Deraya ATP at Wamena on May 31st 2013, runway excursion

Last Update: March 11, 2016 / 12:38:43 GMT/Zulu time

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Incident Facts

Date of incident
May 31, 2013


Deraya Air

Aircraft Registration

ICAO Type Designator

A Deraya Air British Aerospace BAe ATP, registration PK-DGI performing a freight flight from Jayapura to Wamena (Indonesia) with 3 crew, landed on Wamena's runway 15 at 07:09L (22:09Z May 30th) following an unstable approach, went left off the runway, the nose gear collapsed and separated, the aircraft came to a stop about 50 meters off the runway center line with damage to the propellers and nose of the aircraft.

The weather was reported cloudy with visibility at 5km, just at the limit for operation into Wamena.

An observer on the ground saw the aircraft pop out of clouds, the wings were not level at that point. The aircraft touched down a bit hard, veered to the right initially and obviously while correcting the drift the aircraft veered left and went beyond the runway edge, the nose gear collapsed and separated. The side of the runway used to be garden markets and was only recently cleared, however there are still lots of stones and small rocks embedded in the freshly sowed grass.

On Mar 11th 2016 Indonesia's NTSC released their final report concluding the probable causes of the accident were:

The flight did not meet the criteria according to the recommended elements of stabilized approach which required go around.

The aircraft touched down with 2° misalignment with the runway direction then the aircraft veered off to the left.

The recovery action was not in accordance to the correct technique according to the ALAR Tool Kit.

The NTSC reported that the crew contacted Wamena Tower about 8 minutes prior to landing, tower advised to expect runway 15, winds were calm, visibility was 4km, there was low cloud on final and QNH was 1008mb.

The captain (39, ATPL, 3,108 hours total, 1,366 hours on type) was pilot flying, the first officer (49, ATPL, 5,648 hours total, 689 hours on type) was pilot monitoring.

The crew did not perform an approach or landing briefing. The aircraft positioned for final approach and reported on final runway 15, when queried by tower the crew advised they did not yet have the runway in sight about 2 minutes prior to touchdown. About 25 seconds prior to touchdown the crew advised runway in sight and received landing clearance.

During final approach, after receiving landing clearance, the crew received 4 warnings "TOO LOW TERRAIN" and two warnings "SINK RATE".

The aircraft touched down on the runway center line, veered left of the runway about 750 meters past the runway threshold, the pilot flying attempted to recover by applying right rudder and asymmetric reverse thrust, the aircraft however continued to veer left and came to a stop about 10 meters to the left of the left runway edge runway 15. The nose gear was found 250 meters from the aircraft.

The crew shut down both engines and evacuated the aircraft. In addition to the separated nose gear strut all gear struts were found broken and the propellers were bent.

The NTSC reported that the flight data recorder showed the left engine torque was greater than the right hand engine's torque.

The NTSC reported that Wamena Airport is equipped with a NDB, however, no instrument procedure has been published.

The NTSC analysed:

When on final approach position, the pilot reported that the runway was not insight. The CVR data revealed that the pilot reported runway insight 25 seconds after EGPWS call FIVE HUNDRED. The aircraft landed 25 seconds after the pilots have seen the runway.

The Indonesia CASR Part 91.157 stated that a landing shall not be made for as flight under VFR when ground visibility less than 4.8 km or 3 statues miles.

The FDR recorded that the aircraft approach speed was constant at approximately 105 knots or 0.03 miles/ second. The aircraft landed 25 seconds after the pilot report runway insight or approximately at position of 0.8 miles from the runway.

The CVR also revealed that 25 seconds after EGPWS called “FIVE HUNDRED” the pilot reported the runway insight and landed 25 seconds later. The pilot able to see runway at approximately 250 feet AGL with assumption of constant rate of descend.

This can be concluded that the visibility at the time of the accident was less than 3 statues miles or 4.8 km. The approach should not be continued on this visibility condition for a flight under VFR.

The COM determine the stabilize approach criteria which require to all flight operates under VFR flight shall stabilized at 500 feet.

The FDR recorded that when aircraft at 5450 feet (± 400 feet AGL) and 5260 (± 200 feet AGL) until the aircraft touched down showed that the pitch varied from 1° down to 5° up and the aircraft rolled to the left and right up to 20°and the heading changed from 140° up to 164°.This might be a pilot action to align with the runway.

These indicated that on short final the aircraft was on heading 140° and was on the right side of the correct flight path. The pilot then roll to the left up to 20° to align with the runway up to 164°, then rolled to the right to final path runway 15. This correction was conducted at altitude between 400 to 200 feet AGL. This indicated that stabilized approach criteria as required in the COM did not achieved at 500 feet.

After received clearance to land, the EGPWS recorded an aural warning of SINK RATE, this indicated that the rate of descend was greater than 1500. This was contrary to the requirements of the stabilize approach. The COM stated that go around shall be initiated.

The NTSC analysed: "The FDR revealed that the aircraft touchdown with roll angle approximately 2° to the left and heading of 147 while the runway heading was 149°, this was confirmed by the evidence of touch down mark found on the runway. The FDR also recorded that after touchdown the NP drop from 100% to approximately 70% and maintained and the engine torques were asymmetric with the left engine torque greater than the right engine torque. Decreasing of NP value to 70% indicated that the propeller entered the Beta Mode1 and the increased of the torque indicated that the propellers were reversed. The asymmetric value indicated that the reverse on the left side was greater than the right side."

The NTSC analysed: "At 500 feet the runway has not been insight, however there was no communication between pilots to determine the approach would be continued or aborted. The PIC did not communicated the decision and the SIC did not questioning the PIC intention. The CVR recorded 8 EGPWS aural warnings, however these warnings were disregarded. Without having good communication between pilots, a good situational awareness unable to be developed."
Incident Facts

Date of incident
May 31, 2013


Deraya Air

Aircraft Registration

ICAO Type Designator

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