Longitude and Latitude

Understanding Latitude

Latitude lines, also called parallels, run east-west around the globe and are measured in degrees (°) north or south of the equator (0°). The equator divides the Earth into the Northern and Southern Hemispheres. The maximum latitude is 90°N at the North Pole and 90°S at the South Pole. Each degree is subdivided into 60 minutes ('). For example, 44°30'N is 44 degrees and 30 minutes north of the equator.

Understanding Longitude

Longitude lines, or meridians, run from pole to pole and measure angular distance east or west of the prime meridian (0°), which passes through Greenwich, England. Longitude values range from 0° to 180° east or west. Longitudes are always given as three digits (e.g., 049°36'W) to avoid confusion with latitude, which uses two digits.

How to Read Latitude and Longitude in Aviation

A position is given as (latitude, longitude), such as 55°19'48"N 049°36'W. To calculate the difference in latitude or longitude between two points, subtract if both are in the same hemisphere, or add if they are in opposite hemispheres. For longitude, if the two points are on different sides of the prime meridian, add their values and, if needed, subtract from 360° to find the shortest distance.

Coordinates in Navigation

Aviation uses the WGS-84 ellipsoid as the standard Earth model for coordinates. Latitude and longitude allow precise plotting of positions, calculation of distances, and determination of headings. Navigational calculations, such as great-circle routes, rely on accurate understanding of these coordinates.

Longitude and Latitude Causes

Latitude is determined by the angle between the equatorial plane and a line from the Earth's center to the location. Longitude is determined by the angle between the prime meridian and the local meridian at the position. These angular measurements are essential for defining any location on the globe.

Exam Application

You may be asked to calculate the difference in longitude or latitude between two points, convert degrees and minutes, or interpret coordinates on charts. Remember to use correct conventions and arithmetic, especially when positions cross hemispheres or the 180° meridian.