The pilots of Ethiopian Airlines flight 302 were unable to regain control of their plane despite “repeated” attempts to follow Boeing procedures, an interim report has found.
The Boeing 737 Max aircraft failed to gain altitude and nose-dived into the ground shortly after take off from Addis Ababa on 10 March, with the loss of 157 lives.
The Wall Street Journal, citing unnamed sources, has previously reported that early findings about the cause of the crash were pointing to the computer system, designed to make the handling of aircraft more consistent and lessen the risk of a stall.
Aviation authorities imposed a global flight ban on the 737 Max in March after two fatal crashes in five months.
What is MCAS and why is it under question?
The plane’s safety systems have become the centre of the investigation
The “Manoeuvring Characteristics Augmentation System” (MCAS) is designed to prevent the plane stalling when making steep turns under manual control.
A stall can happen when the plane flies at too steep an angle. This can reduce the lift generated by the wings, potentially making the plane drop. To recover from a stall, a pilot would normally push the plane’s nose down.
In the 737 Max, MCAS does this automatically, moving the aircraft back to a “normal” flight position.
The system then repeats the process if the computer detects the plane is still tilted at too-high an angle.
After the Lion Air crash, it was disclosed that the aircraft had experienced problems with a sensor which calculates the angle of flight.
If this sensor gives a false reading, MCAS may activate and push the nose down when nothing is wrong.(BBC)