Concerns grow over BOEING 737 MAX’S anti-stall protection – Why MAX needs MCAS & what is Stall Escape maneuver

Similarities between the Lion Air and Ethiopian Airlines crashes, confirmed by black box data, have focused attention on an anti-stalling system used in the new Boeing 737 Max 8 aircraft.

The Maneuvering Characteristics Augmentation System (MCAS) is an automated safety feature on the 737 Max 8 designed to prevent the plane from entering into a stall or losing lift.

Both the Lion Air jet, which crashed in October, killing 189 people, and the Ethiopian Airlines aircraft, which went down a week ago Sunday, leaving 157 people dead, were fitted with the system.

Both planes experienced similarly erratic steep climbs and descents and fluctuating airspeeds before crashing shortly after takeoff.

A malfunction of the system was implicated in the Lion Air accident in Indonesia.

Investigators found a device known as a jackscrew in the wreckage. The jackscrew, used to set the trim that raises and lowers the plane’s nose, indicates the jet was configured to dive, according to John Cox, a former pilot and an airline-safety consultant with the Washington-based aviation-safety consulting firm Safety Operating Systems

In a preliminary investigation, the crash of a Lion Air Max 8 plane into the Java Sea on Oct. 29 was attributed to a faulty sensor causing an automated system to push the nose of the plane down. The possibility that the same scenario occurred in Ethiopia has prompted precautionary groundings of the plane all over the world. In all, more than 300 people have died in the two crashes involving the Max 8 jet.

Preliminary flight data showed the Ethio­pian Airlines plane in trouble almost immediately and struggling to gain altitude in the high thin air above the Addis Ababa airport. The plane descended and then sharply ascended while moving at speeds far in excess of normal.

The record shows Several pilots made at least five complaints about Boeing 737 Max 8 planes in the months leading up to the deadly Ethiopian Airlines crash on Sunday, which killed all 157 people on board, and was the Second brand-new Boeing 737 Max crash in 5 months

US records show that at least five complaints were lodged with federal authorities in recent months, with one captain even calling the flight manual “inadequate and almost criminally insufficient,” according to the Dallas Morning News.

Two pilots reported their aircraft unexpectedly pitched nose down after engaging autopilot following departure. Another pilot reported a “temporary level off” triggered by the aircraft automation. The captain of a November 2018 flight called part of the aircraft’s flight manual “inadequate and almost criminally insufficient.”

“The fact that this airplane requires such jury-rigging to fly is a red flag,” that captain — who is not identified by name — wrote in a report to the federal Aviation Safety Reporting System. The captain added that part of the plane’s flight system is “not described in our Flight Manual.”

In one complaint, a commercial pilot described issues which occurred during takeoff. As the autopilot was engaged, the aircraft’s nose suddenly pitched down, setting off the plane’s alarm system which sounded “Don’t sink, don’t sink!” according to Politico. The situation was only remedied after autopilot was turned off, the Politico report said.

Another pilot who flies the Max 8 complained in November that it was “unconscionable” that pilots were allowed to continue to fly the planes without adequate training or disclosure on how the Max 8’s system differs from previous models, Politico said.

In an October report, a pilot complained the Max autothrottle system did not work properly even when they were engaged. The problem was rectified after the pilot adjusted the thrust manually and continued to climb.

“Shortly afterward I heard about the (another carrier) accident and am wondering if any other crews have experienced similar incidents with the autothrottle system on the MAX?” the pilot wrote in the report.

 

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