Indonesia Air Transport ATR 42-512 plane crash
Makassar, Indonesia
Updated on
The ATR 42 belonging to IDA Indonesia Air Transport and operated for the Marine and Fisheries Resources Surveillance took off from Yogyakarta, Indonesia, for a flight to Makassar, Indonesia. Four crewmembers and six passengers were onboard. The plane crashed while on approach to Makassar's airport. The wreckage was later found in a mountainous area on Mount Bulu Saraung at about 4,300 feet. All 10 occupants were killed.
The preliminary report issued by Indonesia’s KNKT identified the aircraft as ATR 42-500 PK-THT, operated by Indonesia Air Transport on an aerial surveillance mission for the Ministry of Marine Affairs and Fisheries. The aircraft was within its permitted weight and balance limits. The captain had nearly 15,000 hours of flight experience, including more than 3,300 hours on the ATR 42/72. The co-pilot had just over 500 hours in total, including about 350 hours on type.
Flight recorder data showed that the aircraft’s GNSS navigation system was operating in degraded mode for much of the flight. The position calculated onboard progressively diverged from the position received on the ground through ADS-B. At some stages of the approach, the difference between the two positions reached several nautical miles, creating a substantial discrepancy between the position understood by the crew and the position seen by air traffic control.
During the approach to Makassar, controllers observed that the aircraft was not correctly tracking the assigned navigation waypoints. Several headings were issued in an attempt to reposition it for the Runway 21 ILS approach. The crew also requested several heading changes to avoid adverse weather.
At about 04:20 UTC, the aircraft, at approximately 5,000 feet, entered an area where the published ATC surveillance minimum safe altitude was 8,000 feet. The air traffic control Minimum Safe Altitude Warning system did not activate. A few minutes later, while the aircraft was still descending in mountainous terrain, its EGPWS generated a “TERRAIN - TERRAIN” alert followed by four “PULL UP” warnings. Contact with the aircraft was lost shortly afterwards.
Weather around Makassar included showers and cumulonimbus clouds in the approach area. However, the KNKT has not yet established what role, if any, those conditions played in the accident.