1.18.1. FMA FAULT 2
As per the Boeing Company explanation, FMA FAULT 2 record means that the AFDS identified pitch mode failure that is the a/c could no longer be tracking the glideslope beam (see FCT 747 Pages 5.19 - 5.20).The mode failure results in the following:
- the pitch flight director bars are removed from the PFDs;
- a yellow line is displayed through the G/S mode annunciation on the PFDs (FMA);
- both MASTER CAUTION lights are illuminated;
- a MASTER CAUTION aural is activated;
- an amber AUTOPILOT caution message is annunciated on EICAS.
Meanwhile the A/P will not disengage. In the pitch channel the A/P will maintain an inertial path which track a constant 3° slope regardless of the actual glideslope angle at a certain airdrome. The path will be maintained until a valid glideslope signal is regained or until the crew intervenes by disengaging the A/P or initiating a go-around (TOGA switch pushed).Without crew intervention the A/P will maintain the inertial path until the FLARE mode is engaged. The Autoland status LAND 3 (or LAND 2) will also continue being annunciated. According to the manufacturer’s information the inertial path generation is a feature in Boeing airplane models 737, 747-400/-8, 757, 767, 777, 787 that allows the A/P to continue the approach for disruptions of either G/S or LOC ground station signals.