In December of 1965, the USAF began Project Black Spot. This test program was designed to give the Air Force a self-contained night attack capability to seek out and destroy targets along the Ho Chi Minh Trail. In early-1966, the concept was approved by the Department of Defense and two Fairchild C-123K Providers (#54-691 and #54-698) were modified by E-Systems of Greenville, Texas to the redesignated NC-123K (often referred to as AC-123K) configuration.
The aircraft were equipped with a long, 57.75 inch nose fairing that housed an X-band forward-looking radar. Below and aft of the extended radome was a turret with Forward-Looking Infrared Radar (FLIR), Low-Level Light Television (LLLTV), and a laser range-finder/illuminator. Also, a low-level Doppler navigation radar and weapons release computer were installed.
Two rectangular aluminum weapons dispensers (for CBU bomblets) were stacked within the fuselage. Each container housed 12 cells, each cell containing three Cluster Bomb Units (CBUs). Depending on the type of CBU installed, the containers had a capacity of between 2,664 and 6,372 one pound bomblets. The bomblets were released through 12 openings in the cargo floor that aligned with the cells in the weapons dispenser. The lower fuselage contained 12 inward opening doors that aligned with the openings in the cargo floor, forming a chute. Bomblet release was controlled by a weapons panel in the forward section of the fuselage. In the event of an emergency, the entire load could be jettisoned manually.
The first aircraft (#54-691) was delivered to Eglin AFB, Florida in August 1967 and the second (#54-698), incorporating an AN/ASD-5 Black Crow direction finder set (engine ignition sensor), was delivered in February 1968.
Prior to deploying to Vietnam, the two aircraft were sent to Osan Air Base, South Korea to be evaluated against the high-speed infiltration boats used by North Korea to send agents into South Korea. The unit remained in Korea from 19 August 1968 to 23 October 1968, and were scheduled for a total of 57 missions. Upon completion of their Korean assignment, the unit was deployed to South Vietnam for a combat evaluation of the “Black Spot” weapons system.
It was in South Vietnam where the aircraft operated under the project name and callsign – “Black Spot”. Both aircraft began operations on 15 November 1968, flying from Phan Rang Air Base, with mission staging areas at Binh Thuy and Pleiku. During the combat evaluation period, a total of 69 sorties were flown over target areas consisting of the Mekong Delta and the Ho Chi Minh Trail. From November 1968 to May 1969, these “gunships” flew 186 missions, destroyed 415 trucks and damaged 273 more. While operating as armed night surveillance units in the Mekong Delta, the two aircraft destroyed 151 boats/vehicles, damaging another 108 and noted secondary explosions on 161 targets. Both aircraft completed 70 percent of all missions and had an in-commission rate of 84 percent; not bad for an aircraft that was developed as a testbed and never intended to be used operationally!
Both aircraft were later assigned to the 16th Special Operations Squadron at Udon RTAB. On 5 November 1969, ECM and RAHW gear was installed, and the first aircraft received a Black Crow system. They continued their mission from late-1969 till June 1970 from Udon, often with night fighter escorts because of heavy antiaircraft artillery (AAA) fire.
Although Project Black Spot was a complete success, both aircraft were later refitted to back to the C-123K standard to serve as normal transports. Note: They did retain their unique wrap-around camouflage after the conversion.