Prior to next step, ensure all required
correctly, as they cannot be changed after
selection of NAV mode.
Mode selector switch NAV. GPS
will begin to search for satellite
If COLD alternates with the figure of merit
display, the GPS is performing a cold start.
Data selector switch STAT.
The number of satellites (SAT) being
acquired and tracked can be observed.
Estimated position error (EPE) and figure
of merit (FM) can be monitored. The GPS
will be ready for use for INS updating
when SAT 4 is displayed on STAT page 1
and FM (figure of merit) is PM3 or below.
Select page 2 of STAT. Check
almanac age (ALM). If greater
than 5000 hours, force a cold
While the GPS is acquiring
satellites, periodically check
STAT page I for SAT 4
message. Figure of merit
(FM) is another indication of a
converging position fix and can
be directly monitored from
page 1 of any data selection,
where FM alternates with the
system map datum and other
10. SAT 4 should be displayed
within five minutes. If not, check
that position, time, track, and
groundspeed have been entered
correctly. Also check that
satellites are available. If all
correct and satellites are
available, force a cold start.
(b) GPS quick start.
Mode selector switch Set to
NAV directly from OFF. After
power-on test has been
completed, the GPS uses velocity
estimates from the
(if available). If
available from the
assumed. If position and
are not available from the
aircraft, the position estimate
from GPS memory is used, and
the internal low power time
source (LPTS) is used to initialize
As the GPS is acquiring
satellites, position, time, and
velocity estimates can be checked
to ensure that they are
within startup error limits. If so,
monitor STAT page 1. If not, a
normal start is required.
After SAT 4 is achieved with
good EPE (estimated position
error), and FM (figure of merit)
of FM3 or below, check
velocity, and time.
GPS is now ready for normal
GPS cold start.
Mode selector switch INIT.
Data delector switch OPT.
Slew key Select page 4.
Enter 04 on line 1.
Line select key 2 Press next to
COLD START to initiate.
Line select key 3 Press next to
COLD START to clear cold start
message and resume normal
Mode selector switch NAV.
Change 5 3-76E/(3-76F blank)