User Guide

Appendix B: Glossary
219
B
Glossary
This is a brief glossary of some of the terms that
appear in this Pilot’s Handbook. For extended
definitions and hundreds more terms, see the
Glossary section of the onscreen Help.
aerobatics
Precision maneuvers such as barrel rolls and
loops, and other similar maneuvers not
necessary for normal flight.
ailerons
Movable control surfaces, usually located
near the wing tips, that control the rolling
motion of an aircraft. The ailerons move
simultaneously in opposite directions.
air traffic control (ATC)
A network of control towers, approach and
departure controls, and en route control
centers designed to ensure the safe and
efficient flow of air traffic. ATC’s primary
responsibility is to maintain separation
between aircraft operating under Instrument
Flight Rules (IFR), but ATC also provides
services to aircraft operating under Visual
Flight Rules (VFR).
airspeed
The rate at which an aircraft moves through
the surrounding air. Pilots use several types
of airspeed during flight. For example,
indicated airspeed (IAS) is the speed shown
on the airspeed indicator (usually in knots).
Calibrated airspeed (CAS) is IAS corrected
for instrument and installation error. True
airspeed (TAS) is IAS corrected for changes
in atmospheric temperature and pressure.
The aircraft’s speed over the ground—
groundspeed—is TAS corrected for the effect
of a headwind or tailwind.
altimeter
Cockpit instrument that displays changes in
barometric pressure as changes in the height
of the aircraft relative to sea level.
altitude
Height of the aircraft above a reference level.
Altitude above ground level (AGL) is the
absolute height above the earth. Altitude
above mean sea level (MSL) is the height
above the average level of the earth's
oceans.
angle of attack (AOA)
The angle between the wing and the
oncoming airflow—the relative wind. The
angle of attack is related to the direction in
which the aircraft is moving, not to the angle
the wing makes with the horizon.
attitude
The orientation of the aircraft’s axes relative
to the horizon.
automatic pilot (autopilot)
A device that automatically controls an
aircraft. Similar in concept to the cruise
control feature of an automobile, simple
autopilots keep an airplane’s wings level.
More sophisticated autopilots can fly an
airplane from immediately after takeoff all
the way to its destination and then make an
automatic landing.
avionics
Derived from “aviation electronics,” this term
most commonly refers to the electronic
communication, navigation, and flight-control
equipment onboard an aircraft.