Incident Overview
A pilot requested descent from cruising altitude and was instructed to squawk 1200 and switch to the advisory frequency at the destination airport. The pilot did not acknowledge the instruction, and no further radio transmissions were received from the airplane.
Witness and Radar Observations
Witnesses reported observing the airplane descend to the water in a straight and level attitude with the engines developing power. The wreckage was located in 11 feet of water, about 5 miles south of the destination airport. Review of radar data revealed that the airplane was descending at a rate of about 300 feet per minute on a heading of about 190 degrees. The average groundspeed during the descent was about 163 knots.
Aircraft Systems Examination
The airplane was equipped with an autopilot. Examination of the autopilot annunciator panel by the Safety Board Materials laboratory revealed that the panel contained 15 indicators, each with one 28 Volt 60 milliamp light bulb. The filaments of each bulb were examined with a binocular microscope at magnifications up to 30X. Three filaments were found to be stretched and deformed: those for "AP" (autopilot engagement), "FD" (flight director mode), and "HDG" (heading select/preselect mode).
Pilot-Related Information
The results of the autopsy and toxicological testing on the pilot were unremarkable.
Wreckage Location
The wreckage was located in water approximately 11 feet deep, at a distance of about 5 miles south of the destination airport.