On the German PPRuNe site i saw this one very recently as an excerpt from B737 infos...
"The GPWS provides alerts for potentially hazardous flight conditions involving
imminent impact with the ground.
(Aircraft with EGPWS)
The GPWS monitors terrain proximity using an internal world wide terrain data
base. Proximate terrain data shows on the navigation display. If there is a potential
terrain conflict, alerts are provided based on estimated time to impact. These alerts
are “look-ahead terrain alerts.”
The GPWS provides alerts based on radio altitude and combinations of barometric
altitude, airspeed, glide slope deviation, and airplane configuration. The alerts are
for:
• excessive descent rate
• excessive terrain closure rate
• altitude loss after takeoff or go-around
• unsafe terrain clearance when not in the landing configuration
• excessive deviation below an ILS glide slope
These alerts are “radio altitude based alerts.”
Ground proximity alerts are accompanied by voice aural alerts and the PULL UP
annunciation on the attitude indicators or, for deviation below glide slope alert, the
BELOW G/S light.
(Aircraft with EGPWS)
Note: Terrain ahead of the airplane may exceed available climb performance. A
ground proximity alert does not guarantee terrain clearance.
(Aircraft without EGPWS)
Note: GPWS does not provide alerts for flight toward vertically sheer terrain, or of
shallow descents when the airplane is in the landing configuration.
(Aircraft with EGPWS)
Look-ahead terrain alerts and radio altitude based alerts are prioritized based on the
level of hazard and the required flight crew reaction time. Look-ahead terrain alerts
and radio altitude based alerts are inhibited by an actual windshear warning (airplane
in windshear).
(Aircraft without EGPWS)
Radio altitude based alerts are prioritized based on the level of hazard and the
required flight crew reaction time. They are inhibited by an actual windshear
warning (airplane in windshear).
Look–Ahead Terrain Alerting
(Aircraft with EGPWS)
The GPWS terrain data base contains detailed terrain data near major airports, and
data in lesser detail for areas between airports. Terrain within 2,000 feet of airplane
barometric altitude shows on the navigation display. The terrain data is not designed
to be an independent navigation aid.
Note: The GPWS terrain data base, look-ahead terrain alerting, and terrain display
do not account for man made obstructions.
(Aircraft with EGPWS)
The terrain display is generated from a data base contained in the GPWS computer
and correlated to GPS position.
Terrain and weather radar cannot show together on a display. If one pilot selects
terrain and the other pilot selects weather radar, each display updates on alternating
sweeps. All other displays (TCAS, LNAV routing, etc.) can show with terrain data.
Look-ahead terrain alerts are based on the airplane’s position, barometric altitude,
vertical flight path, and ground speed."