Components and Characteristics of the Instrument Landing System (ILS)
T-45A UJPT & E2-C2 INav-04
CAUTION: Pilots should be aware that vehicular traffic
not subject to ATC may cause momentary deviation in
ILS course or glideslope signals. Also, critical areas
around the ILS equipment-shielded antennas are not
protected at uncontrolled airports or at airports with
an operating control tower when weather or visibility
conditions are above those requiring protective
measures.
6.
Usable range is 10 nm, provided aircraft is on localizer course
a.
Intersects inner marker beacon (if installed) approximately
100 ft above runway elevation
b.
Intersects middle marker beacon approximately 200 ft
above runway elevation
c.
Intersects outer marker beacon approximately 1,400 ft
above runway elevation
d.
Pilots must be alert when approaching the glidepath
interception. False courses and reverse sensing will occur
at angles considerably greater than the published path
e.
Make every effort to remain on the indicated glidepath
(reference: FAR 91.129(d)(2)). Exercise caution; avoid
flying below the glidepath to assure obstacle/terrain
clearance is maintained.
f.
The published glideslope threshold crossing height (TCH)
DOES NOT represent the height of the actual glidepath on
course indication above the runway threshold. It is used as
a reference for planning purposes which represents the
height above the runway threshold that an aircraft's glide-
slope antenna should be, if that aircraft remained on a
trajectory formed by the four-mile-to-middle marker glide-
path segment.
g.
Pilots must be aware of the vertical height between the
aircraft's glideslope antenna and the main gear in the
landing configuration. At the DH, plan to adjust the de-
scent angle accordingly if the published TCH indicates the
wheel crossing height over the runway threshold may not
be satisfactory. Tests indicate a comfortable wheel
crossing height is approximately 20 to 30 feet, depending
on the type of aircraft.
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(6-99) Original
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