Merpati Nusantara Airlines Flight 8968
|Date||7 May 2011|
|Summary||Failure to use checklists, pilot error, inexperienced pilots|
Off the coast of West Papua, Indonesia on visual approach to Kaimana Airport |
|Aircraft type||Xian MA60|
|Operator||Merpati Nusantara Airlines|
|Flight origin||Sorong Airport, West Papua, Indonesia|
|Destination||Kaimana Airport, West Papua, Indonesia|
Merpati Nusantara Airlines Flight 8968 was a passenger flight which crashed off the coast of West Papua, Indonesia, on 7 May 2011. The aircraft involved, a Chinese-built Xian MA60, was operating Merpati Nusantara Airlines' scheduled domestic service from Domine Eduard Osok Airport to Utarom Airport, both in West Papua. It crashed into the sea in heavy rain, while on approach to Kaimana, about 500 metres (1,600 ft) before the runway.
All 25 people on board the aircraft perished. The crash was the deadliest crash in 2011 in Indonesia and the first crash of a Xi'an MA60 involving fatalities. The wreckage was found to be submerged and broke into few pieces. The accident site was about 800 meters south west of the beginning of runway 01 or 550 meters from the coastline. Most of the wreckages were submerged in the shallow sea between 7 down to 15 meter deep.
The final report, published by Indonesian investigator NTSC, concluded that the crash was caused due to pilot error. The evidence indicates that during the final segment of the flight, both crew member were looking outside the aircraft to sight the runway. During this period the flight path of the aircraft varied between 376 and 585 feet and the bank angle increased from 11 to 38 degree to the left. The rate of descent then increased significantly up to about 3000 feet per minute and finally the aircraft impacted into the sea.
The aircraft involved, an Xian MA-60 registered PK-MZK, had entered service in October 2010, and had flown for a total of 615 hours at the time of the incident. The accident flight was part of series of flights scheduled for crew and aircraft which started from Jayapura to Nabire (Flight 8234), Nabire to Kaimana and Sorong (Flight 8967), Sorong to Kaimana and Nabire (Flight 8968), and finally from Nabire to Biak (Flight 8019).
The time of departure for the accident flight was from Sorong to Kaimana at 12:45 P.M and estimated arrival at 13:54 P.M with the Second in Command (SIC) as Pilot Flying (PF) and the Pilot in Command (PIC) as Pilot Monitoring (PM). The aircraft dispatch release from Sorong indicated that the flight was planned under the Instrument Flight Rules (IFR). The destination, Kaimana, had no published instrument approach procedure. Terminal area operations, including approach and landing, were required to be conducted under the Visual Flight Rules (VFR).
The flight crew was provided by Sorong dispatcher with the actual Kaimana weather information observed at 12:00 p.m indicated that the weather was “precipitation near airport, horizontal visibility of 8 kilometers, cloud broken at 1400 feet, south easterly wind at speed of 6 knots and ground temperature 29°C”. The observed weather report was issued by Meteorological Climatological and Geophysical Agency (BMKG), Kaimana. The satellite weather image over Kaimana Airport at 0450 UTC provided to the investigation by BMKG Jakarta indicated that the weather was moderate rain.
At 12:57 p.m the crew of MZ8968 established contact with Biak FSS (Flight Station Service). Later on after passing waypoint JOLAM the crew of MZ 8968 contacted Kaimana Radio and informed that the estimated time of arrival would be 13:54 p.m. The Kaimana AFIS (Aerodrome Flight Information Service) officer informed the crew that the weather at Kaimana was raining, horizontal visibility of 3 up to 8 kilometers, cloud Cumulonimbus broken at 1500 feet, south-westerly winds at a speed of 3 knots, and a ground temperature of 29 °C. Flight crew reported that MZ 8968 was descending and was instructed to call when at a position 5 minutes from Kaimana. On land, the Kaimana AFIS informed the crew that it was still raining at the airport and the ground visibility was 2 kilometers.
The aircraft was on final approach, after being in a holding pattern for fifteen minutes, to the Kaimana Airport at about 1400 local time (0500 UTC). During the approach to Kaimana, the flight crew flew to the south of the airport in an attempt to make a visual approach. The auto-pilot was disengaged at 960 feet pressure altitude. At 376 feet, the crew decided to discontinue the approach and climbed, turned to the left, increased the engine power, retracted flaps from 15 to 5 and subsequently to 0 position and retracted the landing gear. The aircraft rolled to the left with a bank angle of 11 and continuously increased up to 38 degrees. The rate of descend increased significantly up to about 3000 feet per minute. It crashed into the water about 500 metres (1,600 ft) to the runway. The weather at the time of the accident was rain and fog, with visibility less than 2,000 metres (6,600 ft). An official at the Ministry of Air Transportation said that "there was heavy rainfall, which shortened the [pilot's] range of vision. It was also very dark." After impacting the water, the aircraft broke into at least two main pieces and sank in about 30 metres (98 ft) of water. According to a local navy officer, the aircraft "exploded" on impact, killing all on board.
There were 25 people on board the aircraft, all Indonesian. There were 19 passengers, along with two pilots, two flight attendants, and two engineers. Between fifteen and eighteen bodies were recovered in the immediate aftermath of the crash, with the remainder still trapped in the aircraft. Of the dead, three were young children, including a baby. A search involving ten Navy divers was initiated to recover additional bodies, though weather conditions and equipment difficulties made the effort unsuccessful.
There were multiple analysis whether to determine the cause of the crash;
Weight and balance
Based on the estimated weights, the center of gravity was determined to be within the normal operating range for the entire flight. Cargo overload alongside with improper balance were officially ruled out
The two way communication between Kaimana AFIS and the crew was conducted normally and also did not contribute to the accident. However, limited communications were noted, only few conversation between the Captain and the First Officer. When the Captain gave important commands to the First Officer, he did not use standard phraseology as stated in the Company Operation Manual. The CVR revealed limited conversation between the Captain and the First Officer. This situation is uncommon in a good cockpit environment. It was known that the Captain had served the company for more than 30 years while the First Officer was a newly recruited pilot. As the aircraft approached Kaimana, the Captain gave several instructions to the First Officer related to the direction, speed, altitude and power setting of the aircraft. This type of interaction between the Captain and the First Officer suggested a steep trans-cockpit authority gradient in which the First Officer may not challenge the decisions and actions of the Captain. The Captain may have lack of trust to the First Officer, as indicated by giving the First Officer handling instructions and took over the control during the final phase of the approach. The action of the Captain may have created additional workload to the Captain and reduced his situational awareness.
An approach to Kaimana should be conducted in visual approach and require visibility greater than 5 kilometers. At the time of the accident, the weather at Kaimana was raining and the visibility was 2 kilometers. In such condition a visual approach should not be performed. However, flight crews insisted to land in the airport.
From the CVR it was revealed that during the flight, the crew did not perform crew briefing and checklist reading. In absence of crew briefing, the crew could not synchronize the plan to conduct the approach, and what actions they would take if the situation deviated from the normal. As a result of the crew not completing the approach checklist, an action to change the Engine Regime Selector (ERS) from CRUISE to TOGA mode was not carried out. During the course of investigation, it was found that the ERS button was in the CRUISE mode. As a result, the torque only reached 70% and 82% during the discontinued approach, instead of around 95% if the ERS button was in TOGA mode. The lower power would have significantly affected the performance of the aircraft.
During go around the Captain commanded to retract the flaps to 5. The FCOM stated a go around with two engines operation initiated from flaps 30, in which the flaps should be set to 15, and remain at 15 until above 400 feet and the speed reaches 135 knots. There is a strong indication that the PIC reverted to a procedure for a previous aircraft type he had flown when he asked for “Flap 25”, which does not exist on the MA60 aircraft type. Another action was to set flaps position to 5 during the go around. This procedure was a typical action in the Fokker aircraft type. The Captain had 6,982 hours flying time of the Fokker 100 aircraft type, which does have a Flap 25 setting. In contrast, he had flown the MA60 for only 199 hours. Stress and workload can increase the likelihood of regressing to earlier well-learned habit patterns.
It was revealed that the Flight Officer was trained in the first three batches which was conducted by the aircraft manufacturer instructor and syllabus, while the Captain was trained by a Merpati instructor using modified syllabus. Inadequacy/ineffectivity in the training program may lead to actions that deviated from the standard procedure and regression to the previous type.
On May 2012, the National Transportation Safety Committee (NTSC) released its final report on the investigation. It determined that a visual approach should not have been attempted due to low visibility. There was no checklist reading or crew briefing. The flight crew lacked situation awareness while trying to locate the runway and while performing the go-around. The aircraft entered a rapid descent during the go-around due to a 38-degree left roll and crew commanded flap retraction from 15 to 0 degrees. Both crew members had low experience and flying time on type. The inadequacy and ineffectiveness of the training program may lead to actions that deviate from standard operating procedure and that regress to a previous aircraft type.
The aircraft's flight recorder was recovered on 9 May after a search that was hampered by a strong underwater current that necessitated the fuselage to be anchored to the seabed. After examination, it was discovered that the contents of the recorder were encrypted in Chinese; as a result, the recorder was sent to China to be decrypted.
On 10 May, Merpati Nusantara's president, Sardjono Jhony Tjitrokusumo offered to resign if the crash was the fault of the airline, saying that "I am ready to tender my resignation if the error was from Merpati's side."
On 13 May, the Indonesian government ordered Merpati Nusantara to perform safety inspections on its other twelve MA60 aircraft. In announcing the order, President Susilo Bambang Yudhoyono said that "[t]here should be a prevention effort and inspection of the same type of Merpati aircraft [...] This [is] important to the public so they can get clear explanation."
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