Underspeed Protection - Garmin GFC 600 Pilot's Manual

AFCS

UNDERSPEED PROTECTION

While underspeed protection is active, the aircraft will deviate from
NOTE:
the selected reference.
Underspeed Protection is designed to discourage aircraft operation below minimum
established airspeeds and is available when the autopilot is on.
When the aircraft is decelerating to within six seconds of reaching a predetermined
minimum airspeed (specified in the AFMS), the AIRSPEED aural will sound to alert the
pilot of the impending underspeed condition.
If the aircraft continues to decelerate, Underspeed Protection functionality depends
on which vertical mode is selected. For the purpose of this discussion, the vertical
modes can be divided into two categories: Those in which it is important to maintain
altitude for as long as possible (altitude-critical modes), and those in which maintaining
altitude is less crucial (non-altitude critical modes).
ALTITUDE-CRITICAL MODES (ALT, GS, GP, GA)
If the aircraft decelerates to stall warning for at least one second, the vertical and
lateral modes will change from active to armed. IAS and ROL will become the active
vertical and lateral modes and flash for five seconds, and the autopilot will provide
input causing the aircraft to pitch down and wings to level.
The AIRSPEED aural will sound every five seconds and a MINSPEED annunciation
will be displayed on the GMC 605.
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GI 285 Overspeed Indication
Garmin GFC 600 Pilot's Guide 190-01488-00 Rev. B