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Flight Management System (FMS) for the Agusta AW139/AB139 Helicopter
A lateral track alert is given for each waypoint sequence. The alert
D
is given 30 seconds before turning starts.
LNAV Submodes
LNAV ARM -- When initially selected, LNAV ARM becomes the
D
active mode. While armed, the FMS monitors aircraft position and
heading against the active leg. When within the capture zone, the
FMS automatically changes from LNAV ARM to LNAV CAPTURE
and guides the aircraft to capture the active leg. While in the armed
mode, the FMS does not laterally control the aircraft. Normally, the
HEADING lateral mode is used to control the aircraft until the FMS
changes to LNAV CAPTURE.
LNAV CAPTURE -- The FMS begins lateral steering control when
D
the mode changes from ARM to CAPTURE. The FMS uses a 3_ per
second roll rate during en route operations and up to 5.5_ per
second on the approach. Banks are planned between 0_ and 23_
with 25_ as a maximum. In holding, procedure turns and orbit
patterns, and arc legs, the maximum is increased up to 30_.
One of the requirements of LNAV is to keep the aircraft within
protected airspace. This is done by incorporating a model of
protected airspace into the FMS. From the model, the FMS
determines the bank angle required to stay within the protected
airspace boundaries during leg changes. The actual bank angle
used is the greater of the pilot--entered bank factor or the bank angle
from the protected airspace model.
A28- - 1146- - 181
REV 3 Mar 2009
Honeywell International Inc. Do not copy without express permission of Honeywell.
Flight Plan
7-23
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