The Air Force grounded T-6A Texan II flying operations Nov. 15 after pilots reported oxygen problems — the fourth incident since Nov. 1.
According to officials of the 71st Flying Training Wing at Vance Air Force Base, Oklahoma, four instructor pilots and one student pilot reported physiological incidents while flying.
“Vance Air Force Base is committed to ensuring aircrew safety is paramount, and are conducting a full investigation of the reported cases,” said Col. Darrell Judy, 71st FTW commander.
According to the Air Force, the aircraft’s backup oxygen system operated as designed, and pilots followed the correct procedures, landing aircraft safely.
Pilots also were briefed on all the incidents that have occurred and the successful actions taken by the pilots to safely recover their aircraft, officials said.
The grounded planes are limited to Vance Air Force Base T-6s, according to the Air Force.
T-1A Jayhawk and T-38 Talon flight operations will continue, officials said, because the incidents are limited to the T-6 airframe.
Fox News previously reported the Air Force’s oxygen problems, including in June when the 56th Fighter Wing at Luke Air Force Base, Arizona canceled local flying operations for F-35A Lightning II aircraft after pilots reported suffering symptoms similar to hypoxia, or oxygen deprivation.
Fox News’ Lucas Tomlinson contributed to this report.