Operation Thunderhead (31 page)

Even for holders of high security clearances, such as everyone involved directly with the SR-71 flights, information was given on a need-to-know basis. Two missions conducted during the early part of May 1972 were so secret that the pilots and RSOs involved knew what they were going to do and how, but not why.

A flight of three SR-71s was assigned to fly from Kadena to North Vietnam on a daylight mission. The operation required two of the aircraft, the primaries, to overfly Hanoi at a specific time and “lay down” a sonic boom. The crashing thunder of the booms could be heard throughout the Hanoi area.

The mission had come down from the highest command source. There was no question that the pilots and crew would conduct the operation; they did not know the specifics of their signal, only that it was intended for the most important people they could think of in North Vietnam—their fellow fliers and others who were being held as prisoners of war.

The name given to this operation was “Booming the Hanoi Hilton.” The signals were to be given by the primary aircraft at noon on May 2 and 4, the sounds to go out within fifteen seconds of one another. The two booms signal was so important that a third SR-71 was assigned to the mission as an immediate spare. If anything was to go wrong with one of the primary aircraft, the backup would come in and conduct the operation immediately. Timing was so critical that the spare aircraft would follow the primaries all the way to the target zone, well into the very hostile airspace over North Vietnam and the most heavily air-defended city in the world.

Major Tom Pugh was piloting SR-71 #968 (the last three digits of the serial number of the bird); Major Ronnie Rice was his RSO in the rear seat. Theirs was the lead aircraft for the flight. The second primary aircraft for the mission, bird #980, was piloted by Major Bob Spencer while Major Butch Sheffield pulled RSO duties. In the backup aircraft was Lieutenant Colonel Darrel Cobb as the pilot and Captain Reggie Blackwell. Theirs was a somewhat unique SR-71, one of only four to receive its own nickname. On the tail fin of #978 was painted the head and ears of the Playboy rabbit. The aircraft itself was the Rapid Rabbit and had been the second SR-71 delivered to the Air Force.

On this series of missions, the three aircraft split up as they came up to the target area over Hanoi. On one of the operations, #968 approached the target area from the south, coming in at 75,000 feet. The other primary aircraft, #980, came in to the target at 80,000 feet from the southeast. Though not used actively in the operation, #978 would have come in at 70,000 feet from the west.

When the agreed-on code word was transmitted from the primary aircraft, #978 broke off its run short of the target area. Now only Pugh and Spencer were piloting their birds over Hanoi while Rice and Sheffield were conducting some of the most precise navigation and timing of their careers. The planes slowed in their approach, giving up one of the greatest defenses of the SR-71, its tremendous speed, in order to make their signal loud and clear. As the time approached, the pilots let out their throttles and the mighty exhaust of the Pratt & Whitney engines roared out. At noon on May 2, a sonic boom rang out in the air over Hanoi. Fifteen seconds later, a second boom rolled through the air. Two days later, the same actions took place in the air over a puzzled and frightened Hanoi population.

The Booming the Hanoi Hilton missions had been conducted without a hitch, in spite of some very tight time parameters placed on the flights. The missions were successful, but the crews never knew why. For decades after, none of the men involved really knew what their message had been intended to convey. They knew that their mission had been an important one, but it was a seemingly small thing among all of the other accomplishments of the SR-71.

The dangers of flying such sophisticated and demanding aircraft came up less than two months after the Hanoi mission. SR-71 #978,
Rapid Rabbit
, came down in severe crosswind conditions at the Kadena airfield. On the second landing attempt, the undercarriage gave way as one set of the main wheels hit a concrete obstruction. The crew came out of the landing safely, but the
Rapid Rabbit
was a writeoff. The bird was stripped down for spare parts to help keep other SR-71s flying, and the remaining hulk was buried at the airfield.

The amazing career of the SR-71s continued on for years following the end of the Vietnam War. The Air Force in general, and fighter pilots in particular, never “took” to the great black birds and their reconnaissance missions. The birds were retired in the 1990s, the last ones flying having been turned over to NASA. Now they exist primarily as display pieces for the public at museums.

The lead bird for the Booming missions, #968, is the centerpiece of the Virginia Aviation Museum in Richmond, Virginia. Set up just outside the main doors to the museum, the SR-71 was dedicated to the public in November 1999. During the restoration of SR-71 #975 at the March Field Air Museum in California, it was discovered that the left tail fin on that craft was one of the pieces salvaged from the
Rapid Rabbit
after its crash. It is the only part of #978 known to be on public display.

SR-71 #980 continued to fly after life with the Air Force. It was assigned to NASA for research and received the new tail number 844, painted on its upright fins in large white numerals. On October 9, 1999, the last flight of an SR-71 took place. That craft was NASA #844.

Together, these craft and the dedicated men who made up their crews delivered the most expensive two-dot Morse code message ever sent. Those two booms, the letter “I” in International Morse Code, had no real meaning to the pilots of the birds that sent them out. But it meant the possibility of freedom to one of the prisoners below.

OPERATION THUNDERHEAD

In the Yokosuka Naval Shipyard in Japan, U.S. Navy lieutenant commander Edwin L. Towers, a staff officer with the Seventh Fleet, was not expecting any major life changes to take place anytime soon. Even though he was aboard the
Oklahoma City
, the flagship of the U.S. Seventh Fleet, major adventures were more along the lines of completing everyday duties. So he was in for a surprise when he was called down to his captain's office.

There was a lieutenant commander in Captain McKenzie's office when Towers arrived. The new man was introduced as Earle Smith from Washington, D.C., and he had some highly classified information he wanted to discuss with Towers—information that had only been shared with two other people on the ship, Captain McKenzie and Admiral Holloway, the operational commander for all of the naval assets of the Seventh Fleet.

That statement from Smith was startling enough, but it didn't hold a candle to what Towers heard next. There was going to be an escape of POWs from camps in North Vietnam, sometime between June 1 and June 15, 1972. The number of escapees wasn't known and no other details of their plans or pathways to freedom were revealed but one: The men would be making their way to the Gulf of Tonkin and continue on out to sea to the best of their abilities. The Navy was to help identify the escapees and recover them from enemy waters. Authorization for the mission had come from the higher command and Earle had been ordered to come and help put together a plan and execute the mission.

It was an astonishing statement, and the most limited information possible on which to plan a mission. But that was exactly what the higher command had wanted, and that desire had come from the Chairman of the Joint Chiefs of Staff, Admiral Thomas Moorer, Chief of Naval Operations. The only higher authority would have come from POTUS—the President of the United States and Commander in Chief of the U.S. Military, Richard M. Nixon.

This was pretty heady stuff for a middle-ranking officer. The suspicions were that Lieutenant Commander Earle was from some service besides just the Navy, most likely one of the intelligence services: the Central Intelligence Agency itself. That didn't really matter at the time. His authorization was real, the mission was a serious one, and the planners had almost nothing to go on at all.

All that Towers could learn from a private conversation with Earle outside the captain's office a short time later was that the information on the escape had come from the POW camp itself. The methods of communication were classified and weren't open for discussion. Earle was a bit surprised that Towers even knew of such techniques, but he had learned of them during a training school he had attended years earlier. The other news that was given was the deadline. The plan for the mission had to be ready for submission and approval by the admiral inside of forty-eight hours.

It was a daunting task, one that Towers realized would take maximum commitment. But the possible rescue of prisoners of war from North Vietnam was something that just about every member of the U.S. military dreamed of in one way or another. It hadn't been very long since the amazing Special Forces raid had been conducted against the POW camp at Son Tay. In spite of a nearly flawless operation, no American prisoners had been found. On this operation, the information had come from the prisoners themselves. All possible aid had to be given to these men without concern for personal sacrifice or cost.

There was a scramble for information by Towers on just what assets would be available for the mission, and just what their capabilities would be. Operational security was paramount. Only a very minimal number of people could know the object of the mission. If anything leaked out to the North Vietnamese, the repercussions to the prisoners could be terrible. There was no question of just how the North Vietnamese treated the prisoners under their control. A few men had been released and in spite of all of the North Vietnamese efforts, some of the truth had come out. Torture was a very real threat; so was death. And there were the intelligence assets in place that had to be protected. Whoever had helped get the information out of North Vietnam would have their lives snuffed out or worse if the Communists even suspected their existence.

They had to have very brave men who would conduct a difficult mission under extreme conditions of danger. For air assets, there were the combat search-and-rescue crews and the helicopters they flew. For even more special assets, it wasn't long before Towers learned about the Navy SEALs, the UDTs, their capabilities, and a very amazing submarine.

The USS
Grayback
(LPSS 574) had begun her life in the 1950s as part of the most important of the United States military assets, the nuclear triad. To defend against an all-out nuclear war, there had to be a guarantee that some nuclear-capable forces would survive even an effective first-strike by the major enemy of the age, the Soviet Union. The bomber force of the Strategic Air Command was one part of the triad of U.S. forces; ballistic missiles were another. But the most effective of the forces, the one most difficult for the enemy to detect, target, and destroy, were the nuclear missile-launching submarines.

The first of the missile-launching submarines employed by the U.S. Navy did not use a vertical firing missile, as is seen so much today. Instead, the first nuclear-armed missiles fielded by the Navy were winged ones. Resembling a rather small jet aircraft, the Regulus guided missile was very close to what is called a cruise missile today. The weapon was carried with its wings folded and had to be assembled for launch. When fired, the more-than-thirty-foot-long missile launched from a cradle with rocket boosters. A turbojet engine would push it and its 3,000-pound nuclear warhead to a range of over fifty miles. The Regulus II missile had even greater capabilities.

It took a very unusual submarine to carry the Regulus weapon. The sub would have to have a deck hangar that could transport the missile in a dry condition and allow it to be removed, prepped, and launched from the deck of that same submarine. The first boats to carry the missile were modified World War II diesel-electric boats. Soon, they were joined by two purpose-built boats, the
Grayback
and the
Growler
.

For her era, the
Grayback
and her sister ship, the
Growler
, were the two largest conventionally propelled submarines in the world. The huge diesel-electric boats were that size for a reason; their bows were made up of two large bulbous hangers. Regulus missiles could be accessed and serviced from inside the submarine while it was underwater. In just under seven minutes, the submarine could surface, launch its missile, and be back underwater to prepare for another launch. From the late 1950s to 1964, the
Grayback
and her fellow submarines patrolled as part of the nuclear deterrent force of the United States.

In the mid-1960s, with the adoption of the Polaris-launching submarines, the
Grayback
and others of her general type were removed from service. The two World War II fleet subs that had the large hangars on their decks became amphibious transport submarines and operated with the Underwater Demolition Teams, U.S. Marines, and Navy SEALs for a number of years. The
Grayback
also underwent refitting to become the first large transport submarine capable of carrying up to sixty-seven men and their equipment, with the facilities to feed and berth the men without difficulty. In particular, the
Grayback
could transport special miniature submersibles, what were known as Swimmer Delivery Vehicles (SDV), in the two bow hangars that had previously carried missiles.

The bow hangars on the
Grayback
were massive structures, each one a cylinder about eleven feet in diameter and sixty-six feet long, large enough to carry a single Regulus II missile. During her refit into a special operations transport, the hangars on the
Grayback
had a major change in their design, when a bulkhead was fitted in each one. Now the hangars each had a dry and a wet side. Personnel could operate in relative comfort on the dry side, preparing and maintaining equipment. The wet side of the hangers could now be flooded while the submarine was under way. The aft end of the wet side could be opened to the sea to release swimmers, rubber boats, or SDVs.