The tube or line from the pitot tube to the airspeed
indicator applies the pressure of the outside air to the
indicator. The indicator is calibrated so various air
pressures cause different readings on the dial. The
indicator interprets air pressure from the pitot tube and
reflects airspeed in knots.
When working on or around the pitot tube or static
ports, do not obstruct the openings. Obstructed
openings restrict the supply of air to the indicators and
cause false readings.
Severe burns may result from touching a pitot
tube with the pitot tube heaters on. Be sure the pitot
tube heaters are off before installing protective
The altimeter (fig. 7-7) shows the height of the
aircraft above sea level. The face of the instrument is
calibrated so the counter/pointer displays the correct
altitude of the aircraft.
OR CIRCUIT BREAKER
Figure 7-6.Pressure measuring instruments.
Figure 7-7.Counter/pointer altimeter.