How were the last minutes in the cockpit of the Boeing 737 MAX accident in Indonesia?

The pilots of the Lion Air Flight 610 crashed in Indonesia in October, the first of two tragedies that occurred on board a Boeing 737 MAX and resulted in the temporary suspension of the model, They were desperately looking in the aircraft manuals to avoid the tendency to fall, probably caused by a defective automatic navigation system. But they did not find it and collided in the waters of the Java Sea, according to three sources revealed to the agency Reuters.

After the tragedy in Africa, the second for the modern model 737 MAX in less than six months, virtually every country in the world has ordered the suspension of operations with the model until the Boeing Company, the United States Federal Aviation Agency (FAA) and the relevant regulatory agencies thoroughly investigate what happened.

From the beginning, we learned that the accident in Indonesia Probably due to a failure of the sensors that recorded the angle of attack, ie the elevation or the drop of the nose of the aircraft, the speed and the Altitude, and to an erroneous and fatal correction made by the MCAS system, which automatically generates changes in the course of the aircraft to avoid loss, as we know when a plane loses its lift.

In this way, the MCAS of the Lion Air 737 MAX he would have automatically launched a dive, based on erroneous information, that the pilots would not have been able to correct and who caused the accident.

In this regard, it has been said that Boeing did not properly report or provide information on how to bypbad this automatic system, whose drivers apparently did not know the existence of the drivers. On the contrary, the company argues that the crew was not properly trained to deal with the damage according to a specific procedure.

Something similar seems to have happened on the flight Ethiopian Airlinesalthough he has not yet disclosed any information about it.

Problems shortly after takeoff

Now the black box recordings of the Lion Air flight were made public for the first time via three sources who participated in the investigation, according to Reuters.

According to this information, the 31-year-old captain piloted the 737 MAX and the first officer operated the radio. take off from flight 610 from Jakarta airport.

Just two minutes after leaving the floor the first officer reported to the air traffic controllers a "flight control problem" while the captain tried to maintain an altitude of 5000 feet (about 1500 meters).

Although the first officer did not specify the problem,When recording the black box, a reference to the speedometer and a suspected instrument panel problem is heard. according to the sources.

Then the commander He asked his first officer to consult the Quick Reference Manual, which contains a list of common problems.

In the next nine minutes The instrument on board told the pilots that the aircraft was picking up and the MCAS automatically corrected the course by adjusting the elevators and tilting the nose of the plane.

A stand means that the airflow in the wings is too weak to maintain lift and prevent the vessel from falling like a stone, and this usually happens when the speed of the plane approaches very low levels. When planes increase their altitude, they usually lose their speed and, when they fall, they increase it. This is why the MCAS makes small corrections to the elevation of the nose to control this phenomenon.

But the measure was wrong and the plane was not decreasing, said the sources.

Consequently, the captain spent these nine minutes trying to lift the nose of the 737 MAX and prevent it from crashing, while the MCAS did exactly the opposite, triggered by an erroneous measurement.

"They did not seem to know that the system was acting, "said one of the sources consulted, they only talked about speed and altitude. he added.

Boeing, who would not comment on these revelations because the investigation is still ongoing, He stated that there was a procedure to solve this problem, although he had already been criticized for not reporting correctly in this regard.

An antecedent, the night before

In fact, in a report published in November, it was argued that a different crew had suffered the same problem in the same plane the previous night. and had been able to avoid an accident by following the procedure.

More precisely, this flight had the presence in the cabin of an experienced pilot of the airline Batik Air, belonging to the same group as Lion Air. L & # 39; man He accompanied the crew accidentally and did not command the aircraftbut before the damage and being present in the cabin, he lent his help.

The presence of this pilot had already been reported by Bloomberg, but the report of the Indonesian aviation authorities confirms thisaccording to the sources.

But the fact is that none of these pilots or the airline forwarded the incident information to the next crew.

The pilot-in-command and pilot of Flight 610 remained calm for most of the flight. But in the end, the commander gave control of the plane to his co-pilot to try to find the solution to the problem in the manuals.

He asked air traffic controllers to release airspace below 3000 feet (about 1,000 meters).. And then, the first officer lost control of the plane, sources said.

According to flight information, when the 41-year-old co-pilot took control, the 737 MAX worsened the crash.

In the end, the captain, of Indian origin, was silent, while the first in charge, Indonesian, said "Allahu Akbar" (God is the greatest, in Arabic and a clbadic expression of Islam). Then the plane disappeared from the radar.

The final report of the Indonesian authorities is not yet ready, but it has been criticized for its preliminary form to the MCAS system, to a defective sensor and recently changed in the aircraft, as well as to the maintenance and training of the airline.