TM 11-5840-281-35/1
and short pulse width, standby power, other navigation
commissioning flight test and a permanent recording
and fix locations, traffic and holding patterns, and radar
made of results on a selected azimuth radial.
operator performance are tested
Subsequent flight tests fly a similar test on the same
b. Antenna AS-1292/TPN-8 Tilt Angle. The optimum
azimuth radial for a comparison of vertical coverage.
Therefore, if periodical vertical coverage flight test results
tilt angle of azimuth Antenna AS-1292/TPN-8 is
are identical to those of the commissioning flight test, it
determined during the surveillance portion of the flight
can be assumed that the complete radar coverage is
test. Normally, the highest possible tilt angle that will
identical to that of the commissioning flight test, without
permit display of the necessary ground check points and
having to fly a complete radar coverage test. The
fixes and provide the required low altitude coverage is
vertical coverage check is accomplished by flying
desired to minimize ground clutter. The antenna tilt
inbound and outbound through the outer fringe at altitude
angle is lowered initially to an angle required to produce
intervals of 1000 feet, beginning at an altitude of 1000
consistently usable target returns from the ground check
feet and continuing to an altitude of 10,000 feet. Above
points and fixes. Flight test runs at the required
10,000 feet, the vertical outer fringe coverage is checked
minimum altitude are then made through any area of
at 5,000-foot intervals. A periodic vertical check is
heavy ground clutter returns that require radar coverage.
normally made at 1000-, 3000-, 5000-, and 10,000foot
Finally, the tilt angle setting is checked by flying runs on
altitudes. The coverage checks are accomplished in
the radial selected for the vertical coverage check at a
circular polarization with spot checks made on the outer
minimum practical altitude
c. Orientation. The orientation of the radar set group
fringe coverage in linear polarization
e. Fix Coverage. Coverage over air navigation fixes,
and the indicated azimuth bearings of radar returns is
which are used in surveillance operations, are checked
checked by flying inbound or outbound over a well-
to insure adequate radar, radio, and iff coverage.
defined check point of a known bearing, 15 to 20 miles
Normally, the altitude over the fix that provides a
from the radar site. The radar operator rotates the
minimum acceptable radar return (strength 2) or the
overlays on both Control-Indicators C-6988,/TPN-18 until
minimum instrument altitude, whichever is higher, is
the center gridlines are bisecting the flight test aircraft
recorded during the commissioning flight test. All fixes
radar returns. The azimuth bearing indicated on the
are checked during a commissioning flight test, and a
respective compass rose ring by the center gridline
minimum of two fixes are usually checked during
arrow on the overlay must agree with the magnetic
periodic flight tests
azimuth of the check point as measured from an
f. Surveillance Approaches. When surveillance radar
aeronautical chart or other accurate source
d. Radar Coverage. Radar coverage checks are
approaches are made to runways, the approach
accuracy and coverage must be checked for all
made to determine the shape, size, and continuity of the
surveillance
approach
procedures
during
a
complete radiated pattern. This is accomplished by
commissioning flight test. Reliable radar contact must
identifying the limits of coverage at the outer, inner,
be maintained throughout surveillance approaches. To
bottom, and top. The pattern is also checked for weak or
check a surveillance approach, the radar operator
blind spots. Radar contact is generally considered to be
provides courseline (azimuth) corrections relative to the
lost when the average target brilliance falls below 2 (para
runway centerline extended and descent instructions to
4 29) for any three consecutive scans. The outer fringe
the inbound flight test aircraft every mile (measured from
is the maximum range at which an aircraft heading
touchdown), from a point which is usually 5 to 10 miles
outbound can be clearly identified. The inner fringe is
out. The radar return target brilliance (signal strength) is
the minimum range at which an aircraft heading inbound
recorded every scan
can be identified. The bottom fringe is determined by
g. Radar Operator Performance. An evaluation of
flight on an outbound heading at minimum instrument
the performance of each radar operator at a facility is not
altitude to a point where radar contact is lost. The top
required of the official flight test agency, but an initial
fringe is determined by both inbound and outbound
evaluation of the participating radar operators is usually
flights at the maximum altitude of radar coverage. A
conducted prior to
vertical coverage check normally is made during a
4-64
Previous Page
