Casualties unknown

1985-04-19: Piper PA25-235 (N9636P) — Victor G Spezia — Walnut Grove, CA

Walnut Grove, CA, US

On April 19, 1985, a Piper PA25-235 (registration N9636P) operated by Victor G Spezia was involved in an aviation accident near Walnut Grove, CA. Investigators recorded the probable cause as: The pilot's inadequate visual scanning during a procedure turnaround, which resulted in controlled flight into terrain. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

An agricultural aircraft crashed while spraying wheat, striking the ground during a procedure turnaround. The pilot was killed in the accident.

What happened

The aircraft was engaged in an agricultural operation, specifically spraying wheat with a toxic chemical, when it collided with the terrain. The incident occurred during a procedure turnaround maneuver. According to the factual narrative, the airplane did not experience a stall prior to impact. Additionally, witnesses or investigators noted that the engine sound did not change, suggesting no mechanical failure was audible before the crash.

The investigation

Examination of the wreckage revealed a separated aileron crossover cable. Technical analysis of this component showed no signs of fatigue, indicating it likely failed due to the impact forces rather than causing them. To rule out chemical impairment as a factor in the pilot's performance, medical testing was conducted on the pilot's blood. The results showed that cholinesterase levels were within normal limits. This finding is significant because toxic pesticides typically inhibit cholinesterase activity; normal levels suggest pesticide poisoning did not contribute to the accident.

Findings

The investigation determined that the aircraft struck the ground while performing a maneuver common in agricultural flying. The absence of stall characteristics and the lack of fatigue on the control cable point away from mechanical failure or aerodynamic stall as primary causes. The normal blood chemistry further isolates the cause to operational factors rather than pilot incapacitation from chemical exposure.

Probable cause

The pilot's inadequate visual scanning during a procedure turnaround, which resulted in controlled flight into terrain.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X36213. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.