F-22 fighters allowed back in the air

The US Air Force said Monday its fleet of F-22 fighter jets will be allowed back in the air after officials grounded the planes over concerns about the aircraft's oxygen system.

The F-22 Raptors, the most advanced combat aircraft in the world, were barred from flying for four months, a highly unusual move that reflected serious worries over safety.

"We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate," Air Force chief of staff General 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," said.