Garmin G1000 Pilot's Manual page 250

MULTI FUNCTION DISPLAY
The Satellite Status Page also indicates the accuracy
of the position fix, using Estimated Position Error (EPE)
and Dilution of Precision (DOP) figures. DOP measures
satellite geometry quality (i.e., number of satellites
received and where they are relative to each other) on a
range from 0.0 to 9.9. The lowest numbers are the best
accuracy and the highest numbers are the worst. EPE uses
DOP and other factors to calculate a horizontal position
error, in feet or meters.
RAIM Prediction
"RAIM" is an acronym for Receiver Autonomous
Integrity Monitoring, a GPS receiver function that performs
a consistency check on all tracked satellites. RAIM ensures
that the available satellite geometry will allow the receiver
to calculate a position within a specified protection limit
(2.0 nautical miles for oceanic and en route, 1.0 NM for
terminal and 0.3 NM for non-precision approaches).
During oceanic, en-route, and terminal phases of flight,
RAIM is available nearly 100% of the time.
Because of the tighter protection limit on approaches,
there may be times when RAIM is not available. The
G1000 automatically monitors RAIM and warns you with
an alert message when it is not available. If RAIM is not
available when crossing the FAF, the pilot must fly the
missed approach procedure.
The RAIM prediction function also indicates whether
RAIM will be available for a specified date and time.
If RAIM is not predicted to be available for the final
approach course, the approach does not become active
— as indicated by an "Approach is not active" message,
and a "RAIM not available from FAF to MAP" message.
To predict RAIM availability:
1. Select the GPS Status Page.
2. Press the FMS knob. Turn the small and large
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7.
Garmin G1000 Pilot's Guide for Cessna Nav III
FMS knobs to select the 'WAYPOINT' field.
Turn the small FMS knob to display the
Waypoint Information Page.
Turn the small and large FMS knobs to enter
the desired waypoint. Press the ENT key to
accept.
Turn the small and large FMS knobs to enter
an arrival time and press the ENT key.
Turn the small and large FMS knob to enter an
arrival date.
The cursor highlights the 'COMPUTE RAIM'
field. Press the ENT key to compute RAIM. The
following options are displayed:
• 'COMPUTE RAIM?' if RAIM has not been
computed for the current waypoint, time, and
date combination
• 'COMPUTING AVAILABILITY' if the RAIM
calculation is in progress
• 'RAIM AVAILABLE' if RAIM is predicted to
be available for the given combination of
waypoint, time, and date
• 'RAIM NOT AVAILABLE' if RAIM is predicted
to be unavailable for the given combination of
waypoint, time, and date
NOTE: RAIM computations predict satellite
coverage within +/- 15 minutes of the specified
arrival date and time.
190-00498-00 Rev. A