WF710
1988-MAY-06 · Torghatten, near Brønnøysund, Norway

Widerøe — Flight WF710

Widerøe Flight 710 crashed into the Torghatten mountain during a VOR/DME approach to Brønnøysund Airport in foggy conditions. The aircraft was 4 nautical miles ahead of its prescribed descent profile, leading it to strike the hillside at an altitude of 560 feet. All 36 people on board were killed. The investigation highlighted significant human factors, including the presence of an unauthorized passenger in the cockpit jump seat who likely distracted the crew, a lack of sterile cockpit procedures, and systemic training deficiencies within the airline during its transition to the Dash 7 aircraft type.

Aircraft
de Havilland Canada DHC-7-102 Dash 7
Registration
LN-WFN
Phase
Approach
Cause
Controlled Flight Into Terrain (CFIT)
Souls on Board
36
Fatalities
36
Origin → Dest
Trondheim Airport (TRD) → Brønnøysund Airport (BNN)
Report
Final

Investigation Summary

The accident occurred during the second leg of a multi-stop domestic route. After departing Namsos, the crew prepared for a VOR/DME approach to runway 04 at Brønnøysund. Despite the requirement to maintain 1,500 feet until 4 NM from the airport, the crew initiated their final descent at 8 NM. This premature descent placed the aircraft on a collision course with Torghatten, a 258-meter (846-foot) mountain. The aircraft struck the hillside at an altitude of 560 feet, well below the peak. A critical factor was the presence of a non-airline passenger in the cockpit jump seat. CVR analysis suggested the captain was engaged in non-essential conversation with this passenger during the approach, which likely disrupted the crew's situational awareness and mutual monitoring. Furthermore, the airline's maps contained several errors, and the crew used non-standard terminology (referring to 'Torghatten' in briefings despite it not being a designated navigational landmark).

Final Conclusions

The Accident Investigation Board Norway (AIBN) concluded that the primary cause was the premature commencement of the final approach descent by 4 nautical miles. While no single technical reason was found for this error, the board cited a breakdown in cockpit discipline and coordination. Contributing factors included the distraction caused by a jump-seat passenger, the lack of standardized callouts, and the airline's failure to implement adequate internal controls and training for the Dash 7. A supplementary investigation in 2013 confirmed the presence of two NMT-450 mobile telephones in the cockpit but concluded they did not cause electromagnetic interference that could have affected the flight.

Video Analysis

No video analysis linked for this case file yet.

Airframe & Maintenance

Airframe Hours
16,934
Cycles
32,347
Last Major Check
1988-04-15
Engines
Pratt & Whitney Canada PT6A-50

Crew Experience

Captain

Total hours
19,886
On type
2,849

Age 58. Employed by Widerøe since 1960.

First Officer

Total hours
6,458
On type
85

Age 31. Checked out on Dash 7 in February 1988.

Systems & Failure Modes

i

VOR/DME

The primary navigation system used for the non-precision approach; it was tested after the crash and found to be functioning correctly.

i

NMT-450 Mobile Phone

Early mobile phones with 15-watt transmitters; investigated in 2013 for potential electromagnetic interference with cockpit instruments.

i

SCAT-I

A satellite-based landing system later installed at Brønnøysund Airport to prevent similar CFIT accidents.

Interesting Facts

  • 01The accident remains the deadliest involving a de Havilland Canada Dash 7.
  • 02A non-airline passenger was permitted to sit in the cockpit jump seat despite the flight being fully booked and other Widerøe employees being on board.
  • 03The investigation found five specific errors on Widerøe's navigational maps for the Brønnøysund area.
  • 04The captain had recently returned from a six-week vacation and the first officer had only 85 hours of experience on the Dash 7.
  • 05The 2013 supplementary investigation confirmed that two NMT-450 mobile phones (a Mobira MD 50 NA and a Mobira CU 59 D) were recovered from the crash site.

Safety Actions & Advisories

Sterile Cockpit Rule

The commission recommended that Widerøe introduce the Sterile Cockpit Rule to prohibit non-essential conversation during critical phases of flight.

Approach Procedure Modification

The Civil Aviation Administration was advised to increase the minimum altitudes for flight paths around Torghatten to ensure better terrain clearance.

Map and Checklist Updates

Widerøe was ordered to correct errors on its navigational maps and remove requirements for pilots to tune company radio frequencies during descent.

Known Controversies & Unanswered Questions

Mobile Phone Interference

Reference ↗

In 2013, the AIBN reopened the case to investigate if two NMT-450 mobile phones on board could have caused electromagnetic interference. The supplementary report concluded no such interference occurred.

Location

Torghatten, near Brønnøysund, Norway · 65.3933, 12.0867

Case File History

  1. New evidenceUpdated event timeline and findings.
  2. CorrectionUpdated event timeline and investigation summary.

Related Cases

Case ID · wideroe-710-1988Last updated · Filed

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