Automated Systems May Have Caused Lion Air Crash

Kai Huang - 2A Computer Engineering
Posted on: November 14, 2018

On 29 October, Lion Air Flight 610 plunged into the Pacific Ocean minutes after takeoff from Jakarta, Indonesia. The brand new Boeing 737-8 carried 189 passengers and crew, all of which perished, in the first ever crash of the new model of Boeing’s best-selling short-haul passenger jet.

The aircraft involved in the incident – registration PK-LQP – was almost brand new, being delivered to Lion Air on 13 August 2018, but already had a troubled history. The airspeed indicator system, including the Angle-of-Attack (AOA) sensors had suffered issues for the previous flights, with maintenance workers inspecting and replacing the system before the penultimate flight.  Even so, the issues still prevailed, with a near-catastrophic failure on the Bali to Jakarta flight, the last journey of the doomed plane. Passengers reported heavy shaking and sudden changes in altitude, and the Pilots had called for a “pan-pan” emergency, one level below the dreaded “mayday”. Though the pilots managed to complete the flight successfully, a 20 degree difference between the right and left AOA sensors was recorded.

On the morning of the 29th, the Captain of Flight 610 had asked the controller to return to Jakarta three minutes into the flight due to flight control problems. The request was immediately granted, but the plane never turned back. It immediately descended, with the altitude continuously fluctuating. Experts looking at the recorded data noted that Flight 610 was also travelling at unusually high air speeds during the entire descent, in excess of 300 knots when lower altitude flying is restricted to less than 250. The final recorded altitude of the aircraft was 760 metres, having dropped 910 metres just 10 minutes into the flight. Based on the debris, Indonesian authorities concluded that the plane was intact at the moment of collision and was travelling at high speed, with the engines still running. Workers on an offshore oil platform reported seeing the aircraft strike the water at a steep nose-down angle.

Investigations put the design of the new Boeing 737-8 under scrutiny. With the improvements in technology, automation has become a key factor in any modern aircraft systems. One of the new features in this generation of 737’s is an emergency system designed to protect against stalls – statistically the most common cause of accidents. By reading information from the AOA sensors, the plane would automatically push its nose down for up to 10 seconds without the pilot’s authorization. With erroneous data being fed from the sensors, it would thus be possible for the plane to pitch forward at a surprise to the pilots. In 2008, Qantas Flight 72 experienced a similar mishap with an A330-301 utilizing a similar system. The aircraft made two sudden pitch down maneuvers outside of the pilots’ commands, causing serious injuries to the passengers aboard. The pilots declared a Mayday and made an emergency landing.

The FAA and Boeing issued a statement on 6 November that such a scenario would be possible on new 737 models and recommended to all operators that should the aircraft enter an uncontrolled pitch-down, the flight crew should shut off the electricity powering the control surfaces in the tail. For the Lion Air flight, this information comes too late. Prompted with a sudden crisis, it is unlikely that even the most skilled pilots would intuitively think to manually override the aircraft’s advanced control systems.

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