Investigation Summary
The flight was part of a multi-sector schedule (Kathmandu to Pokhara to Jumla to Nepalgunj). Before departing Pokhara, the crew received weather briefings indicating VFR conditions at the destination, but they failed to accurately assess the en route weather, which was affected by a severe western disturbance. Approximately 25 minutes into the flight, the crew began maneuvering to avoid weather and icing. The Pilot-in-Command (PIC) decided to fly a more southern route through the Dang valley, but as conditions worsened, he opted to divert to Bhairahawa. Cockpit Voice Recorder (CVR) data revealed a breakdown in Crew Resource Management (CRM); the First Officer repeatedly warned the PIC not to descend and not to turn, but these warnings were ignored. The PIC reported entering clouds just one minute before the crash. The aircraft struck a ridge near Dihidanda while the crew was occupied with radio communications and navigation in zero visibility.
Final Conclusions
The Nepal Accident Investigation Commission (AAIC) released its final report on 25 August 2014, concluding that the most probable cause was the Pilot-in-Command losing situational awareness while flying in instrument meteorological conditions (IMC), leading to a collision with terrain. Contributory factors included deteriorated weather associated with a western disturbance (including embedded cumulonimbus clouds) and inappropriate crew coordination during the decision to change the course of action.
Photographic Evidence (1)
Video Analysis
The Invisible Wall | Nepal Airlines Flight 183 — A detailed look at the 2014 crash of a DHC-6 Twin Otter in the mountains of Nepal, exploring the weather challenges and crew decisions that led to the CFIT accident.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
First Officer
Systems & Failure Modes
GPS (Global Positioning System)
The crew used the GPS to select a new waypoint (Dang) while attempting to navigate around weather, determining a required altitude of 8,500 feet.
CVR (Cockpit Voice Recorder)
The recorder captured critical disagreements between the pilots, including the First Officer's repeated warnings against descending into the terrain.
Interesting Facts
- 01The aircraft was a 43-year-old Twin Otter that had previously been hijacked in 1973 by members of the Nepali Congress party.
- 02The aircraft (9N-ABB) had survived a previous accident on 5 July 1992, when it ran off the runway and struck a perimeter fence during takeoff from Jumla Airport.
- 03The crash site was located at an altitude of approximately 7,000 to 7,190 feet in the Masine Lek jungle.
- 04All 18 occupants, including one Danish passenger and 17 Nepalese nationals (including one child), were killed.
- 05The First Officer had only 365 total flying hours compared to the Captain's 8,373 hours, contributing to a steep authority gradient.
- 06According to the Nepal Army, wreckage was found scattered as far as 7 kilometers from the primary impact point due to the aircraft disintegrating along a steep mountain slope and valley.
Safety Actions & Advisories
Weather Monitoring and Briefing Improvements
The investigation recommended that the Civil Aviation Authority of Nepal (CAAN) and Nepal Airlines improve the quality of weather briefings and ensure pilots have access to real-time en route weather updates, particularly during monsoon and winter disturbance periods.
CRM and Situational Awareness Training
Nepal Airlines was advised to enhance its Crew Resource Management (CRM) training programs to empower junior officers to challenge senior captains during unsafe maneuvers and to emphasize the importance of maintaining situational awareness in mountainous terrain.