Ethiopian Airlines crash: When software sends a plane into vertical dive

Boeing under attack for system flaw

Updated - November 28, 2021 10:06 am IST

Published - March 18, 2019 12:17 pm IST - NEW DELHI

An American Airlines Boeing 737 MAX 8 sits at a boarding gate at LaGuardia Airport on Wednesday, March 13, 2019, in New York.

An American Airlines Boeing 737 MAX 8 sits at a boarding gate at LaGuardia Airport on Wednesday, March 13, 2019, in New York.

The data from the two black boxes of the Ethiopian Airlines aircraft that crashed near Addis Ababa has been downloaded and will be examined by investigators at France’s bureau of civil aviation safety.


According to a report by the New York Times, investigators have recovered an instrument called ‘stabiliser’ from the crash site.

The angle of this device indicates the nose of the Boeing 737 MAX 8 aircraft was pointed downwards, a similarity with the Lion Air crash last October. Experts have pointed out how both aircraft were on a low level and went into a very steep dive. So, what went wrong with the Lion Air flight?

“The Lion Air B737 MAX experienced multiple failure indications due to a malfunctioning Angle of Attack (AOA) sensor — which shows the angle between the flight path and the nose. The preliminary investigation report indicated that the two AOAs (one each on the pilot’s side and the co-pilot’s) showed a difference of 20 degrees. This error would have made one AOA indicate more than the stalling angle of 27 degrees, triggering the Maneuvering Characteristics Augmentation System (MCAS), a feature Boeing introduced in the MAX,” explains aviation safety expert Captain Mohan Ranganathan.


The MCAS pushed down the nose of the plane, and the pilots tried to counter it, leading to a tug-of-war. The final descent was too strong for the pilots to control, resulting in a vertical fatal dive, he adds. This flight lasted 12 minutes. The Ethiopian Airlines flight had barely climbed to 1,300 feet and lasted all of six minutes.

The debate

The global backlash in which nearly 30 countries grounded the Boeing 737 MAX 8 aircraft even before an advisory from FAA, is “unprecedented”, says John Goglia, independent aviation safety consultant and a former member of the U.S. National Transportation Safety Board.


“This has never happened. Normally, most wait for investigators to get some facts. But this time, airlines said we want to make a decision, but the people responsible [Boeing and FAA], didn’t have the facts.

“Everyone jumped to conclusions that were not yet fact-based,” he says.

Others differ. A former test pilot for Boeing said on condition of anonymity, “There are too many similarities between the two accidents and I believe [grounding] was the correct decision.”

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