T-34C SYSTEMS FAMILIARIZATION
The encoder (front cockpit) altimeter contains a DC-powered digital encoder which encodes
altitude information for transmission by the altitude mode of the operating transponder. Altitude
information is also sent to NACWS. If DC power to the encoder is lost, the altimeter will
continue to operate as a pressure altimeter, but a red CODE OFF flag will indicate that no
altitude signals are being provided to the transponders or NACWS. The aft cockpit altimeter is
known as the barometric altimeter.
When a field elevation check is made, the local barometric pressure is set into the window. For
instrument flight (IFR) the altimeter should agree within 75 feet of the field elevation.
Vertical Speed Indicator
A VSI is installed on each instrument panel and indicates the rate of climb or descent of the
aircraft based on the changes in atmospheric pressure. The indicator is calibrated with 100 foot
divisions from 0 to 1000 feet and 500 foot increments from 1000 to 6000 feet.
Figure 14-3 Vertical Speed Indicator
PITOT STATIC SYSTEM