II Morrow Inc. Apollo Precedus, Руководство пользователя, Страница: 97 / 105

Intersection (INT): A point defined by any combination of
courses, radials, or bearings of two or more navigational aids.
K
Knot (kt): A unit of speed equal to one nautical mile per
hour.
L
Latitude (Lat): Any line circling the earth parallel to the
equator, measured in degrees, minutes, and seconds north
and south of the equator.
Longitude (Lon): Any line from the north to the south pole,
measured in degrees, minutes, and seconds of a circle, east
or west of the Prime Meridian (Greenwich, England).
M
Magnetic North: The region, some distance from the
geographic north pole where the earth’s magnetic lines
concentrate. A magnetic compass points to the magnetic
north.
Magnetic Variation (Mag Var): The angle between the
magnetic and true north. At various points on the earth it is
different due to local magnetic disturbances. It is shown on
charts as isogonic lines marked with degrees of variation,
either east or west. These degrees must be added to or
subtracted from the true course to get the magnetic course.
(Easterly variations are deducted, and westerly variations are
added.) The
Precedus automatically sets magnetic variation
to 0 degrees at positions above 70 degrees north or south
latitude.
Map Datum: A mathematical model of the earth used for
the purpose of creating navigation charts and maps. The
Precedus
contains the set of datums listed in Appendix B.
Meter (m): A metric distance measurement equal to 39.37
inches.
Minute: 1/60th of a degree.
N
Nautical Mile (nm): A distance measurement equal to 6,076
feet, or 1.15 statute mile. One nautical mile is also equal to
one minute of latitude.
89
Glossary of Navigation Terms