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29 Oct 2018 - PK-LQP 737 MAX-8 Loss of Control after take-off

On 29 October 2018, a Lion Air 737 MAX-8, PK-LQP (43000/7058) FF 30/7/18, departed Jakarta (WIII), Indonesia, runway 25L, at 23:21 UTC (06:21 local time).

After two minutes the plot from flight radar (see below) shows a drop in altitude from 2150ft to 1600ft and increase in speed to 334kts G/S. 3 minutes after takeoff, the crew requested to return to Jakarta; ATC granted the request.

The aircraft turned to the North East heading out over the Java Sea and climbed to 5,400ft but not holding a steady altitude. It then descended over the sea and was lost from radar 12 minutes after departure.

The two month old aircraft broke up and sank on impact. The wreckage is under 30m of water. Flight JT610 was enroute from Jakarta to Pangkal Pinang with 181 passengers and 8 crew members on board. There were no survivors.

The weather conditions were good and it was daylight.

WIII 282330Z 16003KT 8000 SCT020 27/25 Q1010 NOSIG=

The KNKT reported on 9 Nov that the angle of attack sensor had been replaced the previous day (28 Oct) following pilot reports of unreliable airspeed. The pilots of the previous flight experienced a 20 dgeree difference in the LH AOA sensor.

The CVR was recovered on 14 Jan under 8m of mud and 30m of water thanks to the pinger still being active after 73 days.

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The KNKT released their Preliminary Report on 28 Nov 2018


According to factual information during the investigation, the KNKT identified findings as follows:

  • On 28 October 2018, a Boeing 737-8 (MAX) aircraft registered PK-LQP was operated as a scheduled passenger flight from Denpasar to Jakarta. Prior to the flight, the Angle of Attack (AoA) sensor had been replaced and tested.
  • The DFDR showed the stick shaker activated during the rotation and remained active throughout the flight. About 400 feet, the PIC noticed on the Primary Flight Display (PFD) that the IAS DISAGREE warning appeared.
  • The PIC cross checked both PFDs with the standby instrument and determined that the left PFD had the problem. The flight was handled by the SIC.
  • The PIC noticed that as soon the SIC stopped trim input, the aircraft was automatically trimming aircraft nose down (AND). After three automatic AND trim occurrences, the SIC commented that the control column was too heavy to hold back. The PIC moved the STAB TRIM switches to CUT OUT.
  • The pilot performed three Non-Normal Checklists (NNCs) consisting of Airspeed Unreliable, ALT DISAGREE, and Runaway Stabilizer. None of the NNCs performed contained the instruction “Plan to land at the nearest suitable airport”.
  • After parking in Jakarta, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML).
  • The PIC also reported the flight condition through the electronic reporting system of the company A-SHOR.
  • The engineer performed flushing the left Pitot Air Data Module (ADM) and static ADM to rectify the IAS and ALT disagree followed by operation test on ground and found satisfied. The Feel Differential Pressure was rectified by performed cleaned electrical connector plug of elevator feel computer. The test on ground found the problem had been solved.
  • At 2320 UTC, (29 October 2018, 0620 LT) the aircraft departed from Jakarta using runway 25L and intended destination Pangkal Pinang. The DFDR recorded a difference between left and right Angle of Attack (AoA) of about 20° and continued until the end of recording. During rotation the left control column stick shaker activated and continued for most of the flight.
  • According to the weight and balance sheet, on board the aircraft were two pilots, five flight attendants and 181 passengers consisted of 178 adult, one child and two infants. The voyage report showed that the number of flight attendant on board was six flight attendants.
  • During the flight the LNI610 SIC asked the TE controller to confirm the altitude of the aircraft and later also asked the speed as shown on the TE controller radar display. The LNI610 SIC reported experienced „flight control problem‟.
  • After the flaps retracted, the FDR recorded automatic aircraft nose down (AND) trim active for 10 seconds followed by flight crew commanded aircraft nose up (ANU) trim. The flaps extended to 5 and the automatic AND trim stopped.
  • At 23:25:18 UTC, the flaps retracted to 0 and several seconds later, the automatic AND trim and flight crew commanded ANU trim recorded began again and continued for the remainder of the flight.
  • The LNI610 PIC advised the controller that the altitude of the aircraft could not be determined due to all aircraft instruments indicating different altitudes and requested to the controller to block altitude 3,000 feet above and below for traffic avoidance.
  • The flight crew and the flight attendants held valid licenses and medical certificates and certified to operate B737.
  • The Aircraft Flight Maintenance Log (AFML) recorded that since 26 October 2018 until the occurrence date, several problems occurred related to airspeed and altitude flag appeared on Captain (left) Primary Flight Display (PFD) three times, SPEED TRIM FAIL light illumination and MACH TRIM FAIL light illumination two times and IAS (Indicated Airspeed) and ALT (Altitude) Disagree shown on the flight Denpasar to Jakarta the day before the accident flight.

According to Bloomberg, an off-duty pilot in the flightdeck helped the crew disable the Stab Trim as the MCAS kicked in.

PK-LQP Radar plot


This is an alleged copy of the maintenance report that is circulating the internet. It is unconfirmed.

"Airspeed unreliable and alt disagree shown after take off. STS was also running to the wrong direction, suspected because of speed difference. Identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree. Decide to continue flying to CGK at FL280, landed safely rwy 25L"

On 7 Nov 2018 the FAA issue an Emergency AD (2018-23-51) and Boeing issue an Ops Manual Bulletin (TBC-19) for MAX Runaway Stabilizer procedure directing operators to “existing flight crew procedures" to address circumstances involving erroneous angle-of-attack sensor information.

FAA Emergency AD 2018-23-51 - This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.

This AD requires revising certificate limitations and operating procedures of the airplane flight manual (AFM) to provide the flight crew with runaway horizontal stabilizer trim procedures to follow under certain conditions.

Ops Manual Bulletin TBC-19

This is a copy of the bulletin, it has a different reference (MLI-15) because it is with a different airline; TBC = The Boeing Company

On 22 Nov 2018 the KNKT released a presentation in Indonesian which included various FDR printouts. It showed that the Captains AoA indicated 20 degrees more than the F/Os AoA triggering the left stick shaker. There then followed various automatic nose down inputs which are presumed to be from MCAS. These inputs were counteracted by the crew with nose up trim until they ran out of trim authority.

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