JAKARTA (BLOOMBERG) - Indonesia’s aviation safety regulator confirmed an off-duty pilot was aboard a Boeing Co 737 Max 8 a day before the aircraft crashed, after Bloomberg reported that a third person was in the cockpit and helped the crew disable a malfunctioning flight control system.
In a press briefing on Thursday (March 21), National Transportation Safety Committee Chairman Soerjanto Tjahjono said the regulator interviewed the pilot, but declined to name the person or say what role he played in saving the aircraft.
The NTSC won’t release details of the discussions until the investigation of Lion Air Flight 610, which crashed in October, is completed, Mr Tjahjono said.
The possibility of a malfunction of the safety system, designed to keep planes from climbing too steeply and stalling, on the 737 Max has come under the spotlight after the Lion Air flight and Ethiopian Airlines Flight 302 crashed less than five months apart from each other, killing all 346 people aboard the two planes.
The presence of an extra pilot may help investigators determine how some 737 Max flight crews faced with the malfunction have been able to avert disaster while the others lost control of their planes and crashed.
The twin disasters, the latest occurring earlier this month, led to a global grounding of the jetliner, with the US notably behind the rest of the world.
The Federal Aviation Administration has since been under scrutiny over its certification of the plane.
The NTSC has offered to cooperate with Ethiopian authorities who are investigating the recent fatal crash of the Ethiopian Air flight earlier this month, Mr Tjahjono said at the press briefing in Jakarta on Thursday.
On the day before the crash, the crew on the same Lion Air plane correctly diagnosed a problem and saved the 737 Max 8 with the help from an off-duty pilot who happened to be riding in the cockpit, people familiar with the matter have said.
The extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight control system, according to the people.
The Indonesian regulator didn’t mention the off-duty pilot in its preliminary report of Lion Air Flight 610 because they hadn’t interviewed him then as they were they were focusing on finding the black box, said Mr Nurcahyo Utomo, lead investigator at the NTSC.
In the wake of the two accidents, questions have emerged about how Boeing’s design of the new 737 model were approved.
The US Transportation Department’s inspector-general is conducting a review of how the plane was certified to fly.
The FAA said last week it planned to mandate changes in the system to make it less likely to activate when there is no emergency.
The agency and Boeing said they are also going to require additional training and references to it in flight manuals.
After the Lion Air crash, two US pilots’ unions said the potential risks of the system, known as the Manoeuvring Characteristics Augmentation System, or MCAS, hadn’t been sufficiently spelled out in their manuals or training.
None of the documentation for the aircraft included an explanation, the union leaders have said.
The system had baffled pilots by pushing the Lion Air plane’s nose downward dozens of times, exerting more and more force until they lost control.
The same measure had kicked in with alarms blaring shortly after takeoff on a flight the evening before the October crash.
The pilot riding in the jumpseat suggested the crew flip switches that cut power to the haywire system.
The MCAS system is meant to help counteract the changed centre of gravity on the Max, which boasts larger and more powerful engines than its 737 predecessors.
The software intervenes automatically, without a pilot’s knowledge, when a single sensor indicates the aircraft may be approaching a stall. The so-called angle-of-attack vane provided a faulty reading to the Lion Air crew.
Separately, the Indonesian commission disputed recent media reports revealing detailed contents of the cockpit voice recorder inside Lion Air 610, saying they were based on people’s opinions, rather than reality.
Reuters earlier reported details of the struggle the crew faced on the day of the disaster, which resulted in the death of all 189 people aboard.