Page 880 - PPL-engelsk 2025

Navigation

9.9.2.7 RMI

In larger aircraft, you have an RMI (radio magnetic

indicator), like the one on the right.

The RMI shows both the course and the ADF needle.

You can read the magnetic bearing to the beacon directly

here, or if there are several pointers, you can have bearings from 2 beacons at

once.

Try your properties / limitations in ADF navigation here (may take a while to

open) - see a tutorial on Youtube here

Back to table of contents

9.9.3 VOR

VOR (VHF OMNI RANGE) is a radio navigation system that works in the VHF

range. Completely accurate on frequencies with even decimals from 108 to 112

MHz, as well as all frequencies between 112 and 117.95 MHz.

The system consists of a ground part, as well as the aircraft part with VOR

receiver (Nav radio) and indicator (pointer instrument - see below).

9.9.3.1 Ground part - transmitter and antenna

The ground part consists of a transmitter and an antenna. The VOR is divided
o
into 360 (radials).

The VOR transmits radials (radio waves) in relation to magnetic north. The theory

behind the system is that you send 2 signals via the ground antenna:

A reference signal and then a variable signal in the form of a positive and a

negative half-period.

Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 880