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Flight Management System (FMS) for the Agusta AW139/AB139 Helicopter
High Latitude Flying
Entering the polar region (above 89_ N or below 89_ S) results in the
message ENTERING POLAR REGION being displayed. When
entering the polar region, the FMS uses highest priority sensor for
navigation. When the highest priority sensor has failed, the next priority
sensor is used. The POS SENSORS page indicates which sensor is
being used. FMS position update is not permitted in the polar region.
Under normal operations, the on--side AHRS is used as the heading
source by EFIS (AHRS 1 for the pilot and AHRS 2 for the copilot). When
the EFIS and FMS are using the same AHRS, a 180_ reversal is
displayed by the EFIS at the same time the FMS crosses the pole.
The plan mode for the EFIS map display is not useful while at or near
the pole. The information presented is correct, but the presentation is
not useful because the plan mode is presented North up. When at the
North pole for example, everything is South. Therefore, the plan mode
must not be used during operations at or near either pole. Instead, use
the regular map mode.
Correctly flown holding patterns are possible while in the polar region.
However, the EFIS airplane symbol does not always show on the
holding pattern. The display error is more pronounced the further away
the aircraft is from the holding fix and/or the closer the aircraft is to the
pole. When a holding pattern is hand flown in the polar region, the HSI
presentation must be used for required track and deviation.
During operations in the polar region, FMS lateral offset is inhibited. Any
entered lateral offset is removed when entering the polar region.
When leaving the region (below 88_ N or above 88_ S), the message
EXITING POLAR REGION is displayed.
A28- - 1146- - 181
Navigation
6-182
REV 3 Mar 2009
Honeywell International Inc. Do not copy without express permission of Honeywell.
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