Jakarta - Boeing says that it is confident about the safety of its best-selling 737 MAX family aircraft, despite concerns
Lion Air Flight JT610 had crashed into the Java Sea in minutes after takeoff from Soekarno-Hatta International Airport. The preliminary data obtained from the flight recorder revealed that the 737 MAX 8 entered into a sharp dive due to the erroneous angle of attack data from a sensor.
It was the first crash involving a MAX family jet. The incident has raised safety concerns about the best-selling model of the U.S manufacturer.
After the crash, Boeing issued a service bulletin to inform the 737 MAX operators about a new safety feature on the aircraft, which is not included on the previous models.
This bulletin gave rise to a new discussion. Some Pilot unions from the United States claimed that the safety measure was not detailed in the training documents.
We are confident in the safety of the 737 MAX. Safety remains our top priority and is a core value for everyone at Boeing,a Boeing spokesperson told local media in Indonesia on November 17.
M.C.A.S - Maneuvering Characteristics Augmentation System
Boeing included a stall recovery system in its new generation 737MAX aircraft automatically reducing the attack angle of the plane in case of a stall situation. The system is called M.C.A.S (Maneuvering Characteristics Augmentation System).
But Flight JT610 investigation revealed that the system could cause the aircraft to enter a sharp dive in case of a false high angle of attack data.
There is a switch on both Yoke, which electrically controls the angle of the stabilizers. If pilots think the M.C.A.S intervenes because of a false command from the flight computer, They can use the trim switch to prevent the aircraft from going nose down.
Pilots have to release the trim switch after a while because the nose of the aircraft can go too high if not released on time. But there is also a risk that the M.C.A.S would reactivate after releasing the switch.
The next step would be turn off a pair of switches located at the central console, which disable electric motor moving the stabilizers up and down. This action prevents the anti-stall system (M.C.A.S) from exercising control over the position of stabilizers.
The final step is to control the stabilizers manually via "Stabilizer Trim Wheel" as shown below to pull them back into the correct position.