Refresher - P-12820112

T-45C TS INav-04; ADV INav-02

Components and Characteristics of the Instrument Landing System (ILS)

REFRESHER

Recall:

Components of an ILS approach ground equipment

PRESENTATION

Instrument Landing System (ILS)

NOTE: The ILS information approach system is made up of three functional

components; the guidance systems, range systems, and the visual systems.

This lesson discusses each of the systems in detail.

Guidance Systems 2.9.4.6.5, 2.9.4.6.5.1, 2.9.4.6.5.2

NOTE: The guidance system of the ILS is made up of two parts, the

localizer transmitter (azimuth information) and the glideslope transmitter

(glidepath information).

A. Localizer - azimuth beacon transmitter

Sg 1, fr 3

Fig 1: FAA Instrument

Landing System (ILS)

1. The localizer is the first half of the ILS guidance system

2. Provides precise horizontal (course) guidance information to the

runway centerline by way of a localized navigational beacon to

localizer equipped aircraft within the sensing area of the localizer

beacon signal

3. Localizer frequency is identified by international Morse code

consisting of a four letter identifier with the first letter of the

sequence beginning with the letter “I” (..)

4. Transmitter operates on one of 40 channels specifically set aside

for ILS/LOC

Sg 1, fr 4

Fig 2: Localizer Transmitter

Signal Acquisition Limits

5. Frequency range of 108.10 to 111.95 MHz (lower end of the VOR

frequency range)

6. Beacon beam is 5 degrees wide as seen on cockpit instruments

and is approximately 4 times as sensitive as conventional VOR or

TACAN NAV signals

7. Beam is produced by two overlapping modulated frequencies

a. Left side of inbound course is a 90 Hz signal and the right side

is a 150 Hz signal

(2-02) Original

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