Departure and Clearance
The aircraft departed from Boeing Field, using Runway 13, under an Instrument Flight Rules (IFR) clearance. The pilot was instructed to climb on the runway heading, then cleared to a cruise altitude of 13,000 feet MSL.
Flight Path Deviation
Before reaching the assigned victor airway, the pilot requested and received clearance for a left turn to join the airway and was told to resume own navigation. However, radar data showed that the aircraft did not change course. It continued flying on a straight path, passing beyond the airway.
Loss of Contact and Impact
All subsequent attempts to contact the flight were unsuccessful. The aircraft continued climbing on a straight course until it struck Mount Rainier at an elevation of 12,800 feet MSL.
Pilot Background
According to available information, the pilot was at risk for cardiovascular disease due to lifestyle factors. The wreckage was inaccessible, and injuries were presumed.