TM 11-5840-281-35/1
the actual flight test by observing the accuracy with which
aircraft and advises the pilot of the aircraft position
the aircraft is controlled, clarity of instructions and
relative to the runway centerline. The azimuth courseline
advisories, conformance to standard radiotelephone
cursor alignment is correct when information from both
procedures, and response to simulated emergency
sources is the same
(2) Visual method. The flight test aircraft flies
conditions. Radar operators participating in official flight
tests are expected to be familiar with flight test
inbound from a point 10 to 12 miles from the touchdown
procedures described in TM 11-2557-25
point, descending at a normal glide angle, the radar
h. Communications. The communication checks are
operator provides information to the flight test pilot to
normally incorporated with other checks. All required
enable him to fly on the azimuth courseline cursor
frequencies, including those of standby equipment are
(runway centerline extended). This information is given
checked for clarity and signal strength to the maximum
as "left," "right," or "on centerline." The aircraft range
radar coverage range. A check for communication blind
from touchdown is given to the flight test pilot at least
spots is maintained during all phases of an official flight
once each mile. The flight test pilot determines whether
test
the azimuth courseline cursor is correct by visual
reference to the runway
c.
Elevation Glidepath Check.
The elevation
4-32.
Precision Approach Radar Phase of Flight
glidepath may be checked by the theodolite method or
Tests
the range mark method. A third method, the checkpoint
method, uses surveyed ground checkpoints or
a. General. The precision approach radar (par)
checkpoints determined by measurements from a large
phase of the flight test checks the accuracies of the
scale map.
The formula and procedure for the
radar siting, azimuth courseline, elevation glidepath,
checkpoint method are provided in TM 11-2557-25.
range marks, and radar coverage. Radar operator
During an official flight test utilizing the theodolite
performance, communications, standby power, and
method, the theodolite operator must have an assistant
operating procedures are also checked.
Only
and two-way communications on a frequency common to
experienced radar operators should participate in the
the radar operator and the flight test aircraft. For flight
courseline alignment checks. Nautical miles are used
testing with local aircraft, the theodolite operator can
and ranges are measured from the touchdown point.
operate with just a receiver (tuned to the frequency
The par checks are made in the circular polarized mode,
common to the radar operator and the flight test aircraft)
with spot checks made in the linear mode. It is important
and an assistant
that the Control-Indicators C-6988/TPN-18 that will be
(1) Theodolite method. The theodolite is set up
used in operating Radar Set AN/TPN-18 be used in the
beside the runway slightly closer to the runway threshold
flight test, since the data displayed (target brilliance and
than the actual touchdown point on the runway, so that
cathode-ray tube persistence) and alignment accuracies
when the glidepath line-of sight is projected through the
(synchro alignment and ANGLE VOLTS control
theodolite, it will intercept a point adjacent to the runway
calibration) can vary between different Control-Indicators
that is exactly opposite the actual touchdown point on the
C-6988/TPN-18
runway. After communications are established between
b.
Azimuth Courseline Check.
The theodolite
the radar operator, pilot, and theodolite operator, the
method or the visual method normally may be used. At
flight test aircraft proceeds inbound from a point
some locations where the runway edges or center of the
approximately 12 miles from touchdown and at an
runway are not easily distinguished from the air, the
altitude of approximately 2500 feet above the touchdown
theodolite method should be used
elevation. The radar operator advises the pilot on
(1) Theodolite method. The theodolite is set up
interception of the elevation glidepath cursor and advises
on the runway centerline or in the clear zone on the
the pilot of the aircraft position relative to the elevation
runway centerline extended. The flight test aircraft flies
cursor in terms of "high," "low," and "on glidepath," for
inbound from a point 10 to 12 miles from the touchdown
the inbound run to as close to touchdown as practical.
point, descending at a normal glide angle. The radar
The theodolite operator
operator will give the flight test pilot continuous
information as to aircraft position relative to the azimuth
courseline cursor, which represents the runway
centerline extended. During an official flight test, the
theodolite operator continuously tracks the flight test
4-65
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