Cirrus DESIGN SR22T Pilot Operating Handbook page 467

Cirrus Design
SR22 / SR22T
GPSS converts this information and sends this heading error directly
to the autopilot.
In the GPSS mode the autopilot can be directly coupled to the roll
Commands produced by the GPS Navigator, eliminating the need for
the pilot to make any further adjustments to the HSI course arrow.
ALT - Altitude Hold Button
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
Programmer/Computer.
VS - Vertical Speed Button
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.
APR - Approach Button
When APR is selected, the autopilot provides increased sensitivity for
VOR or GPS approaches. APR may also be used to provide increased
sensitivity for enroute course tracking
GS - Glideslope Mode
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.
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.
P/N 13772-140
Revision 01: 01-06-10
Section 9
Supplements
17 of 24