The problem with the Mark 28 was more significant than the safety flaws in other weapons. Mark 28 bombs were routinely carried by B-52 bombers on ground alert. And those B-52s sometimes caught on fire, even when they never left the ground. The bomber carried more than 300,000 pounds of highly flammable JP-4 jet fuel, a mix of gasoline and kerosene. In preparation for a typical B-52 flight, the crew would spend at least an hour in the plane, going through checklists, before starting the engines — and then the engines would be started one after another, until all eight were running. It could take an hour and a half for the pilot to get a B-52 into the air. But planes on ground alert were expected to be airborne within ten or fifteen minutes, the maximum time available for a “base escape.” Explosive cartridges on the four engine pods would be detonated by the copilot, as soon as he climbed into the plane, spinning the turbines rapidly and starting all eight engines in about a minute. A “cartridge start” was a memorable sight — a series of small explosions, B-52s filling the runway with clouds of smoke — and crews on ground alert practiced it regularly. And yet it could also start a fire.
The combination of Mark 28 bombs and B-52 bombers on alert was increasingly dangerous. Peurifoy doubted it was worth the risk. Both were aging weapon systems; many of the B-52s were older than their pilots. And most of the planes would probably never reach their targets, let alone return safely from a mission. After a 1975 briefing on the role of the Strategic Air Command’s bombers in executing the SIOP, the head of the CIA, William Colby, expressed surprise that “our B-52s are planned for one-way missions.” Once an emergency war order was transmitted, the bombers on ground alert would quickly take off from their bases in the United States, fly eight to ten hours toward Soviet targets — and find what? The Soviet Union would have already been hit by thousands of warheads delivered by American missiles. Targets that hadn’t been destroyed were likely to be surrounded by antiaircraft missiles, and dust clouds of unimaginable scale would blanket the landscape. Each B-52 was assigned a poststrike base in Europe or the Middle East where it was supposed to land, refuel, and pick up more nuclear weapons for another run at the Soviets. Would any of those bases still exist, if bombers somehow managed to survive their first passage through Soviet airspace? Most B-52 crews didn’t count on it.
Stan Spray added components from the Mark 28 bomb to his Burned Board briefing, along with a dramatic flourish: when the bomb’s wires short-circuited, a flashbulb went off. The briefing was given to hundreds of officials — with little immediate effect. A study of all the nuclear weapons in the American arsenal was completed by one of Peurifoy’s deputies in 1977. It provided the Department of Defense with a list of the weapons posing the greatest threat and a timetable for retiring them or improving their safety. The Mark 28 bomb was at the top of the list, followed by the W-25 warhead of the Genie antiaircraft missile. Despite being the oldest sealed-pit weapon in the stockpile, vulnerable to lightning, and fitted with an outdated accelerometer, the Genie was still being loaded onto fighter planes. On the list of weapons requiring urgent attention, the only strategic warhead was the W-53 atop the Titan II missile. It needed a “retrofit for Enhanced Electrical Safety.”
In 1979 the Department of Defense finally accepted some of the recommendations that Sandia’s safety department had been making for years — but didn’t want to pay for them. The Pentagon agreed to schedule retrofits of weapons like the Mark 28, so long as the cost wouldn’t interfere with the acquisition of new weapons. And until the funds were obtained, the Mark 28 could still be carried by B-52s on ground alert. Although the Air Force balked at devoting a few hundred million dollars to improve the safety of hydrogen bombs, it planned to spend at least $10 billion to equip B-52s with cruise missiles. Instead of trying to penetrate Soviet airspace, the bombers would launch cruise missiles a thousand miles from their targets, turn around, and come home. Until those cruise missiles were available, B-52s were loaded with Short-Range Attack Missiles (SRAMs), carried in a rotary rack. It turned as each missile was fired, like the cylinder of a revolver shooting bullets. The SRAMs were designed to fly a hundred miles or so, destroy Soviet air defenses, and give the B-52 a better chance of reaching its target. The missiles had a destructive force of as much as 200 kilotons, and a single B-52 could carry a dozen of them.
