Originally Posted by
tdracer
Ambient pressure indications to the FADEC. Pamb from the engine is compared to Pamb from the aircraft - if they agree within a tolerance the FADEC will use the aircraft (so that when everything is working normally, all the systems are using the same Pamb). However is the engine Pamb indication is significantly different relative to the aircraft values, the FADEC will use the engine sensed value to protect engine to engine isolation.