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System Overview
Full-time Envelope Alerting is triggered when the DFC100
recognizes an underspeed, overspeed or excessive bank angle
condition and will alert the pilot via text alerts on the PFD pages
and aural alerts.
NOTE
Suppression of Full-time Envelope Alerting
Full-time Envelope Alerting is suppressed during
very low power (near idle) conditions when flaps are
set to the full-flap position in order to minimize
nuisance calls in the landing phase. Full-time
Envelope Alerting is also suppressed anytime
Indicated Airspeed is less than 50 KIAS in order to
minimize nuisance calls during rollout and taxi.
In Flight Director operations, the flight director command bars will
continue to direct a pilot to fly to the commanded pitch and roll
targets as defined by the bug and nav source entries but if an
underspeed condition is recognized, a “
UNDERSPEED
” text alert
is displayed along the top edge of the PFD pages and a
“CAUTION, UNDERSPEED” aural alert is played in the headsets
and is repeated approximately every 6 seconds until the condition
is no longer valid. The autopilot mode annunciators do not flash
during Envelope Alerting. The trigger for this Envelope Alerting
underspeed alert is when the system has determined 1.2V
s
has
been reached. Flap position, bank angle and g-loading are taken
into account to define V
s
at any point in time (assumes max gross
weight).
Similarly, during high-speed flight director operations, the flight
director command bars will continue to direct a pilot to fly to the
commanded pitch and roll targets as defined by the bug and nav
source entries but if an overspeed condition is recognized, a
“
OVERSPEED
” text alert is displayed along the top edge of the
PFD pages and a “CAUTION, OVERSPEED” aural alert is played
in the headsets and is repeated approximately every 6 seconds
until the condition is no longer valid. There is no flashing of any
autopilot mode annunciator during Envelope Alerting. The trigger
for this Envelope Alerting overspeed alert is when the system has
determined V
ne
is about to reached.
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