On Nov. 15, the 71st Flying Training Wing at Vance Air Force Base grounded all T-6A Texan IIs after pilots reported four physiological incidents there since Nov. 1.

In each incident, "the aircraft's backup oxygen system operated as designed" and the aircraft landed safely, according to a Vance press release. T-6A flying operations have been halted while the wing analyzes the data from the reported events.

"Vance AFB is committed to ensuring aircrew safety is paramount, and is conducting a full investigation of the reported cases," said Col. Darrell Judy, 71st FTW commander, in the release.

In...