On a "hunter-killer" mission in South Vietnam, scout helicopter pilot Hugh Mills spotted an enemy bunker and reported it to the accompanying helicopter gunship. Mills got out of the way and the Cobra attack helicopter moved in to fire rockets at the bunker. As the Cobra pulled out, tracer ammunition came at it from a different location. Mills turned around and flew back in order to attack the bunker himself. Working together, the two helicopters succeeded in eliminating the threat. Before that engagement, no scout pilot had ever returned to the site of an engagement in order to protect an attack helicopter, much less assist in firing on the enemy target. Mills’ commander gave him a stern reprimand, but the Cobra pilot, certain that Mills had saved his life, recommended him for a Distinguished Flying Cross decoration.
Hugh Mills, author of Low Level Hell, flew the Hughes OH-6A Cayuse. The Cayuse was a product of the U.S. Army Light Observation Helicopter program, for which the first request for proposals was issued in 1960. The advent of U.S. involvement in the Vietnam War had added impetus to the program, and Hughes was awarded a contract for production in May, 1965. The first Hughes OH-6A observation helicopters arrived in Vietnam in December of 1967. Crews dubbed the new helicopter Loach, a contraction of "light observation helicopter."
Most combat aircraft in Vietnam flew at altitudes and speeds that minimized the probability of being hit by anti-aircraft fire, but scouting activity required more risky behavior. Army Loach pilots flew low, only 5 to 10 feet above the highest obstacle, and at 45 to 60 miles per hour, in order to bait the enemy into opening fire. When that happened, and it did happen with monotonous regularity, the Bell AH-1G Cobra circling above launched rockets at the enemy or moved in for a close-range attack. These hunter-killer teams would be sent to seek out encampments, bunkers, or other signs of an enemy presence.
To call this type of work dangerous would be a ridiculous understatement. Mills was shot three times in the course of three tours in Vietnam: One time he was shot in the right heel, once in the right hip, and once he was shot in the face. In the latter incident, the bullet passed through his chin and out the opposite side of his face. Over the course of those three tours, a helicopter that he was piloting was shot down 16 times. Two of those tours were in Loaches and one was in a Cobra, but of those 16 downings, all but one occurred while he was piloting a Loach. He later recalled:
Of the ten pilots that began with me in February of '69, two of us were left alive in December. For his service Mills was awarded with numerous decorations for valor, including three Silver Stars, four Distinguished Flying Crosses and three Bronze Stars.
A total of 1,419 OH-6A Cayuse helicopters were built by Hughes Helicopters and 842 of them were destroyed in Vietnam. Most were shot down, although many others were wrecked in crashes resulting from flying low to the ground. For the sake of comparison, nearly 1,100 AH-1 Cobras were delivered to the U.S. Army and of those, "only" 300 were lost.
By the time the United States left Vietnam, Cayuse/Cobra hunter-killer teams had been made obsolete by advances in Soviet missile technology. North Vietnam's 1972 Easter Offensive saw the first major use in Vietnam of Soviet SA-7 Grail surface-to-air missiles. These weapons were man-portable, shoulder-launched and were automatically guided by sensors that homed in on infrared energy emitted by aircraft engines. North Vietnamese SA-7 Grails were credited with downing 16 aircraft at the Battle of Quang Tri, during that offensive.