7-20
P/N 13772-005
Section 7
Cirrus Design
Systems Description
SR22T
Altimeter
Primary altitude data is provided by the Air Data Computer and is
shown as a vertical tape along the upper right side of the PFD. The
altimeter scale is graduated with major tick marks at intervals of 100
feet and minor tick marks at intervals of 20 feet. Six hundred (600) feet
of barometric altitude is viewable at any time.
The local barometric pressure is set using the barometric adjustment
knob on the PFD. The selectable altitude reference bug is displayed on
the altimeter tape and is set using the altitude selection knob on the
Flight Management System Keyboard. Barometric minimum descent
altitude (MDA, or Decision Height, DH), can be preset. Altimeter trend
is also displayed as a bar along side of the altimeter tape.
The PFD Altitude is corrected for static source position error (normal
static source / 0% flaps), the altitude calibration errors for the PFD are
zero with flaps up and normal source (typical cruise flight). Calibration
corrections are only necessary when flaps are extended or the
alternate static source is selected
Standby Altimeter
Airplane altitude is depicted on a conventional, three-pointer, internally
lit barometric altimeter installed on the LH bolster panel. The
instrument senses the local barometric pressure adjusted for altimeter
setting and displays the result on the instrument in feet. The altimeter
is calibrated for operation between -1000 and 20,000 feet altitude. The
scale is marked from 0 to 10 in increments of 2. The long pointer
indicates hundreds of feet and sweeps the scale every 1000 feet (each
increment equals 20 feet). The short, wide pointer indicates thousands
of feet and sweeps the scale every 10,000 feet (each increment equals
200 feet). The short narrow pointer indicates tens of thousands feet
and sweeps from 0 (zero) to 2 (20,000 feet with each increment equal
to 2000 feet). Barometric windows on the instrument's face allow
barometric calibrations in either inches of mercury (in.Hg) or millibars
(mb). The barometric altimeter settings are input through the
barometric adjustment knob at the lower left of the instrument.
The standby altimeter does not have automatic position error
corrections, calibration corrections are necessary. Because the PFD
has automatic corrections and the standby does not, differences
between the two indications are typical (difference is the greatest at
high altitudes and high airspeeds, where the position error corrections
are the highest).
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