As missions continued, the limitations of the Shrike were noted by the aircrews. The North Vietnamese radar operators realized the Wild Weasel aircraft had to fly straight at their target so they would turn off their radars whenever they saw a plane coming directly toward them. They also recognized that Wild Weasel hunter-killer teams operated in groups of four or five aircraft. Since this was smaller than the normal strike missions, they would simply shut down while the Americans were nearby. In addition, they started operating their radars for shorter periods.
The U.S. Air Force aviators noticed the North Vietnamese counters and developed new tactics of their own. They would fly threateningly toward enemy SAM sites just to get them to shut down. Sometimes they would bomb suspected radar sites just to keep their opponents off balance while strike missions were in the area. If a radar crew was bold enough to start transmitting, the Wild Weasels would quickly and aggressively attack it. They would also fly close to the strike missions to avoid standing out so the enemy would switch on their radars long enough to be targeted. Over time simply suppressing the radars became more of a priority than actually destroying them.
One of the most famous Wild Weasel mission of the war took place on March 10, 1967, against the Thai Nguyen Steel Works 40 miles north of Hanoi. This factory complex was protected by an extensive radar-controlled antiaircraft network. F-105 pilot Captain Merlyn Dethlefsen took off carrying a load of bombs in addition to a pair of Shrike missiles. The young pilot wondered how much damage the Shrike could do by itself and hoped that by attacking with heavier weapons he might inflict substantial damage.
Dethlefsen was flying with another F-105 Wild Weasel and a pair of F-105D bombers. Together they made up a standard Iron Hand flight. They flew 30 to 45 miles ahead of the main strike force, which equated to about five to seven minutes of flying time. Once over the target, the aircraft would have to stay in the area, otherwise the enemy radar operators would just wait until they were gone and switch their sets back on when the strike force arrived. The factory was defended by both SAMs and traditional antiaircraft guns.
As Dethlefsen and the other flyers of the Iron Hand force approached the target they encountered heavy fire from the ground. It was so dense he soon lost sight of the other aircraft in his flight; the smoke from bursting shells was so thick it obscured them. “The sky was just black,” said Dethlefsen. “You know you’re not bulletproof … when explosions are rocking your wings and you can hear metal hitting metal.” Captain Kevin Gilroy, his EWO, soon located a Fan Song radar despite the deluge of steel they were enduring. The pilot quickly launched a Shrike at it, but just as he did so a pair of MiG-21 interceptors attacked them from behind. One MiG-21 launched a heat- seeking missile at the F-105 and Dethlefsen dove to avoid it, flying straight through the layer of flak from the enemy antiaircraft guns.
Despite the danger, Dethlefsen stayed over- head until his fuel finally ran low. Gilroy detected another Fan Song and Dethlefsen used his other missile to attack it. Destroyed or not, it went quiet. Minutes later the pilot saw a radar van sitting amid another SA-2 missile site. Diving on it, he strafed the van with his 20mm cannon and blanketed the area with bombs. When they returned to base they expected some recognition for their actions, but some fighter pilots had shot down some MiGs and all the celebration was focused on them. Their skilled flying did not go unremembered, though. In early 1968 Dethlefsen was awarded the Medal of Honor and Gilroy received an Air Force Cross for their accomplishments over Thai Nguyen. Both would complete more than 100 missions over Vietnam.
Based on experiences such as those at Thai Nguyen, the U.S. Air Force began changing its tactics. It tightened the flying formations; now the strike force flew one minute behind the leading Iron Hand flight. A second Iron Hand group followed just behind or beside the strike force to deal with other enemy radar-guided weapons. Two flights could cover more area and continue covering the strike force throughout its attack and subsequent withdrawal. One flight could also serve as a decoy, tricking the radar crew into switching on after the first Iron Hand flight passed.
In March 1968, the U.S. Air Force also introduced the AGM-78 Standard Anti-Radiation Missile, which boasted a 219-pound warhead. It also had an improved guidance system that would allow the missile to continue tracking even if the radar was switched off after launch. The Standard Anti-Radiation Missile could turn up to 180 degrees after firing, so that the firing aircraft did not have to be flying directly at the radar to target it. The missile had a range of 75 miles, though Wild Weasel aircraft usually flew too low to fire them at that range and acquiring radar at that range was difficult at best.
In August 1967 another Wild Weasel flight covered a hazardous mission against a well- defended target. Lt. Col. James McInerney and his EWO Captain Fred Shannon flew against the defenses of the Paul Doumer Bridge. This mile-long structure was a key piece of infrastructure in the North Vietnamese railroad network. McInerney and Shannon destroyed two missile sites and suppressed four others, allowing the strike force to hit the bridge. During their attacks they dodged three SA-2 missiles and heavy gunfire. The strike force did not suffer a single loss during the mission. Both received the Air Force Cross for their heroism.
In the final years of the Vietnam War, American forces began the process of Vietnamization by which U.S. combat forces were withdrawn and the South Vietnamese took on the responsibility for defending their country against North Vietnamese incursions. This applied primarily to U.S. ground forces, although it also included the U.S. Air Force. The North Vietnamese Army’s 1972 Easter Offensive, though, required substantial U.S. Air Force assistance to prevent the collapse of South Vietnam.
To assist the South Vietnamese in defeating the offensive, the U.S. Air Force initiated Operation Linebacker. By this point, though, the North Vietnamese had built a large and integrated air defenses system over most of their country, including 200 SA-2 missile sites. Some of the SA-2s could even cover airspace over South Vietnam.
In response, the U.S. Air Force deployed a squadron of the improved F-105G Wild Weasel along with the new F-4C. The F-4C had encountered a longer development period but was finally coming into its own. During Operation Linebacker II, the F-4C flew 460 sorties around Hanoi without a single loss. Most of the targets struck were within 25 miles of Hanoi, meaning they were surrounded by what was then the densest air-defense network in the world. During the period of the Linebacker and Linebacker II operations, the North Vietnamese launched more than 4,000 SA-2s at U.S. aircraft, but they downed only 49 planes. This meant it took 81 missile launches to bring down a single aircraft, a ratio partly due to the efforts of the Wild Weasels.
After the war the Wild Weasel program was evaluated. Its record with early weapons such as the Shrike was mixed because many of the missile strikes could not be confirmed as having actually destroyed the target. It was recognized that even when they did not destroy a radar site, however, they disrupted its operation sufficiently to dramatically reduce its effectiveness. The Air Force continued the program and it is still in effect.
Originally Published January 23, 2019