An investigation by the Aviation Safety Council (ASC) has shown that a failure by pilots to follow a designated flight route may have caused the crash of an aircraft owned by ROC Aviation Corp last year.
The accident occurred on Aug. 30 last year when a BN-2B-26 light utility aircraft was conducting an aerial photography assignment in Hualien and Taitung counties over areas devastated by Typhoon Morakot in 2009.
The crash killed two pilots and one photographer on board.
The council found that the flight crew choose to follow visual flight rules (VFR), rather than instrument flight rules (IFR) about 18 minutes after taking off from the Taipei International Airport (Songshan airport).
They then flew to Hualien to start the assignment.
The investigation showed that air traffic control personnel in Taipei informed the pilots several times that their radar was not picking up the aircraft.
Meanwhile, the communication between the aircraft and air traffic control officers in Taipei was disrupted or unclear about seven times, the report showed.
Although air traffic control personnel in Greater Kaohsiung managed to resume contact with the aircraft, the council said that communications only lasted for 41 seconds before air traffic control officers lost track of the aircraft.
Because the aircraft was not equipped with a flight recorder the council could only determine the cause of the crash using dashboard records and photos taken from the air.
Based on those records, the council said the pilots had turned right after finishing the assignment in Hualien and tried to leave a valley by pulling up the aircraft.
However, the aircraft might have experienced a sudden reduction in lift when it tried to fly over some mountains, which resulted in the crash.
“The pilots might have felt that they were really behind in the project of photographing disaster-stricken zones, so they decided to enter a zone that was not in the flight plan,” the council said.
The council added that the maps provided by the client did not allow the pilots to accurately determine distances, adding that the names and heights of the mountains were not thoroughly noted on the map either.
ROC Aviation Corp did not consolidate the maps given to it, causing them to miss the opportunity to discover the risks involved in the assignment.
According to the council, the aircraft was flying in an area surrounded by 2,500m high mountains, which made it difficult for the aircraft to climb up or turn around.
The council also found that the airline did not follow the manuals in stipulating flight plans and personnel training, nor did it keep a complete record of training.
In view of the accident, the council had requested the Civil Aeronautics Administration to oversee the operation of the airline, particularly the measures it took to improve flight safety.