Twin Astir descends unpiloted after the pilot's in-flight incapacitation

The pilot was killed and the glider destroyed when, after more than two hours of high-altitude soaring on a local flight, he was probably incapacitated and could no longer fly. Left unpiloted, the glider fell into a slow, diverging pitch oscillation — repeatedly rising and stalling in incomplete loops — that grew over about seven minutes as it descended, until it struck a line of trees and the ground at high speed. The pilot had an undisclosed cardiac history he had not declared to his aeromedical examiner; the long flight at altitude might have brought on mild hypoxia, with his age and heart condition as added risk factors.

1. Long high-altitude soaring flight: After an aerotow launch, the pilot soared for over two hours, much of it above 2,000 m, on a local flight.
2. Pilot probably incapacitated: About two hours and forty minutes into the flight, the pilot was probably incapacitated and could no longer control the glider.
3. Unpiloted divergent oscillation: Left unpiloted with a free stick, the glider entered a slow, diverging longitudinal (phugoid) oscillation.
4. Oscillation grew into failed loops: Over about seven minutes the oscillations grew into incomplete loops with stalls at the top as the glider descended.
5. Struck trees and the ground: The glider struck a line of trees and then the ground at high speed; the pilot was killed and the glider destroyed.