They’re vulnerable to bird strikes, damage from jetway equipment, or other obstructions. FAA records showed more than two hundred instances of malfunctioning AoA vanes alone since 2004, some of which had set off cockpit alerts. Ewbank and the others urged implementation of a backup system called “synthetic airspeed” already in use on the Dreamliner—essentially a computer program to compare values of all the sensors. If an illogical reading came from any of them—such as the AoA vanes linked to the new MCAS software—it would be deactivated.
