Amateur-built Glastar N617G accident near Idaho City, Idaho

Probable cause

The pilot’s loss of airplane control during takeoff for reasons that could not be determined.

NTSB analysis

The pilot and a friend were preparing to depart the airfield in their respective airplanes when the accident pilot began to feel physical discomfort. He entered nearby woods to relieve himself and was gone for about 10 minutes. His decision not to walk a short distance to the airport restroom suggests that his discomfort required immediate attention. Upon his return, he resumed preparing to depart. The friend and the accident pilot then taxied their airplanes to the gravel runway. The friend was first to depart and made multiple attempts to communicate over the radio with the accident pilot but received no reply.

An earwitness heard the airplane’s engine power up, and the sound continued until “it just stopped.” He then heard a “slap.” It is likely that the accident pilot applied takeoff power to depart, based upon the loud engine noise heard by the witness and the postaccident positions of the throttle and propeller levers. The airplane remained mostly on the ground and on a left-arcing path until it impacted trees beside the runway. One tree exhibited a deep gouge consistent with impact from a propeller blade that was under power. Evidence was consistent with the airplane continuing to accelerate until it impacted the trees. No skid marks associated with the application of wheel brakes were identified.

Examination of the airplane revealed no preaccident mechanical malfunctions or failures that would have precluded normal operation. Engine data revealed normal operation before the application of takeoff power. The friend reported that he had no problems controlling the airplane and that the airplane sounded normal upon arrival to the airfield.

Toxicology results indicate that the pilot had used cetirizine. It is possible he may have been experiencing some associated impairing effects, such as mild sedation, at the time of the accident. However, the cetirizine levels in cavity blood and urine cannot reliably be used to predict impairment.

An autopsy of the pilot and a medical review revealed no evidence of a preaccident medical event. The pilot’s physical discomfort that required urgent action before the flight suggests that he experienced some type of physical ailment during the preflight inspection. It is possible that after the application of takeoff power to depart, the pilot experienced a physical or medical event that precluded him from operating the airplane; however, no evidence of any such ailment was discovered.

The apparent lack of throttle reduction, lack of braking skid marks in the gravel, and the left yawing indications, which were likely the result of engine torque and propeller asymmetrical forces (P-factor), suggest that after applying takeoff power, the pilot did not or could not control the airplane for reasons that could not be determined and he did not attempt to abort the takeoff.

Text from the NTSB. Open the NTSB docket for WPR23FA301 for the full record.