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System Overview
bars present and no autopilot mode annunciators aside from the
“
AP READY
” one along the top edge of the PFD.
If an underspeed condition is recognized, an “
UNDERSPEED
”
text alert is displayed on the PFD
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repeated approximately every 6 seconds until the condition is no
longer valid.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 trigger for this Envelope Alerting (EA
™)
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. One common
scenario this capability is designed to alert against is a traffic
pattern stall.
Similarly, on the high-speed end of the spectrum with the
autopilot in the standby condition (green “
AP READY
” along the
top strip of the PFD pages), if an overspeed condition is
recognized, a “
OVERSPEED
” text alert is displayed on 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the condition is no longer valid. The trigger for this Envelope
Alerting (EA
™) overspeed alert is when the system has
determined V
ne
is about to reached.
If at any time and in any flight director or standby state, the
system detects an excessive bank condition, a “
BANK LIMIT
”
text alert is displayed on
the PFD pages and a “CAUTION,
EXCESSIVE BANK” aural alert is played in the headsets and is
repeated approximately every 6 seconds until the condition is no
longer valid. The trigger for this Envelope Alerting (EA
™)
excessive bank limit is when the system has determined that the
lesser of aircraft category or aircraft POH bank angle limits has
been exceeded. This number is typically 60 degrees of bank.
Finally, for those aircraft with the optional flap input to the
autopilot, if the autopilot system detects a flap overspeed
condition per POH flap deployment speed limitations, a
“CAUTION, FLAP OVERSPEED” aural alert is played in the
headsets and is repeated approximately every 6 seconds until the
condition is no longer true. There is no associated text alert.
If “
AP READY
” or “
FD
” are not displayed on the PFD page, Full-
time Envelope Alerting (EA
™) may not be available.
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