Ethiopian Air pilots turned off 737 MAX anti-stall system. Then it turned on again
The pilots of Ethiopia Airlines Flight 302 apparently followed the proper steps to shut down an errant flight control system as they struggled to regain control of the 737 MAX aircraft shortly after takeoff. But according to multiple reports, data from the ill-fated aircraft’s flight recorder revealed that the anti-stall feature of the aircraft’s Maneuvering Characteristics Augmentation System (MCAS) was triggered at least three times—and at least one time after the pilots followed the correct steps to shut it down.
Both Reuters and The Wall Street Journal report that the air crew followed procedures laid out by Boeing following the crash of a Lion Air 737 MAX in October, according to officials briefed on the initial findings of the investigation. But the pilots failed to regain control of the system, and the MCAS was reactivated again—triggering yet another automated correction of the aircraft’s stabilizers that would have pushed the nose of the plane down.
Boeing’s safety notice following the Lion Air crash noted that the MCAS’ automated adjustments to a 737 MAX’s stabilizers—the control surfaces on the tail of the aircraft that are used to change the direction of the aircraft’s flight—could be “stopped and reversed” with a thumb switch on the pilot’s yoke but “may restart 5 seconds after the [switch] is released.”