Installation manual

System Overview 1-11

NOTE

Suppression of Full-time Envelope Alerting

Full-time Envelope Alerting (EA™) 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 (EA™) is also suppressed

anytime Indicated Airspeed is less than 50 KIAS.

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 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every 6 seconds until the condition is no longer valid.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

autopilot mode annunciators do not flash during Envelope

Alerting* (EA™). The trigger for this Envelope Alerting (EA™)

underspeed alert is when the system has determined 1.2V

has

been reached. Flap position, bank angle and g-loading are taken

into account to define V

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 on the PFD 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is no longer valid.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 (EA™).* The trigger for this

Envelope Alerting (EA™) overspeed alert is when the system

has determined V

is about to reached.

If the autopilot is not engaged in any Autopilot or Flight Director

modes and is in the standby condition, as indicated by the green

“AP READY” annunciator on the PFD and no green or cyan lights

on the autopilot control head, Full-time Envelope Alerting (EA™)

is still active. In this case, there are no flight director command

Change 3