Cirrus SR22 Pilot Operating Handbook page 362

Section 9 Cirrus Design
Supplements SR22
GS (Glideslope) – The autopilot GS function will capture and track an
ILS glideslope. To arm the GS function, the following conditions must
be met: (1) the NAV receiver must be tuned to the appropriate ILS
frequency; (2) The glideslope signal must be valid – no flag; (3) the
autopilot must be in NAV/APR/ALT modes; and (4) the airplane must
be 60% or more below the glideslope centerline during the approach
to the intercept point, and within 50% needle deviation of the localizer
centerline at the point of intercept – usually the outer marker. When
the above conditions have existed for 10 seconds, the GS annunciator
will illuminate indicating GS arming has occurred (ALT annunciator will
remain on). When the glideslope is intercepted and captured, the ALT
annunciator will go out.
ALT (Altitude Hold), Mode – When ALT is selected, the autopilot will
hold the altitude at the time the mode was selected. Altitude hold will
not engage if an autopilot roll mode is not engaged. Altitude correction
for enroute barometric pressure changes may be made by rotation of
the VS knob on the autopilot programmer/computer. Clockwise
rotation will increase and counterclockwise rotation will decrease
altitude 20 feet for each 'click.' The maximum adjustment is ±360 feet.
Adjustments greater than 360 feet can be made by selecting VS mode
and flying the airplane to the new altitude and then re-engaging ALT
mode.
VS (Vertical Speed) Mode – When VS is selected, the autopilot will
synchronize to and hold the vertical speed at the time the mode was
selected. Altitude hold will not engage if an autopilot roll mode is not
engaged. The vertical speed is displayed in 100-foot increments at the
far right of the programmer/computer window next to the VS
annunciation. A plus (+) value indicates climb and a negative or minus
(-) value indicates descent. Vertical speed can be adjusted by rotating
the VS knob on the programmer/computer. Clockwise rotation
increases and counterclockwise rotation decreases rate of climb (or
descent) 100 FPM for each 'click.' The maximum adjustment is ±1600
FPM.
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Revision 06: 05-09-11