Components and Characteristics of the Instrument Landing System (ILS)
T-45A UJPT & E2-C2 INav-04
Runway length
700 ft (typical)
Amber Light
Point of intersection
runway and glideslope
250 to 600 ft from
extended.
centerline of runway
Provides Final Approach
Fix For Nonprecision
Sited to provide 55 ft
Approach
(+/- 5 ft) runway
threshold crossing height
Keying: Two dashed/second
Modulation 400 Hz. 95%
from threshold
Blue Light
90 MHz
150 MHz
UHF GLIDESLOPE TRANSMITTER
90 Hz
150 Hz
Glideslope
modulation frequency
Outer marker located 4 to 7 miles
from end of runway, where glideslope
intersects the procedure turn
3 above
(minimum holding) altitude,
horizontal
50 ft vertically.
(optimum)
All marker
transmitters approximately
2 watts of 75 MHz
modulated about 95%.
Course width varies
between 3 - 6
tailored to provide
700 ft at threshold
(full scale limited)
Figure 1: FAA INSTRUMENT LANDING SYSTEM (ILS)
Page 4-4
(6-99) Original
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