Wideroe - Wideroe's Flyveselskap

The following factors were identified:
- The crew deviated from the prescribed procedure,
- The crew deviated from the company Standard Operating Procedure,
- The crew failed to comply with CRM requirements as described in the company Flight Operations Manual,
- The crew continued the approach after passing the minimum altitude without adequate visual reference with the runway,
- The crew did not consider 'go around' when passing Decision Point without adequate, visual references to the runway,
- The crew did not consider 'go around' during a landing with apparent flight control problems,
- The crew completed the landing despite the fact that the aircraft was not in a stabilised configuration,
- The non-stabilised landing with a high descent rate overloaded the right undercarriage fuse pin to a point at which it collapsed,
- The public address system did not function when used by the commander for evacuation.

The accident was the consequence of a controlled flight into terrain. The following findings were reported:
- The company had failed to implement a standardized concept of aircraft operation that the pilots fully respected and lived by;
- The approach briefing was not not fully implemented in accordance with the rules. There were deficiencies in:
- "Call outs" during the approach
- Descent rate (feet/min) during "FAF inbound"
- Timing "outbound" from the IAF and the time from FAF to MAPt;
- The crew did not execute the "base turn" at the scheduled time, with the consequence that the plane ended up about 14 NM from the airport;
- The Pilot Flying ended the approach with reference to aircraft instruments and continued on a visual approach in the dark without visual reference to the underlying terrain. During this part of the approach the aircraft's position was not positively checked using any available navigational aids;
- Both crew members had in all likelihood most of the attention out of the cockpit at the airport after the Pilot Not Flying announced that he had it in sight;
- The crew was never aware of how close they were the underlying terrain;
- The last part of the descent from about 500 feet indicated altitude to 392 feet can be caused by inattention to the fact that the plane may have been a little out of trim after the descent;
- Crew Cooperation during the approach was not in accordance with with the CRM concept and seems to have ceased completely after the Pilot Not Flying called "field in sight";
- Before the accident the company had not succeeded well enough with the introduction of standardization and internal control/quality assurance. This was essentially because the management had not placed enough emphasis on awareness and motivate employees;
- The self-control system described in the airline operations manual and the parts of the quality system, was not incorporated in the organization and served as poor safety governing elements;
- Neither the Norwegian CAA nor the company had defined what visual reference to terrain is, what sufficient visual references are and what the references must be in relation to a moving aircraft.

The cause of the accident was that the plane during departure came into the wind that exceeded the aircraft's design criteria. Thus there was a break in the horizontal stabilizer / elevator which meant that the plane could no longer be controlled.

The cause of the accident was that the last part of the approach was started about 4 NM too soon. The aircraft therefore flew below the safe terrain clearance altitude and crashed into rising terrain. The Board cannot indicate any certain reason why the approach started so early.

The exact cause of the accident could not be determined with certainty. However, it is believed that the accident was the consequence of a loss of control in-flight after the vertical stabilizer failed due to the combination of altitude turbulences, strong winds, unfavorable atmospheric currents and inappropriate reaction on part of the flying crew.

The accident occurred during a NATO military exercise, within a self-declared no-fly zone for allied military aircraft. A report in 1987 that radar had observed an unidentified aircraft which was on a collision course with the Twin Otter caused a second investigation to be started. It was concluded that the existence of other aircraft in the area could be ruled out; and that no other airborne objects could have caused the accident. The debate about the accident resurfaced in 1997 when several sources claimed there was new or overlooked evidence of the involvement of NATO aircraft. The Accident Investigation Board Norway (AIBN) decided in 1997 to investigate the new claims and concluded that there was no evidence to support these claims. The accident was ordered investigated again in November 2002 after a retired Norwegian air traffic controller said one of the Harrier pilots, involved in a mission about the time of the accident, had requested an immediate landing because of technical problems. The report was published on 20 September 2005. It fully supported the findings of all three previous reports and found no evidence for an impact with a Harrier or any other aircraft.

The Accident investigation Board was not able to determine whether the pilot meant to make a 180 degree turn and fly back out of the fjord, or initiate a climb to get across a low mountain ridge and out into the next fjord to the west. The Board concluded that the accident was caused by the pilot’s decision to turn towards higher terrain. If the purpose was to exit the fjord, it should have been made to the left over the fjord. If it was to climb across the ridge, it would not have been possible to clear the terrain, given the aircraft’s weight and performance.