INSTRUMENT FLIGHT RULES WORKBOOK
Although the compass card appears to rotate when the aircraft is
turning, it is actually the aircraft turning around the card. When
making a right turn, the card appears to rotate to the left and to the
right for a left turn. Headings will increase numerically when
turning right and decrease when turning left.
The TACAN, or No. 2 needle on the RMI, is used to display radial information from a TACAN
navigation facility. The aircraft's TACAN receiver electronically measures the magnetic bearing
from the station. The head of the TACAN needle indicates the magnetic course to the facility,
and the tail indicates the magnetic bearing from the facility. Remember that a magnetic bearing
from a facility is the definition of a radial, so the tail of the TACAN needle will always indicate
the radial the aircraft is on. Use the TACAN needle when referring to the following examples
Figure 1-23 RMI Example A and Example B
In example A, the aircraft is on the 250 radial. The magnetic course to the facility is 070º. A
turn to a magnetic heading of 070º, placing the head of the TACAN needle at the top of the RMI,
will take the aircraft to the facility. In example B, the magnetic course to the facility is 220. The
aircraft is on the 040 radial and heading 180º magnetic.
The VOR needle on the RMI is used to display radial information from a VOR facility. The
head of the VOR needle indicates the magnetic course to the VOR station and the tail indicates
the radial from the VOR station.
INTRODUCTION TO AIRBORNE NAVIGATION AND COMMUNICATIONS
EQUIPMENT AND PRINCIPLES OF OPERATION 1-29