- The pilots of the doomed Lion Air Flight 610 last month fought with a malfunctioning automated flight system, data from the flight’s black box in a preliminary report reviewed by The New York Times shows.
- The almost new Boeing 737 Max crashed into the Java Sea on October 29, killing all 189 people on board.
- The data in the report seems to suggest the pilots were unaware of how – or unable – to override the automated system.
The New York Times on Tuesday reported on a harrowing breakthrough in the investigation into the crash of the Lion Air Boeing 737 Max 8 that crashed into the Java Sea on October 29, killing all 189 people on board.
The Times cited information from Lion Air Flight 610’s recovered flight data recorder, known as a black box, contained in a preliminary report prepared by Indonesian investigators and released on Wednesday. A more complete account by the investigators is expected later.
The data in the report shows how hard the two pilots battled to stay in the air and the difficulties they faced in dealing with what may have been a rogue automated system, according to The Times.
The newspaper said the data was also consistent with the investigators’ main lead: that a system Boeing installed on its 737 Max planes called the “manoeuvring characteristics augmentation system,” or MCAS, designed to prevent the nose from getting too high and causing a stall, actually forced it down because of incorrect data from sensors on the fuselage.
Flight 610 was repeatedly pushed into a dive position most likely because of the automated system’s malfunctioning sensors, a fault that began moments after it took off from Jakarta en route to Bali, The Times reported.
There were faulty readings even as the plane taxied onto the runway, and as soon as the wing flaps were retracted at 3,000 feet, the pilots were in a life-and-death tug-of-war with the new automated anti-stall system, The Seattle Times reported, citing the black-box data.
Once Flight 610 was airborne, the pilots’ control column began to shake, a precursor to a stall, The Seattle Times reported. Over the 13-minute flight, the pilots pushed back against the system more than 24 times as they sought to retake control until the plane plummeted into the sea at 450 mph, killing all 189 people on board.
Capt. Nurcahyo Utomo, the head of the air accident subcommittee of Indonesia’s National Transportation Safety Committee, has said that “the pilots fought continuously until the end of the flight.” He said that in the case of Lion Air Flight 610, the stall-prevention system had been activated and is a focus of the investigation, according to The New York Times.
While Flight 610’s pilots repeatedly pulled the nose up again, it was unclear why they didn’t switch off the system, something the pilots on the plane’s flight on the previous day did when they encountered a similar problem, The Seattle Times reported.
The New York Times reported earlier this month that “if the pilots of Lion Air 610 did in fact confront an emergency with this type of anti-stall system, they would have had to take a rapid series of complex steps to understand what was happening and keep the jetliner flying properly.”
“These steps were not in the manual, and the pilots had not been trained in them,” that Times report said.
Fight for control
The MCAS was already under investigators’ heavy suspicion.
Boeing and the Federal Aviation Administration earlier in November issued directives to flight crews about the system, which is designed to provide extra protection against pilots’ losing control during a stall, when the nose is lifted too high, by steering the nose down, Bloomberg reported. Boeing has said its safety bulletin was meant only to reinforce existing procedures.
Boeing has been the target of criticism that it did not fully train and prepare pilots to use the system. According to the Allied Pilots Association, a union representing American Airlines pilots, and the Southwest Airlines Pilots Association, many aviators, unions, and flight-training departments have expressed concern that none of the documentation for the Max 8, including pilot manuals, included an explanation of the system, Bloomberg reported.
The system was not explained in the flight manual of the 737 Max 8, Reuters reported earlier this month, citing a copy of the manual.
Boeing has denied that it withheld relevant information about the system. In an email to employees this month, CEO Denis Muilenburg defended his company’s development and deployment of the 737 Max generation’s MCAS, saying pilots were already instructed on how to handle such unwanted movements, The Seattle Times reported.
The Points Guy described Boeing as saying in a memo to pilots and customers a week after the crash that “the system can suddenly push the nose so far down that pilots cannot lift it back up” and that “the system would kick in even if cockpit crews are flying a plane manually and wouldn’t be anticipating a computerised system to take over.”
Earlier this month, Lion Air’s operational director, Zwingli Silalahi, told CNN that the manual failed to sufficiently inform pilots of the MCAS’s behaviours.
“We don’t have that in the manual of the Boeing 737 Max 8,” Zwingli said.
The Times reported: “Boeing has said that the proper steps for pulling out of an incorrect activation of the system were already in flight manuals, so there was no need to detail this specific system in the new 737 jet. In a statement on Tuesday, Boeing said it could not discuss the crash while it is under investigation but reiterated that ‘the appropriate flight crew response to uncommanded trim, regardless of cause, is contained in existing procedures.'”
Indonesian investigators have questioned the role of the faulty airspeed indicators, but safety experts have said pilots should be able to deal with any such faults, The Associated Press reported earlier this month.
Despite the findings in the preliminary report, much remains unknown about Flight 610, including why a plane with apparently problematic sensors was even allowed off the tarmac – though investigators say that one of those sensors was replaced before its penultimate flight because of faulty data readings, The Times said on Tuesday.
Investigators have not recovered the cockpit voice recorder, which could explain what the pilots did to try to regain control of the plane, The Times reported.
Earlier this month, Indonesia’s transport ministry issued a 120-day suspension for Lion Air’s maintenance and engineering directors, its fleet maintenance manager, and the engineer who gave the jet permission to fly, Reuters reported.