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How many AoA sensors does a 737 Max have?
two
Stall is indicated through an angle of attack (AoA) sensor – the 737 Max is fitted with two, but MCAS only used one. If that AoA sensor failed, then the MCAS could activate when it shouldn’t, unnecessarily pushing the nose down.
What was the 737 Max problem?
Airlines pulled dozens of 737 MAX jets from service early last month after Boeing warned of a production-related electrical grounding problem in a backup power control unit situated in the cockpit on some recently built airplanes.
What is the disagree light on a Boeing 737 MAX?
Boeing’s optional safety features, in part, could have helped the pilots detect any erroneous readings. One of the optional upgrades, the angle of attack indicator, displays the readings of the two [angle of attack] sensors. The other, called a disagree light, is activated if those sensors are at odds with one another.
When to activate AOA Disagree alert on Boeing 737?
Accordingly, the software activated the AOA Disagree alert only if an airline opted for the AOA indicator. When the discrepancy between the requirements and the software was identified, Boeing followed its standard process for determining the appropriate resolution of such issues.
Are there angle of attack sensors on 737 MAX?
As I noted in a previous posting, the Pilatus PC-12, a much cheaper and simpler airplane (1 engine and 9 passenger seats), doesn’t do any nose-down pushing unless two separate angle-of-attack sensors, and their respective computers, agree. Boeing’s ideas of a system that works silently (so pilots don’t realize it is operating)
When to use the AOA Disagree alert feature?
In identifying the AOA Disagree alert as one among a number of indications that could result from erroneous AOA, both the OMB and the AD described the AOA Disagree alert feature as available only if the AOA indicator option is installed. Boeing discussed the status of the AOA Disagree alert with the FAA in the wake of the Lion Air accident.