TM 1-1510-223-10
Change 3 3-76.1/(3-76.2 blank)
FOM = 6, then EPE < 1640
FOM = 7, then EPE < 3280
FOM = 8, then EPE < 16404
FOM = 9, then EPE < 16404
(4) GPS normal start-up mode. If there is a large
difference between the initial GPS position and the INS
alignment position (approximately 54 NM or larger), the
ASE/ACS selects the NORMAL start-up mode. When
auto selected, the legend NORMAL appears below the
text NAV INIT and the ASE/ACS will place the GPS in the
INIT mode; send the INS latitude, longitude, and datum
to the GPS; and reselect the NAV mode. When the NOR-
MAL start-up mode is complete, the NORMAL legend
below the NAV INIT text is removed to cue the crew that
the GPS is ready for normal navigation. The transition
from NORMAL start to navigate mode occurs when 3 or
more satellites are being tracked and the figure of merit
is less than 9.
(5) GPS cold start-up mode. If the GPS almanac
data is more than 5000 hours old, the GPS initiates a
COLD start-up mode. When this happens, the legend
COLD will appear below the text NAV INIT and the GPS
will initiate a search for a good satellite to download alma-
nac data (this process can take up to 13 minutes). The
total time to complete the COLD start-up is totally depen-
dent on satellite visibility. If COLD start-up is initiated and
satellite number 14 (the first in the search sequence) is
visible and good, the whole almanac downloading and
start-up sequence should be completed in less than 20
minutes. When the COLD start-up mode is complete, the
COLD legend below the NAV INIT text is removed to cue
the crew that the GPS is ready for normal navigation. The
transition from COLD start to navigate mode occurs
when 3 or more satellites are being tracked and the figure
of merit is less than 9.
(6) Map datum entry. With a local map datum en-
tered in the scratchpad and GPS in the INIT mode, de-
pressing R2 will cause the scratchpadded data to be
displayed to the left of the text at R2. A valid datum is any
number from 1 through 47 except 20. Datum cross refer-
ence is shown in table 3-7. Map datum default is 47.
3-29. CHALS USE OF GPS AND INS.
a. CHALS Concept. CHALS (Communication High
Accuracy Airborne Location System), is an emitter loca-
tion system that provides timely, high accuracy locations
required for targeting and to support emitter associations
and battlefield situation assessment. CHALS provides
this capability through coherent processing of differential
