I guarantee you the amount of medical incapacitations is far more than 1%, it’s just that they can only prove it happened 1% of the time. The NTSB deals in absolutes.
Certainly true. My homebuilt accident database runs for ~22 years and has ~4,500 accidents. I show about 33 cases where that involved pilot incapacitation... and almost twice as many involving the pilot's loss of control for unknown reasons. And, for that matter, there are an additional 71 cases where the NTSB just threw their hands in the air and said, "Cause unknown."
But if every one of those unknown cases is actually a medical incapacitation, it STILL raises the total to less than four percent. Not enough to make it the automatic go-to cause when there's no obvious mechanical or pilot issue.
There are other reasons for unknown loss of control accidents. Suicide, attempted aerobatics, attempted inflight male-female aerobatics, mechanical issues where the evidence is destroyed in the crash, chasing UFOs. I'll certainly grant that SOME are due to undetected medical issues, but there's no way to tell.
Here’s one from an accident that I followed closely and personally suspect medical incapacitation “Probable cause: "A loss of control for reasons that could not be determined based on the available information."
Oh, the line can get quite fuzzy. Anyone here that was on rec.aviation.homebuilt ~20 years ago remember "Badwater Bill" Phillips. Quite a colorful character. Great guy, but he had a huge ego and quite a temper.
He was taking off in his Lancair Legacy when the canopy opened and his wife and his belongings started to spread over the landscape of Utah. Probable cause was "The pilot failed to secure the canopy prior to takeoff, resulting in his inability to control the aircraft during the takeoff." Bill died, his wife was badly injured but recovered (with no memory of the accident). WPR09LA016
Yet, Lancairs can fly with open canopies. My opinion...knowing Bill... is that he blew his stack when the canopy opened. I think his attention focused on the canopy, and he was trying to close it, screaming cuss words, up until the point the Lancair merged with the desert floor.
The situation REALLY would have cranked Bill up. He'd fended off a lot of criticism about the Lancair...he'd bought it from a "hired gun," and there were questions about the legality of its certification. He was a very competent pilot, and while he was quite willing to be kidded, he would get riled up at any perceived serious slight on his flying ability.
And here he was: Either he'd failed to close the canopy, or his brand-new Lancair had a mechanical issue. Neither was something that would sit well with him. He wouldn't have wanted to see the smirks on the faces of the people at the airport. Personally...if he'd gotten the canopy closed, I think he just would have continued on his way. He was rich enough, replacing that was lost wouldn't be a problem. He could even turn it into a funny story.
But at the time, I doubt he was laughing.
But then we come to the OTHER half of the NTSB Probable Cause...the contributing factors. "Contributing to the accident was the pilot’s impairment from prescription medications and possible obstructive sleep apnea."
Part of Bill's larger-than-life online persona was the hint that he was a bit crazy. He used to joke about taking "Thorazine and ant poison" to make it through his day.
Yet... the autopsy after the accident revealed quite a bit. "'Significant conditions' of atherosclerotic coronary artery disease" was found... as well as "acute mixed drug intoxication." Post-mortem toxicology testing found acetaminophen, diazepam, dihydrocodeine, doxazosin, hydrocodone, hydromorphone, and nordiazepam. None of which had been listed on his last medical, 18 months earlier. He wasn't actually legal to fly with that load.
Was he more likely to get fixated on the canopy issue with that drug cocktail in him? Damn it Jim, I'm an engineer, not a doctor.
But in my database, I *did* list this accident as "Pilot Miscontrol." He had almost 5,000 hours. Even with the drugs, I listed this as failure of pilot skills, not incapacitation. He was quite capable of flying the plane, even with his medication load. He'd been taking those medications for months if not years, and had flown the plane ~150 hours.
But did his medications cause him to fixate on the canopy at the expense of maintaining flight? We'll never know.
Ron Wanttaja