User guide

4.2 HEADING FAILURE
Invalid heading is indicated by replacing the digital heading readout
with a red “HDG” flag. The compass card will continue to be dis-
played and will rotate in response to the heading signal received by
the EHSI. If the heading signal is not received by the EHSI, the com-
pass card will freeze at the last valid value for heading and the “HDG”
flag will be in view.
When the “HDG” flag is displayed, the positions of the selected head-
ing bug and selected course arrow should not be trusted. This is
because heading is used to generate the selected heading and
selected course signals received by the EHSI, and the validity of
heading at that location (outside the EHSI) is unknown.
Special Considerations
4-4
FPD 500 FLAT PANEL DISPLAY SYSTEM
Rev. 0
Dec/97
a
Figure 4.2-1
Heading Failure Flag
N
M
R
I
DIM
TEST
BRT
0
33
30
27
24
21
15
12
9
6
3
18
RAD 1
INS1
1234
INS2
1324
HDG
GS