SUPPLEMENT 4
PRIMUS EPIC - FLIGHT
MANAGEMENT SYSTEM
AIRPLANE
F
LIGHT
S4-05 ANAC APPROVED
Page 6 code 01 REVISION 15
Copyright © by Embraer. Refer to cover page for details.
FMS POSITION ANOMALY
This limitation is applicable to airplanes equipped with Primus EPIC
software version 23.1 or 23.2 and it is associated to the following
conditions:
Crossing the 180 degree meridian will cause FMS longitude position
calculation to move by approximately 180 degrees.
When the FMS position change occurs:
- The CDI will deflect indicating the offset from the desired lateral
and vertical path based on the changed position;
- If autopilot is coupled and LNAV is engaged, the airplane will
execute a bank maneuver to intercept the TO waypoint in the flight
plan;
- For map display in heading up, map display will move to the new
FMS position;
- For map display in north up, the airplane symbol will disappear
from the map and move to the new FMS position;
- UNABLE RNP message will be displayed on the MCDU
scratchpad;
- FMS position starts slewing back to the selected sensor positions;
- Caution EICAS message FMS1(2)-GPS POS DISAG will be
displayed.
To avoid this misbehavior, perform the following procedure:
- About 10 nm before crossing 180 degree Meridian line, deselect
all IRS on all FMS;
- About 10 nm after all IRS position crossed 180 degree Meridian
line, reselect IRS.
If the misbehavior does occur, perform the following procedure in order
to mitigate the effects:
- Select Heading Select on the Flight Guidance Panel;
- Perform FMS position update to best sensor position. This puts
the FMS back to the correct position almost instantaneously;
- If synchronous operation was in use, select “RETURN TO
SELECTED CONFIG”.
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