Final answer:
Aircraft ground clearance, glide-slope deviation, and sink rate are monitored by the Enhanced Ground Proximity Warning System (EGPWS), which is an advanced version of older systems with added features for improved accuracy.
Step-by-step explanation:
Aircraft ground clearance, glide-slope deviation, and sink rate are monitored by EGPWS (Enhanced Ground Proximity Warning System). While TAWS (Terrain Awareness and Warning System) and GPWS (Ground Proximity Warning System) are older systems that are designed to prevent controlled flight into terrain by issuing warnings for unsafe conditions, the EGPWS is an advanced version that incorporates additional features such as a database of terrain and obstacles, making it more accurate and reliable than its predecessors.
The RADALT (Radar Altimeter) is a device used to measure the distance from the aircraft to the ground directly below it, providing crucial ground clearance information, particularly during the landing phase. However, it does not directly monitor glide-slope deviation or sink rate as EGPWS does.