FAA History Lesson -- GCA

I was fascinated when I first read this history. I had no idea that the Ground Controlled Approach (GCA) system was almost chosen over the Instrument Landing System (ILS) as the standard for air traffic control.

From the FAA Historical Chronology, 1926-1996...

”Dec 31, 1945: Dr. Luis W. Alvarez received the 1945 Collier Trophy for his outstanding initiative in the conception of the Ground Controlled Approach (GCA) system and his contribution to its use for the safe landing of aircraft. The Armed Forces had introduced the system during World War II. After the conflict, some urged GCA’s use by civil aviation, while CAA continued to favor the Instrument Landing System (ILS). (See May 2, 1940, Mar 30, 1947, and Apr 3, 1947.) “

”Apr 3, 1947: CAA began in service testing of GCA (ground controlled approach) radar systems at Washington National and Chicago Municipal Airports. This modified radar precision landing equipment had been developed for military use, loaned to CAA by the Army Air Forces, and installed by the Airborne Instrument Laboratory of the Air Transport Association. New York's La Guardia Airport received similar equipment later in the year. (See Dec 31, 1945, and Apr 9, 1947.) Another operational service test, started about the same time at Washington National Airport, involved a microwave early-warning radar (MEW), one of the best long-range sets developed during the war. A joint CAA/Army Air Forces undertaking, this test aimed at developing effective means of coordinating MEW data and information from ATC flight progress boards.“

”Apr 9, 1947: CAA granted its first approval of the Air Forces' Ground Control Approach (GCA) radar device for commercial planes, authorizing its use by Pan American Airways at Gander, Newfoundland. (See Apr 3, 1947, and Jul 11, 1947.) “

”Jul 11, 1947: The House Subcommittee of the Committee on Interstate and Foreign Commerce, chaired by Representative Carl Hinshaw (R-Calif.), submitted a report recommending creation of a single instrument landing system to safely and economically serve the requirements of both commerce and national defense simultaneously. Addressing the controversy regarding the merits of CAA's Instrument Landing System, known (ILS) and the military's Ground Control Approach (GCA) system, the committee recommended that CAA stop installation of additional ILS equipment. The committee suggested further that the United States proceed with the development of an instrument landing system satisfactory for fully automatic landing, and that the most modern GCA be installed at selected airports. Congress endorsed the report through its Aviation Policy Board in Mar 1948, and recommended, through the Board, that the "single system" program be undertaken.

Meanwhile, on Jul 15, 1947, CAA Administrator Theodore Wright had announced a new civil-military instrument landing system policy. ILS would remain the primary CAA landing aid, but the agency would supplement ILS at busy airports with an element of GCA designated precision approach radar (PAR), along with airport surveillance radar. The Air Force, however, would still rely primarily on GCA, using ILS for heavy planes and as a backup to GCA. (See Mar 30, 1947, and Feb 4, 1949.)“

”Feb 4, 1949: CAA granted authorization for commercial planes to use ground control approach (GCA) radar as a "primary aid" for bad-weather landings. (See Apr 9, 1947.)“

Don Brown
December 31, 2007


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