Bell 206-L4 N863H accident near Moundridge, Kansas

Probable cause

Inflight collision with terrain for undetermined reasons.

NTSB analysis

While en route to the destination airport, the helicopter impacted terrain in a relatively level attitude at high speed. A review of the helicopter’s Sky Connect flight path showed fluctuations in altitude prior to the helicopter’s impact with terrain. The pilot had severe obstructive sleep apnea known to the FAA and effectively treated it with routine use of a nasal continuous positive airway pressure (CPAP) device, which was found among the pilot’s personal effects in the wreckage. It was not possible to determine whether the pilot had used the device in the days leading up to the accident. Also found among the pilot’s personal effects was a container of nasal swabs marketed for the relief of congestion. It is possible (but could not be conclusively determined) that the pilot had nasal congestion that prevented him from using his CPAP in the day or days leading up to the accident, potentially resulting in severe fatigue on the day of the accident. An examination of the airframe and engine did not detect any anomalies prior to impact. An examination of the helicopter's annunciator panel did not reveal evidence that any lights were illuminated at the time of impact.

Text from the NTSB. Open the NTSB docket for CEN09FA193 for the full record.