On May 21, 1994, a Grumman G-164B (registration N50WS) operated by Fly-it-on, Inc. was involved in an aviation accident near Princeton, ID. Investigators recorded the probable cause as: The pilot's failure to maintain adequate airspeed and altitude during agricultural application, which resulted in an inadvertent throttle reduction caused by his clothing catching on the control, and his inability to recover from the resulting power loss. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During agricultural spraying operations, the pilot's shirt sleeve caught on the throttle, causing an unintended power reduction and resulting in a collision with trees.
What happened
The incident occurred while the pilot was conducting agricultural application runs. During one of these maneuvers, the pilot reached for the hand valve controlling the spray tank. In the process, his shirt sleeve became entangled with the throttle control. This contact pulled the throttle back to the idle position, causing a sudden loss of engine power.
The pilot immediately attempted to push the throttle forward to full power in an effort to recover altitude and avoid impact. However, the engine failed to regain sufficient power in time to prevent a collision. The aircraft subsequently impacted a line of trees. Prior to the impact, the pilot made an attempt to jettison the spray agent from the tank but was unable to complete this action before the crash occurred.
The investigation
The primary mechanical factor identified was the unintended movement of the throttle control. The investigation focused on the sequence of events leading to the power loss and the subsequent impact with terrain.
Probable cause
The pilot's failure to maintain adequate airspeed and altitude during agricultural application, which resulted in an inadvertent throttle reduction caused by his clothing catching on the control, and his inability to recover from the resulting power loss.