Eglin F-35 Crash Blamed on Landing Speed, but Software, Helmet, Oxygen Also Faulted

By John A. Tirpak

Excessive landing speed was the primary cause of the May 19 crash of an F-35A at Eglin Air Force Base, Fla., though faulty flight control logic, the helmet mounted display, the jet's oxygen system, and improper training and were all contributing factors, according to an Air Force investigation.

An Accident Investigation Board found that the principle reason for the crash was the pilot setting a “speed hold” of 202 knots indicated airspeed for the landing, which was 50 knots too fast, while the jet's approach angle was too shallow, according to the report released Sept. 30.

The second main cause was the tail flight control surfaces “conflicting” with the pilot’s apparently correct efforts to recover the jet after it bounced on the runway, a problem the Air Force said was a “previously undiscovered anomaly in the aircraft’s flight control logic.”

The plane and pilot “quickly fell out of sync,” as the flight computer commanded nose down while the pilot commanded nose up, attempting to abort the landing and go around. Sensing that he was being “ignored” by the airplane, the pilot ejected, sustaining significant but non-life-threatening injuries.

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Sensing that he was being “ignored” by the airplane, the pilot ejected,

Sounds like my last marriage...

I hope the pilot can be returned to flight status.

The USAF REALLY needs to get its software under control. Also, one would think that aircrew oxygen systems would have been a fairly mature area of technology by now (though there was nothing written here explaining how that came into play). . .

It might not be what you are thinking of. Maybe parts of the oxygen system interfered with/hampered a real world safe ejection. Something specifically not adequately tested for in development. You never know sometimes.

I read that it was COVID:

"And he had several things on his mind, the report said, including a positive COVID-19 test of a contact of a contact that might require him to quarantine, which contributed to his task over-saturation."

Link

The article I've linked says the oxygen system is a bit different than previous aircraft's and some F35 pilots are reporting more fatigue. It also says the speed hold that was set was normal for that part of the flight when it was set, but not disengaged when it should have been. The pilot had a problem with the HUD in his helmet and was distracted by that.

I'm not a pilot. I'll be interested to read a pilot"s perspective, but this may be a case where the pilot quit flying the plane.

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Originally posted by Hound Dog:
I hope the pilot can be returned to flight status.

The USAF REALLY needs to get its software under control. Also, one would think that aircrew oxygen systems would have been a fairly mature area of technology by now (though there was nothing written here explaining how that came into play). . .

It doesn't sound like a "software" issue. It sounds like a pilot induced oscillation, or what's called a phugoid oscillation. The aircraft responds rapidly, but the pilot is attempting corrections out of sync with the actions he's already commanded. He ends up making the problem worse, and worse; it takes about two of those movements to destroy an aircraft on landing, especially a bounced landing. It usually starts with the pilot pushing forward on the stick to minimize the bounce.

A few knots fast on landing adds substantial distance and means that the jet has more energy than anticipated, resulting in additional float, and potentially behavior not expected; the proper speed must be flown. 50 knots too fast and the jet has a LOT more energy, isn't going to be stopping, and it's going to behave differently to subtle inputs normally made during the landing.

Another article with a few more details

Link

It won't let me cut/paste but it does mention the pilot held the stick aft for 3 seconds but the horizontal stabilizer remained in full deflection down.

And as I understand the O2 system - the F-35 has an onboard oxygen generating system (OBOGS)- whereas the F-15 and others used liquid oxygen.
Sounds like the OBOGS still has a few bugs, from the article. It mentions the "work of breathing" and a physiological toll on the pilot's cognitive abilities.

This also isn't the first time OBOGS have been in the news....

There have been numerous issues with the OBOGS in the A-10, for those aircraft equipped with them.

The F-35, even the simplest F-35A version, seems to have a lot more problems than the arguably more sophisticated F-22.

The OBOGS had been in the new a lot - a stand down was initiated not long ago because of failures - cutting off the oxygen supply to the pilot.

If I recall, a bend in a piece of tubing was found to be the culprit and I thought had solved the problem

50 knots of additional airspeed on landing is a lot of excess energy

I wonder if he is shorter now. When we covering ejection seats in EOD school we were told pilots could be an inch shorted after ejection due to compressing the spine from the main rocket motor on the seat.

The link above discusses a dissonance between the simulation effects, and the actual aircraft, and notes that AIB investigators were able to successfully land the airplane when the situation was recreated in the simulator. The problem, however, is that while the simulator might allow it, the airplane does not respond the same way.

The pilot is cited for lack of systems knowledge.

I find it very hard to believe that during a bounced landing, the pilot held full aft stick for 3 sconds, while the aircraft held full down elevator for that same period. Three seconds is an eternity. Where in that evolution were three seconds to be had? The AIB decided by preponderance of evidence, but that's going to be largely wreckage and pilot account, lacking actual data. I find three seconds a bit incredible. A lot incredible, actually.

It sounds a lot more like the pilot got out of sync with a one hundred eighty million dollar fighter, after attempting to land it 50 knots overspeed, and lost control.

The "work of breathing" issue...means actually having to breathe, rather than having system pressure that requires the pilot to force the air out of the lungs, as some systems do. It sounds more like lack of familiarity.

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I wonder if he is shorter now.

I actually know two Naval Aviators who've punched out and are legit shorter than before their ejection. One was 1/2 an inch shorter, and the other one full inch.
(Oddly enough, the shorter of the two shrank less )

One of my co-workers is a former A-6/S-3 pilot and he's says it's real issue. He's never ridden the seat, but knows plenty who have.

I thought it was built by Lockheed not "Air Bus"