Forward air controllers (FACs) played a significant part in the Vietnam War from the very start. Largely relegated to airborne duty by the constraints of jungled terrain, FACs began operations as early as 1962. Using makeshift propeller-driven aircraft and inadequate radio nets, they became so essential to air operations that the overall need for FACs would not be completely satisfied until 1969. The FAC's expertise as an air strike controller also made him an intelligence source, munitions expert, communication specialist, and above all, the on-scene commander of the strike forces and the start of any subsequent combat search and rescue if necessary.
Present as advisors under Farm Gate, FACs grew even more important as American troops poured into Vietnam after the Gulf of Tonkin incident. The U.S. Air Force (USAF) would swell its FAC complement to as many as 668 FACs in Vietnam by 1968; there were also FACs from the U.S. Army, U.S. Navy, U.S. Marine Corps, and allied nations. For the early years of the war USAF manning levels were at about 70% of need; they finally reached 100% in December 1969. The FACs would be essential participants in close air support in South Vietnam, interdiction efforts against the Ho Chi Minh Trail, supporting a guerrilla war on the Plain of Jars in Laos, and probing home defenses in North Vietnam.
As the war came to center on the Trail in 1969, the FAC role began to be marginalized. Anti-aircraft (AAA) defenses became steadily more aggressive and threatening along the Trail as the bombing of North Vietnam closed down. The communist enemy moved their supply activities to nighttime, quite literally leaving the FACs in the dark. The American response was twofold. They used fixed-wing gunships with electronic sensors to detect communist trucks, and onboard weaponry to destroy them. They also began putting FACs in jet aircraft and in flareships as a counter to the AAA threat. At about the same time, emplaced ground sensors began to complement and overshadow FAC reconnaissance as an intelligence source. FAC guidance of munitions also began to come into play in 1970.
By the time the Vietnam War ended in 1975, the U.S. and its allies had dropped about six times as many tons of bombs as had been dropped in the entirety of World War II. A considerable proportion of this tonnage had been directed by forward air controllers.
Operating environment
Terrain
The Forward Air Controller (FAC) fulfilled many duties during the Second Indochina War. In addition to the usual close air support strike missions to aid South Vietnamese ground forces in their struggle against insurgents backed by the Democratic Republic of Vietnam, he might direct combat search and rescue operations or air interdiction strikes on the Ho Chi Minh Trail. Other FAC duties included escort of supply truck convoys, or involvement in covert operations. The FAC also advised ground commanders on usage of air power, and trained indigenous personnel in forward air control. Most of all, he flew the core mission of visual reconnaissance, seeking information on the enemy.Churchill, p. xvi.
The airborne FAC flew the Cessna O-1 Bird Dog or other light aircraft slowly over the rough terrain at low altitude to maintain constant aerial surveillance. By patrolling the same area constantly, the FACs grew very familiar with the terrain, and they learned to detect any changes that could indicate enemy forces hiding below. The rugged jungle terrain of South East Asia easily hid enemy troop movements. However, the FAC looked for tracks on the ground, dust settling in foliage, roiled water in streams—all signs of furtive enemy movement. Both unexpected campfire plumes and rows of fresh vegetables growing near water in "uninhabited" areas were also tip-offs to communist camps. However, decoy camps were not unknown; ofttimes fires were kept underground, with the smoke plumes being redirected through a laterally extended chimney. The communist insurgents were proficient in both camouflage and disguise. Camouflage extended down to individual soldiers using green branches to garnish backpacks. As part of disguise, the insurgents would sometimes dress as civilians, even going so far as to dress as monks or as women carrying small children. Despite these evasions, by 1968 FAC visual recon had largely suppressed daytime communist activities.Churchill, pp. 15 - 16.
Flying low and slow over enemy forces was very dangerous for the FACs; however the enemy usually held his fire to avoid discovery. However, when the enemy opened fire, it might hit him with anything from rifle bullets to 37mm antiaircraft cannon. A low pass for post-strike bomb damage assessment was another hazardous duty.Churchill, p. 24.
American ground FACs began to supply on-the-job training to South Vietnamese counterparts in Tactical Air Control Parties, in an effort to improve poor performance by the local FACs. However, rough terrain, limited sight lines, and difficulty in communication always seriously hindered ground FAC efforts in Southeast Asia.Walton, p. 31
FAC aircraft
A wide variety of aircraft were used in the forward air control role.
Propeller-driven
Common propeller-driven FAC aircraft were:
Cessna O-1 Bird Dog: This two-seater served as the original FAC aircraft. Slow, unarmed and unarmored, its small size limited its payload and it did not have instrumentation for night operations. Although it carried three radios for air strike coordination—Frequency Modulation, High Frequency, and Very High Frequency—only one radio channel was available at a time.Walton, p. 37Churchill, pp. 15 - 16, 28.
Cessna O-2 Skymaster: 510 were modified for military service. A businessman's aircraft, it was adapted for interim use by FACs, to replace the O-1. It was a faster airplane, with two engines in a tractor/pusher arrangement, four hard points for ordnance, and a seven-hour linger time. Its side by side seating limited the pilot's line of vision to the right and to the rear.Churchill, pp. 50 - 53.
OV-10 Bronco: The first American airplane designed for FAC work; entered combat service on 6 July 1968. With double an O-1's speed, excellent all-around sight lines for observation, an armored cockpit, and an avionics suite that included eight secure radios along with the flight instruments, the OV-10's five ordnance hard points made it a potent combination of FAC and light strike aircraft.Churchill, pp. 57 - 58.Walton, pp. 41 - 42 By 1972, the Bronco was responsible for laser illuminating targets for about 60% of the "smart bombs" dropped in Vietnam.Churchill, p. 61.
Other propeller-driven aircraft were also used as FAC aircraft, usually in an interim, ad hoc, or specialized role:
Cessna U-17 Skywagon North American T-28 Trojan A-26 Invader A-1 Skyraider OV-1 Mohawk Fairchild AC-119 C-123 Provider: Call sign "Candlestick" C-130 Hercules: Call sign "Blindbat"Churchill, pp. 63 - 65. Douglas RC-47PChurchill, p. 25. C-7 CaribouChurchill, p. 80.
Fast FAC jet
Jet aircraft were also used for FAC duties: Grumman F-9 Cougar: Used by U.S. Marine Corps as original Fast FAC experimentChurchill, pp. 134 - 135. F-100 Super Sabre: Call sign "Misty" McDonnell Douglas F-4 Phantom II: Call signs "Stormy", "Wolf", "Night Owl", "Whiplash/Laredo"Churchill, pp. 64 - 65. Martin B-57 Canberra
Rules of engagement
The Rules of Engagement (ROE) placed restrictions on the use and direction of air strikes. In 1961, when American pilots and South Vietnamese FACs began to fly combat missions together, the first ROE was established. The original requirement was that only the Vietnamese FACs could drop ordnance because all air strikes required the approval of the South Vietnamese government. Also, aircraft could return fire if fired upon, in what was dubbed "armed reconnaissance".Churchill, pp. 13 - 14.Walton, pp. 27 - 28
On 25 January 1963, the ROE were updated to establish some free-fire zones containing only enemy troops; permission was not needed to place an air strike there. The requirement for Vietnamese approval was also waived for night missions supporting troops in contact, so long as they were supported by a Douglas C-47 flareship. By 1964, the ROEs had changed to allow U.S. Army aircraft to observe from as low as 50 feet, while the USAF and VNAF were held to a 500-foot minimum. As the war evolved, so did the ROE; they became more complex. Different branches of the military service—U.S. Air Force, U.S. Army, U.S. Marine Corps, U.S. Navy—flew under differing rules. For instance, the requirement for a Vietnamese FAC on-board was waived for U.S. Army FACs. On 9 March 1965, U.S. air was cleared to strike in South Vietnam with airplanes stationed in-country; however, Thailand-based bombers were forbidden to hit South Vietnamese targets.Churchill, p. 28.
The ROE changed according to the location of the action and force involved. Only USAF FACs could support U.S. Army ground forces in South Vietnam, unless the Army was operating in a free fire zone. And while the military approved air strikes in Vietnam, approval of any target in Laos depended on the American ambassador.Churchill, p. 11.
Common to all iterations of the ROE was insistence on aligning strike runs so ordnance was dropped or fired headed away from friendly troops and innocent civilians, and toward the enemy troops. Extraordinary circumstances might find a FAC constrained to direct a drop parallel to friendly lines. Only in dire emergencies would the FAC decree approve strikes in a direction toward friendly forces. The ROE were also clear that, no matter how junior in rank the FAC, he was in complete control of the air strike. Inattentive or disobedient pilots were sometimes told to carry their bombs back to base.Churchill, pp. 18 - 20, 23 - 24. There is anecdotal evidence that "friendly fire" incidents were reported all the way to the U.S. president.
An outstanding example of FAC salvation of the civilian populace occurred on 8 February 1968. Several hundred refugees moving on Route 9 from Khe Sanh to Lang Vei were spared an artillery barrage when Captain Charles Rushforth identified them as a non-military target.Churchill, p. 76.
Staff personnel tested the FACs on the ROE on a monthly basis. The FAC might have to master more than one set of the ROEs. The complexity of the Rules, and the aggravation of conforming with them, were a prime recruiter for the Raven FACs working undercover in Laos.Robbins, pp. 21 - 30.Rowley (1975), pp. 164 - 168.
System
In many cases, the forward air control system began with the forward air controller being pre-briefed on a target. He then planned his attack mission. In other cases, an immediate air request came in requiring a rapid response; the FAC might have to divert from a pre-briefed target. In any case, the FAC would rendezvous with the strike aircraft, preferably out of view of the targeted enemy. Once permission to strike was verified, the FAC marked the target, usually with a smoke rocket. Once the strike aircraft identified the marked target, they were directed by the FAC. Once the strike was complete, the FAC would make a bomb damage assessment and report it.Anthony, pp. 67 - 74.Rowley (1972), pp. 59 - 71.
The FAC was the most important link in any one of the air control systems; in any of them he served as a hub for the strike effort. He was in radio contact not just with the strike aircraft; he also talked to the Airborne Command and Control Center coordinating airstrike availability, to ground forces, and to the headquarters approving the strike. He was supported by Tactical Air Control Parties co-located with ground forces' headquarters ranging down to the regimental, brigade, or battalion level. However, the multiplicity of systems, their equipment shortages, and the inexperience of participants, all handicapped the FAC in the Vietnam War.