When the Final Approach Fix (FAF) is the active waypoint in an SBAS approach using vertical guidance, a Low Altitude Annunciation may appear if the current aircraft altitude is at least 164 feet below the prescribed altitude at the FAF. A black-on-amber ‘LOW ALT’ annunciation appears in the top of the altimeter accompanied by the altitude constraint above the altimeter changing to amber. The 'LOW ALT' flashes for several seconds, and both indications remains displayed until the condition is resolved.