II Morrow Inc. 920 GPS - Manual (Page 94)

Seed Position: A latitude and longitude position fix
approximately equal to the present position which the
GPS receiver uses to determine the location of available
satellites from which signals may be received.
Statute Mile: A distance measurement equal to 5,280
feet or 0.87 of a nautical mile.
TCA: Terminal Control Area
Three-dimensional (3D) Position Fix : A position fix
defined by latitude, longitude, and altitude.
(TRK) Track: The imaginary line which the flight path
of an airplane makes over the earth.
True North: Geographic north, at the earth’s north pole.
TWR (Tower): Airport tower communication
frequency
UNICOM: The radio frequencies assigned to
aeronautical advisory stations for communication with
aircraft. Unicoms may provide such airport information
as active runway, wind direction and velocity and other
conditions of importance to pilots.
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