Mountains

The aircraft departed controlled flight for reasons which could not be determined, and broke up due to high speed.

The most probable cause for the occurrence of this accident was the loss of situational awareness, caused mainly by the change of flight conditions under visual rules to flight under instrumental flight rules, due to the adverse weather conditions in which the descent phase began, so it is possible to establish the Human Factor as the cause of the accident and the Physical Factor as a contributor.

The following findings were identified:
- Factors, such as obesity and sedentariness, associated with the high workload in the moments preceding the collision with the hill, may have contributed for the task demand to exceed the margins of safety, resulting in wrong decision-making by the pilot.
- Upon facing adverse meteorological conditions and being aware that aircraft which landed before him had reached better visibility in altitudes below 3,500 ft. on the final approach of the VOR procedure, the pilot may have increased his level of confidence in the situation, to the point of descending even further, without considering the risks involved.
- The weather conditions encountered in the final phase of the flight may have aggravated the level of tension in the aircraft cabin to the point of compromising the management of the situation by the pilot, who delegated responsibility for radiotelephony communication to a passenger.
- If one considers that the pilot may have decided to descend below the minimum safe altitude in order to achieve visual conditions, one may suppose that his decision, probably influenced by the experience of the preceding aircraft, was made without adequate evaluation of the risks involved, and without considering the option of flying IFR, in face of the local meteorological conditions. In addition, the pilot’s decision-making process may have been compromised by lack of information on Mount Santo Antonio in the approach chart.
- The primary radar images obtained by Anápolis Control (APP-AN) indicated the presence of thick nebulosity associated with heavy cloud build-ups on the final approach of the VOR procedure. Such meteorological conditions influenced the occurrence, which culminated in the collision of the aircraft with Mount Santo Antônio, independently of the hypotheses raised during the investigation.
- The final approach on the course 320º, instead of 325º, made the aircraft align with the hill with which it collided.
- Mount Santo Antonio, a control obstacle on the final approach in which the collision occurred, was not depicted in the runway 32 VOR procedure approach chart, in discordance with the prescriptions of the CIRTRAF 100-30, a fact that may have contributed to a possible decrease of the situational awareness.

The pilot's loss of control following an encounter with moderate to severe weather.

It is highly probable that the aircraft collided with the mountain slope during its in-cloud post-takeoff climb with low climb rate on its VFR flight to Kitakyushu Airport from Kumamoto Airport, resulting in the aircraft destruction and fatal injuries of two persons on board–the PIC and the passenger. It is somewhat likely that the contributing factor to in-cloud flight toward mountain slope with low climb rate is the PIC’s lack of familiarization with terrain features near Kumamoto Airport; however, the JTSB was unable to clarify the reason.

The pilot’s decision to continue visual flight into instrument meteorological conditions, which resulted in an in-flight collision with mountainous terrain.