Using an erroneous barometric reference setting during approach may cause the aircraft to fly lower than the published approach path, when the vertical guidance and trajectory deviations use the barometric reference. This can lead to a risk of controlled flight into terrain in poor visibility conditions or at night.
This article explains the potential consequences of an erroneous barometric reference. It also provides guidance to flight crews on how to detect it, and describes the available system enhancements to alert flight crews when an erroneous BARO reference is detected.