Early detection of enroute weather, Separation of weather and ground targets – BendixKing IN-182A System RDR-2000 User Manual
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Effective Date: 5/98 RDR 2000 Pilot's Guide: Rev 3
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Operation In-Flight
EARLY DETECTION OF ENROUTE WEATHER
To set the antenna tilt to optimize the radar’s ability to quickly identify sig-
nificant weather, follow these steps:
1) Select the Wx (weather) mode of operation. Adjust Brightness control
as desired.
2) Select the 40 or 80 nm range.
3) Adjust the antenna tilt control down until the entire display is filled with
ground returns.
4) Slowly work the antenna tilt up so that ground returns are painted on
or about the outer one third of the indicator area.
5) Watch the strongest returns seen on the display. If, as they are
approached, they become weaker and fade out after working back inside
the near limit of the general ground return pattern, they are probably
ground returns or insignificant weather. If they continue strong after
working down into the lower half of the indicator, you are approaching a
hazardous storm or storms and should deviate immediately.
6) Examine the area behind strong targets. If radar shadows are
detected you are approaching a hazardous storm or storms and should
deviate immediately, regardless of the aircraft’s altitude. If weather is
being detected, move the antenna tilt control up and down in small incre-
ments until the return object is optimized. At that angle, the most active
vertical level of the storm is being displayed.
7) If a target is suspected to be a weather cell, but is partially obscured
by clutter, move the track line over the target and select Vertical Profile.
If the target is clutter, it will appear symmetrical about the ground return.
If the target is weather, it will be asymmetrical and appear above the
ground return (see the section on
this technique).
SEPARATION OF WEATHER AND GROUND TARGETS
One of the most difficult tasks when using airborne weather radar is sep-
arating weather targets from ground targets. This is especially true since
the maximum return from a storm cell occurs when the radiation beam is
centered on the rainfall shaft. In many cases, this shaft may be no
higher than 5,000 feet thus requiring some antenna down tilt to observe
it. If you are flying at an altitude considerably above this, the antenna
beam will also intersect the ground, thus masking the storm cells with
ground targets. Proper adjustment of the antenna tilt will assist you in
target separation.