T-6A Fleet Saw Fewer—But More Frequent—Physiological Episodes in Fiscal 2020

The Air Force saw a total of 33 hypoxia-like events in its T-6A Texan II trainer fleet in fiscal 2020—a nearly 20 percent decrease from fiscal 2019—Air Force Safety Center data obtained by Air Force Magazine shows.

However, the rate of these events—defined as the number of incidents per 100,000 flying hours—within the T-6A fleet increased slightly over fiscal 2019.

And while the T-6A fleet generally saw three or fewer physiological episodes per month in fiscal 2020, the data showed event spikes in November 2019 (six events) and April 2020 (seven events).

Monthly Physiological Episode Totals in Fiscal 2020
Number of Physiological Episodes
October 20193
November 20196
December 20191
January 20202
February 20202
March 20201
April 20207
May 20202
June 20201
July 20203
August 20203
September 20202
SOURCE: Air Force Safety Center data

The Air Force recently made progress on its quest to determine the cause of hypoxia-like events in its T-6A fleet—including ruling out contaminated air as the culprit and putting a greater focus on the potential role of rapid fluctuations in in-flight oxygen levels—but the puzzle has yet to be solved.

How Other Fleets Fared in Fiscal 2020

While the Air Force didn’t provide other fleet-specific physiological episode totals for fiscal 2020, the Air Force Safety Center data showed that the rates observed in the F-22A, F-15C/D, and F-16C/D all decreased from fiscal 2019.

Rates of Hypoxia-Like Events Across USAF Fleets
Per 100,000 Flying Hours, Fiscal 2009-2020
Fiscal 20099.530.003.113.24N/A1.89
Fiscal 20108.115.081.631.03N/A2.76
Fiscal 201165.412.762.670.00N/A1.05
Fiscal 201256.594.724.831.97N/A3.38
Fiscal 201319.147.673.682.12N/A0.60
Fiscal 20146.684.925.623.5937.541.19
Fiscal 20156.2529.286.164.5913.392.48
Fiscal 201616.1949.465.772.4917.631.74
Fiscal 20172.9612.547.897.2567.643.98
Fiscal 201810.4117.918.626.5223.8455.83
Fiscal 201914.5724.174.172.5615.4323.77
Fiscal 20203.688.243.704.0722.5023.83
SOURCE: Air Force Safety Center data

The service’s F-22A and F-15C/D fleets saw the most dramatic drops from fiscal 2019, with the F-22A fleet’s rate of physiological episodes decreasing by nearly 75 percent and the F-15C/D fleet’s rate down about 65 percent.

However, the Air Force’s A-10C and F-35A fleets saw their rates of hypoxia-like events rise in fiscal 2020, the data showed.

The Thunderbolt fleet saw an approximately 59 percent uptick in its physiological episode rate over fiscal 2019, while the F-35A fleet saw an increase of about 46 percent.

An Air Force investigation published Sept. 30 found that an onboard oxygen issue contributed to an F-35A crash at Eglin Air Force Base, Fla., on May 19.

“For the A-10 and F-35 fleet, an increase of one or two physiological episodes per 100,000 hours does make a statistical impact, but the number of episodes in each aircraft remains low,” wrote Air Force spokesperson Lt. Col. Malinda Singleton in a Dec. 10 email to Air Force Magazine. “Our goal is to drive the number to zero episodes per 100,000.”

Editor’s Note: This story was updated on Dec. 10 at 6:12 p.m. EST to include new information from the Air Force.