The first 147T missions were flown in April and May 1969, followed by a second series in October and November 1969. One of the new drones, T-17, was shot down over China on October 28. Further 147T missions were flown during February-May 1970, then again in September 1970.
With this, the program ended after only twenty-eight missions over two years. The same pattern was true for the 147Gs. There were only nineteen 147G flights in 1970, and a mere nine in 1971. In both years, the 147Gs were flown between March and June. This brought the era of high-altitude drone photo reconnaissance to a close. The 147T would find success in another mission.
On April 18, 1969, a navy EC-121 ELINT aircraft was shot down by North Korean MiGs over international waters. All thirty-one crewmen were killed.
Lieutenant Colonel Andy Corra, head of unmanned reconnaissance systems, learned of the incident as he left his hotel for a meeting at Ryan Aeronautical to review the 147T program. When he arrived at the plant, he suggested using the 147T as an ELINT drone. It would carry receivers that would pick up radar and radio transmissions. The data would then be relayed from the drone to a ground station. Operators on the ground would control its operations.
The first briefing was ready a week after the EC-121 was lost. Four 147T drones were modified into a TE configuration. The first test flight was made on November 25, 1969. They were then sent to Osan, South Korea, for operational testing. It was a schedule that many in the National Security Agency had said was physically impossible to meet.
The first 147TE mission was flown on February 15, 1970, beginning a two-month operational test program. The drone was equipped with ten receivers for radio traffic. A ball-shaped radome on the drone's tail relayed the transmissions. Each receiver was individually controlled from a ground station. The 147TE could fly a preprogrammed mission or be controlled by the DC-130 launch aircraft. In some cases, it would have to fly a very tight "race track" pattern to remain within the signal beam. Following the initial 147TE missions, a contract was issued for fifteen production 147TE drones, in a program code-named "Combat Dawn." The first flight of the production TEs was made on October 10, 1970.
Unlike the other drones, the 147TEs remained at least fifty nautical miles offshore. The ELINT drones flew two types of missions — over the Yellow Sea between North Korea and China, and along the Demilitarized Zone between North and South Korea. Several times, MiGs were sent out after the drones. When MiGs were detected, the drone was maneuvered to avoid the fighters. None were lost to enemy action. Late in the TE program, external tanks were added to the drone, which increased the flight time from five hours to nearly eight. The 147TEs provided about ten thousand hours of intelligence data per year. A total of 268 147TE missions were flown up until the replacement of the drone in June 1973.
The replacement was an improved version, the 147TF. They were fitted with the external tanks and ELINT equipment that could pick up either radio or radar transmissions. The 147TF was introduced in February 1973 and would make 216 flights over the next two years, until the end of the drone program.[279]
The most significant of the 276 147SC missions flown in 1970, out of a total of 365 drone flights, was a "package" of seven. Their target was a small, isolated, walled compound twenty-three miles west of Hanoi. It stood on the bank of the Song Con River, outside the provincial capital of Son Tay. It was a POW camp, and the United States was planning to raid it. The camp was identified in May 1970. Comparison of old and new reconnaissance photos showed a guard tower and new wall had been added. It was also noticed that some uniforms had been spread out on the ground to spell out "SAR" — search and rescue. In one corner of the compound the letter K had been stomped in the ground — the code letter for "come get us." The POWs were calling for a rescue mission.[280]
The 147SCs were to provide "prisoner verification" and "positive identification of the enemy order of battle" — whether the POWs were at the camp, and the defenses in the area. Tragically, the drones went through another bad streak of losses. At least two were shot down, and another four had mechanical failure. The final drone, on July 12, suffered an even more frustrating failure. Two of the POWs, air force Lt. Col. Elmo C. Baker and Capt. Larry E. Carrigan, saw it coming and started waving. The drone was supposed to show "the height, color, eyes, and facial expressions" of every man in the compound, but the programmer was slightly off; the drone banked a moment too early and the photos showed only the horizon.
Because too many drones flying over so isolated a site would tip off the North Vietnamese, it was decided to switch to SR-71s. The data they brought back was ambiguous — the camp was not as active as before, but there did seem to be someone there. The raid was given a go-ahead.[281]
It started at 2:18 A.M. on November 21, 1970, when an HH-53 helicopter flew over the camp and blasted the guard towers and a guard barracks with minigun fire. Moments later, an HH-3 crash-landed inside the compound with the assault team. They quickly secured the camp and killed the remaining guards. Two more HH-53s with troops landed outside the camp; a third HH-53 mistook another set of buildings four hundred yards away for the camp and landed there. After a short but fierce firefight, the helicopter picked up the troops and flew them to the camp. The raid took only twenty-seven minutes, but no American POWs were found. Unknown to U.S. intelligence, the POWs had been moved out of Son Tay.[282]
In July 1971, the world's political landscape profoundly changed — President Richard M. Nixon announced he would be making a trip to Communist China. Soon after, it was reported that the United States was suspending overflights of China.
As the political situation eased, so did the shroud of secrecy that had enveloped the drones. Since the first loss of a 147 drone in November 1964, the U.S. government had held to a strict "no comment" policy. During 1970-71, this began to change. The November 9, 1970, issue of Aviation Week and Space Technology carried an article on the drones, based on off-the-record information. By the spring of 1971, the air force allowed release of photos of the 147 drones and a very general statement that the Air Force had developed drones that could be used for reconnaissance. What still could not be discussed were code names, technical details, or any references to operational missions. These were still Black.
The year 1971 saw an increase in drone activity, with a total of 406 missions. Unlike previous years, which had seen a host of different 147 versions, only three types of drones were flown. There were 277 SC missions, 120 TE flights, and the final nine 147Hs.[283]
In the war itself, there was little movement. The peace talks, both the public ones in Paris and secret discussions conducted by presidential adviser Henry Kissinger, were deadlocked. The number of U.S. troops declined, even as the antiwar movement grew. The North Vietnamese had used the respite to rebuild and prepare for a ground invasion of the South. As 1971 ended, it was becoming clear that would not be far off.
The drone operation was the first to reflect the impending North Vietnamese invasion. In late December 1971, the sortie rate of SC drones increased to 1.2 per day, twice what it had been. On March 20, 1972, the Easter Offensive was launched. On May 8, Haiphong Harbor was mined, cutting off the North's main source of supply. The Linebacker I bombing campaign began, hitting such targets as bridges, barracks, barges, and rail lines.
282
Earl H. Tilford Jr.,