Bruce Tognazzini summarizes and analyzes NTSB findings on the airplane crash that killed John Denver in 1997. Bad interface design. Among other serious flaws in the user interface (particularly the readouts and controls for the fuel tanks),

The builder [apparently not Denver] not only placed the valve in a non-standard location, he also rotated it in such a way that turning the valve to the right turned on the left fuel tank. This ensured that a pilot unfamiliar with the aircraft, upon hearing the engine begin missing and spotting in his mirror that the left fuel tank was empty, would attempt to rotate the fuel valve to the right, away from the full tank, guaranteeing his destruction.

Tog's article is from 1999, but I must have missed it.

[via the IxDA list]