Cessna 172R, Operating Handbook

Page: 262 / 500

SECTION 7
AIRPLANE
&
SYSTEMS DESCRIPTION
CESSNA
MODEL 172R
AIRSPEED INDICATOR
The airspeed indicator is calibrated in knots. It incorporates a
true
airspeed window which allows
true
airspeed
to be
read off the
face of
the dial. In addition, the indicator incorporates a
window
at
the twelve
o’clock position. The window displays
true
airspeed, and
the
window
at the twelve o’clock position displays pressure altitude
overlayed with a temperature scale.
Limitation and
range markings
(in KIAS)
include the white arc
(33 to 85
knots), green arc (44 to 129 knots), yellow
arc
(129 to 163
knots), and a red line (163 knots).
To
find true
airspeed, first determine pressure altitude and
outside air temperature. Using this data, rotate the lower left knob
until pressure
altitude aligns with outside air temperature in the
twelve
o’clock window. True airspeed (corrected for pressure and
temperature)
can
now be read in the lower window.
VERTICAL SPEED INDICATOR
The vertical speed indicator depicts airplane
rate
of climb or
descent
in feet
per minute. The pointer is actuated by atmospheric
pressure changes resulting
from changes of
altitude as supplied by
the static
source.
7-42 Dec
2/96