Fairchild C-123 Provider

YC-123E with pantobase landing gear

In 1954, the YC-123D, formerly the XC-123A prototype, flew in its modified state after being converted by Stroukoff Aircraft. While the most obvious change from the original XC-123A was the switch of engines (to two 3,500 hp (2,600 kW) Wright Turbo Compound R3350-89A radial engines, turning four-blade, thirteen foot Aeroproducts constant-speed fully feathering propellers), the YC-123D also had a boundary layer control system fitted. This system directs air from the engines at high speed over the top of the wing, making the wing act as if the aircraft is flying at a higher airspeed. As a result, the YC-123D had a greatly reduced takeoff and landing distance. Compared to the C-123B, the YC-123D could land in 755 feet instead of 1,200, and takeoff with only 850 ft of runway instead of 1,950, with a 50,000 lb total weight.

In 1955, Stroukoff, under contract from the USAF, produced a single YC-123E, designed to be able to take off from any surface, and also equipped with BLC. The new aircraft also featured Stroukoff's Pantobase system, combining a ski system with a sealed fuselage and wing mounted floats, while retaining its normal landing gear. The skis worked both on snow and water, and the system effectively allowed the aircraft to land on water, land, snow or ice.

In 1956, the USAF awarded a contract to Fairchild to design an improved version of the C-123 under the designation C-136, but the contract was cancelled before the aircraft was built.[10]

At much the same time, the YC-123H was under development, the product of a Fairchild modification program started in 1956 and completed in 1957. A "Jet Augmentation Program" for existing C-123Bs had been initiated in 1955 at the behest of the USAF, and in the YC-123H contract the USAF expanded it to allow the mounting of two pod-mounted General Electric J85 turbojets.

In 1979, the Royal Thai government, seeking to extend the life of their C-123 fleet, placed a contract with the Mancro Aircraft Company, supported by the USAF, to convert a single C-123B to turboprop powerplants. Allison T56-A-7 turboprops were used and by the time the aircraft, dubbed C-123T, was complete it had new "wet" wings, an auxiliary power unit (APU) to assist with power movement of the control surfaces, and a heating system for the cargo compartments that also fed a new de-icing system. Budgetary restrictions forced the Thai government to abandon the program in 1981, and with a lack of interested parties development of the C-123T stopped. However, it concluded the life of the C-123 by making it the only aircraft type to operate under jet, piston, and turboprop engine power, and as a glider, during its history.[N 1]

The C-123T has recently been revived by a joint venture between the US-based Fleetwings Aircraft Company and the South African company Elmer Group. In 2010, they announced a project to initially remanufacture old airframes for African customers and, where there was demand, to build new aircraft. The airframes would be fitted with new turboprop Rolls-Royce T56-A-15 engines, a glass cockpit and other enhancements. The proposed C-123T would have had a 25,000 lb payload capability, and a take-off run of just over 1,000 ft at 50,000 lb MTOW. Possible applications included maritime patrol, search and rescue, and even use as a gunship, while roll-on packages have already been developed for mid-air refueling and agricultural applications.[11]

During the Vietnam War, some C-123s were modified for specialized roles. Most of these modifications were on a one- or two-aircraft level. Only the usage of C-123s as "flare ships" to illuminate targets for fixed wing gunships such as the AC-47 and AC-119G were more numerous. These aircraft operating under the call-sign Candle were flown by the USAF's 14th Special Operations Wing.

US Air Force NC-123K "permanent test" model used over the Ho Chi Minh Trail. It was outfitted with a forward looking infrared system, low light level television, a laser rangefinder, and cluster bomb dispensers.

A single C-123B was tested as a possible replacement for the Candle aircraft, with its rear loading ramp removed and replaced with a large box with 28 large lights. The aircraft could continuously light a two-mile circle from an altitude of 12,000 ft. This aircraft, under the provisional designation NC-123B, was dropped because the lights fixed to the aircraft made it far easier for enemy gunners to track compared to the earlier flare ships.

The "Candle" aircraft had an extended life when several UC-123Ks were transferred to Nakhon Phanom Royal Thai Air Force Base in Thailand. During that period, it was used as a flare ship as well as a forward air control (FAC) aircraft. The flare duties were generally used for troops in contact (TIC) while the FAC mission directed air strikes in Laos over the Ho Chi Minh trail.

Another NC-123B was used as a radio relay aircraft over the Ho Chi Minh trail, with equipment to read the signals from various sensors on the ground designed to pick up enemy truck activity.

Two C-123K aircraft modified in September 1965 under Project Black Spot.[12] The Black Spot aircraft were to fit under the "self-contained night attack capability" that was Operation Shed Light's primary focus and E-Systems of Greenville, Texas, was contracted to complete the modifications. These aircraft featured a variety of new sensors including Low Light Level TV (LLLTV), Forward Looking Infrared (FLIR), and a laser rangefinder.[13] The aircraft looked radically different visibly from its transport brethren, as the new equipment required lengthening the nose by over 50 inches.[14] The aircraft also featured an armament system designed to carry BLU-3/B (using the ADU-253/B adapter) or BLU-26/B (using the ADU-272/B adapter) bomblets, or CBU-68/B cluster bombs.[15][16]

The two aircraft, AF Serial Numbers 54-0691 and 54-0698, were first designated NC-123K in 1968 and then redesignated AC-123K in 1969.[N 2] These NC/AC-123Ks were first deployed operationally at Osan AB, South Korea, between August and October 1968, and flying in support of operations against North Korean infiltrators approaching by boat. The operations in Korea met with a certain level of success and as a result the NC/AC-123Ks were transferred to South Vietnam in November 1968. The aircraft operated there until January 1969, when they were redeployed to Ubon RTAB, Thailand. The two aircraft were then returned to the United States to Hurlburt Field, Florida, in May 1969, where a second round of training occurred. Four crews attended a ground school in Greenville, Texas, and returned to Hurlburt where they flew the aircraft for the first time.

The fate of the aircraft is still unclear. Sources have missions terminating in early July 1970 and the aircraft flying to the Military Aircraft Storage and Disposition Center (MASDC) "boneyard" at Davis-Monthan AFB, Arizona, where they were returned to C-123K standard, then returned to South Vietnam still wearing their camouflage and black undersides for transport duty.[14] However, the official history states that combat operations ceased on 11 May 1969, with no mention of the second deployment.[12] While the second deployment is mentioned in associated documentation, the only dates are of the arrival in Thailand and there is no information as to when they departed or where their destination was.[17]

In 1962, the CIA acquired five C-123Bs from USAF for Air America to be used in Laos and Vietnam, and another 5 C-123Bs to be used by Republic of China Air Force (Taiwan) top secret 34th Squadron, a Black Ops units called the "Black Bat", as Flight B section (Flight A section was the two P2V-2U/RB-69A). The five Taiwan C-123Bs were sent to Lockheed Skunk Works for modifications as covert insertion aircraft with "smart" air-to-air jammer, BSTR system to jam the radars of ground anti-aircraft guns, also added a defensive operator's station to operate the jammers on board, with extra fuel in underwing tanks, with 36 Taiwanese crew finished training courses at Pope AFB by November 1962.

The five ROCAF/Taiwan/CIA C-123Bs would be used over North Vietnam as low level and nighttime covert airdrop aircraft, under the South Star II agreement, under the guise of Taiwan's national airline, China Airlines, which had "cover story" of operating Vietnamese Air Transport (VIAT) in South Vietnam, that was formerly operated by Air America. The secret outfit was based in Saigon, but would fly out of Da Nang for airdrop missions going into North Vietnam, with some missions lasting 14 hours.

On 1 February 1964, the overall control of South Star II was transferred from CIA to Studies and Observations Group (SOG), as part of U.S. Military Assistance Command Vietnam (MACV) in Saigon. The outfit was redesignated as Det. 1 of USAF's 75th Troop Carrier Squadron (TCS), but within SOG it was known as the First Flight Detachment (FFD).

In May 1964, under "Project Duck Hook", six more C-123s received extensive modifications by Lockheed Air Service at Ontario, California, equipped with ATIR and BSTR ECM packages, ASN-25 Doppler navigation system, APN-153 terrain-following radar, a console station for radio operator, new HF radio and other radios. These aircraft were issued to the secret Taiwanese Black Bat unit operating in South Vietnam. In October 1964, MACV, CIA and ROCAF/Taiwan signed the South Star III agreement to continue the operation in Vietnam. The six "Duck Hook" C-123Bs were based at Nha Trang Air Base, north of Cam Ranh Bay, officially designated as USAF Det. 12 of 1131 Special Activities Squadron.

The "Duck Hook" C-123Bs were updated with RDR-10 weather radar and ARN-131 homing receiver in 1966 in order to perform missions over the Ho Chi Minh trail. All C-123Bs were converted to C-123Ks in 1968, with two wing-mounted turbjets, plus an ECM upgrade with APR-25 radar warning receiver and ALE-1 chaff dispenser. Project "Duck Hook" designation was ultimately changed to "Heavy Hook". The Det. 12 of 1131 Special Activities Squadron unit at Nha Trang received an outstanding unit award from the USAF, for flying 4,000 classified combat and combat support missions from June 1966 to May 1968.

In May 1970, C-123Ks from the "Black Bats" supported the secret U.S. military incursion into Cambodia. In October 1970, flights into Laos began. In March 1972, the SOG was deactivated, and the Southern Star operation ended with four surviving C-123Ks returned to Taiwan. On 1 March 1973, 34th "Black Bat" Squadron of ROCAF/Taiwan was disbanded.[18]

On 5 October 1986, a Corporate Air Services C-123 Provider (HPF821, previously N4410F and USAF 54-679, (c/n 20128))[19] departed San Salvador-Ilopango Airport in El Salvador loaded with 70 AK-47 rifles and 100,000 rounds of ammunition, rocket grenades and other supplies. It flew along the coastline of Nicaragua and entered Nicaraguan airspace near the border with Costa Rica. Nearing San Carlos, the plane descended to 2,500 feet while preparing to drop off its cargo to Contra fighters.

While conducting the drop, the C-123 was shot down by a Sandinista soldier, using a SA-7 Grail. CIA pilots Wallace "Buzz" Sawyer and William Cooper were killed in the crash. Loadmaster Eugene Hasenfus parachuted to safety and was taken prisoner. He was later released in December 1986.[20] The Fairchild C-123 that was shot down in Nicaragua remains there. Its sister ship, also a Fairchild C-123 that was purchased by the CIA at the same time as the first one, was then left abandoned at San Jose International Airport for a time and then was purchased for $3,000 and disassembled into 7 pieces and transported via boat to Quepos, Costa Rica and then reassembled and is now the center piece of a beachside cocktail lounge just up the road from Manual Antonio national park.

In 2011, a retired Air Force officer, Major Wesley T. Carter, filed a complaint with the Air Force Inspector General alleging that the Air Force knew that UC-123Ks used for spraying Agent Orange in Vietnam remained contaminated and that the Air Force had failed to properly inform subsequent flight crews of the risks following their transfer to the Air Force Reserve at the end of the Vietnam War. In his complaint, Major Carter contends that the Air Force has known since 1994 that the aircraft were contaminated with the defoliant; he cites the fact that when a former C-123 was being prepared for a permanent static display that workers had to use HAZMAT suits and respirators. Additionally, it is asserted that when the aircraft was tested by the Air Force, it contained high levels of the known carcinogen polychlorinated dibenzodioxin, studies since confirmed by the Oregon Health Sciences University and Columbia University's Mailman School of Public Health.

The aircraft which were flown from 1972–1982, were assigned to the Air Force Reserve after their service in Vietnam, and used for normal cargo and aeromedical evacuation missions. Air crews accumulated hundreds of flight hours aboard several contaminated aircraft that were often flown with the windows open due to the smell and eye irritation. Memos surfaced showing that Air Force JAG officers recommended keeping the toxicity information, "...within official channels." Further, Major Carter located Air Force reports of dioxin-contaminated aircraft sold abroad, and of one used at the Robins AFB, Georgia Museum of Aviation with public access to the contaminated surfaces of the aircraft. In 2010, due to concerns about dioxin contamination, the Air Force took the unusual step of shredding all the remaining surplus C-123K/UC-123K aircraft and melting the scraps into ingots for disposal.[21]

On 9 June 2011, the Secretary of the U.S. Air Force's Inspector General rejected Carter's complaints, and in a subsequent message explained, "Unfortunately, we do not have the ability to identify or notify the individuals in the categories you mention" when asked if the military would alert the aircrews regarding their exposure to dioxin. On 18 June 2011, the veterans' complaint was accepted with the Department of Defense Inspector General, adding the request that the UC-123K aircraft themselves be designated by the Secretary of Defense as "Agent Orange Exposure Sites".[22]

In December 2011, the U.S. Department of Veterans Affairs posted two notices of its decision that, while the post-Vietnam aircraft "may" have been contaminated, the aircrews were "unlikely" to have suffered exposure to dioxin. In an unusual response, the U.S. Center for Toxic Substance and Disease Registry quickly countered the VA position on 25 January 2012 with a statement by their Deputy Director concluding that aircrews and maintenance personnel most likely were exposed well beyond military and government surface-wipe screening levels.[23]

In November 2011, the USAF School of Aerospace Medicine began its own investigation into lingering C-123 contamination. In April 2012, the USAF School of Aerospace Medicine released its review of the C-123 Agent Orange exposure issue and reported their researchers were unable to determine the degree of exposure, if any, which aircrews may have had aboard the contaminated aircraft in the period 1972–1982. Their report was, in turn, challenged by university-based experts Richard Clapp and Jeannie Stellman, both of whom continue to assert contaminated aircraft exposed the aircrews as well as aerial port and maintenance veterans. As of August 2012, the U.S. Department of Veterans Affairs has denied service-connection (the linking of a veteran's illness to military service) to every application for medical benefits.

In September 2012, Thomas Murphy, Director of VA Compensation Services, wrote that TCDD (the well-known toxic component of Agent Orange) has not been shown to cause harm to humans in his denial of one veteran's application. On 25 November 2012, a committee of scientists and physicians, chaired by Jeanne Stellman, informed the VA Under Secretary for Benefits Allison Hickey that the VA's scientific conclusions regarding the C-123 situation were ill-founded and called on the VA to involve outside experts in a re-evaluation. In a subsequent telecon, Deputy Chief Consultant Dr. T. Walters informed veterans no C-123 exposure claims would be permitted to be approved, the VA forming a denial basis around redefining the word "exposure" to include bioavailability. No bioavailability equals no exposure, and thus no exposure claims permitted and indeed, since veterans began learning of the contamination of the C-123 fleet, no exposure claims have been approved other than via appeal to the VA Board of Correction.

Veterans have cited the 8 May 2001 Federal Register, page 23166, and the 31 August 2010 Federal Register, page 5320 5, each of which state:carried the VA statement: '"Finally, we wish to make clear that the presumptions of service connection provided by this rule will apply to any veteran who was exposed during service to the herbicides used in Vietnam, even if exposure occurred outside of Vietnam. A veteran who is not presumed to have been exposed to herbicides, but who is shown by evidence to have been exposed, is eligible for the presumption of service connection for the diseases listed in § 3.309(e)."

In August 2013, the Department of Veteran's Affairs approved the disability claim of Lt. Col. Paul Bailey. This is the first time the VA has recognized a crew member's claim related to Agent Orange exposure while flying planes after the Vietnam War.[24] The legal questions attracted significant attention from veterans' advocates, and the National Veterans Legal Services Project and the Yale Law School Veterans Legal Clinic published a comprehensive legal analysis. Exposure was confirmed as the single requirement upon veterans to prove for meeting Agent Orange disability claim requirements, and Yale Law detailed the exhaustive list of proofs establishing the veterans' exposure over the decade of post-Vietnam service of the former Agent Orange aircraft. Besides the legal analysis, Yale's purpose was that their finding be useful for all C-123 veterans in submitting disability claims to the Department of Veterans Affairs.

In February 2014, a team of scientists headed by Dr. Jeanne Stellman and including Dr. Peter Lurker, Dr. Fred Berman and Dr. Richard Clapp published a pivotal scientific article in Environmental Research Titled Post Vietnam Military Herbicide Exposures in UC-123K Agent Orange Aircraft". The authors challenged both VA and USAF testing methods and earlier conclusions that the C-123K fleet was toxicologically harmless. Their research established that veterans had far greater, and more harmful, exposures than earlier estimated, and that the veterans' TCDD exposures exceeded any published safety standard. The authors noted:

In response to developing scientific challenges to its position refusing C-123 veterans' exposure claims, on March 10, 2014 VA began revising their web pages to include reference to the submission of a special C-123 study project for the Institute of Medicine. First promised to the C-123 veterans in 2012, this study directs IOM to consider medical implications of their exposures. The results were published by the IOM on 9 January 2015, solidly confirming the post-Vietnam veterans' herbicide exposures, and faulting the 2012 USAF C-123 Consultative Letter which had relied on incorrect application of a formula in determining toxicity. Under Secretary Hickey assured veterans that VA would abide by the IOM findings, and VA immediately formed a committee to address its next step as C-123 veterans are brought into the VA health care system. Secretary Robert McDonald authorized VA disability benefits on June 19, 2015 for C-123 veterans experiencing any of the recognized Agent Orange illnesses. The expected cost of the benefits and compensation was estimated to exceed $42 million at the time.(VA-2015-VBA-0015, Docket Name: AP43 - Interim Final Rule - Presumption of Herbicide Exposure and Presumption of Disability During Service for Reservists Presumed Exposed to Herbicide)