Embraer EMB145 Operation Manual page 1656

CREW
AIRPLANE
AWARENESS
OPERATIONS
MANUAL
OBSTACLE ALERTING
A database of man-made obstacles is stored internal to the EGPWS
version 216. The terrain "cell" on which the obstacle resides is coded
as an obstacle with an elevation equal to the obstacles MSL height.
The same software algorithms that detect and display terrain conflict
are used to detect and display obstacle conflict. If any obstacle is
"seen" in the database by the algorithms, annunciators are illuminated
and voice "CAUTION OBSTACLE" sounds approximately 45 seconds
prior to potencial terrain conflict and the aural "OBSTACLE
OBSTACLE PULL UP" sounds approximately 30 seconds prior to
potencial terrain conflict.
GEOMETRIC ALTITUDE
EGPWS version 216 and on uses Geometric Altitude algorithm to
determine airplane altitude. The Geometric Altitude computation uses
an improved pressure altitude calculation, GPS altitude, radio altitude,
terrain and runway elevation data to reduce or eliminate errors
potentially induced in corrected barometric altitude by temperature
extremes, non-standard altitude conditions and altimeter miss-sets.
Geometric Altitude also allows continuous EGPWS operations in QFE
environments without custom inputs or special operational procedures.
Page Code
2-04-30 35 01
REVISION 38