BASIC INSTRUMENT PROCEDURES
the heading pointer points toward the CDI will turn the aircraft toward the
The four dots on the course deviation scale are used in conjunction with the
course deviation indicator bar to signify 5 and 10 radials right or left of the
An OFF flag will appear at the top of the instrument when the course
information signal is too weak or unreliable to provide accurate course or course
The TACAN needle and the CDI are each provided navigation data
independently. If there is a difference between the two indications, it can only
be concluded that at least one indication must be incorrect. Both could be
incorrect. Either one (or both) may have failed. A third source of aircraft
location information would be needed to determine which indication is incorrect
(or if both are incorrect), such as a wingman's TACAN indications, a RADAR
position, or a bearing indication on the BDHI #1 (ADF) needle. If only the
TACAN needle is inoperative, the CDI may still be used for navigation.
vii. If it is decided that the TACAN needle is correct and the CDI is still
functioning, but is merely displaying indications that do not agree exactly with
indications of the TACAN needle, the CDI may still be used by rotating the
course set knob until the Course Deviation Indicator matches the indications of
the TACAN needle on the BDHI. The CDI will then accurately indicate
deviations from the radial.
As stated in NATOPS, the Glideslope bar is not enabled in the
T-2C. It is therefore a normal indication to see an orange "off"
flag on the CDI at the nine o'clock position.
Figure 1-5 Course Indicator
BASIC INSTRUMENT PROCEDURES 1-17