What happened
On the evening of the accident, a Widerøe flight departing from Trondheim was conducting a multi-stop domestic service including Namsos, Brønnøysund, Sandnessjøen, and Bodø. After an unremarkable departure from Namsos at 20:07, the crew requested a climb from FL70 to FL90. By 20:20, the aircraft began its descent toward Brønnøysund while transitioning to local air traffic services.
At the time of the approach, weather conditions at Brønnøysund included visibility of 9 km and low-level cloud layers. The crew performed a VOR/DME approach for runway 04, intended to be followed by a circling maneuver for runway 22. During this procedure, the aircraft deviated from its assigned altitude, initiating the descent approximately 4 NM before the designated point. This deviation caused the ATR-type aircraft to strike the Torghatten hillside at an altitude of 560 feet. The accident resulted in all occupants being killed.
Findings
The investigation focused on whether electronic interference played a role in the flight path deviation. A witness reported that a passenger had been seated in the cockpit jump-seat during the Namsos leg with a mobile phone. Given that 450 MHz network devices of that era utilized high-power transmitters, investigators examined the possibility of signal interference affecting flight instruments. However, the Norwegian AIB found no evidence to suggest that any mobile device interfered with the aircraft's systems.
Ultimately, the investigation determined that the primary factor was the premature start of the approach procedure, which led the aircraft into terrain below the minimum safe altitude.