All Boeing 737 MAX production aircraft will have an activated and operable disagree alert and an optional angle of attack indicator.
As the MAX returns to the air after recent software modifications are approved and certified, customers with previously delivered MAX airplanes will have the ability to activate the disagree alert per a service bulletin to airlines, a Boeing statement said Monday.
The disagree alert has not been considered a safety feature on airplanes and is not necessary for the safe operation of the airplane. Boeing did not intentionally or otherwise deactivate the disagree alert on its MAX airplanes.
The disagree alert was intended to be a standard, stand-alone feature on MAX airplanes. However, it was not operable on all airplanes because the feature was not activated as intended.
The disagree alert was tied or linked into the angle of attack indicator, which is an optional feature on the MAX. Unless an airline opted for the angle of attack indicator, the disagree alert was not operable.
On every airplane delivered to our customers, including the MAX, all flight data and information needed to safely operate the aircraft is provided in the flight deck and on the flight deck display. This information is readily accessible to pilots, and it always has been.
The air speed, attitude, and altitude displays, together with the stick shaker, are the primary flight information indicators in the flight deck. All recommended pilot actions, checklists, and training are based upon these primary indicators, not on the AOA disagree alert or the angle of attack indicator.
The Boeing 737 MAX jet has come under intense scrutiny following two catastrophic accidents where the blame has pointed to faulty readings on its AOA indicator.