Instrument Landing System (ILS)

INSTRUMENT FLIGHT RULES WORKBOOK

CHAPTER ONE

Magnetic North

Signals are in Phase at Magnetic

North and Vary Elsewhere Around

the Station.

315

270

225

135

Variable

180

Phase

Signal

Reference

Phase

Signal

Figure 1-4 VOR Signal Phase Angle Relationship

104. INSTRUMENT LANDING SYSTEM (ILS)

The ILS is designed to provide an approach path for exact alignment and descent of an aircraft

on final approach to a runway. The ground equipment consists of two highly directional

transmitting systems and, along the approach, three (or fewer) marker beacons. The directional

transmitters are known as the localizer and glideslope transmitters.

The system may be divided functionally into three parts:

Guidance information: localizer and glideslope;

Range information: marker beacon and DME;

INTRODUCTION TO AIRBORNE NAVIGATION AND COMMUNICATIONS

EQUIPMENT AND PRINCIPLES OF OPERATION 1-7