Basic Radar Antenna Tilt Setup (Gtn 7Xx Only) - Garmin GTN 650 Series Pilot's Manual Upgrade Supplement

5.3

Basic Radar Antenna Tilt Setup (GTN 7XX Only)

The following discussion is a simple method for setting up the weather radar
antenna tilt for most situations. It is not to be considered an all encompassing
setup that will work in all situations, but this method does provide good overall
parameters for the monitoring of threats. Ultimately, it is desired to have the
antenna tilted so that the bottom of the radar beam is four degrees below parallel
with the ground. The following discussion explains one way of achieving this.
With the aircraft flying level, adjust the antenna tilt so ground returns are
displayed at a distance that equals the aircraft' s current altitude (AGL) divided
by 1,000. For example, if the aircraft is at 14,000 feet, adjust the tilt so the front
edge of ground returns are displayed at 14 NM. Note this antenna tilt angle
setting. Now, raise the antenna tilt 6º above this setting. The bottom of the radar
beam is now angled down 4º from parallel with the ground.
Practical Application Using the Basic Tilt Setup
At this point, when flying at altitudes between 2,000 and 30,000 feet AGL,
any displayed target return should scrutinized. If the displayed target advances
on the screen to 5 NM of the aircraft, avoid it. This may be either weather or
ground returns that are 2,000 feet or less below the aircraft. Raising the antenna
tilt 4º can help separate ground returns from weather returns in relatively flat
terrain. This will place the bottom of the radar beam level with the ground.
Return the antenna tilt to the previous setting after a few sweeps.
36
GTN 650/750 Series SW V3.00 Upgrade Supplement 190- 01007-05 Rev A
MPEL
Boundary
11' for 12" antenna
Figure 5-5 MPEL Boundary