Flight Management System (FMS) for the Agusta AW139/AB139 Helicopter
A28--1146--181
REV 3 Mar 2009
Navigation
6-166
Honeywell International Inc. Do not copy without express permission of Honeywell.
FHAF WAYPOINT
The FHAF waypoint is located at 3820 ft or 0.63 NM downwind of the
HOV waypoint on the 3 degree descent path into the HOV waypoint.
The FHAF is placed at the transition to the straight approach leg into
the HOV waypoint. The FHAF waypoint is designated in the flight plan
and on the MFD with the symbol FHAF.
APPROACH TO HOVER
Shortly after passing the FHAF waypoint, the flight director switches
from using the FMS provided roll steering command, VS targets, and
CAS speed targets to the following control data:
D
Lateral
-- The flight director gives the lateral guidance commands
based on the FMS lateral deviation signal. As the helicopter
approaches the HOV waypoint, the flight director automatically
engages the HOV mode with zero lateral velocity as the reference.
During this phase, the FMS outputs a projected along track distance
to the HOV waypoint. The along track distance is a positive value
prior to reaching the HOV waypoint or a negative value when the
aircraft passes the HOV waypoint.
D
Vertical
-- The flight director gives the vertical guidance commands
based on the FMS vertical deviation signal. The FMS vertical
deviation signal provides the vertical deviation in feet from the
3 degree descent path into the HOV waypoint. As the radar altitude
approaches the final radar altitude (selected by the pilot from 50 to
250 ft) the flight director automatically captures the final radar
altitude and engages the RHT mode.
D
Speed
-- The flight director initially follows the FMS CAS target. The
FMS maintains the CAS command at a value corresponding to
30--60 kts GS during the approach to HOV. In this phase, the flight
director uses the FMS distance to the HOV waypoint to generate
ground speed profile to the HOV waypoint. The flight director
continues to follow the FMS CAS target until the helicopter ground
speed converges with the flight director calculated ground speed
profile.
When interception of the calculated ground speed profile occurs, the
flight director automatically captures the ground speed profile and
ignores the FMS CAS target. The ground speed profile guides the
flight director in decelerating to a hover at the HOV waypoint. As the
helicopter approaches the HOV waypoint, the flight director
automatically engages the HOV mode with a zero longitudinal
velocity as the reference.
Summary of Contents for FMZ Series
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