San Pedro Hill Air Force Station

 (1961-1976) - A Cold War Air Force Radar Station first established in 1961 near San Pedro, Los Angeles County, California. Named San Pedro Hill Air Force Station after the location. Initially assigned a Permanent ID of RP-39, later a Sage ID of Z-39, a JSS ID of J-31, and an FAA ID of QLA. The site became an FAA site in 1976 with USAF Height finders operated by a USAF detachment. The site is now known as San Pedro Hill FAA Radar Site.

History
Established in 1960 as a joint-use use (FAA/USAF/Army) site and became operational in 1961 as San Pedro Hill Air Force Station manned by the 670th AC&W Squadron. Initial equipment included an FAA ARSR-1 search radar, and two USAF FPS-6 height-finders.

SAGE System Transition
The 670th AC&W Squadron had moved from San Clemente Island to new facilities on San Pedro Hill to begin SAGE operations. The SAGE system used the FST-2 coordinate data transmitter to digitized the radar returns and transmitted them to the SAGE direction center. Under the SAGE System, interceptor aircraft were directed to their targets by the direction center computers and controllers, greatly reducing the need for local controllers and equipment at every radar station.

The FST-2 was a very large digital system using vacuum tube technology. Over 6900 vacuum tubes were used in each FST-2 requiring 21 air-conditioned cabinets, 40 tons of air conditioning, 43.5 kva of prime power and usually a large new addition to the operations building. The FST-2B modification added two more cabinets but with newer solid-state (transistor) technology to process coded responses from aircraft transponders.

San Pedro Hill Army NIKE Interface
One of the factors behind the move from San Clemente Island to new facilities on San Pedro Hill was the Joint Chiefs of Staff decision to colocate ten U.S. Army NIKE Command Posts with USAF long-range SAGE System radar sites. The Los Angeles NIKE defense was one of the ten and one of the more difficult to implement because three agencies (USAF/US Army and the FAA) were involved. The actual NIKE Command post was to be located on Fort MacArthur proper along with the NIKE acquisition and tracking radars. While the FAA search radar, two sets of two height-finders (one set Army and one set Air Force), and a SAGE annex were to be located atop San Pedro Hill some miles away. A full SAGE annex would have to be constructed next to the radar, and an FST-2 would have to be installed and activated in the SAGE System. In the interim between the move, full SAGE operation, and command post activation a GPA-37 was to be installed to provide USAF target assignments to the Army command post until all the pieces became operational.

SAGE System Operation
The site began operation as a SAGE System site in 1961, initially feeding data to the Norton SAGE Direction Center DC-17. With the closure of DC-17 on 25 Jun 1966 control was transferred to Luke SAGE Direction Center DC-21 at Phoenix, Arizona until it closed in 1983.

By 1963 an FPS-26A height-finder had replaced one of the USAF FPS-6 height finders, The second USAF FPS-6 had become an FPS-6B, then an FPS-90 in 1964. It was further upgraded to become an FPS-116 but was removed circa 1988 and not replaced. An FPS-27 search radar was installed in 1964 and subsequently removed in 1969.

The FST-2 was replaced in the early 1970s by the FYQ-47 Common Digitizer, a set maintainable by the FAA, and that set the stage for USAF to turn over the site to the FAA. The NIKE command post on Fort MacArthur closed on 1 Sep 1974 eliminating the need for USAF/U.S. Army interface.

Closure
San Pedro Hill AFS and the 670th Radar Squadron were deactivated on 1 Apr 1976, and the site operation was turned over to the FAA.

San Pedro Hill FAA Radar Site
After the closure of the Air Force Station, FAA personnel operated the radar site and maintained the search and the height-finder radars. The FPS-116 height-finder radar was operated by a USAF detachment OLE 26 ADS headquartered at Luke AFB, AZ until it was removed circa 1988. As JSS site J-31, the site furnished radar data to Luke SAGE Direction Center DC-21 and Los Angeles ARTCC. The Luke SAGE Direction Center DC-21 closed on 9 Dec 1983 as the last SAGE direction center. Data from the San Pedro Hill FAA Site was rerouted to the JSS System Command Center at McChord AFB (ROCC/SOCC/SAOC) and their FYQ-93 computer system.

This arrangement lasted until a U.S. Navy ARSR-4 3D radar on San Clemente Island became fully operational and assumed the JSS Site J-31A designation at which time the San Pedro Hill FAA Radar Site dropped its JSS J-31 designation. The new Navy ARSR-4 site provided better coverage of the Pacific approaches to Los Angeles and the San Pedro FAA Radar Site data then fed just the Los Angeles ARTCC. In 2007 the McChord AFB Command Center FYQ-156 computer replaced the 1980s era FYQ-93 and enabled each of the two remaining combat centers (EADS and WADS) to display increased numbers of radar sites and the San Pedro data was then available to the JSS System.

By 1990 the site was equipped with an ARSR-1E search radar and a CD-2C Common Digitizer. The San Pedro Hill CD-2C was scheduled to receive an upgrade kit to implement three level weather data processing in June 1992.

CARSR Radar
At the time of the CARSR changeout, the legacy radar in place was still the ARSR-1E and the CARSR conversion included a 7172 Antenna. The secondary radar for the site is the ATCBI-6 Beacon set.

Current Status
Now San Pedro Hill FAA Radar Site Joint Use site J-31 on San Pedro Hill in Los Angeles County, California.

See Also:
 * SAGE System
 * BUIC System
 * JSS System
 * Permanent System Radar Sites
 * US Radar Sets
 * Los Angeles ARTCC
 * Norton SAGE Direction Center DC-17
 * Luke SAGE Direction Center DC-21

Sources:
 * , page 159
 * , page 103


 * , page 86.

Links:
 * Radomes - San Pedro Hill Air Force Station
 * Wikipedia - Ground Equipment Facility J-31