Udorn Royal Thai Air Force Base

Last updated

Udorn Royal Thai Air Force Base
Roundel of Thailand.svg
Part of Royal Thai Air Force (RTAF)
Coordinates 17°23′11″N102°47′18″E / 17.38639°N 102.78833°E / 17.38639; 102.78833 (Udorn RTAFB)
TypeAir force base
Site information
OwnerRoyal Thai Air Force
OperatorRoyal Thai Air Force
Controlled byRoyal Thai Air Force
ConditionMilitary Air Force Base
Site history
Built1955
In use1955–present
Battles/wars Vietnam War
Airfield information
Summary
Elevation  AMSL 579 ft / 176 m
Coordinates 17°23′11″N102°47′18″E / 17.38639°N 102.78833°E / 17.38639; 102.78833
Map
Thailand adm location map.svg
Airplane silhouette.svg
VTUD
Location of Udorn Royal Thai Air Force Base
Runways
Direction LengthSurface
ftm
12/3010,0003,048 asphalt

Udorn Royal Thai Air Force Base (Udorn RTAFB) is a Royal Thai Air Force (RTAF) base, the home of 23rd Wing Air Command. [1] It is in the city of Udon Thani in northeastern Thailand and is the main airport serving the city and province.

Contents

The RTAF 231 Squadron "Hunter" is assigned to Udorn, equipped with the Dassault/Dornier Alpha Jet-A.

History

Establishment

Udorn RTAFB was established in the 1950s.

The civil war inside Laos and fears of it spreading into Thailand led the Thai government to allow the United States to use covertly five Thai bases beginning in 1961 for the air defense of Thailand and to fly reconnaissance flights over Laos. Udorn was one of those bases.

Under Thailand's "gentleman's agreement" with the US, RTAF bases used by the US Air Force (USAF) were considered RTAF bases and were commanded by Thai officers. Thai air police controlled access to the bases, along with USAF Security Police, who assisted them in base defense using sentry dogs, observation towers, and machine gun emplacements.

The USAF forces at Udorn were under the command of the United States Pacific Air Forces (PACAF) Thirteenth Air Force. Udorn was the site of TACAN station Channel 31 and was referenced by that identifier in voice communications during air missions

The APO for Udorn was APO San Francisco 96237.

Air America

Airamericalogo.jpg
Air America headquarters at Udorn, c. 1967 Air America headquarters at Udorn RTAFB.jpg
Air America headquarters at Udorn, c. 1967

Udorn RTAFB was the Asian headquarters for Air America ( 17°23′11″N102°47′17″E / 17.3863°N 102.788°E / 17.3863; 102.788 ), a US passenger and cargo airline covertly owned and operated by the Central Intelligence Agency (CIA) which provided essential resources for the war in Laos and elsewhere. Its predecessor, Civil Air Transport (CAT), started operations from Udorn on 11 September 1955 with the arrival of three C-46s delivering food and emergency aid into Indochina. By the end of September, CAT had flown more than 200 missions to 25 reception areas, delivering 1,000 tons of emergency food. Conducted smoothly and efficiently, this airdrop relief operation marked the beginning of CAT's and, later, Air America's support of US assistance programs in Laos.

Air America's roles supportive of covert and overt situations related to hostilities in Southeast Asia and elsewhere worldwide provided buffers and solutions to problems the United States faced in various locations. Operations were focused in Laos as part of the "secret war" the United States carried out against the Pathet Lao forces operating in the country. Udorn RTAFB also served as the site of "Headquarters 333", the Thai organization in charge of their forces in Laos.

Air America continued operations from Udorn into Laos until 3 June 1974.

US Marine Corps use during the Laotian Crisis

In 1961 the 300-man Marine Air Base Squadron Sixteen was deployed to Udorn to maintain helicopters supporting Royal Lao Army forces in Laos. [2]

Following the defeat of Royal Lao Army in the Battle of Luang Namtha in early May 1962 by People's Army of Vietnam and Pathet Lao forces, it appeared that a communist invasion of northern Thailand was imminent and on 15 May the Kennedy Administration ordered US combat forces into Thailand to deter any attack. On 18 May VMA-332 equipped with 20 A-4 Skyhawks deployed to Udorn from Naval Air Station Cubi Point in the Philippines and HMM-261 helicopters flew into the base. On 19 May detachments of Marine Air Control Squadrons 1 and 4 and Marine Air Base Squadron 12 were also flown into the base. [2] :89–90 On 19 May the command group of the 3rd Marine expeditionary brigade and the Battalion Landing Team 3rd Battalion, 9th Marines began flying in from Bangkok and then moved north to the town of Nong Khai. [2] :90 The Marines conducted field training exercises with the Royal Thai Army and civic action with Thai civilians while Naval Mobile Construction Battalion Ten which arrived in late May established a base camp and repaired public buildings. [2] :92–3 In late June HMM-162 replaced HMM-261. [2] :93

On 29 June 1962 with the situation in Laos stabilizing and international negotiations underway, the Kennedy Administration ordered all US combat forces to begin withdrawing from Thailand. On 1 July, VMA-322 departed Udorn for Cubi Point while HMM-162 flew to Bangkok and transports flew out the 3/9 Marines. By 6 July, fewer than 1000 Marines remained at Udorn. The International Agreement on the Neutrality of Laos was signed on 23 July 1962 and the remaining Marines began to withdraw with all combat units withdrawn from Udorn by 31 July. [2] :93–4

USAF use during the Vietnam War

During the Vietnam War the base was a front-line USAF facility from 1964 through 1976.

USAF advisory use (1964–1966)

The first USAF unit assigned to Udorn was a communications detachment from the 1st Mobile Communications Group, based at Clark Air Base, Philippines, in the summer of 1964. The first permanent USAF unit assigned at Udorn RTAFB was the 333d Air Base Squadron in October 1964. Prior to the formation of the squadron, support personnel were provided by temporary duty personnel from the 35th Tactical Group at Don Muang Royal Thai Air Force Base. The 333d ABS came under the command and control of the 13th Air Force.

On 18 July 1965, the 333rd Air Base Squadron was re-designated the 6232nd Combat Support Group (CSG). This unit also came under the command and control of 13th Air Force and the 6234th Tactical Fighter Wing, a provisional wing at Korat Royal Thai Air Force Base. In July 1965, the 6234th TFW was the only tactical wing in Thailand.

The formation of the 6232d at Udorn was brought about because of expanding USAF programs, an increase in assigned personnel, and increased base support requirements. The majority of personnel at Udorn, prior to the formation of the group, were Temporary duty assignment (TDY). Shortly before the group was activated, a gradual input of permanent party personnel was made to replace those on TDY. On 15 November 1965, the 6232nd CSG was given the responsibility of reporting directly to the Deputy Commander 2nd Air Division, 13th Air Force, rather than directly to the 13th Air Force commander. The 6232nd CSG was re-designated the 630th Combat Support Group on 8 April 1966, with a reporting responsibility to the Deputy Commander, 7th Air Force/13th Air Force (7/13AF), headquartered at Udorn.

Squadrons known to have been deployed to Udorn were the 45th Tactical Reconnaissance Squadron, based at Naha AB, Okinawa with the 39th Air Division(1 November 1965 – 15 August 1966), equipped with RF-101 Voodoos and the 555th Tactical Fighter Squadron, also based at Naha AB (25 February 1966 – 25 July 1966), equipped with the F-4C Phantom II. [3] [4]

Main Gate, Udorn RTAFB, 1973 UdornRTAFB.jpg
Main Gate, Udorn RTAFB, 1973

432nd Tactical Reconnaissance Wing

RF-4C of the 14th Tactical Recon Squadron Rf-4c-14trs-udon.jpg
RF-4C of the 14th Tactical Recon Squadron
McDonnell F-4D-28-MC Phantom 65-0683 of the 555th Tactical Fighter Squadron, 20 January 1972 F-4d-65-0683-555trs-udorn-20jan72.jpg
McDonnell F-4D-28-MC Phantom 65-0683 of the 555th Tactical Fighter Squadron, 20 January 1972

On 18 September 1966, the 432nd Tactical Reconnaissance Wing (TRW) was activated and the 630th CSG was placed under the new wing and re-designated the 432nd CSG. [5] It performed combat tactical reconnaissance and added tactical fighter operations in October 1967, initially using fighters to provide combat air patrol and cover for unarmed reconnaissance planes, but later to fly strike missions. Wing fighter units destroyed many enemy aircraft: 36 confirmed aerial victories between 17 December 1967 and 8 January 1973. It also used AC-47D Spooky gunships to provide air defense of friendly Laotian outposts from June 1969 – June 1970. It ceased combat in Vietnam in January, in Laos in February, and in Cambodia in August 1973. The wing remained in Southeast Asia to perform reconnaissance and routine training to retain combat proficiency, changing designations from reconnaissance to fighter in November 1974. The wing supported Operation Eagle Pull, the evacuation of US personnel from Phnom Penh, Cambodia on 12 April 1975, and Operation Frequent Wind, the evacuation of US and South Vietnamese personnel from Saigon on 29 April 1975. From 13 to 15 May 1975, the wing played a major role in locating the SS Mayaguez and in the military operations associated with the recovery of that US commercial vessel and its crew from the Cambodians. The wing was relieved of all operational commitments on 30 November and inactivated at Udorn RTAFB on 23 December 1975. [5] :226

The 432nd TRW was the most diversified unit of its size in the USAF.

Squadrons of the 432nd TRW were: [5] :225

Tactical reconnaissance squadrons

These three squadrons accounted for more than 80% of all reconnaissance activity over North Vietnam.

Tactical Fighter Squadrons

In addition to reconnaissance the 432d also had a tactical fighter squadron component as follows:

Special Operations Squadrons

Douglas C/AC-47B-45-DK Skytrain Gunship 45-0010 of the 4th Special Operations Squadron - June 1970 Douglas AC-47D of the 4th SOS at Udorn Royal Thai Air Force Base, in June 1970.jpg
Douglas C/AC-47B-45-DK Skytrain Gunship 45-0010 of the 4th Special Operations Squadron – June 1970

By 1967 or earlier, USAF weather modification flights were originating from a special operations group at Udorn. No more than four C‐130s, and usually only two, were assigned to the restricted section of the base. Their mission was to create rainfall over North Vietnam, Laos, and South Vietnam to hamper enemy logistics and tactical initiative. [14]

Beginning in late 1970, Udorn was drawn down as part of the overall US withdrawal from the Vietnam War:

  • On 5 November 1970, the 11th TRS was deployed to Shaw AFB, South Carolina, ending a tour of service with the 432nd TRW.
  • On 29 December 1970 the 4th Special Operations Squadron was inactivated, with its aircraft being transferred to the Republic of Vietnam Air Force.
  • On 15 April 1972 the 7th Airborne Command and Control Squadron with its C-130s was transferred to Korat RTAFB.

1972 augmentation

In 1972, tactical fighter strength was augmented at Udorn by deployed Tactical Air Command continental US-based squadrons in response to the North Vietnamese Easter Offensive. During Operation Linebacker, between May and October 1972, the 432nd TRW had seven F-4 squadrons assigned or attached, making it the largest wing in the USAF. Units deployed to Udorn were: [5] :225

With the signing of the Paris Peace Accords on 27 January 1973, most of the F-4 squadrons that participated in the 1972 campaigns returned to their home stations and the numbers of USAF personnel and aircraft at Udorn were reduced.

By 1975, relations between Washington and Bangkok had deteriorated. The Royal Thai Government wanted the USAF out of Thailand by the end of the year. Palace Lightning was the plan under which the USAF would withdraw its aircraft and personnel from Thailand.

  • The 13th Tactical Fighter Squadron was inactivated in June 1975.
  • The 14th Tactical Reconnaissance Squadron was inactivated in June 1975.

The 423d TRW was inactivated on 23 December 1975 and the last USAF personnel departed Udorn in January 1976. [5] Udorn RTAFB was turned over to Thai authorities. It is now operated by the Royal Thai Air Force with aircraft from the 2nd Air Division being based there.

Sapper attacks

  • 26 July 1968: A team of 25 or more personnel equipped with automatic weapons attacked Udorn RTAFB, causing severe damage to a USAF C-141 and an F-4D, and killing one Thai security guard and the C-141 crew chief [21] [22]
  • 3 October 1972: A group of seven guerillas attempted an attack, with three killed and one captured. One Thai security guard was killed. [23]

Black site

The BBC has reported that the base was the location of a CIA black site, known to insiders as "Detention Site Green", used to interrogate Abu Zubaydah, a 31-year-old Saudi-born Palestinian, believed to be one of Osama bin Laden's top lieutenants. [24] In December 2014 the United States Senate Select Committee on Intelligence (SSCI) published an executive summary of a secret 6,000-page report on CIA techniques. The report alleges that at least eight Thai senior officials knew of the secret site. The site was closed in December 2002. [25] Thailand has denied the existence of the site while the US government has neither confirmed or denied its existence.

Earlier reports alleged that a Voice of America relay station in the Ban Dung District of Udon Thani Province was the CIA black site. [26] [27] Another report pointed to Ramasun Station as a possible black site. [28]

Accidents and incidents

See also

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References

PD-icon.svg This article incorporates public domain material from the Air Force Historical Research Agency

  1. "Udon AFB". Royal Thai Air Force. Retrieved 30 August 2022.
  2. 1 2 3 4 5 6 Whitlow, Robert (1977). U.S. Marines in Vietnam:The Advisory And Combat Assistance Era, 1954–1964. History and Museums Division, Headquarters, U.S. Marine Corps. p. 88. ISBN   1494285290.
  3. "45 Reconnaissance Squadron (ACC)". Air Force Historical Research Agency. 6 May 2013. Retrieved 25 July 2018.
  4. "555 Fighter Squadron (USAFE)". Air Force Historical Research Agency. 15 May 2017. Retrieved 25 July 2018.
  5. 1 2 3 4 5 6 7 8 Ravenstein, Charles A. (1984). Air Force Combat Wings, Lineage & Honors Histories 1947-1977. Office of Air Force History. pp.  225-6. ISBN   0912799129.
  6. "20 Intelligence Squadron". Air Force Historical Research Agency. 3 August 2017. Retrieved 25 July 2018.
  7. "14 Fighter Squadron (PACAF)". Air Force Historical Research Agency. 11 October 2016. Retrieved 25 July 2018.
  8. "11 Attack Squadron (ACC)". Air Force Historical Research Agency. 18 October 2016. Retrieved 25 July 2018.
  9. "435 Fighter Training Squadron (AETC)". Air Force Historical Research Agency. 10 May 2010. Archived from the original on 22 August 2022. Retrieved 25 July 2018.
  10. "13 Fighter Squadron (PACAF)". Air Force Historical Research Agency. 11 October 2016. Retrieved 25 July 2018.
  11. "555 Fighter Squadron (USAFE)". Air Force Historical Research Agency. 15 May 2017. Retrieved 26 July 2018.
  12. "7 Expeditionary Airborne Command and Control Squadron (ACC)". Air Force Historical Research Agency. 1 March 2017. Retrieved 25 July 2018.
  13. "4 Special Operations Squadron (AFSOC)". Air Force Historical Research Agency. 20 March 2016. Retrieved 25 July 2018.
  14. Hersh, Seymour M (3 July 1972). "Rainmaking Is Used As Weapon by U.S." New York Times. Retrieved 23 October 2016.
  15. "523 Fighter Squadron (ACC)". Air Force Historical Research Agency. 29 January 2008. Retrieved 25 July 2018.
  16. "58 Fighter Squadron (AETC)". Air Force Historical Research Agency. 13 October 2016. Retrieved 25 July 2018.
  17. "308 Fighter Squadron (AETC)". Air Force Historical Research Agency. 8 July 2016. Retrieved 25 July 2018.
  18. "307 Fighter Squadron (AFRC)". Air Force Historical Research Agency. 28 October 2011. Retrieved 25 July 2018.
  19. "414 Combat Training Squadron (ACC)". Air Force Historical Research Agency. 30 June 2009. Retrieved 25 July 2018.
  20. "421 Fighter Squadron". Air Force Historical Research Agency. 19 March 2008. Retrieved 25 July 2018.
  21. Vick, Alan (1995). Snakes in the Eagle's Nest A History of Ground Attacks on Air bases (PDF). Rand Corporation. pp. 81–82. ISBN   9780833016294.
  22. "Project CHECO report Base Defense in Thailand" (PDF). Headquarters Pacific Air Force. 18 February 1973. p. 5. Archived (PDF) from the original on 25 April 2021. Retrieved 25 April 2021.
  23. "Guerrilla Attack Reported on a U.S. Base in Thailand, 2d in 24 Hours". The New York Times. 4 October 1972.
  24. Chongkittavorn, Kavi (15 May 2018). "Thailand's black site: Who is accountable?" (Opinion). Bangkok Post. Retrieved 15 May 2018.
  25. "CIA director Gina Haspel's Thailand torture ties". BBC News. 4 May 2018. Retrieved 15 May 2018.
  26. Crispin, Shawn W (25 January 2008). "US and Thailand: Allies in Torture". Asia Times. Archived from the original on 9 May 2008. Retrieved 10 November 2014.{{cite news}}: CS1 maint: unfit URL (link)
  27. "Suspicion over Thai 'black ops' site". Sydney Morning Herald. 5 November 2005. Retrieved 27 April 2018.
  28. Nanuam, Wassana (27 August 2018). "Ex-US base 'not secret prison'". Bangkok Post. Retrieved 27 August 2018.
  29. "Headquarters MACV Monthly Summary April 1970" (PDF). Headquarters United States Military Assistance Command, Vietnam. 17 August 1970. p. 34. Retrieved 15 March 2020.PD-icon.svg This article incorporates text from this source, which is in the public domain .

Bibliography