On 20 November 1970, 2 Warning Stars, using the callsigns Frog 01 and 02 respectively, took off 10 minutes apart at 22:00 from Korat to take station at the low altitude Alpha orbit over the Gulf of Tonkin, with Frog 02 as a backup. The 17-man crews were advised in the air of the nature of the rescue mission and their role, providing MiG warning and directing USAF F-4 Phantom CAP intercepts. As Frog 01 began its climb to the higher Bravo orbit, it experienced a ruptured oil line forcing shutdown of one engine. As planned, Frog 02 became the primary aircraft when Frog 01 made an emergency landing at Danang.