Diana Preston - Before the Fallout

TEN MINUTES AFTER TAKEOFF, the Enola Gay was passing over Saipan and, flying at an airspeed of 213 knots (247 mph), was climbing to 4,700 feet, the initial cruising altitude for the first leg of the six-hour journey—three hours north-northwest to Iwo Jima.

Two minutes earlier, at about the time rear gunner Bob Caron tested his guns, Parsons and his assistant, Morris Jeppson, had, after securing Tibbets’s permission, made their way to the bomb bay. Parsons climbed down through the hatch in the floor, squeezing himself into the small place behind Little Boy’s tail to begin his delicate task of arming the bomb. Using only wrenches and a screwdriver, he had to remove a series of protective shields and then insert an explosive charge. When triggered, the charge would propel a slug of uranium down the gun barrel into the uranium rings fitted into the nose of the weapon to achieve the critical mass necessary to begin the explosive chain reaction.

While Jeppson shone a torch from above, Parsons worked quickly in the confined, cold, and unpressurized space of the bomb bay, trying not to cut himself on the sharp steel casings, as he had done in practice. As Parsons worked, Jeppson used the intercom to tell Tibbets of his progress, and Tibbets, in turn, informed Tinian over his low-frequency radio. Only twenty-five minutes after starting, Jeppson reported the task complete. Because of static interference, Tibbets could not get this final message through to Tinian, but, he recalled, “Progress was such by this time, they had no doubts of Parsons’ success.”

Parsons left three green safety plugs in position. He would have to replace them later with three red arming plugs to unlock the weapon’s fusing circuits, which he would carefully monitor using a bank of electronic equipment. The detonation of the live bomb would then depend on a series of triggers. The primary one was a kind of proximity fuse, a simple radar unit built into the bomb which closed a switch, firing the explosive charge when the bomb fell to a predetermined height of some two thousand feet above ground. [39] The unit had been adapted from an instrument designed to alert pilots to the approach of enemy aircraft to the rear. Instead of bouncing signals off an approaching hostile plane, they would respond to the approaching ground. The second was backup clocks activated mechanically on the bomb’s release and preventing detonation for at least fifteen seconds after that time. Finally, there was a barometric pressure switch, which would not close until the air pressure had increased to that found at a maximum of seven thousand feet above ground. Both the backup systems would give some protection to the aircraft if the primary system were to be activated too early for any reason. All three triggering systems contained duplicates to overcome an individual instrument failure.

Tibbets checked with the plane carrying the scientists and their instruments and then with the photographic plane. Receiving confirmation that all was well aboard them, he made a quick tour of inspection of the Enola Gay, crawling back along the communication tunnel to talk to Caron and others. Satisfied that all was in order, and “having had little sleep in the past forty-eight hours,” he sensed he was “operating on nervous energy alone” and so, making himself as comfortable in his seat as he could with the help of his life jacket and parachute pack, he dozed for about an hour. Copilot Bob Lewis took a bite to eat while he kept an eye on the green-lit instrument panel and on the automatic pilot known in this and in other aircraft as “George.”

Soon Iwo Jima was in sight, and, according to the official log, they reached it at 6:00 a.m. Tinian time. In the pink light of dawn Tibbets circled the island’s highest peak, Mount Suribachi, at 9,300 feet so that his instrument and photographic planes could take closer formation.

As they left Iwo Jima at 6:07 a.m., there were still three prospective targets: the primary target, Hiroshima, and the secondaries, Kokura and Nagasaki. The final choice would depend on reports from the three weather planes that had taken off from Tinian about an hour earlier than the Enola Gay, each assigned to a particular city. At 7:30 a.m. Deak Parsons and Jeppson made their way back to the bomb bay and carefully removed each of the green safety plugs, substituting the red plugs that activated Little Boy’s internal batteries. Bob Lewis, who was keeping some authorized notes for a New York Times journalist, wrote, “The bomb is now alive. It is a funny feeling knowing it is right in back of you. Knock wood.” He worried that if they hit bad weather or turbulence, the bomb might detonate. Tibbets calmed himself by smoking his pipe “with,” in his words, “a little more intensity than usual” as the Enola Gay climbed slowly to the bombing altitude of 30,700 feet.

At just after eight o’clock Tinian time—seven o’clock Japanese time—the weather plane assigned to Hiroshima, Straight Flush, piloted by Claude Eatherly, made a run toward the city. The plane approached, bumping through cloud cover, but then, directly over the city, came a large break in the clouds through which shafts of sunlight illuminated Hiroshima. At his request, Eatherly’s radioman sent a signal consisting of the numbers and letters Q53, B-2, C-1. Aboard Enola Gay, the young radio operator Dick Nelson picked the transmission up, decoded it, and reported the result to Tibbets. The cloud cover at all altitudes was less than three-tenths. “Advice to bomb the primary target.” Tibbets recalled, “Over the intercom I gave the word to members of our crew, ‘It’s Hiroshima.’”

Soon the Enola Gay crossed the first of the Japanese islands. Deak Parsons tested the bomb’s electrical circuits with his instrument console yet one more time. Jacob Beser reported that he could detect no Japanese radio countermeasures. Tibbets recalled, “We were eight minutes away from the scheduled time of bomb release when the city came into view. The early morning sunlight glistened off the white buildings in the distance.” Tibbets reached the initial point of the bomb run. Surrounded by plexiglass panels in the exposed nose of the plane, Tom Ferebee crouched over the bombsight as Tibbets began the three-minute bomb run. There was no antiaircraft fire. Soon the aiming point—the T-shaped Aioi Bridge in the central Salugaku­cho district—was clearly visible in Ferebee’s bombsight. The bombardier activated a sixty-second radio tone to alert the Enola Gay’s crew and the two accompanying planes to the imminent release of the bomb. Bob Lewis scrawded on his notepad, “There will be a short intermission while we bomb our target.” Tibbets remembered that at the end of the tone, at 9:15 Tinian time and 8:15 local time in Hiroshima, the bomb doors opened automatically and “out tumbled Little Boy.” Tibbets immediately pushed the Enola Gay into the 180-degree turn required to take her to safety. Bob Caron recalled, “The manoeuvre felt like being on the cyclone rollercoaster ride at the Coney Island amusement park.”

In making the diving turn, the plane lost 1,700 feet in height. Tibbets was focusing so hard on the controls that the flash of the explosion did not have the effect he expected, but at the instant of the blast he had “a tingling sensation in my mouth and the very definite taste of lead upon my tongue.” According to Tibbets, scientists later told him that this was caused by an interaction between the fillings in his teeth and the radiation released by the bomb.