For example, a plane that is going 120 knots into a 10-knot head wind may have a SOG of 110 knots. The act of going from one waypoint to another in the most direct line and with no turns. The direction to be followed, is always located at the top of the display. Triangulation The location of an unknown point, as in GPS navigation, found by using the laws of plane trigonometry. The direction of the North Pole from your current position.
Magnetic compasses are slightly incorrect due to effects of the Earth's magnetic field.
GPS units correct for magnetic influences. The degrees which must be added to or subtracted from the current heading to reach the course to the intended waypoint. A universal time standard, referencing the time at Greenwich, England. Also referred to as GMT or Zulu time. UTM is the primary coordinate system used on U.S. Geological Survey topographic maps.