We reported problems with the MCAS (Maneuvering Characteristics Augmentation System), which is designed to quietly help pilots fly Boeing 737 Max aircraft in manual mode (when the autopilot is turned off). It is believed that it was she who led to the last two plane crashes with this machine. Recently, the US Federal Aviation Administration (FAA) sent a software patch created by Boeing specialists for revision, so that planes will not take off for a long time even over America. An investigation is currently underway into the Ethiopian Boeing crash on March 10, and Reuters, citing its sources, reported that the MCAS system was activated again after the pilots had turned it off, and put the plane into a dive.
Two sources said a preliminary Ethiopian report on the crash should be released within days and could include evidence that the MCAS system was activated as many as four times before the 737 Max hit the ground. A third source told reporters that the software started up again after the pilots turned it off, but added that there was only one key episode in which MCAS put the plane into a dive before the crash. Allegedly, the software started working again without human intervention.
In a statement to reporters on the data, Boeing said: "We urge caution and not making assumptions or drawing conclusions about the results before the flight data and preliminary report are released." The MCAS system is currently at the center of the scandal surrounding the crashes of Ethiopian Flight 302 and the Lion Air crash in Indonesia five months ago - crashes that killed a total of 346 people.
The stakes are high: The Boeing 737 Max is the company's best-selling aircraft, with nearly 5000 orders already. And now the fleet of sold aircraft continues to sit idle around the world. The resumption of flights depends on the role that the aircraft's design played in the crash, although investigators are also looking at the actions of airlines, crews and regulatory measures. Boeing is looking to update its MCAS software and introduce new pilot training programs.
It was previously reported that in both crashes the problem could be related to the incorrect operation of MCAS, which was guided by erroneous angle of attack data from one of the aircraft's two sensors. Now the investigation is said to have concluded that in the Ethiopian case, MCAS was initially properly disabled by the pilots, but then resumed sending automatic instructions to the stabilizer, which put the plane into a dive.
Following the Indonesia accident, Boeing issued instructions to pilots outlining the procedure for deactivating MCAS. It requires that after shutdown and until the end of the flight the crew does not turn on this system. The Wall Street Journal previously reported that the pilots initially followed Boeing's emergency procedures but later abandoned them as they tried to regain control of the plane. Disabling the system is said to not completely stop MCAS, but it does break the connection between the software, which continues to issue incorrect instructions to the stabilizer, and the actual control of the aircraft. Researchers are now investigating whether there are any conditions under which MCAS could automatically reactivate without the pilots' knowledge.
Analyst Bjorn Fehrm suggested in his blog that the pilots may have failed to manually remove the stabilizer from the dive position. So they may have decided to reactivate MCAS to try to get the stabilizer into position, and the system simply wouldn't let them do it. Safety experts, however, emphasize that the investigation is far from complete, and most aviation accidents are caused by a combination of human and technical factors.
Source: 3dnews.ru