Lesson 16: Aircraft
Instrument Systems
Classification Of Instruments
• Flight Instruments
• Engine Instruments
• Auxiliary Instruments
Flight Instruments
• Those that help visualize the attitude, location and
speeds of the aircraft.
• Those which indicate the relationship to the air
through which we are flying
• Those which relate to our position in space
without considering the air.
Pitot-static System
• Dynamic Air Pressure - Pressure caused by moving
air.
• Ambient Static Air Pressure - Pressure of nonmoving air just outside the aircraft.
Pitot-static System
Pitot Head
Pitot Head
Flush Static Port
Airspeed Indicator
• Differential
pressure
gauge that
measures the
difference
between
dynamic and
ambient static
air pressure.
Airspeed Indicator
• Indicated airspeed
• The speed of an aircraft as shown on the airspeed
indicator.
• True airspeed
• The speed at which an aircraft is moving relative to the
surrounding air.
• Calibrated airspeed
• Indicated airspeed of an aircraft, corrected for
installation and instrument errors.
Altimeter
• A barometer that
measures the
absolute pressure of
the air.
Altimeter
• Indicated Altitude
• The altitude shown by an altimeter set to
current altimeter setting.
• Pressure Altitude
• Height above the standard pressure level of
29.92 in.Hg.
• Density Altitude
• Pressure altitude corrected for nonstandard
temperature variations.
Altimeter
• True Altitude
• The actual height of an abject above mean sea
level.
• Absolute Altitude
• Actual height above the surface of the earth,
either land or water.
Vertical Speed Indicator
• The rate of
climb indicator
• Serves only as
a backup for the
altimeter and
airspeed
indicator as a
pitch indicating
instrument.
• Helps the pilot
establish a rate
of climb or
descent.
Blockage Of The Pitot-Static System
• Pitot Tube
• Affects only the airspeed indicator, but a
clogged static system affects all three pitotstatic instruments.
• If the pitot tube is blocked and its drain hole
remains open, the airspeed reading will drop to
zero.
• If both pitot tube and the drain hole clog, the
airspeed indicator will react like an altimeter.
Blockage Of The Pitot-Static System
• Static port
• The indicated airspeed increases as the
airplane descends and decreases when it
climbs.
• The altimeter: air pressure in the system will
not change and neither will your indicated
altitude.
• VSI continually indicates Zero.
Gyroscopic Instruments
Gyroscopic Instruments
• Turn coordinator
• Attitude indicator
• Heading indicator
Gyroscopic Instruments
• Rigidity In Space – Once a gyroscope is spinning, it
tends to remain in a fixed position in space and
resist external forces applied to it.
Gyroscopic Instruments
• Precession – The
tilting or turning of a
gyro in response to
pressure.
• The reaction to this
force occurs in the
direction of rotation,
approximately 90°
ahead of the point
where the force was
applied.
Sources Of Power
• Gyroscopes may be operated by electrical power or
by a vacuum (suction) system.
Sources Of Power
Attitude Indicator
• Vacuum powered instrument which senses pitching
and rolling movements about the airplanes lateral
and longitudinal axes.
Attitude Indicator
Attitude Indicator
Directional Gyro
• Vacuum powered
instrument which
senses yaw
movement of the
airplane about the
vertical axis.
• Horizontal card
directional gyro
Directional Gyro
• Vertical
card
directional
gyro
Rate Gyros
• Turn And Slip Indicator
• Turn Coordinator
• Inclinometer
Rate Gyros
Turn Coordinator
Floating Magnet-type Magnetic Compass
Engine Instruments
Engine Instruments