Aerospatiale AS350 N157BC accident near El Paso, Texas

Probable cause

The pilot's loss of situational awareness resulting in controlled flight into terrain. Contributing to the accident was the pilot's unfamiliarity with the hazards of a low-contrast area while using night vision goggles.

NTSB analysis

The commercial pilot and two paramedics were dispatched to a remote desert area for a simulated patient pick up. This was the pilot's second company flight and first uninstructed night vision goggle (NVG) flight since his recent company training. While maneuvering for the landing zone, ground personnel observed the helicopter orbit one or two times and the pilot was using the non-NVG spotlight to illuminate the ground. Ground personnel then observed the helicopter make a wide orbit before it banked about 45 degrees, entered a steep nose-down attitude, and impacted the ground. None of the witnesses reported an attempt by the helicopter to avoid an impact with the ground. A postcrash fire ensued. An examination of the airframe and engine did not reveal any preimpact anomalies that would have precluded the safe operation of the helicopter.

On the night of the accident there was zero percent moon illumination and very little cultural lighting in the remote area where the accident occurred, resulting in low visual contrast when using NVG’s. The pilot’s recent NVG training had all been conducted on nights with high moon illumination and in populated areas with high amounts of cultural lighting and did not prepare the pilot for flight in the conditions encountered on the night of the accident. The low visual contrast conditions, combined with the narrow field of view of the NVG’s, reduced the pilot’s ability to maintain situational awareness. The lack of attempted recovery prior to ground impact suggests that the pilot did not recognize the helicopter’s descent rate and bank angle.

Text from the NTSB. Open the NTSB docket for CEN10FA113 for the full record.