Boeing has issued this statement:
We want to provide a response to several news stories yesterday and today reporting on the disagree alert on the 737 MAX.
Boeing included the disagree alert as a standard feature on the MAX, although this 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, the disagree alert 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.
As the MAX safely returns to the air after the software modifications are approved and certified, all MAX production aircraft will have an activated and operable disagree alert and an optional angle of attack indicator. All customers with previously delivered MAX airplanes will have the ability to activate the disagree alert per a service bulletin to airlines.
We are confident that when the MAX returns to the skies, it will be one of the safest airplanes ever to fly.