What happened
A pilot was conducting a positioning flight under night visual meteorological conditions while utilizing night vision goggles. During the flight, the pilot followed a road that separated the departure point from the destination, using vehicle traffic and surrounding terrain as visual references.
Approximately 15 minutes into the flight, the pilot noticed an abnormality in the aircraft's performance. The attitude indicator indicated that the helicopter was engaged in a left descending turn of approximately 60 to 70 degrees. Simultaneously, the altimeters and airspeed indicators showed a corresponding downward trend. Although the pilot attempted to correct the flight attitude, he became disoriented. The helicopter subsequently impacted the terrain and rolled onto its right side. A post-impact fire occurred, which destroyed the aircraft.
Findings
The investigation determined that the pilot experienced spatial disorientation while flying at night.