When the North Vietnamese Outsmarted American Bombers

On July 24, 1965, four McDonnell F-4C Phantom fighter-bombers of Leopard Flight joined an airstrike against the Dien Bien Phu munitions storage depot and the Lang Chi munitions factory in the northwestern part of North Vietnam. The Phantoms bombed their assigned targets and withdrew to provide cover for the incoming Republic F-105D Thunderchief fighter-bombers of the 80th Tactical Fighter Squadron.

“As we started climbing out of the area after our single pass at the target,” recalls F-105 pilot Capt. Vic Vizcarra, “our mission commander informed the Phantoms that we were departing. We all remained on the same frequency as we climbed and headed south. I was left of Lead, which placed me on the Phuc Yen MiG base side of the flight. Suddenly we heard a call from the F-4s. ‘What the hell was that?’ one of them said.”

Leopard Lead called for others in his flight to check in. Leopards 3 and 4 responded, but 2 was never heard from—blotted out of the sky by a guided missile. The blast also damaged the other three Phantoms in the flight. They were the first victims of the soon-to-be-infamous SA-2 surface-to-air missile, or SAM.

Four months earlier President Lyndon B. Johnson, intent on preventing North Vietnam from putting its full military weight into an invasion of South Vietnam, had authorized the Operation Rolling Thunder bombing campaign. The bombing began on March 2, 1965, and targeted North Vietnamese transport and communications lines. However, the White House prohibited U.S. air operations in a 10-mile radius around Hanoi. In addition, restrictions were put on target selection in a larger 30-mile radius, which was under the control of the White House. Only Johnson, with advice from administration officials such as Defense Secretary Robert
McNamara, had authority to order any air operations within that area.

The Johnson administration was afraid that a more aggressive bombing campaign would increase civilian casualties and could escalate the war by provoking the Soviets and Chinese. For example, bombers were banned from the entire seaport of Haiphong Harbor because Soviet ships offloaded cargo there. Those constraints would soon manifest themselves in the debacle of Operation Spring High.

The appearance of the SA-2—code-named “Guideline” by NATO and known to the Soviets as the S-75 “Dvina”—came as a rude shock to the West in the early 1960s. Although the U.S. was aware that the Soviets had developed an anti-aircraft missile, the SA-2 exploded onto the world stage when it shot down a Lockheed U-2 spy plane piloted by Francis Gary Powers of the CIA at an altitude of 70,000 feet.

The SA-2’s liquid-fueled second stage, 35 feet long and carrying a 440-pound warhead, was launched by a solid-fuel booster and streaked to its target at Mach 3.5, about 2,500 mph. The warhead’s lethal radius was more than 220 feet wide at low altitude but spread out to more than 800 feet above 60,000 feet.

Previously, fighter-bombers like the F-4 and F-105 had been able to avoid small-arms anti-aircraft artillery by flying at altitudes out of range for the Soviet-made ZPU-23 and 37 mm guns, but the high-altitude SAMS, guided by SNR-75 azimuth and elevation radar (NATO code-named “Fan Song”), were an extreme hazard to every American plane.

A month after the start of Rolling Thunder, five SAM sites under construction were discovered inside the 10-mile area of prohibited bombing. The Joint Chiefs of Staff were adamant that the sites be destroyed before they could be completed, but McNamara convinced Johnson to keep the SAM sites on the off-limits list. Between May and July1965 the Joint Chiefs asked the White House no fewer than three times to allow the Air Force and Navy to bomb the SAM sites. Each time they were turned down.

After the shootdown of the Phantom on July 24 by SAMs launched from two new batteries, site 6 and site 7, on the western edge of the 30-mile restricted zone, the Joint Chiefs again urged Johnson to authorize a strike on the SA-2 batteries. At last, the Pentagon prevailed. Johnson gave the order: “Take them out.”

The mission was assigned to four Thailand-based tactical fighter squadrons that flew the supersonic F-105D Thunderchief, known affectionately as the “Thud.” The F-105 was the world’s fastest fighter-bomber capable of nuclear weapon delivery. It could carry 8 tons of ordnance.

Even as planning for the mission, code-named Spring High, progressed, the Johnson administration was concerned that the U.S. operation could lead to increased Soviet or Chinese involvement. McNamara argued that only the SAM batteries that fired on the Phantoms, sites 6 and 7, should be eradicated because Russian advisers working with the North Vietnamese Army at other SAM sites might be killed, incurring the wrath of the Soviet government.

On the morning of July 27, 1965, the pilots of four tactical fighter squadrons woke to begin their mission. They would attack only sites 6 and 7. “So the prior night’s flight planning went up in smoke, and we were left scrambling at the last-minute requirements,” Vizcarra said. The mission start time was delayed into the afternoon.

The 12th and 357th Tactical Fighter squadrons, flying out of Korat Royal Thai Air Force Base, were to attack the North Vietnamese 63rd Missile Battalion at site 6. The 80th and 563rd Tactical Fighter squadrons from Takhli (pronounced “Tak-Lee”) Royal Thai Air Force Base would hit the 64th Missile Battalion at site 7.

Each squadron was segmented into three four-plane flights. The Korat flights were named for trees: Pepper, Willow, Redwood, Cedar, Chestnut and Dogwood. The Takhli flights bore automobile names: Healy, Austin, Hudson, Valiant, Rambler and Corvette. A total of 48 F-105s participated in the strike.

Not all of the Thunderchiefs would attack the actual SAM batteries. Some would hit command radar vans, missiles and launchers, while others bombed support facilities and barracks. A portion were deployed to fight possible MiG attacks or held in reserve to cover aircraft that needed to abort their mission. Yet none of the Thuds were assigned to attack the anti-aircraft guns protecting the SAM sites.

Moreover, higher headquarters had the F-105s approaching their targets in a “finger four”—a four-plane flight with a two-plane lead element and a two-plane second element in a formation that looks like four outstretched fingers of a hand. That formation was ill-suited for a low-level, high-speed attack on a fixed site protected by anti-aircraft artillery, Vizcarra explained. “What did they think this was—an air show? One hit could wipe out the whole flight. Four big F-105s flying close together on the deck, nothing like making oneself a bigger target.”

SAM sites 6 and 7 were nestled in the wedge of the delta between the Black and Red rivers about 450 miles from the Thailand bases. Both the Korat and Takhli forces would refuel from orbiting Boeing KC-135 tankers and head into North Vietnam via Laos. The Korat group would approach SAM site 6 from the south, while the Takhli aircraft would fly east and south down the Red River Valley to site 7.

In the Takhli force, a squadron’s first flight carried CBU-2 “cluster bomb units,” or bomblets. Each bomblet, with the explosive force of a large hand grenade, was filled with ball bearings that shot out of the bomblet at high speeds when it struck the ground or some object. When the bomblets were ejected, the 480-knot (550 mph) airstream sent them over a wide area, where they tore through swaths of enemy troops and vehicles. The second and third flights in a squadron were loaded with four BLU-27 napalm canisters.

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Each four-plane flight was to stay about 150 seconds, or 20 miles, behind the preceding flight so the trailing planes would not be hit by exploding ordnance dropped from the planes in front. Creating an additional threat, the CBU-2 bomblets tended to collide with each other after ejecting and explode in the air. An aircraft’s thin-skinned and highly volatile fuel tanks could easily be ruptured by the bulletlike ball bearings.

That frightful possibility weighed on the pilots as they flew toward their targets. In Vizcarra’s flight with the Takhli group, Maj. Art Mearn was call sign Rambler Lead, and Vizcarra was Rambler 2. They were approaching from the northwest down the Red River to hit site 7, and the Korat group was approaching from the south for a simultaneous attack on site 6, less than 3 miles away. The danger of midair collisions was very real.

Vizcarra was off Mearn’s right wing, while Rambler 3, Capt. Jim Hayes, and Rambler 4, Capt. Giles Gainer, were on the left. “Art told me that as soon as we released our bombs, he would call that I had the lead and make a hard right turn to avoid the Korat force coming north off site 6,” Vizcarra recalled.

The decision to attack in a fingertip formation was still a concern, so the flight leaders made their run at the targets in a loose, flexible fingertip formation, which spread the F-105s out to minimize the chance of a single hit damaging more than one plane and give them room to maneuver. Unknown to the Thud pilots, the North Vietnamese had ramped up the danger. The NVA moved all available anti-aircraft guns close to the SAM sites. The Americans would be flying into one of the most heavily defended areas in North Vietnam.

Spring High began shortly after noon on July 27. Two aborts from the Korat squadrons brought in two reserve planes.

In one of those aircraft was Capt. Chuck Horner from the 357th Tactical Fighter Squadron at the Korat base. Like his squadron mates, he had endured a long and frustrating night of arming and rearming the Thuds. The first concern was that the napalm canisters had to be dropped at air speeds no greater than 375 knots (430 mph), dangerously slow for attacking a well-defended target a low altitude.

The 80th Tactical Fighter Squadron planners at Takhli sent word to the air staff in Saigon that the Thuds should use conventional iron bombs and fly at 480 to 500 knots (550-575 mph). The request was approved, and ground crews changed the weapons. As dawn rose, a more senior Air Force general in Saigon said the original weapons load would stand. No reason was given.

Horner and Maj. Roger Myhrum took their places as three and four in the third Redwood Flight. Shortly after refueling but before leaving Laos, the leader aborted with mechanical trouble. He pulled out, followed by the wingman. This left Horner and Myhrum as the sole planes in the lead flight. It was not a good start to an already problematic mission.

A Douglas RB-66 reconnaissance plane monitored the SAM radar emissions of sites 6 and 7, and whenever it found emissions, the code was: “Bluebells are singing.” That call was made during the refueling, but then came another: “Bluebells are silent.” Meanwhile, as the F-105s streaked ever deeper into enemy territory, NVA early-warning radars tracked them until they were lost in the ground clutter 14 miles out.

The Korat force entered North Vietnam at 17,000 feet and descended to its attack altitude of 500 feet. The Red and Black River valleys were alive with the sound of heavily laden Thunderchiefs roaring overhead at 375 knots.

The lead flights saw the flashes and tracers of heavy anti-aircraft fire crisscrossing ahead. They descended below 50 feet to avoid the deadly web. Against orders, the pilots chose to ignore the 375-knot restriction for napalm drops and advanced to 500 knots. Their F-105s churned up roostertails of mud and spray over the rice paddies.

As the fast-moving F-105s skimmed the ground, NVA gunners attempting to knock them down were hampered by the high berms around their emplacements. They could not lower their muzzles enough to hit the jets. The air over the Thuds was filled with a deadly curtain of hot steel. Several planes were hit from above, an unusual situation for aircraft. Some returned to base with branches and leaves caught in the underwing pylons.

Cedar Flight’s Capt. Robert Purcell took some damage, possibly from an object on the ground. He pulled up with the entire underside of the Thunderchief aflame, Horner observed. Purcell ejected as his plane turned into a ball of fire on impact. He was captured and sent to Hanoi.

Takhli force pilot Capt. Marty Case in Hudson 4 of the third flight assigned to site 7, took anti-aircraft artillery fire about 14 miles out. “We were so low that most of it went over us,” he said. “As we got closer to the SAM site it was just flames and smoke and triple-A going across. It looked like the end of the world to me. I didn’t think any of us could make it through that alive.”

Capt. Kile Berg, Hudson 2, was hit on the approach, Case said. “The gunners were trying to hit the lead, but we were going so fast, they hit the No. 2. Kile made it to the target, but as we were on the escape route, I looked ahead and his entire airplane from the intakes back was a mass of flames. It looked like a meteor with a needle sticking out.” Berg ejected. He was captured and spent seven years as a prisoner of war. 

Capt. Jack Redmond in Takhli force’s Valiant 4 was watching to his right “when all of a sudden these other planes zipped past us at our altitude,” he remembered. “We were only about 50 feet up. They were the Korat planes coming off site 6.”

While the Korat force hammered site 6, the Takhli force made its move on site 7. The first three flights dropped CBU-2 bomblets and napalm on the SAM launchers and radar van. After a lull of two minutes, the next flight of four Thuds came in to drop their napalm canisters.

Somehow the 80th Tactical Fighter Squadron’s Valiant leader, Maj. Phil Call, fourth in the attack stream behind the 563rd Tactical Fighter Squadron’s Hudson Flight, misjudged his approach and saw his flight aimed not at the enemy support base north of the missile battery, but at the SAM site itself.

The four Valiant pilots released their cluster munitions a few seconds before passing over site 7. But as Valiant Flight passed over the site, Redmond was stunned and angered to see that the SA-2 missiles they had come to destroy were dummies. “They knew we were coming and set up all those triple-A batteries at the site,” he said. “It was a trap.” 

The first to hit the support facilities half a mile north of the main site was Rambler Flight with Vizcarra on the left. When he looked ahead, he saw two columns of black smoke rising from numerous fires. “All across the valley were the triple-A gun positions,” Vizcarra recalled. “The 37 mm shells looked like orange golf balls when they came at me. They exploded into black puffs, and I saw the black shrapnel spreading out. Art said, ‘Rambler Lead, 3,2,1, Pickle!’ Then we all released.”

The Rambler and Corvette F-105s each carried four BLU-27 napalm canisters filled with jellied gasoline. When the canisters landed, huge fireballs erupted into the sky. Tons of burning napalm immolated men, vehicles and fuel. In seconds Rambler was clear of the anti-aircraft guns.

Meanwhile, in the Korat force, Horner and his leader in Redwood Flight saw the target and released their napalm canisters at 550 knots (630 mph). Horner later admitted he was not certain of a hit, but at least he could report that “100 percent of the ordnance fell in the target area.’”

The NVA gunners, with no F-105s assigned to strike them, were free to fire their 23 mm and 37 mm guns at close range. They shot down four Thuds in the target area. More than half of the F-105s suffered damage from groundfire.

Pepper 2, Capt. Bill Barthelmas, a friend Horner’s, was hit over site 6. Noticing that his plane was leaking hydraulic fluid, he called for Pepper Lead, Maj. Jack Farr, to come close and examine the damage. On an approach to an emergency field just beyond the Thai border, Barthelmas’ controls failed, and he collided with Farr. Both pilots were killed.

In the end, six aircraft were lost—four shot down and two in the collision. Three pilots were killed (Capt. Walter Kosko, Barthelmas, Farr) and two were captured (Purcell and Berg). One of the downed pilots, Capt. Frank Tullo, was found and rescued.

After the returning F-105s landed and the pilots were debriefed, a hard and cruel truth emerged. Both SAM launch sites were devoid of missiles and equipment. The North Vietnamese had set up dummy SAMs made of white-painted bundles of bamboo ranged around a fake radar unit. More than 130 anti-aircraft guns were waiting for the Americans lured into the fake SAMs trap.

Vizcarra, in his memoir Thud Pilot wrote: “Spring High could have been a historic mission. It was the first time in history of an attack against a SAM site. If we had known the site was a trap, we would never have sent the force out. We attacked at low level, which was based on exaggerated assumptions of the SAM’s capabilities. I’m not sure we would have done much better even if we had been able to plan the mission without headquarters’ interference. We had a lot to learn, and you sometimes have to do the wrong thing to know it was wrong.”

An air staff anti-SAM task force was established. Led by Brig. Gen. Kenneth “K.C.” Dempster, it involved the Air Force, Navy and defense contractors. Homing and warning receivers were installed in F-105s in December 1965, four months after Spring High. They alerted the pilot to enemy radar emissions and their source. The Navy’s Shrike anti-radar missile, in early development when the mission took off, was given the highest priority. The Shrike homed in on radar emissions at the center of the SAM battery.

In all, 46 recommendations made by the task force were accepted by the Air Force, leading to the development of SAM-targeting “Wild Weasels,” the code name for aircraft designed to hunt down and destroy SAM batteries, which opened the way for airstrikes in enemy territory. The first Wild Weasels were modified North American F-100F Super Sabre fighter-bombers, which arrived in Thailand in November 1965 and destroyed a SAM site on Dec. 22.

More technology followed. QRC-160 jamming pods reached Southeast Asia in September 1966. For the first time, American fighters could self-jam SAM radars and render them ineffective.

By then the number of SAM sites had risen to 18, with another 18 sites suspected, but even with that increase the effectiveness of Wild Weasel SAM killers raised the life expectancy of U.S. airmen dramatically.

Sadly, it had taken a defeat to make that victory possible. Horner returned to Vietnam in 1967 to fly 70 Wild Weasel missions in addition to the 41 bombing sorties he had flown in 1965. He was greatly affected by the outcome of Spring High and remained highly critical of the White House’s decisions in target selection.

As Horner rose in rank, experience and responsibility, he did his best to see that the Air Force had the tools, training, support and, above all, morale to win future conflicts. As a lieutenant general he commanded the coalition air armada in the 1990-91 Gulf War. The decisive air war over Iraq proved that Horner had learned from Vietnam.

Mark Carlson is a regular contributor to military history magazines and the author of The Marines’ Lost Squadron: The Odyssey of VMF-422 and Flying on Film: A Century of Aviation in the Movies, 1912-2012. He lives in San Diego.

This article appeared in the Autumn 2022 issue of Vietnam magazine.