Navigation information is now available
from the INS for display on the pilot and
co-pilot RMIs and on the pilot and copi-
lot HSIs, as determined by the COURSE
INDICATOR and RMI select switches.
To fly selected INS course:
Pilots COURSE INDICATOR
switch - INS.
2. Pilots RMI select switch - INS.
3. Horizontal Situation Indicators
(pilots and/or copilots HSI) -
Steer toward indicators.
4. CDU ALERT light - Monitor.
Observe illumination approx 1.3
minutes before reaching point for
automatic leg switch. Indicator
flashes on and off after passing a
waypoint, if AUTO-MAN switch
is in MAN.
(9.) Aided TACAN operation:
If high accuracy alignment
wait for the READY NAV
selecting NAV mode.
Mode selector - NAV.
Data selector - DSRTK/STS.
3. Key 4 - Press. Observe right
data display is 000004 and
light is illuminated.
4. INSERT/ADVANCE pushbutton
- Press. Observe right data display
ADVANCE pushbutton light is
Every 30 seconds, the INS will select next
eligible TACAN station in sequence for
updating. To be eligible, TACAN station
range must be between 5 and 150 nm and
channel between 1 and 126.
5. Data selector - L/L WY PT or
UTM WY PT.
Keys 7 and 9- Press simulta-
neously. Observe channel number
of the TACAN station being used
for navigation flashes on and off.
Data displays indicate coordi-
nates of station selected via thum-
7. To monitor station selection -
Observe FROM-TO data display.
Observe only the number of sta-
tions eligible for mixing will be
displayed. A 0 indicates that
none of the 9 stations are eligible
8. Monitor INS UPDATE annun-
Mixing will not be annunciated if: (a)
TACAN control is inappropriately set; (b)
TACAN station data loaded in error; (c)
aircraft look-down angle is greater than
30; (d) horizontal ground distance is less
than two times the altitude. When 2 min-
utes elapse without an update, the NO
INS UPDATE annunciator will illumi-
9. To return INS display to normal
- Set data selector to any position
except WYPT or DIS/TIME.
To monitor program of mix - Set
data selector to DSRTK/STS.
(Observe Accuracy Index (AI) will
decrement to 0.)
To insure favorable geometry during the
update process, the following TACAN sta-
tion criteria should be observed:
One station must be at least 15
nm off course.
For optimum single TACAN
updating, update should continue
until aircraft has passed the sta-
F o r o p t i m u m d u a l T A C AN
TACAN station and one "on-
For optimum multi-TACAN sta-
tion updating, the stations should