#AirWarVietnam – Making a MiG-Killer: Technology and Signals Intelligence for Air-to-Air Combat in Vietnam

#AirWarVietnam – Making a MiG-Killer: Technology and Signals Intelligence for Air-to-Air Combat in Vietnam

By Dr Mike Hankins

Editorial Note: During 2019, From Balloons to Drones is running a series of articles looking at various aspects of the air war over Vietnam from the French-Indochina War through to the end of the Vietnam War. In this article, Dr Mike Hankins discusses the use of signals intelligence via Project Teaball that helped to improve the air-to-air combat ratios of the United States Air Force during the Vietnam War. If you would like to contribute to the series, then please email our editor, Dr Ross Mahoney, at airpowerstudies@gmail.com or via our contact page here. The official call for papers is here.

Air-to-air combat in the Vietnam War has long been a sore subject for some observers.[1] Sources vary, but U.S. forces overall killed approximately 200 MiGs while losing about 90 planes to them, for a ratio of about 2.2:1.[2] Robert Wilcox, in his history of the Top Gun program, calls this ‘embarrassingly low.’[3] Looking just at 1968, the picture is even bleaker. The US Navy was disappointed with its 3:1 ratio and the US Air Force (USAF) traded McDonnell Douglas F-4 Phantoms for MiGs at nearly a 1:1 rate. During the bombing halt between 1968 and 1972, both services sought to upgrade their technology and training, including the creation of the US Navy Fighter Weapons School, also known as ‘Top Gun.’ In 1972 when the LINEBACKER bombing campaign began, the US Navy’s air-to-air record jumped to 6:1. The USAF struggled in the early months of LINEBACKER, earning a negative kill ratio for the first time in the war and perhaps in its existence.[4]

The US Navy is often praised for their changes to training procedures (even though Top Gun initially had little support from US Navy leaders) while the USAF is often criticised for over-reliance on technological solutions.[5] However, the most significant improvement in air-to-air combat for the USAF was the result of a technological system: Project Teaball – a Ground Controlled Intercept (GCI) system that allowed analysts on the ground to track enemy planes in real-time and communicate that information to pilots in the air.

‘Teaball’ was just as critical to the USAF’s air combat success during the LINEBACKER campaigns as Top Gun was for the US Navy. It demonstrated that the USAF was open to change and adapted its technological culture to meet new challenges. This is not to take away from the undeniable success of the Top Gun program, nor to diminish the importance the USAF’s effective RED FLAG program that began shortly afterwards. In the last throes of the Vietnam War, both technology and training worked in tandem.

Web of Confusion

North Vietnamese pilots had long relied on GCI to direct their movements – ground controllers used their extensive radar coverage of the area to track aircraft and give detailed second-by-second instructions to MiG pilots.[6] American forces were different. They tended to rely more on the initiative and skill of individual pilots, but they also had far less radar coverage of the areas they flew over in North Vietnam. Complicating, this was the fact that US radar stations were not well integrated, creating a confusing web of systems competing for pilots’ attention.

NVAF MiG-19 pilots of the 925th fighter squadron discussing tactics in 1971
North Vietnamese MiG-19 pilots discuss air-to-air combat tactics (Source: US Air Force)

The USAF operated a ground radar covering the southeast at Da Nang. Another radar further north at Dong Ha known as ‘Waterboy’ covered the lowest reaches of North Vietnam, although few air-to-air engagements occurred there. For further coverage, USAF flew a Lockheed EC-121 known as ‘College Eye,’ which was excellent over water but was less accurate over land. Other radar stations existed in Thailand, including ‘Brigham,’ at Udorn, and ‘Invert,’ at Nakon Phanom. These stations contributed ground control and navigational assistance, although their short-range provided almost no coverage of North Vietnam itself.

Hankins Radar Map
This map shows the radar coverage of systems prior to Project Teaball. Note that coverage above the 20th parallel, where air combat was much more likely, was almost nonexistent.

The US Navy used a system called ‘Red Crown,’ a ship-based radar located in the Gulf of Tonkin, to provide early warning of approaching MiGs. There was some limited cooperation between ‘Red Crown’ and ‘College Eye’ during Operation ROLLING THUNDER. The bottom line for all these radar systems was that none of them was effective for strikes further North than the 19th parallel, where air combat was more likely, and some of these systems, such as ‘Red Crown,’ could not effectively track planes below 10,000 feet, where MiGs often flew.[7]

However, radar was only one way to gain situational awareness of enemy MiGs. Communications surveillance, or signals intelligence (SIGINT), could track enemy movements and plans. In 1967, the USAF brought in new EC-121s known as ‘Rivet Top; to do just that: Intercept North Vietnamese communications and pass on vital information to American pilots. ‘Rivet Top’ was a success. In its limited time of employment, American forces claimed 20 MiG kills, 13 of which received direct contributions from ‘Rivet Top.’[8] However, the ROLLING THUNDER campaign ended before they could make a more significant contribution. At the beginning of the LINEBACKER Campaign, the US Navy’s ‘Red Crown’ ship returned, and the USAF instituted a system known as ‘Disco,’ essentially a slightly upgraded version of ‘College Eye.’ Under ‘Disco,’ multiple EC-121s provided a larger area of radar coverage and continued the SIGINT role provided by the ‘Rivet Top’ equipment, although the system suffered many of the same problems that plagued the ‘College Eye’ system, such as a limited range, limited crew and equipment capacity, and the need to stay in slow, controlled orbits.[9]

Both sides found that GCI was key to air-to-air victory. General John Vogt, Director of the Joint Staff and later commander of the Seventh Air Force, argued that MiG successes were attributable entirely to how their radar systems connected to their command and control practices.[10] USAF Ace fighter pilot Richard ‘Steve’ Ritchie went so far as to state that flying a protective escort without GCI warning of incoming MiGs was ‘useless,’ and that employment of US GCI ‘was one of the primary reasons that we were able to engage MiGs and effect kills.’[11] Yet the limited range, communications problems, and frequent technical failures limited US GCI efforts.

The F-4D flown by Captains Richard S. Ritchie and Charles B. DeBellevue at Udorn AFB in 1972. This aircraft is currently on display at the Air Force Academy. (Source: US Air Force)

Green Door Syndrome

An equally serious bureaucratic problem aggravated these technological difficulties. Unknown to most fighter pilots, the National Security Agency (NSA) frequently intercepted North Vietnamese communications – including information about MiG flights. Some NSA analysts, such as Delmar Lang, had previously advocated combining these intercepts with GCI to provide a more accurate picture of enemy locations and movements. Lang had developed such a system in the Korean War, contributing to the success of North American F-86 Sabre pilots. Lang had offered to create a similar program in Vietnam, but both NSA and USAF leaders, particularly Major General George Keegan, Director of Air Force Intelligence, repeatedly turned him down.[12] Interception of North Vietnamese transmissions was classified, and American pilots did not have proper security clearance. This policy was not unfounded. Using these intercepts could undoubtedly aid American pilots but using them too frequently risked alerting the North Vietnamese that the US was intercepting their signals.[13]

This was a dilemma for American planners who needed to balance using the data with keeping its existence secret. However, USAF leaders such as Keegan simply refused to pass on any information to American pilots in combat. This created a sense of ill will between pilots and intelligence agents. As former USAF intelligence officer, Gilles Van Nederveen noted, ‘US pilots, already frustrated by the small amount of data provided to them, felt betrayed when they learned that some losses over Vietnam could have been prevented if intelligence data had been shared with them.’ This animosity grew so prevalent that it received a name: ‘green door syndrome,’ so labelled because, in many combat wing bases in the theatre, classified information was kept in vaults usually behind a green door.[14]

LINEBACKER and Project Teaball

When bombing (and air-to-air combat) resumed in earnest with the LINEBACKER campaign in May 1972, the US, particularly the USAF, received what Colonel Russ Everts, an F-4 Pilot, generously called ‘an old fashioned butt kicking, pure and simple.’[15] After some initial successes that May, in June and July, USAF F-4 Phantoms claimed 8 MiGs, with the US Navy shooting down only 3. While the US Navy only lost one F-4, USAF lost 13.[16] The US Navy could still claim their previous 3:1 ratio; the USAF had sunk to its lowest ratio during the war, 0.6:1. For the first time in the war, the kill ratios favoured the North Vietnamese.

These reversals rippled through USAF quickly, prompting investigations into the quality of fighter pilots. General William Momyer, then commander of Tactical Air Command (TAC), who had previously resisted any alterations to training procedures, changed his mind and recommended the creation of an ‘Aggressor’ squadron to simulate MiGs in air combat training (building on a program at Nellis run by Major Roger Wells). Although Chief of Staff of the Air Force General John Ryan approved the Aggressor concept at that time, the program did not begin until after the war was over and thus it had no effect on air combat in Vietnam.[17]

However, one element the USAF could fix in time to make a difference was their GCI system. The summer’s heavy losses, increasing concern from Vogt about the shortcomings of American GCI, and pressure from eager NSA analysts and USAF pilots all overrode earlier concerns with sharing classified intelligence and pushed the issue higher up the chain of command. Ryan directly contacted the head of the NSA, Admiral Noel Gayler – himself a former US Navy aviator – and requested the creation of an improved early warning system to alert pilots to approaching MiGs. With Ryan and Gayler’s approval, General Vogt worked with Delmar Lang and Lieutenant Colonel William Kirk to establish Project Teaball at Nakhom Phanom Air Force Base in Thailand in August 1972.[18]

Teaball 1
The flow of information from various radar and SIGINT sources, to the Teaball center that was eventually disseminated to pilots. (Source: Nederveen, ‘Wizardry’)

‘Teaball’ took the classified NSA intercepts and combined them with other US radar sources. These included the radio calls sent from North Vietnamese pilots to their ground controllers and vice versa, revealing precise locations and vectors for their MiGs. This information was fed into a computer known as ‘Iron Horse’ that took data from these sources and quickly synthesised it into a composite display showing a near real-time picture of the location of all friendly and enemy aircraft over North Vietnam.[19] ‘Teaball’ operators then sent this information directly to pilots via Ultra-High Frequency (UHF) radio signals relayed through a Boeing KC-135 aircraft code-named ‘Luzon.’

There was still tension between some pilots and the intelligence community. Kirk worked to build trust between the two groups and overcome ‘green door syndrome’ by personally visiting every single wing in the theatre to brief them on ‘Teaball’s’ capabilities, the accuracy of its data, and the methods he used to contact pilots directly.[20] Finally, US pilots could have situational awareness of the aerial battlefield and early warning of MiG threats. However, ‘Teaball’s’ implementation differed from the authoritarian North Vietnamese GCI system and simply provided information to pilots. The American ground controllers often suggested courses of action, but individual pilots handled threats at their discretion.

The Best Show We’ve Had

‘Teaball’ was only active from August 1972 until the end of LINEBACKER operations in October. In that time, USAF F-4’s shot down 21 MiGs with only six losses. Of those kills, 13 were a direct result of vectoring from ‘Teaball.’[21] Of those losses, five of the six occurred when ‘Teaball’ was down due to technical failure, demonstrating just how critical the system was to the USAF effort. When examining only MiGCAP flights, USAF F-4s claimed 18 kills with five losses, a nearly 6:1 ratio.[22] During that same timespan, the US Navy got two kills but lost two Phantoms.[23] General Vogt extolled the program’s success:

This is the most effective show we’ve had during the entire war with the battle against the MiGs […] This proved one thing – if you can show the American fighter pilot where [the enemy] is in sufficient time, he’ll shoot him down.[24]

Vogt went on to say:

Same airplane, same environment, same situation, same tactics; largely [the] difference [was] Teaball. It was one of the most impressive developments we’ve had out here.[25]

Pilots praised ‘Teaball’ as well. One mission report stated: ‘A good GCI capability made the difference, and will in the future.’ Another echoed: ‘Computerized real-time intelligence will get more kills than all the fighter sweeps we can put together.’[26]

No matter how well-trained a pilot is, if they do not realise they’re under attack, they cannot use their training. ‘Teaball’ gave them that warning, preventing further losses. ‘Teaball’ also provided more accurate visual recording of encounters than the memory of pilots could provide, enabling both a better study of enemy tactics and a useful training tool. It was also invaluable for search and rescue efforts, as ‘Teaball’ data could pinpoint the location of downed aircrews, enabling rescue craft to arrive quickly.[27]

However, the program, literally operating out of the back of a van, was not without problems.[28] The ‘Iron Horse’ computer was powerful for its time, but processing the data of all the SIGINT and radar inputs took an average of two minutes – an eternity in a dogfight. For this reason, ‘Teaball’s’ role was limited to providing early warning only. Once combat began, most pilots relied on more timely information from ‘Disco’ or ‘Red Crown’ if in range.[29] Also, the UHF radio relays in F-4 cockpits were old and broke down frequently.[30]

Increased American success forced the North Vietnamese Air Force to scale back its operations, flying fewer missions and attempting to counter ‘Teaball’s’ tracking ability by turning off their IFF (Identify-Friend-or-Foe) signals. However, that separated North Vietnamese pilots from their GCI, their chief advantage to this point. They could run with radio silence, but that risked making them vulnerable to their surface-to-air missiles (SAMs). ‘Teaball’ operators could spot them as soon as they tried to alert their missile sites. The more common technique the North Vietnamese used to get around ‘Teaball’ was deception. Ground controllers sent messages pretending to be pilots, essentially creating ‘ghost MiGs.’ However, ‘Teaball’s’ operators could easily distinguish between these fake calls and authentic ones due to differences in the signal itself.[31]

When LINEBACKER ended, so did most air-to-air combat, but ‘Teaball’ stood ready when LINEBACKER II commenced on 18 December 1972. Lieutenant General Horace Wade, Vice Chief of Staff of the Air Force, was impressed enough with ‘Teaball’ to move it into a permanent facility at Nakom Phenom.[32] However, MiGs barely flew during the operation – only 26 were even sighted. USAF Phantoms took down four, the US Navy got one more, and B-52 gunners shot down two. USAF lost two Phantoms to MiGs. North Vietnamese sources claim that MiGs shot down two B-52s as well, but this is unconfirmed by the U.S.[33] This 3.5:1 is above average for the war, if not as impressive as when ‘Teaball’ was most active in LINEBACKER. However, the sample size for LINEBACKER II is incredibly small, and the operation was unique. In any case, although SAMs wreaked havoc on the B-52 fleet, MiGs did not pose a significant threat. By 28 December 1972, North Vietnam had exhausted its SAM supply and was incapable of defending itself from the B-52 raids. When Hanoi expressed its desire to renew serious negotiations, President Nixon halted all bombing north of the 20th parallel. With the signing of final settlements on 23 January 1973, air-to-air combat in the Vietnam War ended.[34]


The typical, perhaps romanticised narrative of air combat in Vietnam is that the US Navy used the ‘correct’ approach when creating the Top Gun program and that the USAF deserves criticism for its failure to produce a similar program and its adherence to technological chimeras. However, this story ignores that the US Navy also used technological improvements, including upgrades to their missiles and the jamming of enemy communications. It fails to note that the US Navy engaged fewer MiGs during the LINEBACKER period, with little contact with the more advanced MiG-21 Fishbed, so perhaps a direct comparison of each service’s kill counts is misleading.

Furthermore, this narrative fails to recognise that the USAF saw a more significant improvement in its effectiveness than did the US Navy in the same period owing to the systems-based, technological approach of Project Teaball. Top Gun worked, but ‘Teaball’ worked better. The role performed by ‘Teaball’ laid the foundation for the later role of Airborne Warning and Control Systems (AWACS) that has become an essential element of American air power strategy. In the final phase of the Vietnam War, the USAF demonstrated that technological solutions could be effective.

Dr Michael Hankins is the Curator of US Air Force History at the Smithsonian National Air and Space Museum. He is a former Professor of Strategy at the USAF Air Command and Staff College eSchool, and former Instructor of Military History at the U.S. Air Force Academy. He earned his PhD from Kansas State University in 2018 with his dissertation, ‘The Cult of the Lightweight Fighter: Culture and Technology in the U.S. Air Force, 1964-1991.’ He completed his master’s thesis at the University of North Texas in 2013, titled ‘The Phantom Menace: The F-4 in Air-to-Air Combat in the Vietnam War.’ He has a web page here and can be found on Twitter at @hankinstien.

Header Image: A U.S. Air Force Lockheed EC-121K ‘Rivet Top’ of the 552nd Airborne Early Warning & Control Wing, based at Korat Royal Thai Air Force Base, Thailand, in 1967-68. (Source: Wikimedia)

[1] This article is adapted from Michael Hankins, ‘The Teaball Solution: The Evolution of Air Combat Technology in Vietnam, 1968-1972,’ Air Power History, 63:3 (2016), pp. 7-24.

[2] John Correll, The Air Force in the Vietnam War, The Air Force Association (Arlington, VA: Aerospace Education Foundation, 2004), p. 17. See also Robert Futrell, et al., Aces and Aerial Victories: The United States Air Force in Southeast Asia, 1965-1973 (Maxwell Air Force Base, AL: Albert F. Simpson Historical Research Center, Air University, 1976); Chris Hobson, Vietnam Air Losses: United States Air Force Navy and Marine Corps Fixed-Wing Aircraft Losses in Southeast Asia 1961-1973 (England: Midland, 2001); and the Red Baron Reports, Volumes I, II, and III, Institute for Defense Analyses Systems Evaluation Division.

[3] Roger K. Wilcox, Scream of Eagles: The Dramatic Account of the US Navy’s Top Gun Fighter Pilots: How they Took Back the Skies over Vietnam (New York, NY: Pocket Books, 1992), p. xii.

[4] Red Baron II Vol. I, C-1–E-2, USAF Fighter Weapons Center, 1973; and Red Baron III, Vol. I, C-1–D-6, USAF Fighter Weapons Center, 1974.

[5] Wilcox, Scream of Eagles, 214-215; See for example Steven A. Fino, ‘Breaking the Trance: The Perils of Technological Exuberance in the US Air Force Entering Vietnam,’ Journal of Military History, 77:2 (2013), pp. 625-55.

[6] United States Air Force Oral History Program, Interview #K239.0512-630, Captain Richard S. Ritchie, 11 Oct 72 and 30 Oct 72, 1, pp. 74-5.

[7] William Momyer, Air Power in Three Wars (Washington D.C.: Office of Air Force History, 1978), pp. 150-5.

[8] Marshall Michel, Clashes: Air Combat Over North Vietnam, 1965-1972 (Annapolis, MD: Naval Institute Press, 1997), p. 114.

[9] Futrell, Aces, p. 14; Momyer, Air Power, p. 155; Michel, Clashes, p. 226.

[10] M. F. Porter, ‘Linebacker: Overview of the First 120 Days,’ Project CHECO Report, 27 Sept 1973, p. 48.

[11] Ritchie Interview, 37, 8.

[12] Thomas R. Johnson, American Cryptology During the Cold War, 1945-1989, Book II: Centralization Wins, 1960-1972 (Fort Meade, MD: Center for Cryptologic History, National Security Agency, 1995), p. 580.

[13] Michel, Clashes, p. 115; See also Walter J. Boyne, ‘The Teaball Tactic,’ Air Force Magazine (July 2008), p. 68; and Gilles Van Nederveen, ‘Wizardry for Air Campaigns: Signals Intelligence Support to the Cockpit’ (Research paper for the College of Aerospace Doctrine, Research, and Education, Airpower Research Institute, Maxwell: 2001), pp. 2-3.

[14] Nederveen, ‘Wizardry,’ 24.

[15] Quoted in Marshall Michel III, “The Revolt of the Majors: How the Air Force Changed After Vietnam” (PhD Thesis, Auburn University, 2006), p. 145.

[16] Red Baron III, C-1–D-6.

[17] Michel, ‘The Revolt,’ 146-52. See also, Brian D. Laslie, The Air Force Way of War: US Tactics and Training after Vietnam (Lexington, KY: University Press of Kentucky, 2015).

[18] Johnson, American Cryptology; Boyne, ‘The Teaball Tactic,’ p. 69; Nederveen, ‘Wizardry,’ p. 25. See also Calvin R. Johnson, ‘Linebacker Operations: September – December 1972,’ Project CHECO Report, 31 December 1978, p. 50.

[19] Author redacted, ‘TEABALL: Some Personal Observations of SIGINT at War,’ Cryptologic Quarterly, 9 (Winter 1991), p. 92.

[20] Quoted in Boyne, ‘The Teaball Tactic,’ pp. 69-70. See also Nederveen, ‘Wizardry,’ p. 25-6.

[21] Johnson, American Cryptology, p. 580. See also Johnson, ‘Linebacker Operations,’ p. 52.

[22] William Sayers, ‘The Red Baron Reports: What They Really Said,’ Air Power History, 52:3 (2005), p. 12, 39. See also Johnson, ‘Linebacker Operations,’ p. 52.

[23] Red Baron III, Vol. 1, C-1–D-6.

[24] Quoted in Porter, ‘Linebacker: Overview of the First 120 Days,’ pp. 46-7.

[25] Quoted in Johnson, ‘Linebacker Operations,’ pp. 52-4.

[26] Red Baron III, vol. III, C-29.

[27] Nederveen, ‘Wizardry,’ pp. 28-9.

[28] Johnson, American Cryptology, p. 579.

[29] Ibid., p. 31.

[30] Ibid., pp. 28-9; Ritchie Interview, p. 8.

[31] Author redacted, ‘TEABALL: Some Personal Observations,’ 94-5.

[32] Ibid., p. 95.

[33] Red Baron III, C-1–D-6. Roger Boniface, MiGs Over North Vietnam: The Vietnam People’s Air Force in Combat (Mechanicsburg, VA: Stackpole Books, 2010), p. 141, 145. See also, István Toperczer, Mig-21 Units of the Vietnam War and MiG-17 and MiG-19 Units of the Vietnam War, both from Osprey Press. Toperczer and Boniface each claimed to have examined North Vietnamese records, but make no mention or citation of specific documents, and their work has not been peer reviewed. Naturally their claims for NVAF victories are significantly higher that official US records. While their claims may have merit, this article has chosen to rely on official US records where possible, admitting that these are also not perfect.

[34] Mark Clodfelter, The Limits of Air Power: The American Bombing of North Vietnam (New York: The Free Press, 1989), pp. 188-9, 198-200.