Investigation Summary
The Yakovlev Yak-40 was conducting a scheduled approach to Nha Trang Airport under deteriorating weather conditions associated with Cyclone Forrest. Meteorological data reported at Nha Trang at the time of the accident included winds from 310 degrees at 1 m/s, temperature of 25°C, and a QFE of 758.9. Cloud cover was significant, with 3 oktas of cumulus at 300 meters, 5 oktas at 500 meters, and 8 oktas of stratocumulus at 1500 meters. Investigators determined that the flight crew failed to correctly interpret their instrument settings, leading to a lateral deviation of 6 kilometers from the prescribed W-13 airway. While off course, the aircraft descended below the sector's minimum safe altitude. The aircraft first struck trees along a mountain ridge at an elevation of 970 meters before crashing 350 meters further on. The crash site was located approximately 33 kilometers southwest of Nha Trang Airport. The impact destroyed the aircraft, but several passengers initially survived. Due to the remote location and severe weather, search and rescue teams did not reach the site for eight days. The sole survivor, Annette Herfkens, sustained multiple injuries and survived on rainwater until rescuers arrived. The investigation highlighted negligence in instrument monitoring and poor altitude awareness as primary factors in the controlled flight into terrain.
Final Conclusions
The accident was caused by the crew's failure to maintain the prescribed airway and their descent below the minimum safe altitude in mountainous terrain during poor weather. Contributing factors included the wrong interpretation of instrument settings and the environmental challenges posed by Cyclone Forrest.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Altimeter and Navigation Instruments
The investigation cited wrong interpretation of instrument settings, which led to the crew's failure to recognize their deviation from the airway and safe altitude.
Ivchenko AI-25 Engines
The aircraft was powered by three Ivchenko AI-25 turbofan engines; no mechanical failure was reported.
Interesting Facts
- 01The aircraft was 6 kilometers off the W-13 airway at the time of impact.
- 02The wreckage was located at an elevation of 970 meters on Ô Kha mountain.
- 03The sole survivor remained at the crash site for eight days before being rescued.
- 04A secondary crash involving a rescue helicopter occurred during the search efforts.
- 05The aircraft was built in the Soviet Union in 1976.
Safety Actions & Advisories
Publication of Survival Memoir
Source ↗The sole survivor, Annette Herfkens, published 'Turbulence: A True Story of Survival' in 2014, which provides a detailed account of the crash and the subsequent eight-day survival period, contributing to the public understanding of post-crash survival and psychological resilience.
Known Controversies & Unanswered Questions
Identification of Remains
Reference ↗Approximately one year after the accident, families in the United Kingdom raised concerns and demanded an investigation following reports that the remains of victims had been returned to the wrong families.