The first SR-71 Mach-3 high-altitude reconnaissance aircraft was delivered to the USAF on 6 January 1966 following four years of operations by the highly secret, CIA-sponsored Lockheed A-12. The aircraft’s unsurpassed performance and intelligence-gathering capability made it a prime candidate for deployment to Southeast Asia. Such was the sensitivity and secrecy of the SR-71 programme that the aircraft were based in special facilities at Kadena AB on the island of Okinawa. The first aircraft arrived at the 9th SRW’s Operating Location-8 on 8 March 1968, followed by two more aircraft in the next few days. This and subsequent deployments to and from the USA were code named Glowing Heat while the SR-71 programme as a whole was named Senior Crown and the operational missions in Southeast Asia were called Giant Scale. The aircraft was soon nicknamed the Habu, after a type of deadly black snake found on Okinawa. The SR-71 flew its first operational mission from Kadena on 21 March 1968 and averaged about one sortie a week for the first two years and two sorties a week in 1970, culminating in a sortie every day by 1972. Operating at altitudes up to 80,000 feet and speeds of around 2,000 mph, the SR-71 could easily outrun SA-2s and MiGs and employed its impressive array of cameras, radar and ELINT equipment to obtain coverage of North Vietnam. Even though the SR-71 arrived in the theatre towards the end of Rolling Thunder, the intelligence provided was of great value. Each flight took off from Kadena and refueled from special KC-135Q tankers before entering the Gulf of Tonkin for a high-speed pass over North Vietnam. The SR-71 would then refuel again from a tanker over Thailand or Laos prior to making a second run over the target area before heading back to Kadena, refueling once more en route. Several occasions arose when SR-71s had to make emergency landings at U-Tapao and the aircraft suffered badly from engine flameouts, especially in the early days. The Kadena detachment was increased from three to four aircraft in the spring of 1970.