Cosmos PHASE II N56078 accident near El Mirage, California

Probable cause

The pilot's improper preflight and starting procedures, which resulted in an inadvertent takeoff with the gust lock still installed.

NTSB analysis

A witness reported that the non-certificated pilot's normal procedure was to start the engine while seated in the weight-shift-control trike. Once started, he would then exit while the engine warmed up, and put on his helmet and glasses. On the day of the accident, the pilot was seated and unrestrained in the aircraft, with the gust lock installed, and appeared to be having difficulty starting the engine. He then moved the throttle to the full forward position and attempted a restart. This time the engine started, and immediately accelerated to high power. The aircraft then accelerated forward, rotated, and began a steep climb followed by a stall and uncontrolled descent to the ground. Throughout the maneuver the pilot appeared to be struggling to stay within the aircraft. The engine manufacturer's instructions specified that the throttle control should be set to the idle position during engine startup. Additionally, the manual stated that the operator should be able to operate the engine controls instinctively at startup, and be in a position to turn off the ignition switch instantly if necessary. No anomalies were noted with the throttle control, which was observed in the full open position. The pilot did not use wheel chocks to secure the trike prior to engine start.

Text from the NTSB. Open the NTSB docket for WPR10LA462 for the full record.