Operation Teaball: Network-Centric Real-Time Intelligence During Vietnam

In 1972, US fighters had an added resource in the fight against MiGs

In past blog posts I've discussed some of the measures taken by the military to reverse the decline in air combat proficiency in the skies over Vietnam. This past November I had blogged about the origins of Red Flag as well as the top secret USAF program to obtain and fly MiGs. Back in March I wrote about the US Navy's own efforts that began with the Ault Report. While these were all steps that would benefit fighter pilots in the skies over Vietnam, there was another effort that took place that has received scant attention in the history books and presaged today's military buzzword of "network-centric" warfare. Between the bombing halt of 1968 and the start of the North Vietnamese Easter Offensive in 1972, air combat over North Vietnam was nearly non-existent. With the start of the NVA offensive in 1972, though, President Nixon reversed the gradual drawdown of US forces in Southeast Asia with a massive buildup and bombing offensive under Operation Linebacker I and Linebacker II. With the ramp up of offensive air strikes on North Vietnam, US aircrews found themselves embroiled in multiplane dogfights that were resulting in growing US losses. In the three months following the start of Linebacker in May 1972, the US lost 48 aircraft, 21 to VNAF MiGs and 27 to improved ground defenses. In the same period, only 31 MiGs were shot down by US aircraft and things worsened in the summer with 13 US aircraft lost to MiGs and only 11 MiGs shot down. 

At the same time, the policy of rotation of air crews meant that experienced personnel were rotated out of combat and replaced with novice air crews on their first combat tour. In the days before Red Flag and dissimilar air combat training, the loss rate of first tour air crews was staggering enough the General John Vogt, commander of the Seventh Air Force which oversaw combat air operations in Southeast Asia, ordered the minutes of mission critique conferences to be disseminated to all units in theater, not just the units involved. But it wasn't enough for General Vogt. He reported to the USAF Chief of Staff, General John Ryan, that the US was losing the air war over Vietnam in 1972. As a result, General Ryan ordered his staff to create a plan to assist US pilots in the skies over Vietnam- no studies, no plans, but what General Ryan wanted was something in place that could offset the fact that the VNAF MiG pilots were battle-experienced and had excellent GCI controllers who could relay the MiG air crews detailed descriptions of the tactical situation. 

General John Vogt, commander USAF Seventh Air Force

Ryan tasked a three-man "action group" with setting something up- USAF officers Lt. Col. William Kirk and Maj. Ernie Short teamed up with Delmar Lang, an intelligence specialist with the National Security Agency. Lang was brought in as he had several times in the years prior repeated offered to set up an eavesdropping facility that could listen in on the communications between the VNAF MiG pilots and their GCI controllers to provide real time information to US pilots. Lang's idea had historical precedence- during the Korean War, the USAF had a listening post on the island of Cho-do off the coast of Korea that was staffed with linguists and air control specialists that would listen in on North Korean, Chinese, and Russian communications to give US pilots a real-time picture of what was going on in "MiG Alley". Since the Korean War, the pace of technological progress in electronic and signals intelligence (ELINT and SIGINT) improved by leaps and bounds, but national security and a variety of compartmentalized secret programs kept many of these new methods out of sight to those on the front line. Delmar Lang's NSA position, however, coupled with the access given Lt. Col. Kirk and Maj. Short, intended to cut through the institutional resistance to using those technological resources to win the war in the skies of over Vietnam. 

On 26 July 1972, literally in just one month, General Ryan's "action group" set up the Operation Teaball Weapons Control Center at the Thai air base of Nakhon Phanom (nicknamed "Naked Fanny" by US pilots). Working with the intelligence specialists of the USAF's 6908th Security Squadron, the Teaball control room had map displays where data from a variety of intelligence sources already in place was collected and synthesized to form a single tactical picture that could be disseminated to US pilots in real time by specialist ground controllers. Orbiting high over the Gulf of Tonkin and Laos, specialist ELINT/SIGINT RC-135s listened in on communications between MiG pilots and their GCI controllers- this data was then relayed to a Lockheed U-2 orbiting high overhead that then relayed the information direct to the Teaball control center at Nakhon Phanom. Ground and ship-based (like "Red Crown" in the Gulf of Tonkin) radar pictures were added to refine the tactical picture. Finally, radar and SIGINT data from specialist EC-121s- such as the famous radar early warning EC-121 that used the call sign "Disco"- was also relayed to the Teaball specialists as well. Also little known was a US capability to trigger the IFF systems of the MiGs so they could be easily tracked. The stream of data from all these sources made use of a top-secret NSA computer system called "Ironhorse" that was designed to analyze and synthesize all the data to create a cohesive tactical picture that was then displayed on the map screens for the Teaball controllers to relay via another radio relay RC-135 to US pilots over North Vietnam. Once the system was up and running, the delay was as little as 45 to 60 seconds before the Teaball controllers were issuing advisories to US pilots!

"Combat Lightning" was one many specialist KC-135 variants used

Each combat air crew, regardless of service branch, were notified of a discrete UHF channel to monitor that advisories from the Teaball control center were broadcast. Teaball controllers also knew the call signs of each and every combat mission for that day going into North Vietnam. Positions of VNAF MiGs were given in relation to a notional point called the "Bull's Eye" which was Hanoi. Distance and bearing from the Bull's Eye was given and air crews often programmed the Bull's Eye into their aircraft's own navigational equipment. "Blue Bandits" were MiG-21s, "White Bandits" were MiG-19s, and "Red Bandits" were MiG-17s. The code word "Green Bandit" indicated an exceptionally experienced VNAF MiG pilot was airborne. "Heads up" meant MiGs were nearby. Teaball controllers and analysts noted that certain combat flights were targeted especially heavily by the MiGs at times, and these US air crews were designated "Queen for a Day". A Teaball controller might inform a flight of F-4s about "Red Bandits, 25 miles SE of Bull's Eye, heading NE 300 knots" over a designated UHF channel. In effect, the Teaball controller acted as a GCI controller for the US pilots, constantly feeding them information on the position and action of any MiGs nearby to allow the US pilots to exploit the situation.

Lt. Col. Kirk briefed every unit that was flying combat missions over Vietnam and warned them explicitly "Pay attention when I call you on that channel!" Within the first month of Operation Teaball's operation, American fighters had moved from a 1:1 kill ratio to a 3:1 ratio and by the end of the Linebacker operations, the ratio had risen to 4:1 in favor of US air crews. The system saved many an air crew's life in the skies over North Vietnam, to the point that inbound flights often checked in with the Teaball control center once they had taken off to be sure they had their call signs!

Operation Teaball was one of the earliest and most successful uses of data fusion and what today we would call "network-centric" warfare- to use diverse data collection sources fused together to give situational awareness to our men and women in combat. It was the first time that such diverse sources of intelligence that were once the sole realm of distant analysts in the United States were used to deliver real-time actionable information to win battles. 

Sources: The Linebacker Raids: The Bombing of North Vietnam, 1972 by John T. Smith. Arms and Armour, 1998, p95-97. Air Force Magazine, July 2008, Volume 91, Number 7. "The Teaball Tactic" by Walter Boyne.

Baptism of Fire; The North Vietnamese Air Force in 1965

Following the French defeat at Dien Bien Phu in 1954 that resulted in the partition of Vietnam in to the North and South, the Ministry of Defense for the Communist north embarked on an upgrade of the country's military infrastructure which included laying the foundation for a modern jet-equipped air force. All the former French and Japanese airfields were modernized to handle jet fighters and by the summer of 1955, nine bases had been made operational. In March 1956 the first group of 110 North Vietnamese flight students were sent abroad for flight training- most went to China, some went to the Soviet Union. One-third of the students were earmarked for fighter aircraft, another third for transport aircraft, and the last third directed into helicopter training. At the end of the year, the Chinese military assisted in setting up local flight training programs at the air bases of Cat Bai and Gia Lam, with MiG-15UTI two-seat trainers soon to follow. By 1958, the Vietnamese People's Air Force (VPAF) had 44 operational airfields capable of operating the more capable Mikoyan MiG-17 "Fresco". Just a year later all primary flight instruction took place in North Vietnam, but advanced jet conversion to the MiG-17 still had to take place in the Soviet Union, the first group of VPAF pilots making the conversion to the Fresco in 1960. A few months later, the North Vietnamese had arranged for a second operational conversion site in China to accelerate the build up of jet fighter pilots. By 1962 the nascent VPAF had 36 MiG-17s as its front-line jet fighter along with a small number of MiG-15UTI trainers. On 3 February 1964 the VPAF established the 921st Fighter Regiment at Noi Bai AB as the first operationally-trained Vietnamese fighter pilots returned from the Soviet Union. It would be quite an accomplishment in just 10 years for a nation as limited in resources as North Vietnam. 

Following the Gulf of Tonkin incident on 2 August 1964, President Lyndon Johnson ordered Operation Pierce Arrow which saw Navy aircraft from the carriers Ticonderoga and Constellation hit targets in North Vietnam, opening the first US air combat missions of the Vietnam War.  The VPAF at the time was still not at an operational state to defend against these initial strikes but the perceived American aggression intensified Soviet and Chinese logistical support to bring the VPAF up the strength. VPAF commanders feared the USAF and US Navy would use their numerical advantage and tactical experience to vary their attack patterns, but to their surprise, US forces adhered to very routine and obvious patterns that made planning interception missions easy. Even worse, the Vietnamese could determine the possible target area as US reconnaissance aircraft would make repeated runs against certain areas the day prior to an attack. Continued escalation on both sides resulted in Operation Flaming Dart in March 1965 which then transitioned to the 44-month long Operation Rolling Thunder that would finally introduced air combat over the skies of Vietnam.

The first strikes of Operation Rolling Thunder took place on 2 March 1965 when a USAF strike force of Republic F-105D Thunderchiefs and North American F-100 Super Sabres hit an ammunition dump near Vinh in the far southern part of North Vietnam and out of range of the VPAF's small MiG force. As the air strikes of Rolling Thunder moved northward over the course of the month, the VPAF prepared for action. On 3 April 1965 the 921st Fighter Regiment went on alert and six MiG-17swere armed and prepared for takeoff. Observing the US reconnaissance flight patterns led the VPAF to conclude the rail bridges at Ham Rong were the target and ground radars were already tracking the inbound US Navy strike force. With pilots already sitting in their cockpits, the order was given at 0940 to scramble to intercept the strike force on the VPAF's first operational combat mission. Four of the MiGs were the "intercept flight", responsible for attacking the Navy strike force. Two more MiGs formed the "covering flight" to follow the intercept group and defend against any attacks. Flying in a "finger four" formation, Pham Ngoc Lan was the flight leader, with Phan Van Tuc as his wingman on the left, Ho Van Quy as #3 on the right, and Tran Minh Phuong in the #4 position. The group raced southward at low level to avoid getting targeted by an over-enthusiastic SAM units and it also masked the group from airborne radar. 

Arriving in the vicinity of the bridge, the four VPAF pilots could see a mixed force of Vought F-8 Crusaders and Douglas A-4 Skyhawks attacking the bridge. The four accelerated and then pulled up to gain an altitude advantage against the strikers which had not seen their approach. Pham Ngoc Lan and his wingman zeroed in on a pair of unsuspecting Crusaders. His wingman, Phan Van Tuc, fired his MiG's cannon first before Pham Ngoc Lan had to cut across him to narrow the distance and fired on one of the Crusaders at only 400 yards, scoring hits and an explosion. Believing that another pair of Navy aircraft were closing in on them from below and to the right, Pham Ngoc Lan had his wingman take the lead and Phan Van Tuc fired again, scoring hits on a second aircraft that crashed. It would later turn out after the war that the Crusader Pham Ngoc Lan thought he had shot down was severely damaged, but its pilot, Lt. Commander Spence Thomas of VF-211 from the USS Intrepid, managed to nurse his stricken Crusader to an emergency landing at Da Nang where it had to be written off due to battle damage. Phan Van Tuc's kill was most likely the A-4C Skyhawk that was listed by the US Navy has having been downed by AAA fire. 

The MiG force was then ordered to return to base before running out of fuel (the MiG-17s were short-legged, particularly as it took a lot of afterburner use in dogfights to maintain speed), but the flight leader, Pham Ngoc Lan, got separated from his men and his compass failed. Having trained in the area during his basic flight instruction, he had a rough idea where he was and with his fuel supply dwindling, he set up to make a crash landing on the banks of the Duong River south of Hanoi. Ignoring his ground controller's order to bail out, Pham Ngoc Lan wanted to try and save the MiG knowing that there were only a small number operational with the VPAF. Missing a sampan by only a few feet, his aircraft skipped along the water and knocked him unconscious before coming to rest on a mud flat. When he came to, he found himself surrounded by a local Vietnamese militia pointing their guns at him, thinking he was a downed American pilot. Despite showing them his identity papers, it took a local village elder to defuse the situation. Given that Pham Ngoc Lan was born and raised originally in the South, his accent made him sound like he was from South Vietnam which complicated matters. Before long a helicopter from his base arrived to retrieve him and the MiG was also recovered and put back into service, a testament to the toughness of the design. Returning his base, he found out that the other men of his flight had managed to land safely. 

The aggressive performance of the VPAF that day surprised the Americans as they weren't expecting any significant aerial opposition. However, while the VPAF managed to learn and adapt into facing a numerically and technologically superior adversary in their subsonic MiGs, rigid doctrines and political interference would continue to handicap the US war effort for years to come.  Pham Ngoc Lan would finish out the war with three kills and his wingman, Phan Van Tuc, would finish out the war as an ace with six kills.

Since that day in 1965, the Vietnamese government made the third of April a public holiday called "Air Force Day".

Source: MiGs Over North Vietnam: The Vietnam People's Air Force in Combat, 1965-1975 by Roger Boniface. Stackpole Books, 2010, p1-9.

How A Top Secret Program Restored American Air Superiority

At the height of the Vietnam War, the skies were filled with technologically-advanced American aircraft from both the US Navy and the USAF, yet the air battles were a thread-bare echo of past glories in the 1950s skies over Korea's MiG Alley. By 1967 the Navy had a kill ratio of only 3.7 to 1 (3.7 MiG kills for every Navy fighter lost to a MiG) and the USAF was even worse, with a kill ratio of only 2.2 to 1. By comparison, at the end of the Korean War, the USAF pilots of the North American F-86 Sabre alone had a kill ratio of 10 to 1. While various studies and reports like the Navy's Ault Report offered many suggestions, the basic fact of the matter was that the art of dogfighting as a skill had been lost. In the USAF, for instance, the solution in the 1960s to an increasing accident rate in the McDonnell Douglas F-4 Phantom II was to simply ban air combat maneuvering training (ACM)- the accident rate fell, but legions of Air Force Phantom drivers entered the skies of Vietnam with little experience in knowing that their aircraft could and couldn't do in a dogfight with North Vietnamese MiGs. While a the solutions that eventually restored American supremacy in the skies are complex and beyond the scope of today's blog post, the foundations were being laid down in the black world in the latter half of the 1960s. 

The story begins on 16 August 1966 in the Middle East. Operation Rolling Thunder, the sustained air bombardment of North Vietnam, had begun the year prior and would continue until 1968. Monir Radfa, an Iraqi Air Force captain, took off in his Mikoyan MiG-21F from Rashid AB outside of the Iraqi capital for what was supposed to be a local navigation exercise. Instead, he made a dash to the southwest at low level, intending to defect to Israel. The Jordanians failed to intercept him as he streaked low across their country, the RJAF's Hawker Hunters too slow at low level. Once over Israel, he lowered his landing gear and wagged his wings to two intercepting Israeli Mirage III fighters, signaling his intentions and was escorted to Hatzor AB and given asylum. With the MiG-21 being one of the most potent fighters in the Arab air forces that threatened Israel, they immediately set about flight testing the MiG-21 for over 100 hours over the next 12 months, learning its strengths and weaknesses and teaching the Mirage III pilots (the French delta was the main fighter of the IDF in those days) how to defeat the MiG in a dogfight. Initially hesitant to share its prize with the United States, Israel eventually concluded an agreement brokered by the US Defense Intelligence Agency (DIA) to loan the MiG-21 to the US for study in exchange for being allowed to buy the F-4 Phantom II, the American front-line fighter of the day. At the time the Israelis had made several overtures to the Johnson Administration to purchase the Phantom, only to be rebuffed out of a fear by President Johnson of escalating matters in the Middle East. Now that the Israelis had leverage, the Phantoms would be on their way and the US would finally get to study its vaunted adversary in the skies of Vietnam up close. 

The MiG was disassembled and transported by a Lockheed C-5 Galaxy to the USAF's secret testing base at Groom Lake, Nevada (Area 51). Responsibility for evaluation of the MiG-21 was given to the USAF's Foreign Technology Division (FTD) that was part of the Air Force Systems Command based at Wright-Patterson AFB in Ohio. AFSC assigned all of its programs with the code word prefix "HAVE". For example, the original stealth demonstrator aircraft that gave rise to the Lockheed F-117 Nighthawk was code named "HAVE BLUE". In the case of the MiG-21 on loan from Israel, it was code named "HAVE DOUGHNUT". Two categories of flight testing were performed on the MiG- the first type concerned technical analysis- performance, flight envelope, engineering, structures, and so on. The second part of the tests were operational- the MiG would be flown in mock dogfights against US fighter aircraft. Because AFSC/FTD's emphasis was technical in nature, most of the HAVE DOUGHNUT flying concerned technical analysis. 

The first flight out of Groom Lake took place in January 1968 and continued until April of that year before the MiG was returned to Israel. For three intensive months, the MiG was flown in various profiles to determine how it could be detected by both radar and infrared systems, it flew against the bombers of the Strategic Air Command to see how well the bombers' systems could detect and counter it, and infrared signature tests were carried out using a specially-fitted T-39 Sabreliner that could mount the seeker heads of various missiles in the US inventory. Out of a total of 102 sorties flown as part of HAVE DOUGHNUT, 33 sorties were devoted to operational testing in mock dogfights with the USAF and 25 sorties were devoted to mock dogfights with the Navy. 

Not four months after the end of HAVE DOUGHNUT, two Syrian MiG-17Fs on a navigation exercise got lost and inadvertently landed at an Israeli air base. Acquisition of the MiG-17s was of high importance to the United States as the MiG-17, though slow and dated, was nimble and the main adversary type encountered in the skies of Vietnam. Though limited to subsonic performance, VNAF MiG-17s were flying circles around American fighter pilots leading to the dismal kill ratios I mentioned above. After testing by the Israelis, the two MiG-17s were then turned over to the United States for analysis. The first MiG-17 made its first US flight at Groom Lake in January 1969 with the code name HAVE DRILL. The second MiG-17 then flew in March of that year with the code name HAVE FERRY. Both programs wound down by June 1969 and the findings were shared with the Navy's new TOPGUN school that was established to reintroduce dogfighting skills to Navy pilots. In addition, the findings of HAVE DOUGHNUT, HAVE DRILL, and HAVE FERRY were shared with the instructors at the USAF's Fighter Weapons School at Nellis AFB, Nevada, where they would go on to establish the Red Flag exercises. 

On 25 November 1969 a Cambodian Khmer Air Force pilot defected to South Vietnam in the Chinese copy of the MiG-17F, the Shenyang J-5. The USAF pilot who flew the MiG-17 in HAVE FERRY and HAVE DRILL, Col. Wendell Shawler, was tapped by the AFSC/FTD to go to South Vietnam and make several evaluation flights of the J-5 to establish that it had the same flight characteristics as the MiG-17. This short program of just five flights from Phu Cat AB in South Vietnam was code named HAVE PRIVILEGE. 

As a result of these four top secret exploitation programs, both USAF and Navy fighter tactics were changed and pilots were once again trained to exact as much capability and performance out of the aircraft as possible to win the dogfight. It wasn't until 1989 that a Pentagon official confirmed that in the 1981 combat of two US Navy F-14 Tomcats versus two Libyan Sukhoi Su-17 fighters over the Gulf of Sidra that the tactics used had been developed out of mock combat testing with US-operating Soviet fighters. Not long afterwards, HAVE DOUGHNUT, HAVE DRILL, HAVE FERRY, and HAVE PRIVILEGE were declassified. What didn't get mentioned was that a much bigger program succeeded those programs and would remain top secret for 20 years! But more on that program in a future blog post! 

Source: Red Eagles: America's Secret MiGs by Steve Davies. Osprey Publishing, 2008, p16-20.

The Mikoyan I-320 Interceptor

One of the best aspects of being an avgeek comes when you find out about an aircraft you never knew even flew. I recently got the vastly upgraded edition of OKB Mikoyan and learned about the I-320 two-seat all-weather interceptor. From several different angles it looks a lot like the MiG-17 and it's clearly derived from that aircraft. In the late 1940s the Soviet Ministry of Defense issued a specification for a long-range interceptor- three bids were submitted from the OKBs of Lavochkin, Sukhoi, and Mikoyan. Late to the party but accepted for consideration was also a design from OKB Yakovlev. All of the designs were twin-jet aircraft.

Mikoyan's submission had the internal designation I-320/R-1 and it was designed and built in 1949- in tandem with the development of the famous MiG-15/17 family of jet fighters, accounting for its similarities in general layout. The main difference, however, was that the I-320 was a much larger and heavier aircraft with two crew and two engines. The engines were uniquely mounted in a stepped-tandem arrangement. The forward jet engine was mounted low in the forward fuselage with its exhaust semi-recessed underneath the fuselage just behind the cockpit. The aft engine was mounted in the aft fuselage just behind the wings much in the same way as the single engine of the MiG-15/17 with its exhaust at the end of the fuselage under the cruciform tail. The large nose intake had two splitters instead of the one intake splitter of the smaller MiG-15/17. The central portion of the nose intake fed the forward engine and the two lateral portions fed ducts that ran on each side of the cockpit to the aft engine.

The pilot and radar operator sat side-by-side under a broad cockpit canopy. This way both crew could scan the radar scopes and the radar operator had full dual controls and could relieve the pilot on long air patrols. The Toriy-A radar was mounted in a bullet-shaped projection above the nose intake and two 37mm cannons flanked the intake on each side of the nose.

Powered by two Klimov RD-45 engines of 5,000 lbs thrust, the I-320 was rolled out in April 1949 and made its first flight that month. Mikoyan's flight tests continued through 1950 and the aircraft was then delivered to the Soviet air defense forces, the PVO, for state acceptance and combat testing. The first version of the I-320, the R-1, didn't get accepted due to some stability issues at high speeds. Following the R-1 version in flight testing was the R-2 version which had more powerful Klimov VK-1 engines (the VK-1 was an upgraded and more reliable version of the earlier RD-45 engine used on the R-1 variant), aerodynamic refinements, and a third 37mm cannon mounted under the nose. With better performance in testing with the PVO, the R-2 got a more advanced Korshun radar to replace the earlier Toriy-A unit. During operational testing in 1951, a 37mm shell exploded in the feed belt and damaged the R-2's nose.

Mikoyan took the opportunity to try and rectify some of the stability issues dogging the I-320 as the R-2 was being repaired. As a result, it was redesignated as the R-3 version. The repaired and upgraded aircraft made its first flight on 31 March 1951 and it would make 60 flights during state acceptance trials for a total of nearly 46 flight hours. However, the I-320 never went into production as its performance was deemed inadequate. With the cancellation of Lavochkin's design, the La-200, and the crash of the Sukhoi entry, the Su-15 (the first use of the designation, not to be confused with the later and totally different Su-15 "Flagon" interceptor), Yakovlev's late entry won the competition and went into production as the Yak-25. For a while, though, Mikoyan retained the R-1 and the R-3 versions of the I-320 interceptor to develop instrument landing systems for the Soviet Air Force.

Source: OKB Mikoyan: A History of the Design Bureau and its Aircraft by Yefim Gordon and Dmitriy Komissarov. Midland Publishing, 2009, p127-130.

In the spring of 1966 the airbases of the Vietnamese People's Air Force (VPAF) were targeted for the first time by American aircraft. Previously considered off-limits by Washington (and later in the war the bases were not allowed to be attacked), the attacks on the MiG airfields at Dong Hoi and Vinh forced a rethink of North Vietnam's air strategy against a numerically superior American military.

To provide rapid repair of the airfields, over 70,000 steel-reinforced concrete plates were stockpiled at the airfields. Large amounts of bamboo stems were also stockpiled to be used in airfield repairs. Camouflaged revetments were created and some were even disguised as huts along with the construction of underground command centers for the base staff. To protect the VPAF's small MiG-17 force, the aircraft were dispersed out into the country side, carried by large Mil Mi-6 helicopters to the dispersal sites and carried back to the airfields when missions were to be flown. Later in the war, fuel and ammunition were also dispersed at these sites as it was found an Mi-6 could carry a fully-fueled and armed MiG-17 to the airfields from as far away as 30 miles. Underground shelters were built into the mountains near the bases where the aircraft were prepared for their missions against incoming American strike packages. An Mi-6 would then carry the fighter as an underslung load to the nearest airbase where it would take off, fly the mission and then return to base to be carried back to the underground shelters miles away by the helicopters.

In areas where the terrain prevented construction of underground shelters for the MiG force, the fighters were dispersed into villages and agricultural co-operatives as well.
Source: Wings of Fame, Volume 8. Aerospace Publishing, 1997. "MiG-17 Over Vietnam" by Zoltan Buza and Istvan Toperczer, p106-107.