Avidyne IFD540 Pilot's Manual page 98

TA can be triggered by either terrain or database obstacles (e.g.
towers > 200' AGL tall buildings, etc). Any terrain that is within a
10nm radius of aircraft position and between 100' below aircraft
altitude and 1000' below aircraft altitude will generate yellow
hatched indications on the map pages. Any terrain that is within a
10nm radius of the aircraft position and is 100' below aircraft to
anything above aircraft altitude will generate red hatched
indications on the map pages.
Any obstacle in the database within a 5nm radius of the aircraft
position and whose top is within 2000' vertically (above or below)
of the aircraft altitude will generate a cyan (blue) threat bubble
over the obstacle on the map pages. Obstacles inside a 3nm
radius of the aircraft position and whose top is between 100'
below aircraft altitude and 1000' below aircraft altitude will
generate a yellow threat bubble over the obstacle. Obstacles
inside a 1.5nm radius of the aircraft position and whose top is
between 100' below aircraft to anything above aircraft altitude will
generate a red threat bubble over the obstacle.
TA can be turned off via the "User Options" LSK of the SETUP
tab on the AUX page. When turned off, there is no terrain TA
display on the map pages for the individual IFD.
A rectangular suppression area exists for all runways in the FMS
database and user waypoints that have been designated to be an
airfield (see User Waypoints section earlier in this manual).
Terrain inside this suppression area will not generate any TA
indication. Dimensions of the TA runway suppression area are
0.25 nm laterally and 0.5 nm off each runway end. Airports with
no known runway orientation use a 1nm circular suppression
area. Obstacle threat bubbles can still appear inside the
suppression area.
Runway Suppression Area Depiction
3-22 Map Pages