More aerial intelligence systems used during Vietnam War

By Command History Office, USAICoEJuly 7, 2015

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Fort Huachuca, Arizona - During the Vietnam War, the Army possessed three distinct aerial intelligence capabilities.

The U-6 Beaver fixed-wing airborne radio-direction finding (ARDF) platform was discussed in last month's article. In addition to the U-6 first used for ARDF, the Army Security Agency (ASA) also modified U-1 Otter, U-8 Seminole, CV-2B Caribou, and P-2E Neptune aircraft for the airborne signals intelligence (SIGINT) collection mission. These aircraft intercepted and collected enemy communications and non-communications (radar) signals emissions. They were respectively known as LAFFING OTTER / CAFÉ GIRL, CHECKMATE / WINEBOTTLE / CEFISH PERSON, GOFER DELTA, and CRAZY CAT / CEFLIEN LION, depending on the type of equipment installed.

Additionally, in 1968, ASA introduced the RU-21D LAFFING EAGLE with automated direction-finding capability and, in 1971, the JU-21A LEFT JAB provided the first airborne collection system with 360-degree direction-finding coverage. Both platforms met the requirement for airborne interception of enemy communications, including voice and Morse code signals, along the Demilitarized Zone (DMZ). The LAFFING EAGLE was credited with intercepting elements of the North Vietnamese Army's 1st Division and their plans to launch a 1969 Tet Offensive.

In addition to the fixed-wing ARDF platforms, the Army fielded a heliborne system.

In mid-1967, specially-configured UH-1 helicopters with LEFT BANK direction-finding equipment were assigned directly to the 1st Cavalry and 4th Infantry divisions in Vietnam. The helicopters were flown by division pilots with on-board ASA operators whose mission was to locate and target time-sensitive enemy threats.

These platforms were the only airborne SIGINT systems that fell under the direct operational control of the maneuver commander. The four-man crew flew four-hour missions to establish the locations of targets to which a scout and gunship helicopter team responded. The LEFT BANK received credit for locating 234 enemy targets and 50 enemy base areas, as well 151 enemy killed in one three-month period.

In 1970, Maj. Gen. E.B. Roberts, commander of the 1st Cavalry Division praised the LEFT BANK: "I cannot overstate the highly valuable intelligence, reported on a near real-time basis, that the Cav [sic] has accrued as a result of this splendid system."

The advantages of airborne SIGINT collection over ground-based sites was clear. Airborne systems could cover a larger area more quickly and get closer to enemy transmitters for more accurate locations. Finn Larsen, deputy director of the Department of Defense Research and Engineering organization, stated, "During my recent visit to South Vietnam I observed and was told by our senior commanders that ... airborne direction finding and airborne intercept is providing 80 to 85 percent of the intelligence used in planning and operations against the Communist forces in South Vietnam."

The third aerial intelligence capability was an imagery platform. Army personnel flying OV-1 Mohawks supported combat operations with day and night visual and photographic surveillance and targeting. The OV-1 Mohawk was the only fixed-wing aircraft built specifically for the Army's intelligence mission.

The first OV-1 Mohawk arrived in Vietnam in 1962 with the 23d Special Warfare Aviation Detachment. By the end of the war, A (photographic), B (side-looking airborne radar [SLAR]), and C (infrared radar) models were under direct operational control of field commanders.

The SLAR capability provided long-range surveillance of moving targets, especially at night and in poor weather conditions. The advanced infrared system mounted on the OV-1C could detect heat traces from small cooking fires, a recoilless rifle flash, or from truck engines that had been parked for as long as 16 hours, allowing surveillance through darkness, camouflage or jungle cover. The addition of these new types of imagery from the systems on board the Mohawks led to the name change from photographic intelligence (PHOTINT) used since World War I to imagery intelligence (IMINT) still used today.

The significance of these airborne systems as key providers of intelligence for combat commanders in Vietnam cannot be overstated. But the Army paid a heavy price. More than 60 Mohawks were lost in Vietnam, Laos and Cambodia. Most were shot down by enemy ground fire; one was lost to a surface-to-air missile while on a mission in the DMZ in 1966; one was destroyed on the ground during an enemy attack on its base in 1968; another was shot down by a MiG in 1969. Another 36 Mohawks were lost to operational accidents.

The planes were not the only loss. Seventy-two American personnel and their South Vietnamese counterparts lost their lives conducting Mohawk missions. In addition, two U-6, two U-8, one JU-21 LEFT JAB, and two EH-1H LEFT BANK helicopters and their crews were lost during the war.

A memorial plaque dedicated to Military Intelligence aviators who have given their lives in pursuit of aerial intelligence, including those from the Vietnam War, is located at the Army Intelligence Aviation Memorial Park on the corner of Hatfield and Irwin streets on Fort Huachuca.