What happened
On June 3, 2017, at approximately 14:50 JST, a Cessna 172P, registered JA3989, crashed into the vicinity of the Mt. Shishi-dake summit in the Tateyama Mountain Range. The aircraft, operated by New Central Airservice Co., Ltd., had departed from Toyama Airport with the intention of flying to Matsumoto Airport.
During the flight, the aircraft encountered cloud cover while operating under Visual Flight Rules (VFR) over mountainous terrain. The impact occurred at an elevation of approximately 2,700 meters. There were four fatalities among the occupants, which included the pilot in command, a second pilot, and two passengers. While the aircraft was destroyed upon impact, no fire was reported at the scene.
The investigation
The Japan Transport Safety Board (JTSB) examined the flight history, meteorological conditions, and the physical state of the aircraft. Investigators looked into the weather forecasts for the mountainous region and the crew's decision-making processes regarding flight path and altitude. The investigation also assessed the functionality of the aircraft's Emergency Locator Transmitter (ELT) and the safety equipment used by the occupants.
Findings
Investigators determined that the primary cause of the accident was likely the loss of visual reference to the terrain after the aircraft entered clouds during a VFR flight. This loss of situational awareness made it difficult for the crew to maintain a safe distance from the mountain peak.
Several contributing factors were identified:
- The crew likely failed to thoroughly review the weather forecast for the mountainous area prior to departure.
- There was a delay in the decision to turn back once weather conditions began to deteriorate.
- The possibility of aircraft icing or a stall condition was considered, as the aircraft encountered clouds at temperatures near 0°C.
- Severe turbulence may have also played a role in the loss of control or altitude.
- The investigation noted that the crew and passengers were not all utilizing shoulder harnesses, and the aircraft's ELT was inoperable due to a broken auxiliary antenna.