Indonesian Authorities Release Information Recovered From The Airplane's 'Black Box'

Indonesian authorities have released information recovered from the Flight Data Recorder aboard Lion Air Flight 610 which went down in the Java Sea resulting in the fatal injury of all 189 people on board.

ABC News reports that, according to the data recovered from the device, the MCAS aboard the Boeing 737 MAX 8 airplane incorrectly detected an approaching stall and reacted by activating the stick chaker and placing the airplane in a nose-down attitude. The FDR data indicates that the condition occurred more than two dozen times, and the pilots continued to fight with the controls rather than shut off the system.

Former NTSB Director of the Office of Aviation Safety Tom Haueter, an ABC News consultant said shutting off the system is a straightforward solution that is included in commercial pilot training. He said that the crew did not handle the aircraft properly, and should have returned to the airport at the first indication of a problem.

A 78-page preliminary report released by the Indonesian authorities does not incude any analysis or conclusion, but does say the 6,000 hour pilot should not have continued the flight. "The flight from Denpasar to Jakarta experienced stick shaker activation during the takeoff rotation and remained active throughout the flight," the report reads. "This condition is considered as un-airworthy condition and the flight shall not be continued."

The Cockpit Voice Recorder has not yet been recovered.

In a statement, Boeing said it appreciates Indonesia’s National Transportation Safety Committee (NTSC) for its ongoing efforts to investigate the causes of the accident. Boeing says it is taking every measure to fully understand all aspects of this accident, working closely with the NTSB as technical advisors to support the NTSC as the investigation continues.

The report explains that the maintenance logs for the accident aircraft recorded problems related to airspeed and altitude on each of the four flights that occurred over the three days prior to Flight 610. The logs indicate that various maintenance procedures were performed, but issues related to airspeed and altitude continued on each successive flight. The logs indicate that, among other procedures, on Oct. 27, two days prior to the incident flight, one of the airplane’s Angle of Attack (AOA) sensors was replaced.

On Oct. 28, before the flight immediately prior to Flight 610, the pilot in command and the maintenance engineer discussed the maintenance that had been performed on the aircraft. The engineer informed the pilot that the AOA sensor had been replaced and tested. The report does not include records as to the installation or calibration of the new sensor, nor does the report indicate whether the sensor was new or refurbished.  Although the report states that the pilot was satisfied by the information relayed by the engineer that the AOA sensor had been replaced and tested, on the subsequent flight the pilots again experienced problems with erroneous airspeed data, and also experienced automatic nose down trim.

The report states that the flight crew of the Oct. 28 flight turned off the stabilizer trim switches within minutes of experiencing the automatic nose down trim, and continued with manual trim through the end of the flight. The report further notes that the pilot performed three non-normal checklist procedures, including the runaway stabilizer non-normal checklist, which is a memory item prescribed by the 737 MAX Flight Crew Operations Manual, and reaffirmed in Boeing Flight Crew Operations Manual Bulletin TBC-19 and FAA Emergency Airworthiness Directive (AD) Number 2018-23-51, as the appropriate procedure to address unintended horizontal stabilizer movement, regardless of source.

The report indicates that the remainder of the Oct. 28 flight was uneventful and that the flight continued to its destination. The report also states that, after landing, the pilot reported some of the experienced issues both on the aircraft maintenance log and to engineering. The report states that the pilot ran the runaway stabilizer non-normal check list, but it does not state that he communicated that fact in the maintenance documentation following that flight.

The following day, Oct. 29, shortly after taking off, the pilots experienced issues with altitude and airspeed data that the pilots had previously experienced on the earlier flights, due to erroneous AOA data. Data from the flight data recorder summarized in the report also makes clear that, as on the previous flight, the airplane experienced automatic nose down trim. In response, the flight crew repeatedly commanded nose up trim. This sequence repeated for the remainder of the flight, during which the flight crew was able to maintain control of the airplane for approximately ten minutes. Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabilizer procedure or cut out the stabilizer trim switches.

In accordance with international protocol, all inquiries about the ongoing accident investigation must be directed to the NTSC.

(Image from file. Not accident airplane)

FMI: Source report, www.boeing.com