Arrow Falcon Exporters Inc OH-58A+ N911RN accident near Somerton, Arizona

Probable cause

The pilot's failure to maintain aircraft control while maneuvering at a low altitude in dark night conditions, which resulted in collision with terrain. Contributing to the accident was the pilot's fatigue due to his working at a time when he normally would be asleep and a relatively long time since awakening and the pilot's lack of total experience in the task environment.

NTSB analysis

The pilot reported that, at the time of the accident, he had been awake for about 14 hours. The accident flight occurred about midnight as he was completing his 15th agricultural application to a field in dark night conditions with no moon and a cloud layer. Forward-projecting flood lights had been mounted on the helicopter to illuminate the terrain directly in front of it. The pilot stated that, while in a left turn to align with a narrow field that had a row of power lines running along one side, he applied left cyclic until it hit the stop. The helicopter continued to drift toward the power lines, so he increased the collective and left pedal to maneuver over them. Although the helicopter cleared the power lines, it started to rotate to the right in an uncommanded fashion and subsequently collided with terrain. The pilot reported no preimpact mechanical malfunctions or failure with the helicopter that would have precluded normal operation. The pilot had accumulated 40 hours of night-time flying experience, and this was his first season being employed as a pilot for agricultural application operations. However, due to his working at a time when he normally would be asleep and a relatively long time since awakening, the pilot was most likely fatigued at the time of the accident.

Text from the NTSB. Open the NTSB docket for WPR13LA215 for the full record.