S-TEC System 55X, Pilot Operating Handbook

Page: 24 / 24

24 of 24 P/N 13772-108
Section 9 Cirrus Design
Supplements SR22
DH (Decision Height) – The DH button allows entry and arming of
altitude alerting at a set decision height. To set a DH, first enter the
data (DTA) entry (ENT) mode, press the DH button, and rotate the
selector knob to input the desired decision height to the nearest 100
feet above the specified decision height. For example, for a DH of
1160 feet set 1.2 (1200 feet). After setting the desired decision height,
press the DTA button again to accept the entered DH. The display will
show the selected DH for approximately 5 seconds and then revert to
Alt mode until the selected DH is reached during descent. The DH
annunciator will remain illuminated indicating a decision height is set.
As the airplane approaches within approximately 50 feet of the
decision height, the alert will sound and the DH light will flash. As the
airplane passes through approximately 50 feet beyond the decision
height, the alert will sound and the light will flash again. Pressing the
DH button again will disable the DH function causing the DH
annunciation to go out. Repeated activation of the DH button
alternately activates and deactivates the DH mode.
VS (Vertical Speed) – At initial start up, after self-test, pressing the
Altitude Selector / Alerter VS button enables vertical speed selector
mode. The initial vertical speed will be set at + 2 indicating a climb at
200 feet per minute. Rotating the selector input knob will change the
selected vertical speed in 100 FPM increments. Rotate CW to
increase vertical speed or CCW to Decrease vertical speed. The
maximum vertical speed is ± 1600 FPM (± 16). Zero vertical speed is
not selectable.
The vertical speed display is the only Altitude Selector / Alerter
function available in the ‘operate’ mode. Therefore, vertical speed
changes can be commanded by rotating the selector input knob.
Vertical speeds can also be entered in the data (DTA) entry (ENT)
mode by pressing the VS button and using the selector input knob to
enter a new vertical speed. The DTA button must be pressed again to
accept the new vertical speed and enter the ‘operate’ mode.
The Altitude Selector / Alerter VS mode can be disabled by pressing
the Altitude Selector / Alerter MAN button.
MAN (Manual) – Vertical Speed selection can be completely
decoupled from the autopilot system by depressing the Altitude
Selector / Alerter MAN button.
Revision 5: 08-15-07