GPS receiver itself. With Selective Availability turned off as currently, the
accuracy is usually better than 75 feet and with Selective Availability
turned on, short term accuracy is on the order of 400 feet, but the geo-
metric altitude should be within 100 feet.
TERRAIN AWARENESS DISPLAY
Graphical display of EGPWS terrain and obstacle data is the most impor-
tant enhancement to Situational Awareness. This is especially true for
lower performance aircraft. In addition to showing terrain ahead of the
aircraft, (depending on configuration settings and display types) the
system shows MSL altitude, Magnetic Track, Range in NM, and the ele-
vations of the highest and lowest terrain features shown on the display.
The color and intensity of the terrain displayed instantly alerts the pilot to
areas of dangerous terrain and conversely to areas of less precipitous
terrain. Range of the Terrain Display is selectable by the pilot from 1 nm
to 320 nm.
The following figure shows the Terrain Display color patterns when the
aircraft is at lower altitudes, with terrain near or above the aircraft altitude
for the display range selected by the pilot.
Rev 2 September/2001
KMD 550/850 Terrain Addendum