Eurocopter AS350 N124LN accident near Andalusia, Alabama

Probable cause

The pilot’s acute incapacitation by a syncopal episode, which resulted in the helicopter departing controlled flight and colliding with terrain.

NTSB analysis

The medical helicopter was flying a 15-minute flight from its base to a hospital to pick up a patient for transfer to another hospital. The cruise portion of the flight was uneventful. As the helicopter began its descent to the hospital helipad, the pilot lost consciousness, as witnessed by the flight paramedic. The helicopter then departed controlled flight and impacted a field about 1 mile from the hospital helipad. During a posaccident examination of the helicopter, no evidence of any preimpact mechanical malfunctions or failures of the helicopter were identified, nor did the pilot report any.

After the accident, the pilot was admitted to a hospital and underwent evaluation for injury and syncope (loss of consciousness), but no definitive cause of the syncope was identified. Toxicological testing detected ethanol at 0.024 g/dL in a blood specimen collected from the pilot more than 1.5 hours after the crash and detected ethanol in his urine. Testing also detected the cocaine metabolites benzoylecgonine and cocaethylene in the pilot’s urine but not in his blood. Based on the pilot’s blood ethanol level and an estimated ethanol elimination rate of 0.01 to 0.035 g/dL per hour, the pilot’s blood ethanol level at the time of the accident was likely between 0.04 g/dL to 0.08 g/dL. Ethanol at this level would not sufficiently explain the pilot’s loss of consciousness but would be expected to have adverse effects on his performance capacity. Thus, it is likely that the pilot was impaired by effects of ethanol at the time of the accident.

The benzoylecgonine detected in the pilot’s urine indicated that he had used cocaine. The cocaethylene in his urine indicated that both cocaine and ethanol had been in his system at the same time, with more than a small amount of cocaine likely used. The time elapsed between the pilot’s last cocaine use and his blood specimen collection was sufficient for cocaine to be metabolized and for its metabolites to fall below detectable levels in his blood. However, the precise time of his last cocaine use could not be determined, and the possibility of residual adverse effects from his cocaine use could not be excluded.

The pilot also had a history of obstructed sleep apnea (OSA) and had called out sick the day before the accident, reporting a stomach illness. At the time of the accident, the pilot likely was experiencing some impairing effects from alcohol use and may also have been experiencing impairing effects related to his use of cocaine. However, the event that precipitated the loss of helicopter control was the pilot’s acute incapacitation by a syncopal episode, the precise medical cause of which is unknown. Whether the pilot’s substance use, reported illness, or OSA (or a combination thereof) contributed to his syncopal episode cannot be determined.

Text from the NTSB. Open the NTSB docket for ERA22FA343 for the full record.