Like all sensors out there in the atmosphere, icing is an issue. So not only are they error prone, but failures are sometimes not independent. Airbus planes fro

Like all sensors out there in the atmosphere, icing is an issue. So not only are they error prone, but failures are sometimes not independent. Airbus planes from the A320 family have three such sensors, but it so happened that on November 5th, 2014, an A321 had two sensors freeze in the wrong position during flight. Two sensors against one win, so the flight envelope protection system kicked in and the aircraft started to nose dive. It lost 4000 feet in altitude before the crew regained control... Details of the flight if you want to do some research: Lufthansa Airbus A321-200, registration D-AIDP, performing flight LH-1829 from Bilbao, SP (Spain) to Munich (Germany) on November 5th, 2014.