BendixKing IN-182A System RDR-2000 - Manual (Page 14)

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Effective Date: 5/98 RDR 2000 Pilot's Guide: Rev 3
RADAR TILT ANGLE CALCULATOR USER INSTRUCTIONS
This instructional tool includes overlays for 10”, 12” and 18” antennas.
Use the overlay for the antenna size installed in the aircraft. If desired,
the unwanted overlays may be detached by cutting the plastic of the
unwanted overlay from the bottom edge to the fastener. Then, pull the
plastic apart until it releases from the fastener.
Use the following procedure while viewing the following diagram to
determine the proper radar antenna tilt angle in a given situation:
1) Choose one of the three range diagrams that matches the range
selected on the radar. In this case we have chosen the 80 nm scale
diagram.
2) Slide the overlay so that the left indice aligns with the aircraft alti-
tude. This is best done keeping the overlay parallel to the diagram and
grasping the extension tab and the overlay at the time.
3) Now, tilt the overlay (without sliding it up or down) so that the
center line of the radar beam intersects the red (below freezing alti-
tude) part of the range diagram at the range of the echo in question
displayed on the radar screen. The above freezing part of the thunder-
storm cell gives the best reflectivity for radar energy.
4) The correct tilt angle is shown where the degree mark aligns with
the Tilt Angle Reference Line.
Note: To improve distinction between the weather echo and the clutter,
increase the tilt angle. Remember, the correct weather intensity is
shown at the tilt angle determined with the calculator.
The higher the altitude, the more down tilt is required. Therefore,
clutter distinction is more of a problem. In this case, the intensity of the
weather displayed should be noted from the tilt angle shown on the cal-
culator. Now raise the tilt angle to push the ground clutter out in range
to separate it from the weather display. The echo intensity will appear
to weaken because the radar is looking at the freezing part of the cell.
Remember to also use Vertical Profile on suspected cells.
Theory of Operation