Tag Archives: Broken Arrow

13 February 1950

Convair B-36B-1-CF Peacemaker of the 7th Bombardement Wing. (U.S. Air Force)
Convair B-36B-1-CF Peacemaker, 44-92033, of the 7th Bombardment Wing (Heavy). This bomber is similar to 44-92075. (U.S. Air Force)

13 February 1950: Two Convair B-36B Peacemaker long-range strategic bombers of the 436th Bombardment Squadron (Heavy), 7th Bombardment Wing (Heavy), Strategic Air Command, departed Eielson Air Force Base, Fairbanks, Alaska, at 16:27 Alaska Standard Time, on a planned 24-hour nuclear strike training mission.

B-36B-15-CF 44-92075 was under the command of Captain Harold Leslie Barry, United States Air Force.¹ There were a total of seventeen men on board.

Also on board was a Mark 4 nuclear bomb.

The B-36s were flown to Alaska from Carswell Air Force Base, Fort Worth, Texas, by another crew. The surface temperature at Eielson was -40 °F. (-40 °C.), so cold that if the bomber’s engines were shut down, they could not be restarted. Crews were exchanged and the airplane was serviced prior to takeoff for the training mission. In addition to the flight crew of fifteen, a Bomb Commander and a Weaponeer were aboard.

After departure, 44-92075 began the long climb toward 40,000 feet (12,192 meters). The flight proceeded along the Pacific Coast of North America toward the practice target of San Francisco, California. The weather was poor and the bomber began to accumulate ice on the airframe and propellers.

Convair B-36B-1-CF Peacemaker, 44-92033, of the 7th Bombardment Wing (Heavy). This bomber is similar to 44-92075. (U.S. Air Force)

About seven hours into the mission, three of the six radial engines began to lose power due to intake icing. Then the #1 engine, outboard on the left wing, caught fire and was shut down. A few minutes later, the #2 engine, the center position on the left wing, also caught fire and was shut down. The #3 engine lost power and its propeller was feathered to reduce drag. The bomber was now flying on only three engines, all on the right wing, and was losing altitude. When the #5 engine, center on the right wing, caught fire, the bomber had to be abandoned. It was decided to jettison the atomic bomb into the ocean.

The Mark 4 did not have the plutonium “pit” installed, so a nuclear detonation was not possible. The conventional explosive would go off at a pre-set altitude and destroy the bomb and its components. This was a security measure to prevent a complete bomb from being recovered.

The bomb was released at 9,000 feet (2,743 meters), north-northwest of Princess Royal Island off the northwest coast of British Columbia, Canada. It was fused to detonate 1,400 feet (427 meters) above the surface, and crewmen reported seeing a large explosion.

Flying over Princess Royal Island, Captain Barry ordered the crew to abandon the aircraft. He placed the B-36 on autopilot. Barry was the last man to leave 44-92075. Descending in his parachute, he saw the bomber circle the island once before being lost from sight.

Convair B-36B-1-CF Peacemaker, 44-92033, of the 7th Bombardment Wing (Heavy). This bomber is similar to 44-92075. (U.S. Air Force)

Twelve of the crew survived. Five were missing and it is presumed that they landed in the water. Under the conditions, they could have survived only a short time. The survivors had all been rescued by 16 February.

It was assumed that 44-92075 had gone down in the Pacific Ocean.

Approximate path of B-36B 44-92075, 13 February 1950. (Royal Aviation Museum of British Columbia)

On 20 August 1953, a Royal Canadian Air Force airplane discovered the wreck of the missing B-36 on a mountain on the east side of Kispiox Valley, near the confluence of the Kispiox and Skeena Rivers in northern British Columbia.

The U.S. Air Force made several attempts to reach the crash site, but it wasn’t until August 1954 that they succeeded. After recovering sensitive equipment from the wreckage, the bomber was destroyed by explosives.

Bomb, Mark 4. (Nuclear Weapons Archive)
Bomb, Mark 4. (Nuclear Weapons Archive)

The Mark 4 bomb was designed by the Los Alamos National Laboratory (LANL). It was a development of the World War II implosion-type Mark 3 “Fat Man.” The bomb was 10 feet, 8 inches (3.351 meters) long with a maximum diameter of 5 feet, 0 inches (1.524 meters). Its weight is estimated at 10,800–10,900 pounds (4,899–4,944 kilograms).

The core of the bomb was a spherical composite of plutonium and highly-enriched uranium. This was surrounded by approximately 5,500 pounds (2,495 kilograms) of high explosive “lenses”—very complex shaped charges designed to focus the explosive force inward in a very precise manner. When detonated, the high explosive “imploded” the core, crushing it into a smaller, much more dense mass. This achieved a “critical mass” and a fission chain reaction resulted.

The Mark 4 was tested during Operation Ranger at the Nevada Test Site, Frenchman Flat, Nevada, between 27 January and 6 February 1951. Five bombs were dropped from a Boeing B-50 Superfortress of the 4925th Special Weapons Group from Kirtland Air Force Base in New Mexico. The first four bombs were dropped from a height of 19,700 feet (6,005 meters) above ground level (AGL) and detonated at 1,060–1,100 feet (323–335 meters) AGL. Shot Fox was dropped from 29,700 feet (9,053 meters) AGL and detonated at 1,435 feet (437 meters) AGL. (Ground level at Frenchman Flat is 3,140 feet (957 meters) above Sea Level).

Operation Ranger, Shot Able, 5:45 a.m., 27 January 1951. Mark 4 bomb with Type D pit, 1,060 foot (323 meters) air burst. Yield, 1 kiloton. This was the first nuclear test in the continental United States since Trinity, 16 July 1945.

The Mark 4 was produced with explosive yields ranging from 1 to 31 kilotons. 550 were built.

Convair B-36B-15-CF Peacemaker 44-92075 was completed at Fort Worth, Texas, on 31 July 1949. It had been flown a total of 185 hours, 25 minutes.

The B-36B is 162 feet, 1 inch (49.403 meters) long with a wingspan of 230 feet (70.104 meters) and overall height of 46 feet, 8 inches (14.224 meters). The empty weight is 140,640 pounds (63,793 kilograms) and the maximum takeoff weight was 311,000 pounds (141,067 kilograms).

With a wing area of 4,772 square feet (443 square meters) and 21,000 horsepower, the B-36 could fly far higher than any jet fighter of the early 1950s.

A Pratt & Whitney R-4360-41 Wasp Major aircraft engine on display at the National Museum of the United States Air Force. This engine weighs 3,404 pounds (1,544 kilograms). Wikipedia
A Pratt & Whitney Wasp Major B4 (R-4360-41) aircraft engine on display at the National Museum of the United States Air Force. This engine is 9 feet, 1¾-inch (2.788 meters) long and 4 feet, 6 inches (1.372 meters) in diameter. It weighs 3,567 pounds (1,618 kilograms). Wikipedia

The B-36B was powered by six air-cooled, supercharged and turbocharged 4,362.49 cubic-inch-displacement (71.488 liter) Pratt & Whitney Wasp Major B4 (R-4360-41) four-row, 28-cylinder radial engines placed inside the wings in a pusher configuration. These had a compression ratio of 6.7:1 and required 115/145 aviation gasoline. The R-4360-41 had a Normal Power rating of 2,650 horsepower at 2,550 r.p.m. Its Takeoff/Military Power rating was 3,500 horsepower at 2,700 r.p.m., with water injection. The engines turned three-bladed Curtiss Electric constant-speed, reversible propellers with a diameter of 19 feet, 0 inches (5.791 meters) through a 0.375:1 gear reduction. The R-4360-41 is 9 feet, 1.75 inches (2.788 meters) long, 4 feet, 6.00 inches (1.372 meters) in diameter, and weighs 3,567 pounds (1,618 kilograms).

The B-36B Peacemaker had a cruise speed of 202 miles per hour (325 kilometers per hour) and a maximum speed of 381 miles per hour (673 kilometers per hour) at 34,500 feet (10,516 meters). The service ceiling was 42,500 feet (12,954 meters) and its combat radius was 3,740 miles (6,019 kilometers). The maximum range was 8,175 miles (13,156 kilometers).

The B-36 was defended by sixteen M24A-1 20 mm automatic cannons. Six retractable gun turrets each each had a pair of 20 mm cannon, with 600 rounds of ammunition per gun. These turrets were remotely operated by gunners using optical sights. Two optically-sighted 20 mm guns were in the nose, and two more were in a tail turret, also remotely operated and aimed by radar.

In this photograph, two of the B-36's retractable gun turrets are visibile behind the cockpit, as well as the nose gun turret. (Unattributed)
In this photograph, two of the B-36’s retractable gun turrets are visible behind the cockpit, as well as the nose gun turret. The plexiglas “blister” just ahead and below the dorsal turrets is a gunner’s sighting station. The bomb bay doors are open. (Unattributed)

The B-36 was designed during World War II and nuclear weapons were unknown to the Consolidate-Vultee Aircraft Corporation engineers. The bomber was built to carry up to 86,000 pounds (39,009 kilograms) of conventional bombs in the four-section bomb bay. It could carry the 43,600 pound (19,777 kilogram) T-12 Cloudmaker, a conventional explosive earth-penetrating bomb. When armed with nuclear weapons, the B-36 could carry several Mk.15 thermonuclear bombs. By combining the bomb bays, one Mk.17 25-megaton thermonuclear bomb could be carried.

Between 1946 and 1954, 384 B-36 Peacemakers were built by Convair. 73 of these were B-36Bs, the last of which were delivered to the Air Force in September 1950. By 1952, 64 B-36Bs had been upgraded to B-36Ds.

They were never used in combat. Only four still exist.

[Trivia enthusiasts might note that the U.S. military code for a lost nuclear weapon is “Broken Arrow.” In 1950, Academy Award-winning actor Jimmy Stewart, himself a Brigadier General, U.S. Air Force Reserve, and highly decorated World War II bomber commander, starred in the Delmer Daves western movie, “Broken Arrow.” In 1954, Stewart starred as a B-36 aircraft commander in Anthony Mann’s “Strategic Air Command.” Coincidence?]

¹ Captain Barry was killed along with other 11 crewmen, 27 April 1951, when the B-36D-25-CF on which he was acting as co-pilot, 49-2658, crashed following a mid-air collision with a North American F-51-25-NT Mustang, 44-84973, 50 miles (80 kilometers) northeast of Oklahoma, City, Oklahoma, U.S.A. The Mustang’s pilot was also killed.

© 2018, Bryan R. Swopes

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5 February 1958

Boeing B-47E-55-BE Stratojet 51-2394, similar in appearance to Ivory Two. Photographed 7 April 1956. (U.S. Air Force)

On the night of 4–5 February 1958, two Boeing B-47 Stratojet bombers from MacDill Air Force Base, Florida, were flying a simulated bombing mission. The second bomber, B-47B-50-BW serial number 51-2349, was under the commander of Major Howard Richardson, USAF, with co-pilot 1st Lieutenant Bob Lagerstrom and radar navigator Captain Leland Woolard. Their call sign was “Ivory Two.”

Aircrew of B-47, left to right, Major Howard Richardson, Bob Lagerstrom and Leland Woolard. (U.S. Air Force)

Carried in the bomb bay of Ivory Two was a 7,600-pound (3,448 kilogram) Mark 15 Mod. 0 two-stage radiation-implosion thermonuclear bomb, serial number 47782. The bomb had an explosive yield of 1.69–3.8 megatons.

Bomb, Thermonuclear, Mark 15.
Bomb, Thermonuclear, Mark 15. (Nuclear Weapons Archive)

After completing their simulated bombing mission, the B-47s were returning to their base in Florida.

On the same night pilots of South Carolina Air National Guard were on alert at Charleston Air Force Base with their North American Aviation F-86L Sabre interceptors. The fighters were fully armed with twenty-four 2.75-inch (70 mm) rockets. At 00:09 a.m., the pilots were alerted for a training interception of the southbound B-47s. Within five minutes three F-86Ls were airborne and climbing, with air defense radar sites directing them. In of of the F-86Ls, 52-10108, an upgraded F-86D Sabre, was 1st Lieutenant Clarence A. Stewart, call sign “Pug Gold Two.”

The flight of interceptors came in behind the bombers at about 35,000 feet (10,668 meters). Tracking their targets with radar, they closed on the lead B-47, Ivory One, from behind. Ivory Two was about 1 mile (1.6 kilometers) in trail of Ivory One, but the airborne radars of the Sabres did not detect it, nor did the ground-based radar controllers.

This North American Aviation F-86L-60-NA Sabre, 53-1047, of the 444th Fighter Interceptor Squadron, Charleston, South Carolina, is similar to 1st Lieutenant Clarence A. Stewart's F-86L-50-NA 52-10108, destroyed in the collision with the B-47, 5 February 1958. (U.S. Air Force)
This North American Aviation F-86L-60-NA Sabre, 53-1047, of the 444th Fighter Interceptor Squadron, Charleston Air Force Base, South Carolina, is similar to 1st Lieutenant Clarence A. Stewart’s F-86L-50-NA 52-10108, which was destroyed in the collision with the B-47, 5 February 1958. (U.S. Air Force)

At 00:33:30, 5 February, Lieutenant Stewart’s fighter collided with the left wing of Major Richardson’s bomber. The Sabre lost both wings. Lieutenant Stewart fired his ejection seat. His descent from the stratosphere took twenty-two minutes and his hands were frostbitten from the cold. He spent five weeks in an Air Force hospital. Pug Gold Two crashed in a farm field about 10 miles (16 kilometers) east of Sylvania, Georgia.

Damage to the left wing and aft fuselage of B-47B 51-2349. (U.S. Air Force)

The B-47 was heavily damaged. The outboard engine had been dislodged from its mount on the wing and hung at about a 45° angle. The wing’s main spar was broken, the aileron was damaged, and the airplane and its crew were in immediate jeopardy. If the number six engine fell free, the loss of it’s weight would upset the airplane’s delicate balance and cause it to go out of control. The damaged wing might itself fail, and the damage to the flight controls made it difficult to fly.

Damage to the left wing of B-47B 51-2349. (U.S. Air Force)

Major Richardson didn’t think they could make it back to MacDill, and the nearest suitable airfield, Hunter Air Force Base, Savannah, Georgia, advised that the main runway was under repair. A crash on landing was a likely outcome.

Damage to the aft fuselage and vertical fin of B-47B 51-2349. (U.S. Air Force)

With this in mind, Richardson flew Ivory Two out over Wassaw Sound, and at an altitude of 7,200 feet (2,195 meters) the hydrogen bomb was jettisoned. It landed in about 40 feet (12 meters) of water near Tybee Island. No explosion occurred.

The B-47 safely landed at Hunter AFB, but was so badly damaged that it never flew again. Major Richardson was awarded the Distinguished Flying Cross for his handling of the incident.

The missing Mark 15 has never been found and is considered to be “irretrievably lost.” It is known as “The Tybee Bomb.”

Boeing B-47B-50-BW 51-2348, sister ship of Ivory Two. (U.S. Air Force)

Designed by Boeing, the Stratojet was a high-subsonic-speed strategic bomber and reconnaissance aircraft, in service from 1951 until 1977. The B-47 could fly higher and faster than jet fighters of the time, and it was also highly maneuverable. The B-47 was flown by a two pilots in a tandem cockpit. A navigator/bombardier was at a station in the nose.

The Boeing B-47B Stratojet was the first full-production model. The B-47B is 106 feet, 10 inches (32.563 meters) long with a wingspan of 116 feet , 0 inches(35.357 meters), and an overall height of 27 feet, 11 inches (8.509 meters). The wings are shoulder-mounted with the leading edges swept at 35°. The B-47B has an empty weight of 78,102 pounds (35,426 kilograms), and a gross weight of 184,908 pounds (83,873 kilograms). The maximum takeoff weight was 200,000 pounds (90,718 kilograms).

From 1953 to 1957, the B-47B fleet underwent an extensive modification program which brought them up to the B-47E configuration.

A Boeing B-47B-40-BW Stratojet 51-2212 of the 306th Bombardment Wing (Medium) rolling out after landing at MacDill AFB, Florida. This airplane is similar to B-47B 51-2349, Ivory Two. (U.S. Air Force)

The B-47B was originally powered by six General Electric J47-GE-11 turbojet engines in four nacelles mounted on pylons below the wings. All B-47Bs after serial number 51-2046 were equipped with J47-GE-23 engines. The airplanes built with the -11 engines were retroffitted with the -23s. Under the modification and upgrade program, the -23s were replaced by the J47-GE-25. This engine has a 12-stage axial-flow compressor, eight combustion chambers, and single-stage turbine. The J47-GE-25 is rated at 5,970 pounds of static thrust at Sea Level, at 7,950 r.p.m. and 1,250 °F. (677 °C.) turbine outlet temperature (TOT). (7,200 pounds of thrust with water injection). It has a maximum diameter of 3 feet, 1 inch (0.940 meters) and length of 12 feet, 0 inches (3.658 meters) and weighs 2,653 pounds (1,203 kilograms).

The B-47B Stratojet had a cruise speed of 498 miles per hour (801 kilometers per hour), and maximum speed of 608 miles per hour (978 kilometers per hour) at 16,300 feet (4,968 meters) and 565 miles per hour (909 kilometers per hour) at 35,000 feet (10,668 meters). The service ceiling was 33,900 feet (10,333 meters) and combat ceiling 40,800 feet (12,436 meters).

The combat radius of the B-47B was 1,965 miles (3,162 kilometers with a 10,000 pound (4,536 kilograms) bomb load. Two jettisonable underwing fuel tanks could carry 1,780 gallons (6,738 liters) each. The maximum ferry range was 4,444 miles (7,152 kilometers).

For defense the B-47B was armed with two Browning AN-M3 .50-caliber machine guns in a remotely-operated tail turret. The co-pilot acted as the gunner using an optical sight. The machine guns were replaced by two M24A1 20 mm autocannons and radar control.

The maximum bomb load of the B-47B was 18,000 pounds (8,165 kilograms). The B-47 could carry two 7,600 pound (3,447 kilogram) Mark 15 two-stage radiation implosion thermonuclear bombs, each with an explosive yield of 3.8 megatons, or a single 10,670 pound (4,808 kilogram) B-41 three-stage, 25 megaton bomb.

Beginning in 1953, the B-47B fleet underwent an extensive modification program which brought them up to the B-47E configuration.

A total of 2,032 B-47s were built by a consortium of aircraft manufacturers: Boeing Airplane Company, Wichita, Kansas; Douglas Aircraft Company, Tulsa, Oklahoma; Lockheed Aircraft Company, Marietta, Georgia. 399 of these were B-47Bs.

The Stratojet is one of the most influential aircraft designs of all time and its legacy can be seen in almost every jet airliner built since the 1950s: the swept wing with engines suspended below and ahead on pylons. The B-47 served the United States Air Force from 1951 to 1977. From the first flight of the Boeing XB-47 Stratojet prototype, 17 December 1947, to the final flight of B-47E 52-166, was 38 years, 6 months, 1 day.

© 2018, Bryan R. Swopes

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24 January 1961

Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0187. The numeral "3" on the vertical fin and the white cross-in-back square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)
Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0187. The numeral “3” on the vertical fin and the white cross-in-back square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)

24 January 1961: “Keep 19,” a Boeing B-52G-95-BW Stratofortress, serial number 58-0187, of the 4241st Strategic Wing, was on a 24 hour airborne alert mission off the Atlantic Coast of the United States. The bomber was commanded by Major Walter S. Tulloch, U.S. Air Force, with pilots Captain Richard W. Hardin and First Lieutenant Adam C. Mattocks. Other crewmembers were Major Eugene Shelton, Radar Navigator; Captain Paul E. Brown, Navigator; First Lieutenant William H. Wilson, Electronics Warfare Officer; Major Eugene H Richards, Electronics Warfare Instructor; Technical Sergeant Francis R. Barnish, Gunner. It was armed with two Mark 39 thermonuclear bombs, each with an explosive yield of 3–4 megatons.

The B-52 refueled in flight from an air tanker. The tanker’s crew notified Major Tulloch that the B-52’s right wing was leaking fuel. The leak was severe and more than 5,400 gallons (37,000 pounds/17,000 kilograms) of jet fuel was lost in less than three minutes. The B-52 headed for Seymour Johnson Air Force Base in North Carolina.

Boeing B-52G-95-BW Stratofortress 58-0190, the same type as Keep 19. (U.S. Air Force)

As they descended, the unbalanced condition made the bomber increasingly difficult to control. The bomber went out of control and Major Tulloch ordered the crew to abandon the doomed ship. Five crewmen ejected and one climbed out through the top hatch. (Lieutenant Mattocks is believed to be the only B-52 crewmember to have successfully escaped through the upper hatch.)

58-0187 broke apart and exploded. Its wreckage covered a two square mile (5.2 square kilometers) area. Three crewmen, Majors Shelton and Richards, and Sergeant Barnish, were killed.

As the B-52 broke up, its two Mark 39 bombs fell free of the bomb bay. One buried itself more than 180 feet (55 meters) deep. The other’s parachute retarding system operated properly and it touched down essentially undamaged. It was quickly safed by an explosive ordnance team and hauled away.

 

One of teh two Mk 39 bombs that fell from the B-52 as it broke up near Goldsboro, South Carolina, 24 January 1961.
One of the two Mk 39 bombs that fell from the B-52 as it broke up near Goldsboro, North Carolina, 24 January 1961. The parachute retarding  system had deployed, allowing the bomb to touch down with minimal damage.

Recovery of the buried bomb was very difficult. After eight days, the ordnance team had recovered most of the bomb, including the 92 detonators and conventional explosive “lenses” of the “primary,” the first stage implosion section. The uranium-235/plutonium-239 “pit”—the very core of the bomb— was recovered on 29 January. The “secondary,” however, was never found.

Most of the Mark 39 bomb was uncovered from an excavation at the farm field near Goldsboro, North Carolina. (U.S. Air Force)

The secondary contains the fusion fuel, but it cannot detonate without the explosion of the primary. Although the secondary remains buried, there is no danger of an explosion.

“During a B-52 airborne alert mission structural failure of the right wing resulted in two weapons separating from the aircraft during aircraft breakup at 2,000 – 10,000 feet altitude. One bomb parachute deployed and the weapon received little impact damage. The other bomb fell free and broke apart upon impact. No explosion occurred. Five of the eight crew members survived. A portion of one weapon, containing uranium, could not be recovered despite excavation in the waterlogged farmland to a depth of 50 feet. The Air Force subsequently purchased an easement requiring permission for anyone to dig there. There is no detectable radiation and no hazard in the area.”

An accident of this type, involving the loss of nuclear weapons is known by the military code name BROKEN ARROW. Though official statements were that there was no danger that either of the bombs could have exploded, others indicate that five of the six steps (or six of seven) required for a thermonuclear detonation did occur. Only the aircraft commander’s arming switch had not been activated.

Bomb, Mark 39Y1 Mod 2, P/N 300611-00, serial number 4215, at the National Museum of the United States Air Force. Behind it is a Convair B-36 Peacemaker ten-engine strategic bomber. (U.S. Air Force)

The Mark 39 was a two-stage, radiation-implosion thermonuclear bomb. It was in production from 1957–1959, with more than 700 built. It was fully fused, meaning it could be detonated by contact with the ground, as an air burst, or “lay down”— a series of parachutes would slow the bomb and it would touch down on its target before detonating. This allowed the bomber time to get clear.

The Mark 39 was considered a light weight weapon, weighing 6,500–6,750 pounds (2,950–3,060 kilograms). The bomb’s length was approximately 11 feet, 8 inches (3.556 meters), with a diameter of 2 feet, 11 inches (0.889 meters). The explosive yield of the Mark 39 was 3–4 megatons. (For reference, the 1956 nuclear weapons test at Bikini Atoll, Redwing Cherokee, had a yield of 3.8 megatons.)

Fireball from detonation of TX-15 weapon, Operation Redwing Cherokee, 21 May 1956. (Nuclear Weapons Archive)

The Mark 39 was withdrawn from service in the mid-1960s and replaced with the more powerful Mk 41.

© 2018, Bryan R. Swopes

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21 January 1968

Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0188. The numeral "3" on the vertical fin and the white cross-in-back square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)
Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0188. The numeral “3” on the vertical fin and the white cross-in-black square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)

21 January 1968: A United States Air Force Boeing B-52G-100-BW Stratofortress, serial number 58-0188, assigned to the 380th Strategic Aerospace Wing, was flying an Airborne Nuclear Alert mission as part of Operation Chrome Dome. The bomber, call sign Hobo 28, had a crew of seven and was armed with four B28FI nuclear bombs carried in its bomb bay.

Prior to takeoff, the third pilot, Major Alfred D’Mario, had placed three foam cushions under the navigator’s seat on the lower deck of the B-52. During the flight the crew cabin became very cold and additional heat was directed into the heating ducts from an engine’s bleed air system. Due to a malfunction, the bleed air was not cooled before entering the heating system and this very hot air ignited the cushions. Very quickly a fire developed.

Boeing B-52G-100-BW Stratofortress 58-0190, the same type as Hobo 28. (U.S. Air Force)

At 12:22 p.m., Atlantic Standard Time (16:22 UTC), the aircraft commander, Captain John Haug, declared an emergency and requested an immediate landing at Thule Air Base, Greenland, which was about 90 miles (140 kilometers) to the north. The crew’s fire extinguishers were quickly depleted and the fire continued to spread. The bomber’s electrical system failed and the cabin filled with smoke. Captain Haug ordered the crew to abandon the aircraft at 16:37 UTC.

Hobo 28 passed directly over the air base and six of the seven crewmen ejected. The co-pilot, Captain Leonard Svitenko, who was temporarily in a jump seat on the lower deck rather than in an ejection seat, tried to jump from an open hatch on the lower deck. He struck his head and was killed.

Captain Haug and Major D’Mario landed on the air base, and three others were very close by. The sixth, gunner Staff Sergeant Calvin Snapp was 6 miles (9.7 kilometers) south on an ice floe, and was rescued 21 hours later.

Concentric cracks in the sea ice at the upper center of this photographic mosaic show the impact point of Hobo 28. The aircraft burned for several hours, covering the ice downwind with soot. (U.S. Air Force)

The B-52, now unmanned, continued north and then began a 180° turn to the left. It crashed onto the sea ice of North Star Bay, about 7.5 miles (12 kilometers) west of Thule.

The conventional explosives inside the four B28 bombs detonated on impact. No nuclear detonation occurred but radioactive plutonium, uranium and tritium was scattered over a wide area.

Hobo 28’s gunner, Staff Sergeant Calvin Waldrep Snapp, was rescued 21 hours later. (U.S. Air Force)

A massive cleanup effort was required. Under the circumstances, this was much more difficult than at Palomares, Spain, two years earlier.

As a result of these two nuclear accidents, referred to by the code words “Broken Arrow,” Operation Chrome Dome, which had kept armed B-52s in the air 24 hours a day since 1961, was ended.

Thule Air Base, Greenland. Mount Dundas is the flat-topped mountain just right of the center of the image. Saunders Island is in the distance. Hobo 28 crashed into North Star Bay, covered with sea ice in this photograph.
Thule Air Base, Greenland. Mount Dundas is the flat-topped mountain just right of the center of the image. Saunders Island is at the upper left. Hobo 28 crashed into North Star Bay, covered with sea ice in this photograph.

The Mark 28 was a two-stage radiation-implosion thermonuclear bomb which was designed by the Los Alamos National Laboratory and produced from January 1958 to May 1966. In 1968, it was redesignated B-28. More than 4,500 were manufactured in as many as 20 variants. Explosive yield varied between 70 kilotons and 1.45 megatons. The bomb remained in service until 1991.

Three airmen position a B28Y1 1.1 megaton thermonuclear bomb for loading aboard a B-52 Stratofortress. (U.S. Air Force)

© 2018, Bryan R. Swopes

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17 January 1966

Boeing KC-135A-BN Stratotanker 58-0004 refuels Boeing B-52G-75-BW Stratofortress 57-6741. These are the same type aircraft that were involved in the 1966 Palomares Incident. (Boeing)

17 January 1966: A United States Air Force Boeing B-52G-115-BW Stratofortress, 58-0256, and its 7-man crew, along with a second B-52, were flying an Airborne Nuclear Alert patrol over the Mediterranean Sea. The bomber, call sign “Tea 16,” was armed with four Mark 28 nuclear bombs carried in its bomb bay.

At approximately 10:30 a.m., the two B-52s rendezvoused with two Boeing KC-135A-BN Stratotankers, based at Morón Air Base, Spain, for the second aerial refueling of the mission. The aircraft were at 31,000 feet (9,448 meters) off the southern coast of Spain.

Major Larry G. Messinger, a veteran of World War II, aboard as a relief pilot, was flying Tea 16 from the left seat. The aircraft commander, Captain Charles J. Wendorf, was in the right, co-pilot’s seat, while 1st Lieutenant Richard J. Rooney, the assigned co-pilot, rode in a jump seat behind them.

Major Messinger later said, “We came in behind the tanker, and we were a little bit fast, and we started to overrun him a little bit. . . .”

A boom operator’s view as a B-52 Stratofortress refuels. (John E. Considine/NASM)

B-52G 58-0256 collided with the refueling boom of “Troubadour 14” (KC-135A 61-0273). The boom penetrated the bomber’s fuselage, broke structural members and the left wing broke off. The B-52 exploded. The fully-loaded tanker, on fire, went into a steep dive. At 1,600 feet (488 meters), it also exploded.

The four crewmen aboard the tanker were killed. Three of the seven men on the B-52 ejected, and the co-pilot, who was not in an ejection seat, literally fell out of the disintegrating bomber. The navigator’s parachute did not open and he was killed. Three others were unable to escape the doomed airplane and were also killed.

Wreckage of B-52G 58-0256 at Palomares, Spain, January 1966. (Kit Talbot/The New York Times)

As the B-52 broke apart, the four nuclear bombs it carried in the bomb bay fell free. Three of them fell near the fishing village of Palomares. In two of these, the conventional explosives that “implode” the plutonium to start a chain reaction, detonated on impact, but a nuclear explosion did not occur. However, plutonium was scattered over the area. The third bomb was recovered intact, though it was slightly damaged. The retarding parachute of the fourth Mark 28 opened and it was carried offshore by the wind and fell into the Mediterranean Sea.

A massive recovery operation took place. The fourth bomb was recovered after five months. It had come to rest in an underwater canyon at a depth of 2,550 feet (777 meters).

1,400 tons of soil was packed into more than 6,000 steel drums and taken to the United States.
1,400 tons of soil was packed into more than 6,000 steel drums and taken to the United States.

558 acres (226 hectares) of land in and around Palomares was contaminated. The soil was removed and placed in steel barrels for transportation to the United States for burial at the Savannah River Plant, a nuclear reservation in South Carolina.

Three airmen position a B28Y1 1.1 megaton thermonuclear bomb for loading aboard a B-52 Stratofortress. (U.S. Air Force)
Three airmen position a B28-Y1 thermonuclear bomb for loading aboard a B-52 Stratofortress. (TSgt. Boyd Belcher, U.S. Air Force)

The Mark 28 was a two-stage radiation-implosion thermonuclear bomb which was designed by the Los Alamos National Laboratory and produced from January 1958 to May 1966. In 1968, it was redesignated B-28. More than 4,500 were manufactured in as many as 20 variants. Explosive yield varied between 70 kilotons and 1.45 megatons. The B-28-Y1 in the photograph above is a 1.1 megaton weapon. The bomb remained in service until 1991.

© 2016, Bryan R. Swopes

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