Re Terrain profile / EGPWS alerts;
I recall a briefing by Honeywell at an operator’s conference (8 yrs ago ?) which indicated continuing improvements in the terrain clearance warnings to help avoid undershoots.
The terrain clearance floor (TCF) ‘cut off’ distance originally ended at 1nm from the runway threshold, but was to be reduced to 0.5nm assuming accurate runway detection and availability of survey data, which should be the case in the US.
A further reduction to 0.25 nm might be available with GPS based aircraft position. The effect of these changes would provide a warning boundary of 150 ft above threshold datum at 1.25nm to 0 ft at 0.25nm.
Does anyone have further details of this, and if the modifications were adopted which software mod package (SW 218-218)?
w.r.t. this accident what was the EGPWS mod state, and what navigation source was used for EGPWS position?