190-00820-08 Rev. A
Cirrus Perspective
™
by Garmin – Pilot’s Guide for the SR20/SR22/SR22T
479
AUTOMATIC FLIGHT CONTROL SYSTEM
SY
STEM
O
VER
VIEW
FLIGHT
INSTRUMENTS
EIS
AUDIO P
ANEL
& CNS
FLIGHT
MANA
GEMENT
HAZARD
AV
OID
ANCE
AFCS
ADDITIONAL
FEA
TURES
APPENDICES
INDEX
Figure 7-45 MINSPD Annunciation
Airspeed
Indicator
If the aircraft continues to decelerate, Underspeed Protection functionality depends on which vertical flight
director mode is selected. For the purpose of this discussion, the vertical flight director 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, TO, GA)
If the aircraft decelerates to stall warning for at least one second, the lateral and vertical flight director
modes will change from active to armed (Figure 7-46). The autopilot will provide input causing the aircraft
to pitch down to maintain an airspeed no less than stall warning activation speed plus two knots, and the
wings to level.
Lateral and
Vertical FD
Modes Armed
Figure 7-46 Lateral and Vertical Flight Director Modes Armed
An aural “AIRSPEED” alert will sound every five seconds and a red “UNDERSPEED PROTECT ACTIVE”
annunciation (Figure 7-47) will appear in the CAS window.
Figure 7-47 Underspeed Protect Active Annunciation
When airspeed increases (as a result of adding power/thrust) to above the IAS at which stall warning turns
off, plus two knots, the autopilot will cause the aircraft to pitch up until recapturing the vertical reference.
The vertical and lateral flight director modes will change from armed to active.
Summary of Contents for Cirrus Perspective SR20
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