Overview
A certificated airline transport pilot, along with one non-revenue passenger, departed in a twin-engine turboprop airplane from a rural airport on a Part 135 VFR cargo flight over ocean waters. The flight did not reach its intended destination and was subsequently reported overdue.
Search and Debris
Search personnel conducted an aerial search along the anticipated route of flight over ocean waters. Shortly after the search began, airborne searchers sighted floating debris, which included what appeared to be aircraft seats, cardboard boxes, and small portions of aircraft wreckage. The debris field was located approximately 30.5 miles southwest of the departure airport and about 10 miles from shore. The airplane is presumed to have sunk in ocean waters estimated to be between 50 and 70 feet deep. Underwater search and recovery efforts were unsuccessful, and the airplane, pilot, and passenger remain missing.
Radar Data
A review of archived radar data disclosed that as the accident airplane approached an area about 30.5 miles southwest of the departure airport, it descended to 500 feet mean sea level (msl) and then entered a right turn. As the turn progressed, the airplane continued to descend to 400 feet msl, with a radar-derived ground speed of 180 knots. The last radar return was recorded with the same radar-derived groundspeed, on an approximate heading of 200 degrees. A pilot familiar with the area reported that migrating whales are commonly sighted in the area where the radar depicted a descending right turn.