atr42,
If the aircraft is configured for landing with landing flap selected, the only possible GPWS warnings are the Mode 5 alerts ie deviation below the glideslope. If there is no GS then, unless the aircraft is fitted with EGPWS, I dont see what can prevent flying into the ground short of the runway.
EGPWS as fitted to the RJ100 provides RAD ALT auto calls of 500, 100, 50, 40, 30, 20, 10 (feet)
(edited to add last paragraph)
[ 25 November 2001: Message edited by: GearUp CheerUp ]