Glossary of Navigation Terms
A
Altitude (GPS ALT): Altitude, as calculated by the
Apollo GX55, based upon a mathematical model of
the
earth’s
surface
curvature.
A
substantial
difference between this altitude value and altitude
referenced to sea level may exist.
Almanac: Data transmitted by a GPS satellite
including orbit information on all satellites, clock
correction, and atmospheric delays.
ATC Ring: On the map display, an artificial ring
five nm in diameter is drawn around airports that
have a control tower.
Automatic
Terminal
Information
Service
(ATIS): Recorded information about weather and
other conditions at an airport, periodically updated
when conditions change.
Autonav: The function that allows you to set the
GX55 to scroll automatically through selected
navigation displays .
Azimuth: an arc, as measured clockwise from true
or magnetic north.
B
Bearing (BRG): The direction to any point, usually
measured in degrees relative to true or magnetic
north.
C
Circular Error Probable (CEP): As applied to
GPS position fix accuracy, the radius of a circle
inside of which there exists a 50 percent chance of
being located.
Constellation: A group of stars or objects, such as
GPS satellites, in the heavens.
Coordinates: Values for latitude and longitude that
describe a geographical point on the surface of the
earth.
Glossary of Navigation Terms
151