Forward air control is the provision of guidance to close air support (CAS) aircraft intended to ensure that their attack hits the intended target and does not injure friendly troops. This task is carried out by a forward air controller (FAC).
83-609: The Raven Forward Air Controllers , also known as The Ravens , were fighter pilots (special operations capable) unit used as forward air controllers (FACs) in a clandestine and covert operation in conjunction with the US Central Intelligence Agency (CIA) in Laos during America's Vietnam War . The Ravens pinpointed targets for most of the air strikes against communist Lao People's Liberation Army and People's Army of Vietnam (PAVN) infiltrators in support of
166-541: A turf war over doctrine raged between the U.S. Air Force and the U.S. Army for the entire war. Additionally, the U.S. Marine Corps maintained its own FAC operation during the war. Also, U.S. Navy carrier aviation would not completely coordinate its operations with the Air Force/Army system until the final month of the war. With no common doctrine agreed upon during the war, forward air control systems were shut down postwar in 1956. Forward air controllers played
249-826: A FAC, at least 100 hours' flight time as a fighter pilot or FAC, at least 750 hours flying time overall, and six months or more time remaining on his tour in Southeast Asia. Those who volunteered for the program did so with no knowledge of their destination. After screening by the 56th Special Operations Wing at Nakhon Phanom RTAFB , they received temporary duty orders, and were sent to the US Embassy, Vientiane , Laos. There they were stripped of all military identification and gear, supplied with USAID identification, and garbed in civilian clothing to be worn at all times. The screening system tended to select experienced and aggressive FACs. The Ravens belonged only tangentially to
332-574: A Lao or Thai interpreter in the back seat. The Air Commando sergeants directed the air strikes according to USAF doctrine, using the radio call sign "Butterfly". Two of the Butterfly US Combat Control Teams (CCT) were Master Sergeant Charles Larimore Jones , soon joined by Technical Sergeant James J. Stanford . Another of the Butterflies was Major John J. Garrity, Jr., who in future would spend several years as
415-669: A TACAN-only equipped aircraft cannot receive bearing information from a VOR-only station. The TACAN navigation system is an evolution of radio transponder navigation systems that date back to the British Oboe system of World War II . In the United States, many companies were involved with the development of TACAN for military aircraft. Hoffman Laboratories Div. of the Hoffman Electronics Corp.–Military Products Division (now NavCom Defense Electronics)
498-552: A computerized fire control system. On 1 November 1968, President Lyndon Johnson declared a halt to the bombing of North Vietnam . With that act, the focus of the contending forces became the Ho Chi Minh Trail. As the U.S. more than quadrupled the number of airstrikes aimed at interdiction , North Vietnamese anti-aircraft guns and gunners transferred south to the Trail to match this new onslaught. Both sides realized that
581-545: A considerable portion of the tactical air strikes. By the cessation of hostilities, airborne forward air controllers alone were credited with flying 40,354 forward air control sorties, and directing air strikes that killed an estimated 184,808 communist troops. At times, tactical air was credited with inflicting about half of all communist casualties. Despite having agreed on a common forward air control doctrine as embodied in Field Manual 31 - 35 Air-Ground Operations ,
664-435: A constantly changing situation and the fog of war all increase the risk. Present day doctrine holds that Forward Air Controllers (FACs) are not needed for air interdiction , although there has been such use of FACs in the past. An additional concern of forward air controllers is the avoidance of harm to noncombatants in the strike area. As close air support began during World War I , there were pioneer attempts to direct
747-467: A day. Ron Rinehart exceeded that, logging a 14-hour flight day. Incoming air strikes arrived en masse, with as many as six flights of fighter-bombers stacked up at various altitudes awaiting their turn to bomb. Rinehart would remain on station until his marking rockets were expended, all windows on his O-1 slathered in grease-penciled notes of air strikes, and his fuel tank empty. On three occasions, he landed dead stick back at base when he ran out of gas. In
830-406: A flurry of self-published texts on the subject, generally by participants. The self-published texts below do not meet Misplaced Pages standards as reliable sources. However, they contain a sizeable body of information unprocessed by historians, and are useful and interesting further reading for those wishing more insight into the subject. Forward air control A primary forward air control function
913-607: A ground or ship-borne station. It is, from an end-user perspective, a more accurate version of the VOR / DME system that provides bearing and range information for civil aviation . The DME portion of the TACAN system is available for civil use; at VORTAC facilities where a VOR is combined with a TACAN, civil aircraft can receive VOR/DME readings. Aircraft equipped with TACAN avionics can use this system for enroute navigation as well as non-precision approaches to landing fields. However,
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#1732771993828996-548: A large counterpoise and a fairly complex phased antenna system. A TACAN system theoretically might be placed on a building, a large truck, an airplane or a ship, and be operational in a short period of time. An airborne TACAN receiver can be used in air-to-air mode to provide the approximate distance between two coordinating aircraft by selecting channels with 63 channels of separation (e.g., aircraft #1 sets channel 29 into its TACAN and aircraft #2 sets channel 92 into its TACAN.). It does not provide relative bearing. For military usage
1079-630: A major part in the largest bombing campaign in history during the Vietnam War . While World War II had featured indiscriminate mass air raids on major cities worldwide, bombing during the Vietnam War was aimed at smaller targets in a country the size of New Mexico. Unless bombs were dropped in a free fire zone, or on a pre-briefed target, the bombing in Vietnam was directed by FACs. Also unlike World War II, serious efforts were made to avoid hitting
1162-634: A participating Raven at his end of tour was that 90% of the Raven planes had been hit by ground fire during their tours of duty; 60% had been downed by enemy action at some point; 30% had been killed in action . Note: Craig Duehring, who made this calculation, later became an Assistant Secretary of the Air Force. The roster of 161 Ravens includes the Butterfly FACs, none of whom were killed in action , as well as an army attaché, who was. Twenty-three of
1245-409: A primary drawback is lack of the ability to control emissions ( EMCON ) and stealth. Naval TACAN operations are designed so an aircraft can find the ship and land. Since there is no encryption, an enemy can use the range and bearing provided to attack a ship equipped with a TACAN. Some TACANs have the ability to employ a "Demand Only" mode: only transmitting when interrogated by an aircraft on-channel. It
1328-554: A radio transmitter in his airplane to send changes via morse code to an artillery battery on the ground. Colonel Billy Mitchell also equipped his Spad XVI command airplane with a radio, and the Germans experimented with radios in their Junkers J.I all-metal-structure, armored-fuselage sesquiplanes . The Marines in the so-called Banana wars of the 1920s and 1930s used Curtiss Falcons and Vought Corsairs that were equipped with radios powered by airstream-driven generators, with
1411-472: A range of up to 50 miles. Another method of communication was for the pilot to drop messages in a weighted container, and to swoop in and pick up messages hung out by ground troops on a "clothesline" between poles. The objective was aerial reconnaissance and air attack. Using these various methods, the Marine pilots combined the functions of both FAC and strike aircraft, as they carried out their own air attacks on
1494-711: A single month, he directed over 1,000 tactical air strikes, flying over 280 combat hours. If President Lyndon B. Johnson ’s March 1968 partial bombing halt diverted a steady stream of air power from Vietnam into Laos, his 1 November 1968 moratorium flooded the kingdom with US air power and overwhelmed the four Ravens stationed in northeastern Laos. Tactical air power was allocated at a conference by 7/13th Air Force in Saigon. Air Attaché Colonel Robert Tyrell came away from this with 60% of all tactical air strikes in Southeast Asia scheduled for attacks within Laos. The position of Head Raven
1577-551: A skill equivalency to that of a JFO. The Australian Army operatives developed this capability within the ANA in late 2015 to 2016 to include NVG, ISR, Afghan Air Force/Army/Police and other units, which culminated in the enduring Joint exercise Tolo Aftab which was first held in January 2016 ( https://www.armynewspaper.defence.gov.au/army-news/may-5th-2016/flipbook/6/ ). This was enhanced and developed by ADF personnel from RAAF and ARA until
1660-469: A small contingent of advisors which it withdrew from the country. The North Vietnamese deliberately ignored the accords because they were intent on keeping their supply corridor, the Ho Chi Minh trail , to continue their war against South Vietnam . North Vietnam's representatives repeatedly stated they had "no military presence in Laos" , even though they had at least 4,000 troops stationed there from
1743-485: A station in range in "search" mode, then drop down to ≈30 per second when acquired in "track" mode. Memory circuits in the ranging function enable a track to be quickly reestablished when ranging pulses are temporarily suppressed by other TACAN functions (see below). Bearing information is derived from amplitude modulation (AM) of the responding station's pulse-pair signals, the AM signal being generated via physical rotation of
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#17327719938281826-404: A station's directional antenna or electronic steering of the same signal using an antenna array. Two AM signals are generated: a fundamental AM signal at 15 Hz, and an auxiliary AM signal (implemented using fixed signal reflectors in rotating-antenna installations) at 135 Hz, the ninth harmonic of the fundamental signal. These correspond to a "coarse" and "fine" bearing signal, the latter improving
1909-495: Is allocated a FAC or JTAC . Such assignment (designated as a "B-Billet") is given to Marine aviators often as they are most knowledgeable about close air support and air superiority doctrines. The Afghan National Army (ANA) relied on coalition partners to raise and sustain its FAC and Joint Fires Officer (JFO) capability. The ANA capability, known as the Afghan Tactical Air Coordinator maintained
1992-541: Is ensuring the safety of friendly troops during close air support . Enemy targets in the front line ("Forward Edge of the Battle Area" in US terminology) are often close to friendly forces and therefore friendly forces are at risk of friendly fire through proximity during air attack. The danger is twofold: the bombing pilot cannot identify the target clearly, and is not aware of the locations of friendly forces. Camouflage,
2075-526: Is likely that TACAN will be replaced with a differential GPS system similar to the Local Area Augmentation System called JPALS. The Joint Precision Approach and Landing System has a low probability of intercept to prevent enemy detection and an aircraft carrier version can be used for autoland operations. Some systems used in the United States modulate the transmitted signal by using a 900 RPM rotating antenna. Since this antenna
2158-447: The éminence grise of the US Embassy in Laos. They, and their successors, controlled air strikes without notice or objection until General William Momyer discovered that enlisted men were directing air strikes. At that point, he ordered their replacement with rated fighter pilots. By that time, the number of Butterflies had increased to six. In April 1966, General Momyer put an end to both the impromptu efforts to control air strikes and
2241-619: The Force Intervention Brigade operations in the Democratic Republic of the Congo , an FAC called 27 missions. For NATO forces the qualifications and experience required to be a FAC are set out in a NATO Standard (STANAG). FACs may form part of a Fire Support Team or Tactical Air Control Party , they may be ground based, airborne FACs in fixed-wing aircraft (FAC-A) or in helicopters (ABFAC). Since 2003
2324-784: The Korean War and the Vietnam War . French colonial operations in the Rif War from 1920–1926 used air power similarly to the Marines in Nicaragua against the Sandinistas but in a different environment, the desert. The French Mobile Groups of combined arms not only used aircraft for scouting and air attack; the airplanes carried trained artillery officers as observers. These aerial observers called in artillery fire via radio. The German military noted close air support operations in
2407-854: The Korean War broke out. The United Kingdom and Commonwealth continued to build on their experience in the Second World War in various campaigns around the world in the second half of the twentieth century, including the Malayan Emergency , the Suez Crisis , the Indonesian Confrontation and operations in Aden and Oman . With the re-formation of the Army Air Corps in 1957 this new corps's functions included airborne forward air control. Although
2490-500: The Spanish Civil War and decided to develop its forward air control capability. By 1939, they had forward air control teams called Ground Attack Teams attached to every headquarters from regiment level upwards. These Teams directed air strikes flown by Luftwaffe close air support units. Extensive coordinated training by air and ground troops had raised this system to state of the art by the beginning of World War II. When
2573-1142: The United States Armed Forces have used the term joint terminal attack controller (JTAC) for some of their ground based FACs. NATO is making efforts to increase the safety and reduce the risk of fratricide in air to ground operations. Co-operation between different NATO agencies such as the NATO Standardization Agency and the JAPCC resulted in the development of common standards for Forward Air Controllers and these are now set out in STANAG 3797 (Minimum Qualifications for Forward Air Controllers). NATO FACs are trained to request, plan, brief and execute CAS operations both for Low Level and Medium/High Level operations and their training NATO FACs includes electronic warfare , suppression of enemy air defences , enemy air defence, air command and control, attack methods and tactics, weaponeering and Joint Air Attack Team Tactics . FACs in
Raven Forward Air Controllers - Misplaced Pages Continue
2656-579: The United States Army Air Forces (USAAF) was founded on 20 June 1941, it included provisions for Air Ground Control Parties to serve with the United States Army at the division, corps, and Army headquarters. The Air Ground Control Parties functions were to regulate bombing and artillery in close conjunction with the ground troops, as well as assess bomb damage. They were thus the first of similar units to try to fulfill
2739-626: The Vietnamese Demilitarized Zone (VDZ). Upon their return to Nakhon Phanom Royal Thai Air Force Base , they were told that their unauthorized aerobatics and drunken transgressions would be forgotten if they volunteered for a secret program—the Ravens. Joined by a third Raven, they began 90-day TDY tours flying support for the Royal Lao Army . In December, 1966, they acquired the use of an O-1 Bird Dog assigned to
2822-549: The 1024-1150 MHz band, split into 1 MHz channels numbered 1-126; the responding station (ground, ship, or another aircraft) is 63 MHz (63 channels) above or below the originating frequency, depending on the channel and mode of operation selected. Spacing between pulses in an individual pulse-pair is also determined by TACAN operating mode. Range information is functionally identical to the method provided by civilian DME: pairs of 3.5 microsecond (μs) pulses (measured edge-to-edge at 50% modulation strength) from an aircraft are repeated by
2905-713: The Air Force Ravens died during the Secret War; Army Attaché Joseph Bush was the 24th. Robbins lists all Ravens deceased prior to the publication of his book. USAF Ravens are not listed in the 1988 directory of names of the Vietnam Veterans Memorial , although they do appear on the wall. Laos became the most bombed nation in history, largely due to the Raven FACs. Approximately the same tonnage of bombs were dropped on Laos as were dropped by
2988-579: The Butterfly effort. Development of rules of engagement by the embassy placed more emphasis on increased control over in-country close air support. So did the introduction of an integrated close air support system for Southeast Asia. Beginning in April 1966, as part of its effort to better direct air strikes, the USAF installed four Tactical air navigation systems in Laos to guide US air strikes. One of these
3071-780: The CIA operatives running the local ground troops. In November 1964, Roy Dalton was the first rated officer to augment the Butterflies. He was stationed at LS 36, a dirt air strip near Na Khang, Laos; he directed air strikes by the Royal Lao Air Force (RLAF) while riding in Air America helicopters, or from observation posts on mountaintops. The Raven program was officially founded on 5 May 1966. It began with two pilots on 90 days' temporary duty, working out of aircraft borrowed from Air America. Lieutenants Jim F. Lemon and Truman Young had been directing air strikes on either side of
3154-429: The Ho Chi Minh Trail; A-26 Invaders began a dual FAC/strike mission under call sign "Nimrod". The U.S. Air Force began Operation Shed Light as a test of night time battlefield illumination. In response to increasing pressure from air strikes, the communists turned entirely to night operations in Vietnam by 1968. C-123 Provider cargo aircraft were used as flareships to light up the Trail and direct air strikes, under
3237-782: The Indian Army, flying a HAL Krishak , played a crucial part in a close air support defense against steep odds. The Pakistani loss of armor in December 1971 was one of the most severe since the great armored clashes of World War II . Major Singh won the Maha Vir Chakra for his performance under heavy ground fire. During the Portuguese Overseas War , the Portuguese Air Force used mainly Dornier Do 27 and OGMA/Auster D.5 light aircraft in
3320-668: The Laotian Hmong guerrilla army. On 23 July 1962, the United States and the Democratic Republic of Vietnam (DRV) signed the Geneva Accords guaranteeing the neutrality of the Kingdom of Laos . One of the provisions of the accords called for the withdrawal of all foreign troops from Laotian soil. North Vietnam had troops still remaining in Laos from the end of the First Indochina War . The United States had
3403-514: The Pacific for the rest of the war. By November 1943, the U.S. Marines were using forward air control during the Battle of Bougainville . The United States would end World War II still without an air control doctrine. When the U.S. Air Force split from the U.S. Army in 1947, neither took on the responsibility for forward air control; the U.S. military thus had no functional forward air control when
Raven Forward Air Controllers - Misplaced Pages Continue
3486-460: The Ravens began when air force personnel reported for duty assignments in Vietnam. Forward air controllers beginning a tour in Southeast Asia were told as part of their orientation briefing that halfway through their year's tour of duty in Vietnam, they were eligible to volunteer for special duty via the "Steve Canyon Program". To be accepted for Steve Canyon, a pilot had to have a minimum of four months combat duty, including at least 60 days' service as
3569-611: The Royal Lao Air Force at Savannakhet . Unlike the borrowed Air America planes, the O-1 had additional radios and smoke rocket tubes for improved communications and target marking. A de Havilland Canada DHC-2 Beaver and a Helio Courier were also acquired, but seemed not to be used for directing air strikes. By August 1967, the three Raven FACs on duty in Laos were augmented by three more Ravens stationed with Detachment 1, 606th Air Commando Squadron at Nakhon Phanom. At about
3652-521: The Sandinistas in Nicaragua in 1927. The commonality of pilots and ground troops belonging to the same service led to a close air support role similar to that sought by use of FACs, without the actual use of a FAC. On 27 October 1927, a Marine patrol used cloth panels to direct an air strike—arguably the first forward air control mission. This distinctive U.S. Marine doctrine of interaction between Marine infantry and aviation would persist, recurring in
3735-540: The US Air Force. By presidential directive, the ambassador controlled all US military activity in Laos. The Ravens performed their duties under direction of the air attaché who in turn reported to the ambassador. The air force kept the Ravens' records and paid them, but had no operational control over them, although 7/13th Air Force was formed in an attempt to regain control of their pilots. Generals William Westmoreland and William Momyer both wanted to gain control of
3818-534: The US in the entirety of World War II. Approximately 20% of the Laotian populace became refugees, largely relocating because of bombing. As of 2020, Laos is still plagued by unexploded ordnance . As information about the Laotian Civil War is being declassified and publicly released, historians will continue to write additional reliable texts published by mainstream media. In the meantime, there has been
3901-526: The USAF began using laser guided ordnance. By May 1971, U.S. Air Force intelligence concluded that air strikes had wiped out all the North Vietnamese trucks on the Ho Chi Minh Trail. This was a demonstrably untrue conclusion, as trucks still traversed the Trail until the communist takeover in 1975. After war's end, the U.S. Air Force ended the forward air control mission, just as they had following World War II and Korea. Major Atma Singh, of
3984-569: The USAF originally assigned four sergeants from Combat Control Teams in 1963. These sergeants turned in their uniforms and military identification and were supplied with false identification so they could work in civilian clothing. This process was designed to preserve the fiction of US non-involvement. Once "civilianized", these "Butterflies", as they were known, flew in the right (co-pilot's) seat in Air America Helio Couriers and Pilatus Porters . They were often accompanied by
4067-780: The United Kingdom are trained at the Joint Forward Air Controller Training and Standards Unit (JFACTSU) where controllers are drawn from all three services: Naval Service ( Royal Marines and Royal Marines Reserve ), the Army , and the RAF ( RAF Regiment ). UK FACs operate as TACPs or form part of Royal Artillery Fire Support Teams which direct artillery as well as close air support. The Army Air Corps provides Airborne Forward Air Controllers. When deployed on operations each USMC infantry company
4150-668: The United States, as part of the United Nations Command (UNC) in the Korean War, entered the war on 26 June 1950 with no forward air controllers, it rapidly improvised close air support procedures for UNC forces. By 20 July, jury-rigged systems were not only controlling air strikes against the communist foe, but also occasionally directing aerial interceptions of opposing aircraft. Both the U.S. high command and North Korean General Nam Il agreed that only tactical air power saved United Nation forces from defeat during
4233-417: The accuracy of the former. The time is compared between the point of peak positive signal strength with a reference train or "burst" of pulse-pairs of specific repetition rate and duration, timed to transmit at a specific point in the signal's sweep; these replace all other pulse types when transmitted. The civilian VOR system differs from TACAN in utilizing a single continuous-wave 30 Hz modulation signal, using
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#17327719938284316-486: The call sign "Candlestick", until late 1969. Withdrawn in the face of mounting opposition, the flareships would still serve elsewhere in theater until 30 June 1971. In a similar role, Lockheed AC-130 gunships, call sign "Blindbat", not only lit the Trail and directed air strikes, but used its own copious firepower on enemy trucks. The gunships carried both electronic sensors tied into Operation Igloo White and night observation devices for spotting enemy trucks, as well as
4399-400: The civilian populace, which also called for FAC intervention. In 1961, when forward air control was revived , it promptly ran into the recurring problems of unreliable radios, a shortage of supplies, lack of suitable aircraft, differing concepts of close air support, and unfavorable terrain. The first manning requirement for FACs, levied in 1962, amounted to 32 slots in Vietnam. Even as
4482-440: The desired pulse rate. This ensures that sufficient signal is present to support demodulating bearing signals. TACAN stations are identified by Morse code . The transmitting station periodically replaces the randomized ranging pulse-pairs with regularly spaced pairs that de-modulate to a 1350 Hz tone, keying a three-letter identification code at approximately 6-7 wpm every 40 seconds. Ranging and squitter pulses are permitted during
4565-663: The end of the First Indochina War on. Prince Souvanna Phouma , the Prime Minister of Laos, asked for US help to stop North Vietnamese incursions. To avoid the appearance of unilaterally violating the accords, US President John F. Kennedy directed the United States Air Force (USAF) to initiate clandestine and covert operations in Laos to help the Lao fight the North Vietnamese communists. As USAF tactical air strikes began in Laos, it became apparent that, for
4648-412: The fall of the elected Government. Tactical air navigation system A tactical air navigation system , commonly referred to by the acronym TACAN , is a navigation system initially designed for naval aircraft to acquire moving landing platforms (i.e., ships) and later expanded for use by other military aircraft. It provides the user with bearing and distance (slant-range or hypotenuse) to
4731-586: The first Airborne Command and Control Center. As additional ABCCC aircraft were added, they would constantly govern the air war in Southeast Asia. By early 1966, a rising level of communist anti-aircraft fire against propeller-driven FAC aircraft necessitated the use of jet aircraft for FACs in high-risk areas in North Vietnam. The Fast FAC mission would supplement the FAC mission in Southeast Asia until war's end. In July 1966, night FAC operations began against
4814-715: The forward air control role, in the several theatres of operation: Angola , Portuguese Guinea and Mozambique . During the Rhodesian Bush War the Rhodesian Air Force mounted Airborne FACs in Aermacchi AL60 B Trojans and Lynx aircraft. South Africa deployed both Airborne FACs (in AM.3CM Bosboks ) and ground-based FACs during the Border War including the Battle of Cassinga . During
4897-449: The front lines. The requesting unit would direct the air strikes. The U.S. Army would not copy the British system until the Allied invasion of Italy , but adapted it for use there and in France after the Invasion of Normandy of 6 June 1944. In the Pacific Theater, 4 Squadron of the Royal Australian Air Force began forward air control at the Battle of Buna-Gona , New Guinea in November 1942. The RAAF continued forward air control in
4980-463: The functions of the FAC without being airborne. However, these units were often plagued by turf wars and cumbersome communications between the respective armies and air forces involved. As a result, it could take hours for an air strike requested by ground troops to actually show up. However, forward air control during World War II came into existence as a result of exigency, and was used in several theaters of World War II. Its reincarnation in action
5063-429: The gaps between dots and dashes. There is no capability for voice transmission in a TACAN-only system. There are two basic channel configurations available: X (the original implementation) and Y (added in the 1960s to expand available channels and reduce mutual interference between closely-spaced stations). These configurations differ in pulse-pair width, fixed receiver response delay, and polarity of frequency offset from
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#17327719938285146-501: The interrogation channel. TACAN interrogators can operate in four modes: receive (for bearing/identification only), transmit/receive (for bearing, range, and ID), and air-to-air versions of the previous two. The typical TACAN onboard user panel has control switches for setting the channel (corresponding to the desired station's assigned frequency), the operation mode for either transmit/receive (T/R, to get both bearing and range) or receive only (REC, to get bearing but not range). Capability
5229-413: The last quarter of 1968. Karl Polifka (call sign Raven 45) reported 26 in a month, apparently February 1969. The upcountry USAF technicians were then replaced by Air America mechanics. The chief mechanic at Pakse was Stan Wilson and at Long Tieng was Dan Williams. This led to all the O-1s being cycled through Udorn to have their fuel tanks cleaned out. Some of them had 18 years of crud and mud contaminating
5312-428: The manning levels of assigned FACs would run about 70% of need until December 1969. Other branches of the U.S. military also had FACs; the U.S. Army had at least two aviation companies of FACs, the U.S. Marine Corps had an organic FAC squadron within its forces, and the U.S. Navy established its own FAC squadron in the Mekong Delta . U.S. involvement had begun with a South Vietnamese FAC training program; later in
5395-469: The mobile warfare stage of the war. When the front lines bogged down into static trench warfare in Summer 1951, forward air control diminished in importance. To cope with the communist switch to night operations, both radar and Shoran bombing techniques were developed. However, close air support continued, and sometimes used to direct interdiction missions against the communist lines of communications . By this time, Allied air forces were contributing
5478-595: The ninth-harmonic auxiliary bearing signal. Theoretically a TACAN should provide a 9-fold increase in accuracy compared to a VOR, but operational use has shown only an approximate 3-fold increase. Operational accuracy of the 135 Hz azimuth component is ±1° or ±63 m at 3.75 km. Manufacturers of TACAN sets mention the ability to track stations out to 400NM, though these systems will cap their instrumented range signals at approximately 200NM. Per official FAA service volume information, reliable TACAN/DME reception can be guaranteed out to 130NM below 45,000 feet above
5561-427: The outfit and the war in Laos. However, Ambassador William Sullivan , and his successor, G. McMurtrie Godley , continued to oversee air strikes in Laos. This was intolerable to the air force. In some cases, individual Ravens received poor ratings and slow promotions due to their participation in the program. The Ravens, however, liked the ambiguity of the situation because it left them free to coordinate air strikes with
5644-465: The phase difference between a fixed-phase and variable phase (rotating) component to derive bearing info. TACAN stations transmit pulse-pairs at a composite rate of 3600 pairs/second: 900 of which are bearing reference bursts, and the other 2700 being composed of ranging and identification pulses. When insufficient interrogation pulses from aircraft are present, the station will use a squitter circuit to inject additional randomized pulse-pairs to maintain
5727-651: The safety of noncombatants, some means of control was necessary. Beginning at least as early as July 1964, the absence of a close air support control system caused a variety of enterprising individuals to improvise procedures for marking ground targets. At various times, ground markers, including bamboo arrows and dropped smoke grenades, were used. Those marking targets often had little or no training in close air support (CAS). They varied in nationality, being Thai, Lao, or Hmong, as well as American. Both Continental Air Services, Inc and Air America pilots would sometimes serve as ad hoc forward air controllers. To begin operations,
5810-649: The same time, the air attaché in Vientiane requested O-1s unmarked by national insignia be supplied by 7/13th Air Force, on the grounds that the Ravens needed their own airplanes instead of riding with civilian pilots. The O-1s were supplied. By November 1967, the Raven head count had increased to eight. The number of Ravens would increase in a futile attempt to keep up with the swelling tide of air strikes Laos, but they would never number more than 22 assigned at one time. The chronic shortage of Ravens meant that they often spent long stretches flying combat missions. Raven John Mansur recalled flying as long as 11 hours, 45 minutes in
5893-421: The slots slowly filled, the requirement proved inadequate. The 19th Tactical Air Support Squadron was then assigned in-country in mid-1963 to augment the FAC force. By January 1965, there were still only 144 USAF FACs in Southeast Asia. While the U.S. Air Force would continue to add more FACs, projecting a need for 831 FACs, and stationing four more Tactical Air Support Squadrons in Southeast Asia by April 1965,
5976-520: The station being interrogated, using the round-trip time to calculate slant-range distance. Randomized spacing between interrogation pulse-pairs allows the interrogator to separate its own signal from that of other aircraft, enabling multiple users to access the ranging function without mutual interference. A fixed-round trip delay time (dependent on system mode) is added to each pulse-pair when being retransmitted by its station. The interrogator will generate up to 150 pulse-pairs per second when first acquiring
6059-549: The supply of military necessities being moved south to insurgents would be crucial to a communist victory. At about this time, the Raven FACs began supporting Vang Pao 's Central Intelligence Agency -supported guerrilla army on the Plain of Jars in northern Laos with air strikes serving as aerial artillery blasting the way clear for offensive sweeps by the partisans. In early 1970, in an attempt to improve bombing accuracy,
6142-461: The surface for a high-altitude certified unit. On the first Space Shuttle flight, Capcom Joseph P. Allen reported up to the crew that their TACANs had locked onto the Channel 111X signals at St. Petersburg , FL at a range of 250 miles. Because the azimuth and range units are combined in one system it provides for simpler installation. Less space is required than a VOR because a VOR requires
6225-464: The tanks. Radio wiring, engine re-timing, and fuel system cleaning were accomplished on each aircraft and by May 1969 engine problems dropped drastically after that. Anti-aircraft fire could be intense and accurate. Some Raven aircraft were known to take up to 50 rounds in battle damage on a single sortie. Working as a Raven FAC was an exhausting, high-risk, high-stress job. The casualty rate among them ran about 50% wounded and killed; one calculation by
6308-401: The trench strafing by the ground troops marking their positions by laying out signal panels on the ground, firing flares, or lighting smoke signals. Aircrews had difficulty communicating with the ground troops; they would drop messages or use messenger pigeons . Benno Fiala von Fernbrugg , an Austro-Hungarian pilot, pioneered the use of radio for fire control; at the Battle of Gorlice he used
6391-529: The war, Laotians and Hmong were also trained as FACs. There was a great deal of technical innovation in forward air control operations during the course of the Vietnam War. The United States came up with a number of ways to make its forward air control system more effective. As early as 1962, Douglas C-47 flareship FACs began the forward air control mission in South Vietnam, mostly on night missions. In September 1965, another C-47 went into action as
6474-594: Was a leader in developing the present TACAN system in the US starting in the late 1950s. TACAN in general can be described as the military version of the VOR/DME system, though despite providing similar information as its civilian counterpart, its method of operation is significantly different. It operates in the UHF frequency band 962-1213 MHz , utilizing a pulse-pair transponder system not dissimilar to that of secondary surveillance RADAR . Interrogating aircraft transmit in
6557-629: Was a result of field expedience rather than planned operations. On the Allied side, British forces in the North Africa campaign began using the Forward Air Support Links, a "tentacle" system that used radio links from front line units to the rear. Air force teams were co-located with the army command. Close air support would be requested by forward units and if approved delivered from "cab ranks" of fighter-bombers held near
6640-471: Was created to serve as a de facto Air Liaison Officer, and the number of Ravens in-country doubled to handle the new work load. General Vang Pao , the ground commander of the CIA's clandestine army of Hmong hill tribesmen, used tactical air as airborne artillery. His combat operations became dependent upon it. Both the O-1s and the later-supplied U-17s had severe maintenance problems in the beginning. Maintenance
6723-705: Was emplaced on a mountain top at Lima Site 85 , aimed across the border at Hanoi . A successor operation, code-named Palace Dog , began replacing the original Butterfly effort in 1966. CIA's agent James William Lair recommended the use of Lao interpreters flying in the rear seat of light aircraft flown by US pilots, thus establishing the Ravens. The Ravens were fighter pilots in unarmed light aircraft who flew observation missions, marked enemy targets with smoke rockets, directed air strikes onto them, and observed and reported bomb damage assessments post strike. They were based in five Lao towns: Vientiane , Luang Prabang , Pakse , Savannakhet , and Long Tieng . Recruiting for
6806-424: Was later upgraded to include an air-to-air mode (A/A), where two airborne users can get relative slant-range information depending on specific installations, though an air-to-air mode allows distance to be established between transmitters/receivers. When initially deployed, TACAN was intended to provide a bearing accuracy of ±0.22°, based on the main bearing signal's own accuracy of ±2° and the corrections applied by
6889-519: Was spotty. It was performed by pilots, poorly trained Lao mechanics, or USAF technicians. The piston engines were tuned for optimum performance at Udorn Royal Thai Air Force Base 's low elevation. They would run raggedly in the highlands of Laos. Adding to the woes were high power settings needed for maximum weight takeoffs, toting maximal loads, or short-field takeoffs. Engine life in O-1s fell from 1,800 hours to 400 hours flight time. Engine failures became epidemic. Eighteen engine failures occurred during
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