Increase Descent RA's are inhibited below ______ AGL, with different values when climbing vs descending.

Increase Descent RA's are inhibited below ______ AGL, with different values when climbing vs descending.

• A. Below 1,650 ft AGL when climbing; below 1,450 ft AGL with descending.
• B. Below 2,000 ft AGL when climbing; below 1,800 ft AGL when descending.
• C. Below 1,000 ft AGL when climbing; below 800 ft AGL when descending.
• D. Below 3,000 ft AGL when climbing; below 2,800 ft AGL when descending.

Answer: (A)

This tests how TCAS suppresses an Increase Descent resolution advisory near the ground to keep alerts practical and safe. The system uses different lift-off and approach geometries for climb versus descent, so it applies different inhibit thresholds to avoid spurious or disruptive advisories when you’re close to terrain or the runway environment. Specifically, an Increase Descent advisory is inhibited below 1,650 ft AGL during climb, and below 1,450 ft AGL during descent. Above these altitudes, the advisory can be issued if traffic demands it. This is why the correct limits are 1,650 ft for climbing and 1,450 ft for descending. The other options propose different thresholds that don’t match the standard TCAS inhibit values.

This tests how TCAS suppresses an Increase Descent resolution advisory near the ground to keep alerts practical and safe. The system uses different lift-off and approach geometries for climb versus descent, so it applies different inhibit thresholds to avoid spurious or disruptive advisories when you’re close to terrain or the runway environment.

Specifically, an Increase Descent advisory is inhibited below 1,650 ft AGL during climb, and below 1,450 ft AGL during descent. Above these altitudes, the advisory can be issued if traffic demands it. This is why the correct limits are 1,650 ft for climbing and 1,450 ft for descending. The other options propose different thresholds that don’t match the standard TCAS inhibit values.