THE final moments of Lion Air Flight 610 as it hurtled soon after dawn from a calm Indonesian sky into the Java Sea would have been terrifying but swift.
The single-aisle Boeing aircraft, assembled in Washington state and delivered to Lion Air less than three months ago, appears to have plummeted nose-first into the water, its advanced jet engines racing the plane towards the waves at as much as 640kph in less than a minute. The aircraft slammed into the sea with such force that some metal fittings aboard were reduced to powder, and the aircraft’s flight data recorder tore loose from its armoured box, propelled into the muddy seabed.
United States and Indonesian investigators are not focusing on a single lapse, but on a cascade of issues that ended with the deaths of all 189 people on board. While investigators have not yet concluded what caused Flight 610 to plunge into the sea, they know that in the days before the crash, the plane had experienced repeated problems in some of the same systems that could have led the aircraft to go into a nose-dive.
On Wednesday, the US Federal Aviation Administration (FAA) warned that erroneous data processed in the new, best-selling Max 8 jet could cause the plane to abruptly nose-dive. Investigators examining Flight 610 are trying to determine if that is the case.
Boeing this week issued a global bulletin advising pilots to follow its operations manual in such cases. But to do so, experts said, would have required Flight 610’s captain, Bhavye Suneja, a 31-year-old Indian citizen, and his co-pilot, Harvino, a 41-year-old Indonesian, to have made decisions in seconds at a moment of panic.
They would have had to recognise that a problem with the readings on the cockpit display was causing the sudden descent. Then, according to the FAA, they would have had to grab physical control of the plane.
That would not have been a simple matter of pushing a button. Pilots said Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, with all his strength. Or he could have undertaken a four-step process to shut off power to electric motors in the aircraft’s tail that were wrongly causing the plane’s nose to pitch downward.
Lion Air’s story began nearly 20 years ago, when an Indonesian travel agent and his brother established it as a carrier to offer cheap flights between islands scattered across the country’s densely populated archipelago.
Even as the politically connected company fuelled its aggressive expansion with borrowing from banks and government credit agencies, it also racked up at least 15 major safety lapses. Pilots complained that they were overworked and underpaid, and some who challenged the company on contract issues are now in jail.
A former investigator for Indonesia’s National Transportation Safety Committee said Lion Air repeatedly ignored orders to ground planes for safety issues. Pilots and former safety regulators said Lion Air flight and maintenance crews regularly filled out two logbooks, one real and one fake, to hide malfeasance.
Edward Sirait, general affairs director of Lion Air, said in an interview the airline considered safety, along with business expansion, its top priorities. He disputed the existence of fake pilot logs.
In the two days before Flight 610’s final journey, there were repeated indications that pilots were being fed faulty data — perhaps from instruments measuring the speed and a key angle of the plane — that would have compromised their ability to fly safely. Engineers tried to address the issue in at least three airports, Indonesian investigators said.
After the plane’s penultimate flight, for instance, technicians recorded in a maintenance log that they had fixed the pitot tubes, external probes on the airplane that measure relative airspeed. Earlier that day, on Bali, engineers swapped out a sensor that measures the angle at which oncoming wind crosses the plane.
Called the angle of attack sensor, this instrument tells the pilot if the nose of the plane is too high, which could cause the aircraft to stall. In the Max 8, if the data indicates the nose is too high, the aircraft’s systems will automatically pull the nose down. If the sensor data is wrong, the system could cause the plane to dive.
When the 11th minute of Flight 610 began, the plane was still in nearly level flight at an altitude of about 5,000ft. By the end of that minute, it had shattered into pieces in the water, after hurtling earthward nose-first at perhaps 640kph, according to measurements from the Flightradar24 online data service. What caused the aircraft to tip downward so sharply in that final minute is the greatest enigma. Investigators have been looking into whether it was a maintenance failure or a possible shortcoming in the Boeing 737 Max 8 that could affect other fleets operating the popular jet. They are exploring the possibility the pilots were not adequately trained in how the plane differed from earlier models.
Older versions of the Boeing 737 have a reputation among pilots for being easy to adjust the angle of the plane’s nose should a problem arise, said John Cox, former executive air safety chairman of Air Line Pilots Association in the United States and now chief executive of Safety Operating Systems, a consulting firm.
But in the new version, Boeing introduced an emergency system that automatically corrects the nose angle to prevent the plane from stalling. In its safety bulletin, Boeing said the system could push the nose down for a full 10 seconds without the pilot’s authorisation.
Boeing’s new system was intended to safeguard against what some studies have suggested is the most frequent cause of plane crashes — a stall. The recommended response issued by Boeing and FAA this week would not be a pilot’s natural reaction. The flight crew is instructed to switch off the electricity powering stabilisers in the tail of the aircraft that are propelling the downward pitch of the nose.
But without training on this anomaly, what pilot would think to turn off part of the plane? When crews learn how to helm a new model, they typically study differences between older and newer models. Experts worry that pilots at hard-driving carriers like Lion Air may not be given adequate time for such training.--NYT