Glossary

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 Apollo GX automatically sets magnetic variation to 0 degrees at positions above 70 degrees north or south latitude. See Declination.

MAHP: Missed Approach Hold Point.MAP: Missed Approach Point.

Map Datum: A mathematical model of the earth used for the purpose of creating navigation charts and maps. The Apollo GX uses the WGS-84 map datum.

MESA: Minimum En route Safe Altitude is the highest MSA for every point between the aircraft present position and the “TO” waypoint with a 5 nm buffer around the course.

Meter (m): A metric distance measurement equal to 39.37 inches.Minute: 1/60th of a degree.

MSA: Minimum Safe Altitude. The elevation of the highest obstruction near the aircraft plus a 1,000 or 2,000 foot buffer added for safety. In non-mountainous terrain, a 1,000 foot buffer is added. In mountainous terrain, a 2,000 foot buffer is added. The result is rounded to the nearest 100 feet.

15-7