleared to return to service, flying above 50,000 feet. There are 40 stealth fighters based in Anchorage.
All planes will have their life support systems inspected before they are allowed to fly, and then will have additional daily inspections. Pilots will have physiological tests, and will have to use additional protective equipment, the release says.
The Air Force has groups studying both the hypoxia reports and safety issues with the Raptors' oxygen systems, with findings expected later this year.
Capt. Jeffrey Haney was killed in November 2010 when his F-22 crashed during a training exercise about 100 miles north of Anchorage. An Air Force report on his death has not yet been released, but spokeswoman Maj. Maureen Schumann said Air Force officials have previously indicated evidence recovered at the crash site indicated his death was not hypoxia-related. No other details were immediately available.
The F-22 Raptor was introduced in 2005, and the Air Force says it has flown over 300 missions in Operation Noble Eagle.