[Azimuth]

Lion Air flight data: Pilots struggled against anti-stall system

Nov. 27 (UPI) -- Information from the flight data recorder in the deadly crash of Lion Air Flight 610, released Tuesday, showed an anti-stall system was pushing the Boeing 737's nose down.

Data from the so-called black box recorder showed the new Boeing maneuvering characteristics augmentation system, or MCAS, repeatedly pushed the nose of the plane down, forcing the pilots to pull the nose back up more than a dozen times throughout the 11-minute flight.

The pilots' efforts were ultimately unsuccessful and the plane was left careening into the Java Sea at 450 mph, as all 189 people on board were killed.

Investigators believe the MCAS began malfunctioning because a sensor on the outside of the 737 was receiving incorrect readings. They also found it had reported incorrect readings on its three previous flights and the problem persisted even after the sensor was replaced.

Earlier this month, airline safety experts and pilots' groups said Boeing failed to disclose information about about MCAS.

Jon Weaks, president of the Southwest Airlines Pilots Association, said pilots and companies should have been informed of the automated stall-prevention system after pilot unions and other experts said they had no idea it was added to the new 737 model and were unaware of the potentially fatal consequences.

Boeing said the proper details for how to pull out of an incorrect activation of the system were already included in flight manuals and there was no need to the specific system in the new 737 jet.

The company reiterated that stance in a statement Tuesday, saying "the appropriate flight crew response to uncommanded trim, regardless of cause, is contained in existing procedures."

The flight's voice recorder has yet to be recovered and could eventually provide more insight into what happened in the cockpit during the crash.

source

[Hunted]

On Nov 28th 2018 Indonesia's KNKT (also known as NTSC) released their preliminary report (alternatively via AVH due to congestion at KNKT website) releasing following findings so far:

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.

The KNKT already released two safety recommendations to LionAir basically stating, the aircraft was not airworthy on the flight from Denpasar to Jakarta, the flight should not have continued to Jakarta:

04.O-2018-35.1

Refer to the CASR Part 91.7 Civil Aircraft Airworthiness and the Operation Manual part A subchapter 1.4.2, the pilot in command shall discontinue the flight when un-airworthy mechanical, electrical, or structural conditions occur.

The flight from Denpasar to Jakarta experienced stick shaker activation during the takeoff rotation and remained active throughout the flight. This condition is considered as un-airworthy condition and the flight shall not be continued.

KNKT recommend ensuring the implementation of the Operation Manual part A subchapter 1.4.2 in order to improve the safety culture and to enable the pilot to make proper decision to continue the flight.

04.O-2018-35.2

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. This indicated that the weight and balance sheet did not contain actual information.

KNKT recommend ensuring all the operation documents are properly filled and documented.

The KNKT summarized the events on the last completed flight from Denpasar to Jakarta, which according to the safety recommendations was already flown with the aircraft in an "un-airworthy condition":

On 28 October 2018, a Boeing 737-8 (MAX) aircraft registered PK-LQP was being operated by PT. Lion Mentari Airlines (Lion Air) as a scheduled passenger flight from I Gusti Ngurah Rai International Airport (WADD), Denpasar to Jakarta as LNI043. During pre-flight check, the PIC discussed with the engineer of the maintenance actions that had been performed including replacement of the AoA sensor and had been tested accordingly.

The aircraft departed at 1420 UTC (2220 LT) at night time, the DFDR showed the stick shaker activated during the rotation and remained active throughout the flight. About 400 feet, the PIC noticed on the PFD the IAS DISAGREE warning appeared. The PIC handed over control to the SIC and cross checked the PFDs with the standby instrument and determined that the left PFD had the problem. The PIC noticed the aircraft was automatically trimming AND. The PIC moved the STAB TRIM switches to CUT OUT and the SIC continued the flight with manual trim without auto-pilot until the end of the flight.

The PIC declared “PAN PAN” to the Denpasar Approach controller due to instrument failure and requested to maintain runway heading. The PIC performed three Non-Normal Checklists and none contained the instruction “Plan to land at the nearest suitable airport”.

The remainder of the flight was uneventful and the aircraft landed Jakarta about 1556 UTC. After parking, the PIC informed the engineer about the aircraft problem and entered IAS and ALT Disagree and FEEL DIFF PRESS problem on the AFML.

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.

The KNKT then summarized the accident flight:

At 2320 UTC, (0620 on 29 October 2018 LT), the aircraft departed from Jakarta with intended destination of Pangkal Pinang. The DFDR recorded a difference between left and right 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.

During the flight the SIC asked the controller to confirm the altitude of the aircraft and later also asked the speed as shown on the controller radar display. The SIC reported experienced „flight control problem‟.

After the flaps retracted, the DFDR recorded automatic AND trim active followed by flight crew commanded ANU trim. The automatic AND trim stopped when the flaps extended. When the flaps retracted to 0, the automatic AND trim and flight crew commanded ANU trim began again and continued for the remainder of the flight. At 23:31:54 UTC, the DFDR stopped recording.

Until the publishing of this Preliminary Report, the CVR has not been recovered, the search for CVR is continuing. The investigation will perform several tests including the test of the AoA sensor and the aircraft simulator exercises in the Boeing engineering simulator. The investigation has received the QAR data for flight for analysis.

The KNKT reported that a tug boat found first floating debris at position N5.8156 E107.1231 about 35 minutes after the flight data recorder stopped recording.

The aircraft was flown by a captain (31, ATPL, 6,028 hours total, 5,176 hours on type) and a first officer (41, CPL, 5,174 hours total, 4,286 hours on type).

The occurrence aircraft had flown 895 hours and 433 cycles since new.

On Oct 26th 2018 following a flight from Tianjin Binhai to Manado the crew noted following faults: "Speed and Altitude Flag show on Captain Primary Flight Display (no speed and altitude indication)" and "Maintenance light illuminate after landing", maintenance performed following actions for the first tech log entry: "Performed check Onboard Maintenance Function (OMF), found maintenance message 27-31000. Refer to Interactive Fault Isolation Manual (IFIM) 27-31000, performed Stall Management and Yaw Damper (SMYD) number 1 system test carried out, result normal." and for the second note: "Performed check OMF, found message 27-31-000. Performed erase maintenance message check out maintenance light goes off."

On Oct 27th 2018 following a flight from Manado to Denpasar the flight crew noted following faults in the tech log:

- Speed and Altitude Flag show on Captain Primary Flight Display (no speed and altitude indication)
- SPEED TRIM FAIL light illuminate and MACH TRIM FAIL light illuminate
- Auto-throttle Arm disconnect, during aircraft takeoff roll

Maintenance actioned for all log entries: "Refer to IFIM task 27-32-00-810-816 rev October 2018. Perform check OMF status found message “STALL WARNING SYS L”. initial evaluation performed SMYD number 1 self-test result failed message 27-31-12 (AD data invalid) and 27-31015 (ADIRU data invalid). Check OMF existing fault (34) found message 34-21107 (AIR DATA SIGNAL INVALID) and 34-21123 (AOA SIGNAL OUT OF RANGE). BITE ADIRS L via CDU found message 34-21023 (AOA SIGNAL FAIL). Reset CB ADIRU L AC and DC and ADIRU L carried out. System test pass. DFCS BITE result PASS. Erase status message carried out and check message not active." In addition maintenance decided: "For troubleshooting due to repetitive problem perform replaced angle of attack sensor in accordance with Aircraft Maintenance Manual (AMM) Task 34-21-05-000-001 and task 34-21-05-400-801 carried out. Installation test and heater system test result good." (Editorial note: the text does not identify directly, whether left or right hand AoA was replaced, the AMM tasks probably identify which AoA sensor was replaced, AME's are kindly requested to contact us via the contact form if such identification of which AoA sensor was replaced is possible from the maintenance tasks).

On Oct 28th 2018 following the flight Denpasar to Jakarta the crew noted in the tech log of the aircraft:

- IAS and ALT Disagree shown after take off
- feel diff press light illuminate

Maintenance wrote down as maintenance activity for the first entry: "(Refer to IFIM task 34-20-00-810-801 REV 15 June 2018). Performed flushing Left Pitot Air Data Module (ADM) and static ADM. Operation test on ground found satisfied." and for the second entry: "Refer IFIM 27-31-00-810-803 Rev 15 June 2018, performed cleaned electrical connector plug of elevator feel computer carried out. test on ground found OK."

The preliminary report confirms (and contains also) the FDR graphs already shown to Indonesia's parliament and previously published by the AVH.

The KNKT reports that they have obtained the AoA Sensor that was replaced in Denpasar, the sensor will "undergo further testing and analysis under the supervision of the KNKT."

As result of the investigation so far Boeing issued their Operator's Manual Bulletin and the FAA subsequently their Emergency Airworthiness Directive (already reported previously).

On Nov 10th 2018 Boeing sent out multi-operator messages informing operators about the MCAS (Maneouvering Characteristics Augementation System) stating:

A pitch augmentation system function called 'Maneuvering Characteristics Augmentation System’ (MCAS) is implemented on the 737-8, -9 (MAX) to enhance pitch characteristics with flaps UP and at elevated angles of attack. The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and dunng flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column tnm switch or stabilizer aisle stand cutout switches to override MCAS input. The function is commanded by the Flight Control computer using Input data from sensors and other airplane systems.

The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer Incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer Input is lower at high Mach number and greater at low Mach numbers. The function Is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.

[Bletch]

Engine and landing gear debris

[PirateHitler]

The black box recorder has been recovered (Jan 2019)

Time will let what it reveals

[RiversEdge]

awful. looks pretty unsurvivable.

[dropkic]

Boeing's lame-ass excuse in saying that the procedure for getting out of a false stall recovery was covered in the manual. What load of shit! Let me get this straight, you're going to build a plane with a faulty/bad sensor and then provide instructions on how to get around it. How about fixing the faulty sensor! Unbelievable!

[Hunted]

On Jan 14th 2019 the KNKT reported that the cockpit voice recorder was recovered at about 09:00L (02:00Z).

Marine divers reported a number of bodies were recovered at the same time. The CVR was found in 8 meters deep mud at the bottom of 30 meters deep water, about 50 meters from the position where the FDR had been recovered from. 73 days (Jan 10th) after the crash the pinger's signal was still active though weaker. So far it is unclear whether the CVR is damaged, the box has scratches on it.

On Jan 19th 2019 the KNKT reported the CVR data have been successfully downloaded, 124 minutes of audio of good quality have been retrieved. The data are now being transcribed.

[Bletch]

Any news about the content on the CVR?

[LOI91]

As someone who's been in and out of Indonesia since his mid-twenties, you CANNOT get me to fly any of their full service or low cost carriers in or out of their country.

Their service record, as a country and regardless of the operator, is atrocious. They, as a whole, average an accident (fatality or not) almost every year of which 57% are due to human error.

[Hunted]

Originally Posted by Bletch ↗

Any news about the content on the CVR?

Been looking but haven't seen anything yet