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Status: Accident investigation report completed and information captured
Date:Saturday 9 January 2021
Time:14:40
Type:Silhouette image of generic B735 model; specific model in this crash may look slightly different
Boeing 737-524 (WL)
Operator:Sriwijaya Air
Registration: PK-CLC
MSN: 27323/2616
First flight: 1994-05-13 (26 years 8 months)
Total airframe hrs:62983
Cycles:40383
Engines: 2 CFMI CFM56-3B1
Crew:Fatalities: 6 / Occupants: 6
Passengers:Fatalities: 56 / Occupants: 56
Total:Fatalities: 62 / Occupants: 62
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:19 km (11.9 mls) NE of Jakarta-Soekarno-Hatta International Airport (CGK) (   Indonesia)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Jakarta-Soekarno-Hatta International Airport (CGK/WIII), Indonesia
Destination airport:Pontianak Airport (PNK/WIOO), Indonesia
Flightnumber:SJ182
Narrative:
Sriwijaya Air flight 182 crashed into the sea, shortly after departure from Jakarta-Soekarno-Hatta International Airport, Indonesia. All 56 passengers and 6 crew members died in the accident.
The aircraft, a Boeing 737-500 registered PK-CLC, arrived at Jakarta-Soekarno-Hatta International Airport at 12:11 hours local time after a flight from Pangkal Pinang. The subsequent flight for the aircraft, SJ182, was due to depart at 13:40.
Weather at the airport was poor with heavy rainfall and low clouds due to a thunderstorm in de vicinity. This caused a delay in departure. At 14:18 the aircraft was cleared to taxi to runway 25R. Take-off from runway 32R was commenced at 14:35 (07:35 UTC).
At 14:36:46, the pilot contacted the Terminal East (TE) controller and was cleared for an unrestricted climb to FL290. Five seconds later, at altitude of 1,980 feet, the Autopilot (AP) system engaged.
At 14:38:42, as the aircraft climbed past 8150 feet, the thrust lever of the left engine started reducing, while the thrust lever of the right engine remained in position. FDR data showed that the left engine N1 was decreasing whereas the right engine N1 remained the same.
Nine seconds later flight requested a heading change to 075° to avoid weather conditions, which was approved by the TE controller.
At 14:40:05, the aircraft reached the highest altitude of about 10,900 feet. The autopilot system disengaged at that point with a heading of 016°, the pitch angle was about 4.5° nose up, and the aircraft rolled to the left to more than 45°. The thrust lever position of the left engine continued decreasing while the right engine thrust lever remained in position.
Five seconds later the the autothrottle (A/T) system disengaged and the pitch angle was more than 10° nose down. The aircraft had entered a high speed descent and impacted the surface of the sea about 20 seconds later.
The wreckage was located and appeared to be distributed across an area of about 80 by 110 meters on the seabed at a depth of approximately 16 meters.

The Indonesian NTSC reported on February 10 that the aircraft had a repeating issue the autothrottle in the days before the accident.
On 3 January 2021, a pilot reported that the autothrottle was unserviceable. An engineer rectified the problem by cleaning the autothrottle computer’s electrical connector. After re-installation, the Built-in Test Equipment (BITE) test result was good.
On 4 January 2021, a pilot again reported that the autothrottle was unserviceable. An engineer tried cleaning the autothrottle computer’s electrical connector but the problem remained and it was transferred to the Deferred Maintenance Items.
On 5 January 2021, an engineer rectified the problem by cleaning the autothrottle Takeoff and Go Around (TOGA) switch and conducted a BITE test on the autothrottle computer. The BITE test result was good.

Probable Cause:

Contributing Factors:
- The corrective maintenance processes of the A/T problem were unable to identify the friction or binding within the mechanical system of the thrust lever and resulted in the prolonged and unresolved of the A/T problem.
- The right thrust lever did not reduce when required by the A/P to obtain selected rate of climb and aircraft speed due to the friction or binding within the mechanical system, as a result, the left thrust lever compensated by moving further backward which resulted in thrust asymmetry.
- The delayed CTSM activation to disengage the A/T system during the thrust asymmetry event due to the undervalued spoiler angle position input resulted in greater power asymmetry.
- The automation complacency and confirmation bias might have led to a decrease in active monitoring which resulted in the thrust lever asymmetry and deviation of the flight path were not being monitored.
- The aircraft rolled to the left instead of to the right as intended while the control wheel deflected to the right and inadequate monitoring of the EADI might have created assumption that the aircraft was rolling excessively to the right which resulted in an action that was contrary in restoring the aircraft to safe flight parameters.
- The absence of the guidance of the national standard for the UPRT, may have contributed to the training program not being adequately implemented to ensure that pilots have enough knowledge to prevent and recover of an upset condition effectively and timely.

Accident investigation:
cover
Investigating agency: NTSC Indonesia
Status: Investigation completed
Duration: 1 year and 10 months
Accident number: KNKT.21.01.01.04
Download report: Final report
Language: English

Classification:
Loss of control

Sources:
» Antara
» Flightradar24 track

METAR Weather report:
07:00 UTC / 14:00 local time:
WIII 090700Z 30007KT 4000 VCTS RA FEW016CB OVC018 25/24 Q1007 NOSIG

07:30 UTC / 14:30 local time:
WIII 090730Z 30006KT 5000 -RA FEW017CB OVC018 25/24 Q1006 NOSIG

08:00 UTC / 15:00 local time:
WIII 090800Z 28008KT 4000 -RA BKN016 OVC018 26/24 Q1006 NOSIG


Follow-up / safety actions

NTSC issued 2 Safety Recommendations

Show all...

Photos

photo of Boeing-737-524-PK-CLC
accident date: 09-01-2021
type: Boeing 737-524 (WL)
registration: PK-CLC
photo of Boeing-737-524-PK-CLC
accident date: 09-01-2021
type: Boeing 737-524 (WL)
registration: PK-CLC
photo of Boeing-737-524-PK-CLC
accident date: 09-01-2021
type: Boeing 737-524 (WL)
registration: PK-CLC
photo of Boeing-737-524-PK-CLC
accident date: 09-01-2021
type: Boeing 737-524 (WL)
registration: PK-CLC
 

Aircraft history
date registration operator remarks
13 May 1994 N27610 Boeing first flight
31 May 1994 N27610 Continental Airlines delivered
29 October 1994 N27610 Continental Airlines bird strike incident (1 bird ingested in engine)
4 November 2004 N27610 Continental Airlines bird strike incident (1 bird hit fuselage on approach to Austin, TX (KAUS))
12 July 2005 N27610 Continental Airlines bird strike incident (1 gull hit left side of radome fuselage on approach to Raleigh, NC (KRDU))
1 October 2010 N27610 United Airlines merger
19 March 2012 N27610 United Airlines TT: 45359 hours; 24306 cycles
15 May 2012 PK-CLC Sriwijaya Air registered
23 March 2020 PK-CLC Sriwijaya Air parked/stored at Surabaya
19 December 2020 PK-CLC Sriwijaya Air resumed service

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Jakarta-Soekarno-Hatta International Airport to Pontianak Airport as the crow flies is 728 km (455 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Boeing 737-500

  • 390 built
  • 11th loss
  • 5th fatal accident
  • 3rd worst accident
» safety profile

 Indonesia
  • 13th worst accident
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