Aviastar DHC6 near Makassar on Oct 2nd 2015, aircraft collided with terrain

Last Update: January 4, 2017 / 16:36:41 GMT/Zulu time

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Incident Facts

Date of incident
Oct 2, 2015


Aircraft Registration

ICAO Type Designator

On Jan 4th 2017 the NTSC released their final report concluding the probable cause of the crash was:

Deviation from the company visual route without properly considering the elevated risks of cruising altitude lower than the highest terrain and instrument meteorological condition in addition with the absence of the EGPWS warning resulted in the omission of avoidance actions.

The NTSC reported the captain (40, ATPL, 2,911 hours total, 2,911 hours on type) was pilot flying, the first officer (39, ATPL, 4,035 hours total, 4,035 hours on type) was pilot monitoring.

Following departure the aircraft climbed to 8000 feet MSL. After levelling off at 8000 feet the crew discussed flying direct to BARRU about 35nm north of Makassar, both pilots agreed to fly direct.

About 14 minutes later the captain intended to climb the aircraft, however, the cockpit voice recorder recorded the sounds of impact one second later.

The NTSC reported that the CVR did not record any sounds consistent with an EGWS warning. The cause of the lack of EGPWS warning could not be determined. The NTSC reported further, that no test result document concerning the Terrain Awareness System KGP-560 could be found.

The NTSC wrote: "The operator procedures stated the pilot shall report any detected malfunction in the Aircraft Flight and Maintenance Log (AFML) when a malfunction was detected during operational5 test or while being operated. However, the operational test of the TAWS system was not included in the pilot checklist. According to operator, there was no system failure reported during the operation. The investigation could not determine the proper TAWS installation and configuration including the updating terrain database and proper functional system test since there was no functional test results available."

The NTSC analysed:

At 0637 UTC, the pilots agreed to fly direct to point BARRU. The aircraft impacted terrain and the CVR stopped recording at 0651 UTC. The CVR did not record any EGPWS aural warning.

One second prior to impact, the CVR recorded the pilot state his intention to climb. The pilot statement might indicate that the pilot was uncertain of the terrain condition in the vicinity of the flight track. The uncertainty might be triggered by information provided on the visual chart or the displayed terrain on the Garmin GMX 200. Forward visibility may also have been affected by reported cloud in the vicinity.

Any action to avoid collision that would happen in one second would be aggressive and immediate action such as an immediate climb, turn or increase in power.

The absence of avoiding action indicates that the terrain was not visible to the pilot and there was no EGPWS terrain aural warning as recorded on the CVR. These conditions mean that the pilot was not fully aware of the terrain.

The meteorology information provided by BMKG showed that the area of the accident was covered by clouds. This was also supported by the local villager statement that the area was covered by clouds at the time of the accident.

The NTSC continued analysis:

At 06:37:17 UTC the aircraft was on cruising at 8000 feet, the PF suggested flying direct to point BARRU and was agreed by the PM which then explained of his experience where he flew safely on a similar direct track on a previous flight.

The operator’s visual route guidance, satellite weather image and the predicted route along the suggested route by the PM showed a mountainous area with approximate terrain heights of between 9,600 and 11,000 feet and partially covered by cloud formation approximately 25 to 30 Nm ahead from the point when the pilot decided to fly direct to Barru. In respect to the aforesaid conditions, the investigation considered the Situational Awareness and the process of the decision making to fly direct to Barru.

Situational Awareness is “the perception of the elements in the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future”. Situational Awareness is defined in terms of the goals and decision tasks for the job. The pilot needs to know a great deal of information related to the goal of safely flying the aircraft.

The good decision and performance has correlation with working and long term memory. The research to the pilots showed that the working memory related to the relevant Situational Awareness information will be stored for five to six minutes in working memory.

The pilot’s conversation recorded between 0637 UTC when they decided to fly to Barru until 0651 UTC did not indicate any discussion concerning to the environmental condition head. Especially on the VFR limitation and the mountain heights which were indicated as being higher than the aircraft cruising altitude. The absence of discussion in regard to the conditions ahead, meant that the pilots had not properly considered the operational implications of flying the direct route, leading to a loss of situational awareness.
Incident Facts

Date of incident
Oct 2, 2015


Aircraft Registration

ICAO Type Designator

This article is published under license from Avherald.com. © of text by Avherald.com.
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