
The pilots of a doomedย Lion Airย Boeing 737 Maxย flight desperately scoured a handbook to find out why the jet was plummeting downwards but ran out of time before it crashed into theย Java Sea, killing everyone on board.
According to three people who have heard aย cockpit voice recordingย from the aircraft, the captain and first officer on board the ill-fated flight JT610 searched through checklists in a race against time after the jet warned them it was in a stall and pushed the nose down in response.
It has also emerged that anย off-duty pilot riding along in the aircraft just a day earlierย helped another crew save the plane from the same issue.
The investigation into theย crash in Indonesiaย in October 2018, which killed all 189 people on board, has taken on new relevance since the model was grounded last week after a second deadly accident inย Ethiopiaย on 10 March.
According to a preliminary report issued in November, the first officer on board the Lion Air flight last year reported a โflight control problemโ to air traffic control just two minutes after take-off and said the pilots intended to maintain an altitude of 5,000 feet.
The captain, who was at the controls, asked the first officer to check the quick reference handbook, which contains checklists for abnormal events, the first source with knowledge of the cockpit recording said.
For the next nine minutes, the jet warned the pilots it was in a stall and pushed the nose down in response.
The captain fought to climb, but the computer, still incorrectly sensing a stall, continued to push the nose down using the planeโs trim system, which usually ensures the aircraft flies straight and level.
The third source said: โThey didnโt seem to know the trim was moving down. They thought only about airspeed and altitude. That was the only thing they talked about.โ
The pilots of JT610 remained calm for most of the flight, the three sources told Reuters, and near the end the captain asked the first officer to fly while he checked the manual for a solution.
As the 31-year-old captain tried in vain to find the right procedure in the handbook, the 41-year-old first officer was unable to control the plane, two of the sources said.
โIt is like a test where there are 100 questions and when the time is up you have only answered 75,โ one of the sources said. โSo you panic. It is a time-out condition.โ
The Indian-born captain was said to be silent at the end before the plane hit the water, while the Indonesian first officer said โAllahu Akbarโ, or โGod is greatestโ, a common Arabic phrase in the majority-Muslim country that can be used to express shock or distress.
The cause of the crash has not been determined, but a preliminary report mentioned the Boeing system, a faulty, recently replaced sensor, and the airlineโs maintenance and training.
Boeing Co declined to comment while the investigation is ongoing, but the manufacturer said there was a documented procedure to handle the situation.
A different crew on the same plane the evening before encountered the same problem but solved it after running through three checklists.
However they did not pass on all of the information about the problems they encountered to the next crew, the November report said.
Two of the sources said a captain at Lion Airโs full-service sister carrier, Batik Air, was riding along in the cockpit and told the crew how to disable the malfunctioning flight-control system and save the plane.
His presence on that flight, first reported byย Bloomberg, was not disclosed in the preliminary report.
The report also did not include data from the cockpit voice recorder, which was not recovered from the ocean floor until January.
French air accident investigation agency BEA said on Tuesday the flight data recorder in the Ethiopian crash that killed 157 people earlier this month showed โclear similaritiesโ to the Lion Air disaster.
Since the Lion Air crash, Boeing has been pursuing a software upgrade to change how much authority is given to the Manoeuvring Characteristics Augmentation System, or MCAS โ a new anti-stall system developed for the 737 MAX.
Soerjanto Tjahjono, head of Indonesian investigation agency KNKT, said the report could be released in July or August as authorities attempted to speed up the inquiry in the wake of the Ethiopian crash.
On Wednesday, he declined to comment on the cockpit voice recorder contents, saying they had not been made public.
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