Garmin CIRRUS PERSPECTIVE SR22T Reference Manual page 50

GPS Navigation
Altitudes associated with approach procedures are "auto-designated". This means
the system automatically uses the altitudes loaded with the approach for giving vertical
flight path guidance outside the FAF. Note these altitudes are displayed as small light
blue text.
Altitudes associated with arrival procedures are "manually-designated". This means
the system does not use the altitudes loaded with the arrival for giving vertical flight
path guidance until designated to do so by the pilot. Note that these altitudes are
initially displayed as white text. These altitudes may be "designated" by placing the
cursor over the desired altitude and pressing the ENT Key. After designation, the text
changes to light blue.
Altitudes that have been designated for use in vertical navigation may also be
made "non-designated" by placing the cursor over the desired altitude and pressing
the CLR Key. The altitude is now displayed only as a reference. It will not be used
to give vertical flight path guidance. Other displayed altitudes may change due to
re-calculations or rendered invalid as a result of manually changing an altitude to a
non-designated altitude.
NOTE: Making course changes greater than 90° during a descent with vertical
guidance may cause excessive and rapid movement of the vertical deviation
indicator, and SVS Pathways.
The system updates vertical path guidance continuously using ground speed and
the calculated distance to the Bottom of Descent (BOD). Due to turn anticipation
guidance (turn-smoothing), distance to the BOD can be affected by course changes
greater than approximately 5 degrees. Ground speed can be affected by factors such as
shifts in wind direction, aircraft power management, pitch angle, and course changes.
Abrupt and/or substantial changes to either the distance to the BOD, ground speed, or
both can cause similarly abrupt/substantial changes in vertical path guidance.
Because of turn-smoothing, changes to both distance to the BOD and ground speed
tend to be more extreme when the BOD is also a waypoint that marks a large course
change. These speed and distance changes will be accounted for in the computed
required vertical path and reflected in the vertical guidance indications.
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Cirrus Perspective ™ by Garmin – Cockpit Reference Guide for the SR20/SR22/SR22T
190-00821-09 Rev. A