Boeing failed to inform the pilots about the new stall recovery system (MCAS) on 737MAX, which linked to Lion Air crash


Southwest and American Airlines pilots flying Boeing 737MAX says that they were “kept in the dark” about the new “Manoeuvring Characteristics Augmentation System” on 737MAX, that linked to the Lion Air 737MAX crash last month.

Jon Weaks, president of the Southwest Airlines Pilots Association, said in an interview Monday the airline and the pilots “were kept in the dark.”.. “We do not like the fact that a new system was put on the aircraft and wasn’t disclosed to anyone or put in the manuals,” What’s more, he noted, Boeing and the Federal Aviation Administration (FAA) have now warned “that the system may not be performing as it should.”

Dennis Tajer, a 737 captain at American Airlines said, “This is not about silos and layers of bureaucracy, this is about knowing your airplane,”

When Boeing developed 737MAX, it made some design changes to accommodate much larger and fuel efficient engines and extended the landing gear by eight inches. This developed a “pitch up” condition during higher thrust, and Boeing introduced a new 737 MAX system — called MCAS (Maneuvering Characteristics Augmentation System), but failed to add it to operators manuals or inform operators.

MCAS (Maneuvering Characteristics Augmentation System) is implemented on the 737 MAX to enhance pitch characteristics with flaps UP and at elevated angles of attack. The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column trim switch or stabilizer aislestand cutout switches to override MCAS input. The function is commanded by the Flight Control computer using input data from sensors and other airplane systems.

Last Tuesday, after the crash Boeing sent out a warning bulletin to all 737MAX operators, and the next day the FAA issued an emergency airworthiness directive mandating that all airlines make pilots aware of the procedure.


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