Disengaging the locking pin in the bomb bay was not easy. It was above the bomb, which was a hulking five feet in diameter, and there was not really any place to stand in the cramped space as the plane bounced around in the sun-baked turbulence at Kirtland. The co-observer found it by feel and jerked it out, but he lost his balance and grabbed for something. His hand found the bomb-release cable.
Instantly, the 42,000-pound MK-17 cleared the plane, taking the bomb bay doors with it. It hit the ground hard, detonating all of the primary high explosive, making a 25-foot-wide crater, and throwing shrapnel as far as a mile from the impact point. The largest piece found weighed 800 pounds, a half mile away.
Four more bombs were lost in quick succession. Two were dropped into the Atlantic Ocean, and two were burned up when B-47s blew out tires trying to take off, but on February 5, 1958, there occurred an odd incident. It happened off Tybee Island, near Savannah, Georgia.
Tybee has long been an interesting place, populated at various times by pirates, Spanish colonists, Yankee siege batteries, General George C. Marshall, tourists, hangers-on, and the world’s first Days Inn. It has one of the last remaining 18th-century lighthouses which, when first built in 1736, was the highest man-made structure in America. It has been blown down and rebuilt several times, but the bottom 60 feet of the current building was erected in 1773. At 3:00 a.m. on Wednesday, February 5, 1958, Tybee Island was mostly asleep.
Major Howard Richardson, First Lieutenant Robert J. Lagerstrom, and Captain Leland W. Woolard left the ground at 2151 Zulu from Homestead Air Force Base, Florida, in a B-47 for a Unit Simulated Combat Mission (USCM), looping them up to Radford, Virginia, and back down to Homestead.[202] The bomber was loaded with an MK-15 mod 0 thermonuclear weapon, serial number 47782, having a dummy (lead) type 150 nuclear capsule installed. Burdened with the 7,600-pound dead weight, the B-47 made a decent approximation of a Soviet bomber trying to unload over the Savannah River Project (SRP), a secret plutonium production facility in Aiken, South Carolina. Code name for the flight was Ivory 2.[203]
A pair of F-86L Sabre interceptors, Pug Silver Flight and Pug Gold 2, were scrambled to find two B-47s and give them simulated grief.[204] Ivory 2 did a simulated bombs-away over SRP at 0455 Zulu, then banked into a 200-degree turn and headed for his check-point at Charlotte, North Carolina. Pug Gold 2, one of the interceptors, caught up with Ivory 2 as directed by the ground-based radar system, but the radar-return signal was weak and the position of the target was not well defined. The pilot, First Lieutenant Clarence Arville Stewart, keyed his microphone and called “twenty seconds,” indicating the impact time of his simulated rocket attack.[205] After 34 seconds of silence, his microphone keyed again without a voice signal. His F-86L had just collided with the B-47 as he ducked down in the cockpit, jammed the control stick forward, and accidentally hit the microphone switch. It was 0533 Zulu, or 12:33 a.m. With no remaining control of the aircraft, the pilot bailed out and watched his broken F-86L spiral out into the Atlantic Ocean.
The crew of Ivory 2 felt a severe yaw to the left and saw and felt a blinding explosion off the right wingtip. Number six engine was suddenly pointed up at 45 degrees and running out of control. Nothing would stop it until Richardson pulled the number six fire extinguisher and choked out the burners. The pilots started calling mayday while they executed a slow left turn and a descent. They noticed that the right wing tank was missing, and they jettisoned the left tank for the sake of symmetry, first noting no lights on the ground that would indicate civilization.
The heavily damaged bomber was given permission for an emergency landing at the closest field, Hunter Air Force Base in Savannah. They were in worse shape than they had thought, and the bomber came in too fast and too high to land. They had too much weight on board to make an emergency landing with the damaged wing. They decided, with permission, to take the MK-15 out over the water and lose it. They made a left turn to the east, out over Wassaw Sound off the shore of Tybee Island, and then released the bomb from 7,300 feet. There was no explosion when it hit the water 22 seconds later. Just a splash. The newly formulated implosion explosives, made insensitive to shock-detonation, performed correctly when it hit the water by not going off. The crippled B-47 and its crew made it back to Hunter and landed without catching fire, and Stewart and his parachute were recovered unscathed on the ground.
There remained a loose end. Somewhere out there was an MK-15 mod 0 thermonuclear weapon with a fake pit installed. The impact point was hard to pin down, as there was no usable radar scope recording made when the bomb was released, but it was near the coast, off Tybee Island. The U.S. Navy was given priority for the recovery operation, with the USAF Explosive Ordnance Detachment (EOD) acting as liaison at the scene. The EOD coordinated a search of the beaches for any bomb debris and an underwater visual search with hand-held sonar gear. The Navy brought in a submarine rescue ship, two minesweepers with high-resolution sonar, a Coast Guard cutter, a troop transport, a 1,000-ton barge, two 15-foot motorboats, a catamaran, two Higgins landing craft, and a helicopter. In the close confines of Wassaw Sound, the fact that no watercraft crashed into each other speaks well for the seamanship involved.
The search was called off on April 16, 1958, without any leads as to where the MK-15 could be. Since it was not a complete bomb with capsule, it was not worth further effort, and so the search was abandoned.[206] As far as the Air Force was concerned, the bomb had been swallowed by the mud at the bottom of the sound, and it was probably buried for good under 15 feet of silt by this point.
Nevertheless, the search for the missing MK-15 has continued sporadically over the past 50 years, mostly by amateur treasure hunters. In 2004, retired Air Force Colonel Derek Duke claimed to have narrowed the search down to a small area by towing a Geiger counter behind a motorboat and mapping the radioactivity over a patch of water. The Air Force came out to investigate and left disappointed.[207]
A little over a month after the bomb was jettisoned off Tybee, another B-47 was forced to drop their bomb. This time it was over Florence, South Carolina, in what became known as the Mars Bluff Incident. Unlike events happening out over the ocean, on Air Force property, or in remote mountain ranges, the public relations aspect of this Broken Arrow would prove challenging. The bomb was dropped on an American family, and the voting public would be smacked right in the face by the remote, abstract, and carefully hidden world of nuclear warfare.
It all started on March 11, 1958, 3:53 P.M. at Hunter Air Force Base, when a B-47E manned by Captain Koehler, the pilot, Woodruff, copilot, and Bruce Kulka, the bombardier, left the ground, headed for England on a training mission named Operation Snow Flurry. They had on board an MK-6 atomic bomb with a 30-kiloton yield. It was a practice exercise, so the nuclear capsule was not installed. In case of a sudden war breakout, the manually insertable capsule would be stored on board in its birdcage.[208]
202
“2151 Zulu” is armed forces lingo meaning 2151 Coordinated Universal Time, or the time at Greenwich, England, in 24-hour notation. The local time was five hours earlier, or 9:51 P.M.
203
204
The F-86L was a special modification of the F-86D, equipped with electronic equipment linking it to the Semi-Automatic Ground Environment (SAGE) system. SAGE was a computer network of ground-based early warning and air-surveillance radars, built in the late 1950s to provide interceptor planes with real-time data for heading, speed, altitude, target bearing, and range of intrusive aircraft. L-modifications included an AN/ARR-39 datalink receiver and an AN/APX-25 identification radar. The directions from SAGE were uploaded into the interceptor’s E-4 fire control system, automatically pointing the plane at the target, which in this case was a B-47. The SAGE system, which was vacuum-tube-based, was way ahead of its time. The purpose of this USCM,
205
Rockets carried by the F-86L were the MK 4 FFAR, or the “Mighty Mouse,” an unguided, inadequately spin-stabilized weapon with a 6-pound warhead. The only way you could hit something as small as a six-engine strategic bomber with a Mighty Mouse was to be very close to it, which is what caused this mid-air collision. Live testing of Mighty Mice in California caused massive brush fires and destroyed a lot of private property, as they would diverge from the aiming point and find their own targets.
206
Assistant Secretary of Defense W. J. Howard stated in a 1966 congressional investigation that the Tybee Island bomb was a complete weapon, with the 150 capsule installed. The source of his statement is not clear. At the time of the loss, it was Air Force policy not to fly training or test missions simulating combat with the capsule on board, and the receipt signed by Major Richardson mentions no capsule.
207
There is an ongoing misconception about nuclear weapons. Many assume that such a device can be detected at a distance using a radiation-measuring instrument, such as a Geiger-Mueller counter. While it is true that uranium and plutonium give off gamma rays, these emissions are weak and are almost completely shielded from outside detection by the substantial metal bomb-case and the thick layers of chemical explosive that surround the nuclear components. The fusion materials in a thermonuclear weapon, lithium-6 and deuterium, are not radioactive at all. Even if the bomb had contained the plutonium capsule and if the case had corroded away, a couple of feet of water shielding would make it invisible to any type of radiation counter. It is true that the remaining bomb mechanism included a uranium tamper, which is radioactive, but the radiation in Wassaw Sound, often reported, is actually due to monazite sand on the bottom, composed of radioactive thorium oxide.
208
Most accounts of the Mars Bluff Incident refer to the bomb as an MK-6, although the bomb-type is blacked out on released government documents. This does not agree with