INSTRUMENT FLIGHT RULES WORKBOOK
Visual information: approach lights, touchdown and centerline lights, runway lights.
Compass locators located at the outer marker (OM) or middle marker (MM) may be substituted
for marker beacons. DME, when specified in the procedure, may be substituted for the OM
(marker beacon receiver not installed in T-34).
108.10 to 111.95 MHz. Signals provide the pilot with course guidance to the runway centerline.
The approach course of the localizer is called the front course and is used with other functional
parts, e.g., glideslope, marker beacons, etc. The localizer signal is transmitted at the far end of
the runway. It is adjusted for a course width (full scale fly-left to a full scale fly-right) of 700
feet at the runway threshold.
The course line along the extended centerline of a runway, in the opposite direction to the front
course is called the back course.
Unless the aircraft's ILS equipment includes reverse sensing
capability, when flying inbound on the back course it is necessary
to steer the aircraft in the direction opposite the needle deflection
when making corrections from off-course to on-course. This
"flying away from the needle" is also required when flying
outbound on the front course of the localizer. Do not use back
course signals for approach unless a back course approach
procedure is published for that particular runway and the approach
is authorized by ATC.
Identification is in International Morse Code and consists of a three-letter identifier preceded by
the letter I ( WUDQVPLWWHG RQ WKH ORFDOL]HU IUHTXHQF\
The localizer provides course guidance throughout the descent path to the runway threshold from
a distance of 18 NM from the antenna between an altitude of 1000 feet above the highest terrain
along the course line and 4500 feet above the elevation of the antenna site. Proper off-course
indications are provided throughout the following angular areas of the operational service
To 10º either side of the course along a radius of 18 NM from the antenna; and
From 10 to 35 degrees either side of the course along a radius of 10 NM (Figure 1-5).
1-8 INTRODUCTION TO AIRBORNE NAVIGATION AND COMMUNICATIONS
EQUIPMENT AND PRINCIPLES OF OPERATION