On April 19, 1967, Major Thorsness and his Electronic Warfare Officer, Captain Harold E. Johnson, flying F-105F AF Ser. No. 63-8301, led Kingfish flight (three F-105F Weasel aircraft and an F-105D single-seater) on a Wild Weasel SAM suppression mission. The strike force target was JCS target 22.00, the Xuan Mai army training compound, near heavily defended Hanoi. Thorsness directed Kingfish 03 and 04, the second element of F-105s, to troll north while he and his wingman maneuvered south, forcing defending gunners to divide their attention. Thorsness located two SAM sites and fired a Shrike missile to attack one, whose radar went off the air. He destroyed the second with cluster bombs, scoring a direct hit.