Rhumb Line

A line on the Earth's surface that crosses every meridian at the same angle, allowing a pilot to fly a constant magnetic heading from departure to destination. On a Mercator-projection chart, a rhumb line appears as a straight line, making it easy to plot. However, except along the equator or along a meridian, a rhumb line is longer than the corresponding great circle route. For the relatively short distances typical of VFR cross-country flights, the difference between a rhumb line and a great circle is negligible, so pilots commonly use rhumb line navigation.