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Castle Air Force Base
Merced Army Airfield

Shield Strategic Air Command.png

Part of Strategic Air Command
Merced County, near Atwater, California
Castle Airport CA 2006 USGS.jpg
2006 USGS Aerial Photo

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Type Air Force Base
Coordinates Latitude:
Built 1941
In use 1941–1995

Merced Army Airfield, November 1942

Castle Air Force Base (1941–1995) is a former United States Air Force Strategic Air Command base located northeast of Atwater, northwest of Merced and about 123 miles (198 km) east southeast of San Francisco, California.

The base, located in unincorporated Merced County, was closed after the end of the Cold War in 1995. It is now known as the Castle Airport Aviation and Development Center.


Castle AFB was named in honor of Brigadier General Frederick W. Castle (1908–1944) on 17 January 1946. When on Christmas Eve 1944 near Liege, Belgium, seven Messerschmitts set General Castle's B-17 Flying Fortress afire, he remained at the controls while his crew bailed out. He bravely refused to release his bombs over territory occupied by friendly forces, and died with the pilot when the aircraft exploded. General Castle received the Medal of Honor posthumously.

The facility was officially renamed Castle Air Force Base on 13 January 1948 as part of the establishment of the United States Air Force as a separate military service.

World War II

The airfield was opened on 20 September 1941 as the Army Air Corps Basic Flying School, one of the fields utilized to meet the needs of the 30,000 Pilot Training Program. As the original name indicated, it provided basic air training for beginning pilots and crewmen. Many pilots and crews were trained here during the war including a number of Women's Air Service Pilots (WASP). Auxiliary air fields used by Merced Army Air Field during the war were:

Postwar years

Sign at front entrance of deactivated Castle AFB

With the end of the war 444th Bombardment Group (Very Heavy) arrived on 15 November 1945 from West Field, Tinian with four squadrons (344th, 676th, 677th, and 678th) of wartime B-29s. The 444th operated from Merced for about six months with the 678th BS being redesignated as the 10th Recon Squadron and its aircraft being converted to the RB-29 configuration.

The three B-29 squadrons inactivated at Merced on 6 May 1946 with the 10th Reconnaissance Squadron relocating to Davis-Monthan Field, Arizona where turned in its RB-29 aircraft. The 444th was inactivated on 16 November 1947.

During the summer of 1945, when most other air fields were winding down, Merced was expanded to accommodate the large air tankers then programmed to come into service. After the war ended Merced was home to several air tanker squadrons and remained a training center for pilots and air crews.

93d Bombardment Wing

Three B-52Bs of the 93d Bomb Wing prepare to depart March AFB for Castle AFB, after their record-setting round-the-world flight in 1957.

The 93d Bombardment Group (Very Heavy) was activated at Merced on 21 June 1946, starting a nearly 50-year relationship with the airfield. The 93d was a former Eighth Air Force B-24 Liberator group which was assigned to Merced for Boeing B-29 Superfortress training. The 93d was one of SAC's first ten bomb groups. There were three initial operational squadrons (328th, 329th, and 330th) which absorbed the equipment and aircraft of the inactivated 444th BG.

On 1 October 1946 the base was put on "minimal operations on caretaker status", with control of the facility under Colorado Springs AAF. The 93d Bomb Group, however remained active. It, along with the 509th Composite Group at Roswell Army Air Field, New Mexico, was all there was of Strategic Air Command at that time. The base remained in this status until 1 May 1947 when it was reactivated.

On 1 May 1947, Castle Army Airfield was reactivated under Strategic Air Command. On 28 July 1947, the 93d Bombardment Wing, (Very Heavy) was established and took over responsibility from the group. During 1947–1948, it flew Boeing B-29 Superfortresses, but soon received the upgraded version of the B-29, the Boeing B-50A. In 1948, the entire wing deployed to Kadena AB, Okinawa, becoming the first Strategic Air Command bomb group to deploy in full strength to the Far East.

On 27 June 1949, the Air Force Reserve 447th Bombardment Group was activated at Castle and equipped with the B-29s formerly of the 93d Bomb Wing. The 447th remained active until 16 June 1951 when the group was activated and the aircraft and personnel sent to Far East Air Forces as replacements for combat losses during the Korean War. With the unit's departure, the 447th was inactivated.

The Convair B-36 Peacemaker entered SAC's inventory in 1948. The huge plane dwarfed the earlier bombers. The 93d, along with all other B-29 and B-50 bomb groups was redesignated "Medium." Only the B-36 groups were "Heavy."

The wing began aerial refueling operations in October 1950, providing aerial refueling and navigational assistance for the July 1952 movement of the 31st Fighter-Escort Wing from the United States to Japan, the first jet fighter crossing of the Pacific Ocean, during the Korean War. From 1953 to 1955, the wing flew Boeing KC-97 Stratotankers. Jet propelled Boeing KC-135 tankers came on line in 1957.

The 93d Bombardment Wing, Medium, received Boeing B-47s in May 1954, but its involvement with the new Stratojet was curtailed on 29 June 1955, when the wing received the first production line Boeing B-52B Stratofortress, making it the first SAC bomb wing to receive the new aircraft. The wing became SAC’s primary B-52 aircrew training organization, incorporating KC-135 aircrew training for refueling in mid-1956. For this purpose, it set up the 4017th Combat Crew Training Squadron which was supposed to handle all B-52 crew training for the next few years. When the mission of B-52 training became too great a task for just one squadron, the Wing's other three squadrons took over the flight training role and the 4017th assumed responsibility for ground instruction in 1956. The 93d was SAC's primary B-52 training organization. The 93d retained some of its B-47s until 1956 for crew training purposes. It was one of the few wings to have both jet bombers.

Although most of the wing’s components were used for B-52 and KC-135 aircrew training between 1956 and 1995, one or more of its units sometimes participated in tactical operations, including aerial refueling.

From April 1968 to April 1974, the 93d operated a special B-52 replacement training unit to support SAC’s B-52 operation in Southeast Asia. Also, the 328th and 329th Bomb Squadrons deployed to U-Tapao Royal Thai Navy Airfield, Thailand where they flew combat missions over Vietnam, Cambodia, and Laos during the Vietnam War.

The wing won the SAC Bombing and Navigation Competition and the Fairchild Trophy in 1949, 1952, and 1970, and the Omaha Trophy as the outstanding SAC wing in 1970.

In August 1990 the wing operated an aerial port of embarkation for personnel and equipment deploying to Southwest Asia during Desert Shield.

In addition to aerial refueling, Castle-based tankers ferried personnel and equipment, while B-52s deployed to strategic locations worldwide, including Saudi Arabia. B-52s bombed the Iraqi Republican Guard and targeted Iraqi chemical weapons, nuclear, and industrial plants during Desert Storm, January–February 1991. On 1 June 1992 the wing was relieved from SAC and reassigned to the new Air Combat Command.

Notable operations

  • Non-stop B-52 flights of some 16,000 nautical miles (29,600 km) around North America and to the North Pole (November 1956)
  • First jet aircraft nonstop flight around the world (January 1957)
  • Nonstop, unrefueled KC-135 flight from Yokota AB, Japan, to Washington, D.C. (April 1958).
  • The home of one of very few B-36 peacemakers still in existence.


The end of the Cold War brought many changes to the Air Force, and Castle AFB was selected for closure under the Defense Base Closure and Realignment Act of 1990 during Round II Base Closure Commission deliberations (BRAC 91).

On 1 June 1992 the 93d was relieved from assignment to SAC and was reassigned to the newly formed Air Combat Command (ACC). It was then redesignated as the 93d Bomb Wing and its B-52G aircraft given the ACC tail code of "CA" and carried blue tail stripes. The 328d Bomb Squadron was inactivated 3 May 1994, and the wing was placed on non-operational status.

However, the 93d continued to supervise the closure of Castle AFB. The 93d Bomb Wing was inactivated on 30 September 1995 with the closure of Castle AFB.

Just four months later, however, it was redesignated as the 93d Air Control Wing and was reactivated at Robins AFB, Georgia on 29 January 1996. It was equipped with the E-8C Joint Surveillance Target Attack Radar System (Joint STARS) and it accepted its first production aircraft on 11 June 1996.

As of 2008, local government plans to convert the dormant facility to civilian commercial use has become an active political issue.[citation needed] It has been identified as the preferred location for the central maintenance facility of the proposed California High-Speed Rail system.[1]

Previous names

  • Army Air Corps Basic Flying School, Merced, CA, 20 September 1941 – 7 April 1942
  • Merced Army Flying School, 7 April 1942 – 8 May 1943
  • Merced Army Airfield, 8 May 1943 – 17 January 1946
  • Castle Field, 17 January 1946 – 13 January 1948

Major Commands to which assigned

  • West Coast Air Corps Training Center, 20 September 1941
Re-designated: West Coast AAF Training Center
Re-designated: AAF West Coast Training Center, 1 May 1942
Re-designated: AAF Western Flying Training Comd, 31 July 1943
  • Continental Air Forces, 1 July 1945
Re-designated: Strategic Air Command, 21 March 1946 – 1 June 1992

Note: Base directed to revert to "minimum operations on caretaker status;' 1 Oct 1946; base under administrative control of Colorado Springs Army Air Base, Colorado, 1 Nov 1946-1 luI 1947. Activated from caretaker status, 1 May 1947

Major units assigned

  • Air Corps Basic Flying School
Re-designated: AAF Basic Flying School
Re-designated: AAF Pilot School, Basic, 20 September 1941 – 30 June 1945
  • 89th Air Base Group, 3 November 1941 – 15 December 1942
  • 90th Base HQ and Air Base Sq, 13 June 1942
  • 35th Flying Training Wing, 8 June-11 September 1943
  • 3026th AAF Base Unit, 1 May 1944 – 30 June 1945
  • 446th AAF Base Unit, 1–18 July 1945
  • 482d AAF Base Unit, 19 July 1945 – 15 August 1947
  • HQ I Staging Command, 7 October 1945 – 3 April 1946
  • 444th Bombardment Group, 15 November 1945 – 6 May 1946
  • 93d Bombardment Group, 21 June 1946 – 16 June 1952
Later: 93d Operations Group, 1 September 1991 – 30 June 1995

Federal prison

United States Penitentiary, Atwater stands on a portion of the grounds of the former Air Force Base.

See also


 This article incorporates public domain material from the Air Force Historical Research Agency website

  • Endicott, Judy G. (1999) Active Air Force wings as of 1 October 1995; USAF active flying, space, and missile squadrons as of 1 October 1995. Maxwell AFB, Alabama: Office of Air Force History. CD-ROM.
  • Maurer, Maurer (1983). Air Force Combat Units Of World War II. Maxwell AFB, Alabama: Office of Air Force History. ISBN 0-89201-092-4.
  • Mueller, Robert (1989). Volume 1: Active Air Force Bases Within the United States of America on 17 September 1982. USAF Reference Series, Office of Air Force History, United States Air Force, Washington, D.C. ISBN 0-912799-53-6, ISBN 0-16-002261-4
  • Ravenstein, Charles A. (1984). Air Force Combat Wings Lineage and Honors Histories 1947–1977. Maxwell AFB, Alabama: Office of Air Force History. ISBN 0-912799-12-9.
  • Rogers, Brian (2005). United States Air Force Unit Designations Since 1978. Hinkley, England: Midland Publications. ISBN 1-85780-197-0.
  • Shaw, Frederick J. (2004), Locating Air Force Base Sites History’s Legacy, Air Force History and Museums Program, United States Air Force, Washington DC, 2004.
  • Manning, Thomas A. (2005), History of Air Education and Training Command, 1942–2002. Office of History and Research, Headquarters, AETC, Randolph AFB, Texas ASIN: B000NYX3PC

External links

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