OMEGA was the first truly global radio navigation

Radio navigation

Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...

 system for aircraft, operated by the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 in cooperation with six partner nations.
OMEGA was originally developed by the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 for military aviation users. It was approved for development in 1968 with only eight transmitters and the ability to achieve a four mile (6 km) accuracy when fixing a position. Each Omega station transmitted a very low frequency signal which consisted a tone/duration unique to the station that was repeated every ten seconds.