Nav

• Meridian: A line of longitude that extends from the North Pole to the South Pole, connecting points with the same longitude.
• Prime Meridian: The meridian at 0 degrees longitude, from which other longitudes are measured. The Prime Meridian passes through Greenwich, London.
• Longitude: The angular distance measured in degrees, minutes, and seconds, east or west of the Prime Meridian.
• Equator: The imaginary circle around the Earth equidistant from the poles, dividing the Earth into the Northern and Southern Hemispheres.
• Latitude: The angular distance measured in degrees, minutes, and seconds, north or south of the Equator.
• Rhumb Line/Great Circle: Rhumb Line: A line that crosses all meridians of longitude at the same angle; a constant compass direction.
• Great Circle: The shortest distance between two points on the surface of a sphere; the circumference of a circle that divides the sphere into two equal halves.
• Variation: The angular difference between true north and magnetic north at a particular location.
• Isogonal: A line on a map connecting points of equal magnetic variation.
• Agonic Line: The line along which magnetic variation is zero; the line where true north coincides with magnetic north.
• Deviation: The error introduced in a magnetic compass reading due to local magnetic fields within the aircraft or vessel.
• Track: The actual path over the ground that an aircraft or vessel follows.
• Heading: The direction in which the nose of an aircraft or the front of a vessel is pointing, usually expressed in degrees from magnetic north.
• Ground Speed: The speed of an aircraft over the ground, taking into account the effect of wind.
• Ground Position: The geographical location of an aircraft or vessel on the Earth's surface.
• Bearing: The direction from one point to another, usually expressed in degrees from a reference point.
• Wind Velocity: The speed and direction of the wind, usually measured in knots.
• Drift: The lateral movement of an aircraft or vessel caused by wind.
• VFR Flight Rules: Visual flight rules are designed for good weather conditions where visual contact with the ground and other aircraft is possible.