In a shocking press release from Boeing on Sunday, the largest aircraft manufacturer has admitted publically to have known about the issue with 737 MAX aircraft months before the Lion Air incident on November 6th, 2018.
Aerospace experts and aviators around the world are in a state of disbelief as Boeing not only kept the Federal Aviation Agency (FAA) in the dark but also linked the recent crashes to a warning light indicator of Angle of Attack (AOA), calling it an “Optional Feature”.
Issues With the MAX
Boeing introduced a flight control system called MCAS (Maneuvering Characteristics Augmentation System) in the 737 MAX. MCAS assists the flight computer on board the aircraft in case the angle of attack of the aircraft exceeds the upper threshold. Angle of attack (AOA) is the relative angle between the aircraft’s nose and incoming wind.
MCAS gets the AOA information from two sensors on the fuselage and automatically pushes the nose down if the angle is higher to avoid stalling. However, if the sensors malfunction or provide erroneous data to the MCAS, it can unnecessarily activate the anti-stall function and direct the aircraft into a nose dive.
In case of a faulty AOA sensor data, the warning alert in the cockpit’s display system could have provided critical information to the pilot about the AOA disagreement and helped them override the MCAS. Boeing is now taking the heat for making an essential safety feature a premium option.
Boeing’s Official Statement and Software Fixes
The official statement on Boeing’s web site reads:
The software delivered to Boeing linked the AOA Disagree alert to the AOA indicator, which is an optional feature on the MAX and the NG. Accordingly, the software activated the AOA Disagree alert only if an airline opted for the AOA indicator. Boeing discussed the status of the AOA Disagree alert with the FAA in the wake of the Lion Air accident. At that time, Boeing informed the FAA that Boeing engineers had identified the software issue in 2017.
After the crashes, Boeing has now made the AOA disagreement alert a standard option in the display system software of the MAX series. It has also assured the airlines that all MAX aircraft will have the ability to activate this warning alert before the airliner enters service again.