INSTRUMENT FLIGHT RULES WORKBOOK
COURSE DEVIATION INDICATOR
The CDI displays radial information received by the aircraft's VOR or TACAN receiver (Figure
1-26). The CDI indicates the aircraft's position in relation to the selected course. A toggle
switch on the instrument panel above the CDI marked VOR-TACAN allows the pilot to select
either the VOR or the TACAN navigation system as the source of information displayed on the
Figure 1-26 IND-350
In review, a radial is one of 360 magnetic bearings which radiate from a VOR or TACAN
facility and the radial the aircraft is on is indicated by the tail of the VOR/TACAN needle.
Review Figure 1-27.
1-32 INTRODUCTION TO AIRBORNE NAVIGATION AND COMMUNICATIONS
EQUIPMENT AND PRINCIPLES OF OPERATION