On October 29, 2018, Lion Air Flight 610 crashed shortly after take-off killing all 189 passengers and crew. Flight 610 was a scheduled domestic flight from Soekarno-Hatta International Airport in Jakarta to Depati Amir Airport in Pangkal Pinang that should have taken a little over an hour. The aircraft, a relatively new Boeing 737 Max 8 aircraft, Registration Number PK-LQP, crashed approximately 11 minutes after take-off due to a steep uncontrolled descent into the Java Sea off the coast of Java.
Shortly after take-off the flight crew contacted air traffic control and requested to return to the airport although they did not declare an emergency. The aircraft, however, never turned back toward Jakarta, but instead banked to the left and made significant altitude deviations. The aircraft then entered a steep dive crashing into the Java Sea.
The search and recovery efforts have located the Digital Flight Data Recorder (“DFDR”) although the Cockpit Voice Recorder (“CVR”) has yet to be recovered. The DFDR and radar data demonstrated that the flight had undergone extremely significant altitude deviations during its tragic 11-minute flight.
Early reports from the Indonesia’s National Transportation Safety Committee indicate that in the days leading up to the crash, the aircraft recorded numerous inaccurate airspeed readings. Indeed, on the flight that immediately preceded the accident flight the flight crew contacted air traffic control shortly after take-off and issued a “Pan Pan” declaration which means an urgent message to air traffic control. However, it appears the flight crew was experiencing inadequate airspeed readings; however, the crew ultimately chose to continue with the flight after the inaccurate air speed readings had apparently been resolved.
Airspeed is measured from pitot tubes that are located on the nose of the aircraft. These components are critical to the safe operation of the aircraft as faulty readings can result in disaster. Due to the flight crew’s difficulties on the prior flight, Lion Air conducted maintenance on the pitot tubes immediately prior to the departure of Flight 610.
The investigation is focusing on the fact that the aircraft’s computers may have received incorrect data from the aircraft’s angle of attack sensors. These sensors measure the angle of the aircraft in relation to the air that comes across it. This data is critical in preventing the aircraft from entering an aerodynamic stall. It is presently unknown whether there was an issue with the sensors or the computer software that processes the data received from the sensors. If the sensors and computers detect that the aircraft is entering an aerodynamic stall, the aircraft will automatically lower its nose to prevent the stall from occurring. The investigation is looking into whether inaccurate angle of attack readings caused the aircraft to enter a steep descent that the flight crew could not prevent. The angle of attack sensors were changed the day before the crash as a result of repeated airspeed indicator problems in the aircraft’s four flights prior to the crash of Flight 610.
Boeing, who is also participating in the accident investigation, has stated in the days since the crash that the aircraft experienced inaccurate angle of attack readings. Boeing advised that such inaccurate readings could cause the aircraft to enter a rapid descent. On November 7, 2018, the Federal Aviation Administration issued an Emergency Airworthiness Directive advising that based upon Boeing’s post-crash analysis, if an erroneously high angle of attack input is received by the aircraft’s flight control system, the flight crew could have difficulty controlling the aircraft and this could lead to an excessive nose down attitude, significant altitude loss and possible impact with terrain. The Emergency AD set forth certain procedures that the flight crew must follow if this occurs to enable the crew to control the aircraft. The AD, however, did not address any specific potential problem with the angle of attack sensors or the computer software itself. The partners at Speiser Krause are closely monitoring the investigation and will provide more information as it becomes available.