The Ground Proximity Warning System (GPWS) generates aural and visual warnings, when one of the following conditions occurs between radio heights 30 ft and 2 450 ft

Mode 1: Excessive rate of descent

Mode 2: Excessive terrain closure rate

Mode 4: Unsafe terrain clearance when not in landing configuration

Mode 5: Too far below glideslope.

A Terrain Awareness Display (TAD), which predicts the terrain conflict, and displays the terrain on the ND.

A Terrain Clearance Floor (TCF), which improves the low terrain warning during landing.

On newer aircraft the GPWS occurs between radio heights 10 ft and 2 450 ft.

For more info see FCOM DSC-SURV-040