BendixKing IN-182A System RDR-2000 - Manual (Page 32)

In practice, when flying over fairly even terrain, ground returns are diffi-
cult to paint when the angle of incidence of the radiated beam becomes
large (see Looking Angle pg. 22) and, therefore, causes the beam to
travel almost parallel to the ground (see figure below.)
However, objects such as large buildings in cities, steep hills, mountains
or storms will reflect the signal and can show strong returns at distances
greater than those shown below.
Ground Returns and Tilt Management
Over-scanning and Tilt Management
When flying at high altitudes, the use of proper tilt management ensures
observation of weather targets without over scanning. For example, a
low altitude storm detected on the long range setting may disappear from
the display as it is approached. While it may have dissipated during your
approach toward the storm, don’t count on it. It may be that you are
directing the radiated energy from the antenna above the storm as you
get closer. Judicious management of the antenna tilt control will avoid
over-scanning a weather target.
Note: Please be aware that equivalent ground returns will require dif-
ferent tilt settings because of different ground reflectivities (for example,
dry soil requires a different tilt setting than the more reflective tropical
forest).
28
Effective Date: 5/98 RDR 2000 Pilot's Guide: Rev 3
Operation In-Flight
150 NM or Greater