The Boeing tragedy: how software can be at the origin of accidents – 03/12/2019

The investigation into the tragedy in Ethiopia highlighted the Boeing 737 Max 8 automatic control system, the model of the aircraft fell Sunday shortly after taking off from Adís Adeba and left 157 people dead.

This Tuesday, the company Boeing announced the update of the operational program The reaction came shortly after US regulators ordered "urgent improvements" and more and more companies decided to stop using the model, including Aerolineas Argentinas.

"Boeing is the builder of the Boeing 737 line for many years and its level of reliability is very high because they wanted to make this type of aircraft more efficient, they built the new aircraft called Boeing 737 Max". Clarin Juan Pablo Mazzieri, pilot experienced in this aircraft and member of the Association of Line Pilots (APLA).

"To this aircraft, in order to maintain the same flight characteristics as its predecessor (the Boeing 737-800), a new software, called MCAS (Maneuvering Increasing System) has been integrated, which displays the same characteristics of flight than the previous one, "continues Mazzieri.

"He needs this system because this new plane has bigger engines, they are positioned later (than the previous version) and what it does is that generates a moment of "nose in the air". That is to say that the nose lifts the plane. Thus, in order to maintain the same flight conditions (as in the previous model), he needs software to lower this altitude ", continues the pilot.

How the software works

The MCAS system was created to prevent the ship from entering what is called a "loss". He tries to prevent the plane from raising his nose too much. Then, automatically, the nose is lowered and thus neutralizes a potential error of the pilot.

But this novelty would have generated disadvantages. "What happens here is that the computer understands that the plane is the raised nose, it lowers the nose, but it's not really with the nose up", Sicardi badysis.

For Mazzieri, this system "automatically contributes to give the aircraft maneuverability". Before the request of if the driver can disable it, responds that it "is possible" but only "to solve or use an error protocol that is not specifically related to this specific failure".

"In principle, it was designed so that the automatic system overrides the information provided by the pilot, unless the pilot decides to discontinue this system," Mazzieri continued.

In this regard, Pablo Biró said that "this system works very slowly and that the pilots can not identify the fault". And he concluded: "The trade war has become more aggressive and the size of the aircraft and the power of the engines have increased, and they use control systems in the flight controls where the driver does not have any interference or there are no instructions. "

For its part, pilot and aeronautical consultant Ezequiel Sicardi told TN that it was a system seeks to take the responsibility of the pilot. "We are facing a situation of great uncertainty in which the pilot does not know how to solve the emergency, because automation is so important, the situation in which the computer and the software are acting on the The plane is so powerful that the pilot does not have the solution, "he said.

A hidden system for pilots

In October 2018, in Indonesia, there was another accident with a Boeing 737 Max from Lion Air, which killed 189 people. Only then was the aircraft equipped with this system and this new software was made explicit.

"J & # 39; was hidden for pilots. We had no information about this system or how to deal with a potential failure, "Mazzieri said.

For his part, Biró pointed out that "information had been omitted" in the manual and that "neither the technicians nor the pilots had the precision to know how the system worked completely".

Although Sicardi denounces the fact that "it is a serious position that led the company Boeing to launch this product on the market without giving the crew a precise information of what they had implemented".

PS