Boeing CEO Dennis Muilenburg chastised media outlets in an internal memo to employees last week over what he characterized as false reporting on Boeing’s alleged lack of communication about the function of the 737 Max’s maneuvering characteristics augmentation system (MCAS). In the memo, Muilenburg called “simply untrue” reports that Boeing withheld information about the potential for the automated stall protection system to force the airplane’s nose downward in the event it detects the danger of a stall and emphasized that the model’s flight crew operations manual describes the relevant function.
Adding that media speculation has introduced false assumptions, Boeing’s chief executive also stressed the company’s regular engagement with customers about how to operate the company’s airplanes safely. “Teammates across the enterprise are pouring significant energy into actively supporting the investigation and our Max customers, and we won't rest until the work is complete,” Muilenburg wrote.
Boeing, in fact, has begun evaluating the need for software changes in the Max following the October 29 crash of a Lion Air 737 Max 8 in which all 189 people on board died. According to flight data recorder readouts, faulty angle of attack sensor inputs led the flight control system to force the airplane’s nose downward starting two minutes after takeoff and repeatedly until the crash 11 minutes later.
Meant to improve pitch response at high angles of attack and prevent pilots from raising the airplane’s nose too high, the MCAS in the 737 Max 8 and Max 9 does not appear in the 737 NG. Engineers made the change to address differing stall characteristics in the Max resulting from its larger and heavier CFM Leap-1B engines. However, pilot groups in the U.S. have said that Boeing failed to communicate with 737 Max operators new procedures for addressing cases in which the airplane’s automatic stall prevention system commands the nose of the airplane downward.
Asked for comment on plans for software changes and the potential need for further pilot training, a Boeing spokesman suggested that Boeing’s response to this accident did not deviate from its normal practice.
“As part of our standard practice following any accident or incident, we examine our aircraft design and operation, and when appropriate, issue bulletins and make recommendations to operators to further enhance safety,” he said. “Boeing continues to evaluate the need for software or other changes as we learn more from the ongoing investigation.”