Existing comment:
Radar and Precision Landing Systems
Radar-"radio detecting and ranging"-was developed by the British in the 1930s and widely used during World War II. By war's end, two precision landing systems were available for civil use: Ground Controlled Approach (GCA), which used radar, and Instrument Landing System (ILS), which used radio transmissions.
The first U.S. civilian control tower equipped with radar began operating at Indianapolis Airport in 1946. By 1951 the use of radar had begun to supercede pilot-reported positions by radio. |