The Reeves AN/MSQ-77 Bomb Directing Central, Radar (nickname "Miscue 77") was a USAF automatic tracking radar/computer system for command guidance of military aircraft during Vietnam War bomb runs at nighttime and during bad weather. Developed from the Reeves AN/MSQ-35, the AN/MSQ-77 reversed the process of Radar Bomb Scoring by continually estimating the bomb impact point before bomb release with a vacuum tube ballistic computer. Unlike "Course Directing Centrals" which guided aircraft to a predetermined release point, the AN/MSQ-77 algorithm continuously predicted bomb impact points during the radar track while the AN/MSQ-77's control commands adjusted the aircraft course. A close air support regulation prohibited AN/MSQ-77 Combat Skyspot bombing within of friendly forces unless authorized by a Forward Air Controller, and "on several occasions" strikes were as close as .
Post-war the MSQ-77 was used on US and other training ranges for Radar Bomb Scoring (RBS). The AN/MSQ-77 was also periodically used for post-Vietnam commanding of bombers during simulated ground directed bombing to maintain aircrew and radar crew GDB proficiency (RBS could be used to score the simulated GDB mission). Most AN/MSQ-77s were replaced by solid-state equipment near the end of the Cold War.
History
Ground radar systems for automated guidance of aircraft to a predetermined point (e.g., for bomb release using a bombsight or avionics radar) included the July 1951 AN/MPQ-14 Radar Course Directing Central. By 1954, the MARC (Matador Airborne Radio Control) used the AN/MSQ-1A for missile guidance to the terminal dive point, and SAGE GCI provided computer-controlled guidance of aircraft to continuously computed interception points (1958 AN/FSQ-7 Bomarc missile guidance and the later Ground to Air Data Link Subsystem for fighters). Despite the availability of solid-state military guidance computers in 1961, planning for a USAF vacuum-tube trajectory computer/radar system began in early 1965. In October 1965, F-100s tested the AN/MSQ-77 at Matagorda Island General Bombing and Gunnery Range on the Texas Gulf Coast.
In March 1966, AN/MSQ-77 operations using the "reverse MSQ method" began and continued through August 1973 for guiding B-52s and tactical fighters and bombers ("chiefly flown by F-100's"). By March 1967, 15,000 Skyspot sorties had been flown, and raids controlled by AN/MSQ-77s included those of Operation Menu from Bien Hoa Air Base, Operation Niagara, and Operation Arc Light. Additional AN/MSQ-77 missions included those with MC-130 Commando Vault aircraft to clear landing zones and at least 1 helicopter evacuation of wounded on August 13, 1966.
Commando Club To allow command guidance bombing of Hanoi and Haiphong targets out of range of the initial Skyspot AN/MSQ-77 sites, the "1st CEVG began "Combat Keel" tests using F-4s guided by an MSQ-77 on the USS Thomas J. Gary" in the Gulf of Tonkin during late 1967 after the March 1967 "Combat Target" task force recommended a closer site. By 1 November 1967, the USAF Heavy Green operation had prepared a Laos mountaintop site and installed an MSQ-77 variant in rugged shelters without trailer frames, wheels, etc. for helicopter transport. Although the central's range was limited by the UHF radio reliability for A/C commands during the bomb run, "Commando Club" used a relay aircraft to retransmit communications between Lima Site 85 and the bomber. LS-85's operations ended with the 1968 Battle of Lima Site 85 defeat by sappers after North Vietnam had correlated bombings were occurring during LS-85 transmissions (the site's central and other buildings were destroyed by a later U.S. air raid.)
Additional casualties of AN/MSQ-77 personnel included 1 killed in an enemy rocket attack and 6 Skyspot personnel killed in a 1966 ambush on a survey mission. Following -77 modifications in 1968, subsequent changes included a solid-state digital printer for RBS ("Digital Data System") and implementation of a USAF suggestion for RBS to use a late-1970s programmable calculator to supersede the Bomb Trajectory Group, eliminating alignment procedures for its amplifiers. In 1989, remains of an F-4C Weapon System Officer shot down during a November 10, 1967, AN/MSQ-77 bomb run were recovered in Southeast Asia.