Hiroshima Atomic Bombing Timeline
Hiroshima Atomic Bombing Timeline was prepared by David A. Wargowski for the Atomic Heritage Foundation. Please see their website for further details.
[Times are in Tinian time unless otherwise noted. The time in Hiroshima is one hour behind Tinian.]0000:
Colonel Paul Tibbits gives a final briefing at one end of the crew lounge to the crews of Special Bombing Mission No. 13, consisting of the seven B-29’s. The target of choice remains Hiroshima. Tibbets is pilot, Robert Lewis is co-pilot of the weapon plane, The Enola Gay. The two observation planes (The Great Artiste and Necessary Evil) would be carrying cameras and scientific equipment and accompany the Enola Gay.
0015: Tibbets summons Chaplain William Downey, who invites the crews to bow their heads. Downey then reads a prayer that he composed specifically for this occasion.
“Almighty Father, Who wilt hear the prayer of them that love thee, we pay thee to be with those who brave the heights of Thy heaven and who carry the battle to our enemies. Guard and protect them, we pray thee, as they fly their appointed rounds. May they, as well as we, know Thy strength and power, and armed with Thy might may they bring this war to a rapid end. We pray Thee that the end of the war may come soon, and that once more we may know peace on earth. May the men who fly this night be kept safe in Thy care, and may they be returned safely to us. We shall go forward trusting in Thee, knowing that we are in Thy care now and forever. In the name of Jesus Christ. Amen."
0112: Trucks pick up the crews of the two observation planes that will accompany the Enola Gay.
0115: A truck picks up the crew of the Enola Gay. Tibbets and Parsons sit in the front with the driver. In the back of truck are Dutch Van Kirk, Thomas Ferebee, Robert Lewis, Jacob Beser, Morris Jeppson, Bob Caron, Robert Shumard, Joseph Stiborik, and Richard Nelson. The crew wears pale green combat overalls. The only identification they have are the dog tags around their necks. Jacob Beser’s dog tag is stamped “H” for "Hebrew."
0137: The three weather planes, Straight Flush, Jabit III, and Full House, take off, each one independently assigned to assess weather conditions over Hiroshima, Kokura, and Nagasaki.
0151: Big Stink takes off to assume its stand-by role as the strike spare plane at Iwo Jima.
0220: The final Enola Gay crew photo is taken. Tibbets turns to his crew and says, “Okay, let’s go to work.”
0227: Enola Gay’s engines are started.
0235: Enola Gay arrives at her takeoff position on the runway.
0245: Enola Gay begins takeoff roll. Colonel Paul Tibbets says to co-pilot Robert Lewis, “Let’s go." He pushes all of the throttles forward. The overloaded Enola Gay lifts slowly into the night sky, using all of the more than two miles of runway.
0247: The Great Artiste takes off.
0249: Necessary Evil takes off.
0255: Ten minutes after takeoff, Dutch Van Kirk writes his initial entry in the navigator’s log.
0300: Capt. William "Deak" Parsons taps Tibbets on the shoulder, indicating that they were going to start arming Little Boy. Parsons and Morris Jeppson, the Electronic Test Officer, climb into the bomb bay.
0310: Parsons inserts the gunpowder and the detonator into Little Boy.
0320: Parsons and Jeppson complete inserting the charge into Little Boy, and climb out of the bomb bay.
0420: Van Kirk provides an estimated time of arrival over Iwo Jima of 5:52am.
0600: The B-29s rendezvous over Iwo Jima, climb to 9,300 feet, and set their course for Japan.
0715: Jeppson removes Little Boy's safety devices and inserts the arming devices (changing from green plugs to red plugs).
0730: Tibbets announces to the crew: "We are carrying the world's first atomic bomb." He pressurizes the Enola Gay and begins an ascent to 32,700 feet. The crew puts on their parachutes and flak suits.
0809: The weather planes fly over the possible target cities. In Hiroshima, an air raid alert is communicated.
0824: The pilot of the Straight Flush weather plane sends Tibbets a coded message that states: “Cloud cover less than 3/10ths at all altitudes. Advice: bomb primary." Tibbets turns on the intercom and announces, “It’s Hiroshima.” Tibbets then asks Richard Nelson to send a one word message to William L. Uanna, squadron security chief on Iwo Jima: "Primary.”
0831: The weather planes depart their locations. In Hiroshima, the all-clear is sounded.
0850: Flying at 31,000 ft, Enola Gay crosses Shikoku due east of Hiroshima. Bombing conditions are good, the aim point is easily visible, and no opposition is encountered.
0905: Van Kirk announces, “Ten minutes to the AP." The Enola Gay is at an altitude of 31,060 feet with an air speed of 200 miles an hour when the City of Hiroshima first comes into view. It is high tide in the Sea of Japan, so the seven branches of the Ota River are completely full and still. Male students are on their way to work at the munitions factory. Schoolgirls are already demolishing more buildings to create additional fire lanes.
0912: Control of the Enola Gay is handed over to the bombardier, Thomas Ferebee, as the bomb run begins. A Radio Hiroshima operator reports that three planes have been spotted.
0914: Tibbets tells his crew, “On glasses."
0914:17 (0814:17 Hiroshima time): Ferebee's aiming point, the T-shaped Aioi Bridge, is in clear range. The 60-second sequence to automatic release of the bomb is engaged with the Norden bombsight. Luis Alvarez, one of the Manhattan Project’s senior scientists aboard The Great Artiste, releases two pressure gauges on parachutes in order to determine the bomb’s yield. People on the ground, looking at the single bomber six miles above, observe the small object as it floats down.
0915:15 (8:15:15 Hiroshima time): The bomb bay doors snap open, and Little Boy, drops clear of its restraining hook. Ferebee announces, "Bomb away." The nose of the Enola Gay rises ten feet as the 9,700 pound Little Boy bomb is released at 31,060 feet. Tibbets immediately pulls the Enola Gay into a sharp 155 degree turn to the right. Ferebee watches the bomb wobble before it picks up speed and falls away.
On the ground, a second air raid alert is called for. For an additional 44.4 seconds, the Enola Gay continues to flies north as the bomb drops toward its aiming point. When the designated detonation altitude is reached, Little Boy explodes over the city of Hiroshima.
At the time of the detonation, the Enola Gay is already eleven and a half miles away. Tibbets, with his back to the explosion, observes a silver blue flash and experiences a strange feeling in his mouth, the same feeling as if he touched the lead and silver fillings in his mouth with a fork.
Bob Caron, the tail gunner of the Enola Gay, is the only crew member facing Hiroshima at the time of detonation. He sees a shimmer in the atmosphere coming towards the plane. Not understanding what is happening, Caron remains quiet. Soon after, the first of the three consecutive shockwaves strike the Enola Gay and the fuselage creaks and groans with the sound of crinkling aluminum foil.
0916:02 (8:16:02 AM Hiroshima time): After falling nearly six miles in forty-three seconds, Little Boy explodes 1,968 feet above the Dr. Shima’s Clinic, 550 feet away from the aiming point of the Aioi Bridge. Nuclear fission begins in 0.15 microseconds with a single neutron, initiating a supercritical chain reaction that increases the temperature to several million degrees Fahrenheit hotter than the surface of the sun at the time the bomb casing blows apart. The yield is 12.5-18 Kt (best estimate is 15 Kt).
It is the peak of the morning rush hour in Hiroshima. Above the city, the fireball is rapidly expanding.
.1 seconds: The fireball has expanded to one hundred feet in diameter combined with a temperature of 500,000°F. Neutrons and gamma rays reach the ground. The ionizing radiation is responsible for causing the majority of the radiological damage to all exposed humans, animals and other biological organisms.
.15 seconds: The superheated air above the ground glows. A woman sitting on steps on the bank of the Ota river, a half a mile away from ground zero, instantly vaporizes.
0.2-0.3 seconds: Intense infrared energy is released and instantly burns exposed skin for miles in every direction. Building roofing tiles fuse together. A bronze Buddha statue melts, and even granite stones. Roof tiles fuse together, wooden telephone poles carbonize and become charcoal-like. The soft internal organs (viscera) of humans and animals are evaporated. The blast wave propagates outward at two miles per second or 7,200 miles per hour.
1.0 second and beyond: The fireball reaches its maximum size, approximately 900 feet in diameter. The blast wave slows to approximately the speed of sound (768 miles per hour). The temperature at ground level directly beneath the blast (hypocenter) is at 7,000° F. The mushroom cloud begins to form.
The blast wave spreads fire outward in all directions at 984 miles per hour and tears and scorches the clothing off every person in its path. The blast wave hits the mountains surrounding Hiroshima and rebounds back. Approximately 60,000 out of the city's 90,000 buildings are demolished by the intense wind and firestorm.
Approximately 525 feet southwest from the hypocenter, the copper cladding covering the dome of the Industrial Products Display Hall is gone, exposing the skeleton-like girder structure of the dome. However, most of the brick and stonework of the building remains in place.
The ground within the hypocenter cools to 5,400°F. The mushroom cloud reaches a height of approximately 2,500 feet. Shards of glass from shattered windows are imbedded everywhere, even in concrete walls. The fireball begins to dim but still retains a luminosity equivalent to ten times that of the sun at a distance of 5.5 miles.
Nuclear shadows appear for the first time as a result of the extreme thermal radiation. These shadows are outlines of humans and objects that blocked the thermal radiation. Examples are the woman who was sitting on the stairs near the bank of the Ota River. Only the shadow of where she sat remains in the concrete. The shadow of a man pulling a cart across the street is all that remains in the asphalt. The shadow of a steel valve wheel appears on a concrete wall directly behind it because the thermal radiation was blocked by the outline of the wheel.
Russel Gackenbach, the navigator aboard Necessary Evil, at a distance of 15 miles from the atomic blast, is illuminated by light so bright that, even with his protective goggles on, he could have read the fine print of his pocket Bible.
On the ground, the firestorm continues to rage within an area which had now grown to over a mile wide. A gruesome, raging red and purple mass begins to rise in the sky. The mushroom column sucks superheated air, which sets fire to everything combustible. Bob Caron likens the sight to "a peep into Hell.”
A coded message drafted by Parsons is sent to General Thomas Farrell at Tinian. It stated: “Clear cut, successful in all aspects. Visible effects greater than Alamogordo. Conditions normal in airplane following delivery. Proceeding to base."
Enola Gay circles Hiroshima a total of three times beginning at 29,200 feet and climbing towards 30,000 feet before heading for home. It was 368 miles from Hiroshima before Caron reported that the mushroom cloud was no longer visible.
0930 (0830 Hiroshima time): The Kure Navy Depot sends a message to Tokyo that a bomb has been dropped on Hiroshima.
1055 (0955 Hiroshima time): The US intercepts a message from the Japanese 12th Air Division reporting “a violent, large special-type bomb, giving the appearance of magnesium.”
1100 (1000 Hiroshima time): A message from Hiroshima to the Army Ministry references information about a new American bomb and reports that “this must be it.”
1458: Enola Gay lands in Tinian Island at the North Field. The first atomic bombing mission has lasted a total of twelve hours and thirteen minutes.
1500 (1400 Tokyo time): The Domei News Agency telegram in Tokyo reports an attack on Hiroshima, but not the magnitude of the destruction.
Evening: A senior Japanese government administrator reports enormous destruction in Hiroshima.