A Few Words About That Idaho Crash...
Last week's video of the crash of a Stinson 108-3 in the Idaho outback drew intense attention and the predictable lynching by YouTube of the pilot by post-accident armchair experts. I'm not willing to go that far, but the video does give rise this question: As the industry attempts to lower the fatal accident rate, how can we get inside the head of a pilot who would take the risks evident in this video? Assuming no mechanical failure—and none was obvious—how do we train pilots to recognize when they've crossed the risk threshold from edgy into likely accident?
To summarize, the group took off in a heavily loaded Stinson—four aboard--from Bruce Meadows at an elevation of about 6300 feet at a density altitude the NTSB calculated at almost 9200 feet. The intended route of flight might have been toward higher terrain, some of it rising to as much as 9000 feet. The Stinson 108-3 was last built in the late 1940s to 1950, with a Franklin 165-HP engine. So it's a CAR 3 airplane, meaning it probably doesn't have any much less good performance tables. The Stinson is relatively light with a typical useful load of around 1000 pounds. With four people and reasonable fuel, it will be near gross weight.
As a surrogate, I used data from the Cessna 172R, which has about the same power, but whose empty weight is a little higher with a lower useful load. At 6000 feet on a ISA +20-degree day, the 172 needs 3500 feet of runway to clear a 50-foot obstacle. Bruce Meadows is 5000 feet, so adding a 20 percent margin makes it still doable. The problem then becomes climb rate. At 9100 denalt, the 172 POH gives a climb rate between 200 and 300 FPM and it'll get worse the higher you go. Knock a safety margin off that and you basically have no climb rate worthy of the name. And you certainly wouldn't have any reserve climb for the downdrafts that aren't unusual in the mountains.
Pilots fly in and out of these mountain strips in all kinds of airplanes, some of them low powered. But the ones that expect to survive keep the airplanes light, try to make the takeoffs in the early-morning cool and probably remember to ground lean to get best power.
And they're largely successful. We write about density altitude accidents in the aviation press, but there really aren't many of them. Searching a couple of years of NTSB data, I found two in Idaho and two in Colorado, just to use two representative western mountain states. There are far more fuel exhaustion accidents than denalt accidents. Perhaps pilots are just getting wiser.
Still, I can't explain why the pilot involved here didn't pick up on the needle going red when that Stinson wouldn't get off the runway or climb well. In this news clip, a reporter interviewed three of the occupants, including the pilot. She obviously failed to ask any of the questions a pilot would, so there's more heat than light.
Not that it really matters. In my view, they did a terrific service in posting the crash video online. Nothing could do a better job of saying: don't do this.