TM 55-1510-215-10
Section XI. FLIGHT INSTRUMENTS
2-75. Airspeed Indicators.
(1) Encoding Altimeter. The altimeter is a
self-contained unit which consists of a sensitive pressure
Two airspeed indicators are installed separately on the
altimeter combined with an altitude encoder.
The
pilot and copilot sides of the instrument panel (fig. 2-22).
display indicates and the encoder transmits,
The indicator dials are calibrated in knots from 40 to 260.
simultaneously, pressure altitude reporting. Altitude is
displayed on the altimeter by a 10,000 foot counter, a
1000 foot counter, and a single needle pointer which
indicates hundreds of feet on a circular scale in 50 foot
increments. Below an altitude of 10,000 feet, a diagonal
2-76. Turn-And-Bank Indicators.
warning symbol will appear on the 10,000 foot counter.
A barometric pressure setting knob is provided to insert
Two turn-and-bank indicators are installed, one each
the desired altimeter setting in inches Hg.
A DC
on the pilot and copilot sides of the instrument panel
powered vibrator operates inside the altimeter whenever
These indicators are gyroscopically
aircraft power is on. If DC power to the altitude encoder
operated. The pilot's unit is operated by DC power and
is lost, a warning flag placarded CODE OFF will appear
is protected by a 5-ampere circuit breaker, placarded
in the upper left portion of the instrument face, indicating
T&B IND, located on the right subpanel (fig. 2-7). The
that the altitude encoder is inoperative, and that the
copilot's indicator is driven by the aircraft vacuum
system is not reporting altitude to ground stations.
system.
(2) Barometric Altimeter.
The barometric
altimeter, displays altitude in hundreds of feet by a long
pointer, in thousands of feet by a second pointer, and in
ten-thousands of feet by a disc mounted pointer. A
2-77. Pilot's Encoding Altimeter.
barometric pressure setting knob is provided to insert the
desired altimeter setting in inches Hg. This unit requires
The pilot's altimeter is located on the upper left side
no electrical power for operation.
of the instrument panel (fig. 2-22). Altitude is displayed
on the pilot's altimeter by a 10,000 foot counter a 1,000
An alternate unit may be installed which is similar in
foot counter, a 100 foot counter, and a single needle
appearance to the encoding altimeter. This unit requires
pointer. Below an altitude of 10,000 feet, black and
DC power for proper operation. It does not contain the
white cross-hatching will appear on the 10,000 foot
CODE OFF flag, and does not have altitude encoding
counter. Altitude below sea level is indicated by a wavy
capability.
blue and white line in the 10,000 foot counter. A
barometric pressure setting knob is provided to insert the
desired altimeter setting. The altimeter contains dual
baroscales which permits barometric pressure setting in
both millibars and inches of mercury (Hg). A red and
white striped warning flag will cover the digital altitude
2-79. Vertical Velocity Indicators.
indicator if DC power is lost. The encoding altimeter is
protected by a 1-ampere circuit breaker, placarded ENC
Two vertical velocity indicators are installed
ALT, located on the right subpanel (fig. 2-7).
separately on the pilot and copilot sides of the
instrument panel (fig. 2-22). They indicate the speed at
which the aircraft ascends or descends based on
changes in atmospheric pressure. The indicator is a
direct reading pressure instrument.
2-78. Copilot's Altimeter.
2-80. Pilot's Fight Director Indicator.
a. Copilot's Altimeter. The copilot's altimeter is
The pilot's flight director indicator (FDI) (fig. 3-10)
located on the upper right side of the instrument panel
combines the attitude sphere display with computed
steering information to provide the commands required to
installed.
intercept and maintain a desired flight path. All guidance
Change 5 2-67
