Your biggest problem may be after the bomb has left your aircraft. The shock waves from the detonation could crush your plane. I am afraid that I can give you no guarantee that you will survive.

The bomb you are going to drop is something new in the history of warfare. It is the most destructive weapon ever produced. We think it will knock out almost everything within a three-mile radius. No one knows exactly what will happen when the bomb is dropped from the air. Even if it exploded at the planned altitude of 1850 feet it might crack the earth's crust. The explosion's flash of light would be much brighter than the sun and could cause blindness.

The first atomic bomb struck squarely in the centre of Hiroshima on August 6 with a flash and concussion that to the Super-Fortress crew ten miles away had the effect of the close explosion of anti-aircraft artillery. Colonel Paul W. Tibbits, who piloted the 'plane, and Captain William S. Parsons, a United States Navy Ordnance expert, described the explosion as tremendous and awe-inspiring.

"It was hard to believe what we saw," said Colonel Tibbits. Colonel Tibbits was awarded the Distinguished Flying Medal immediately he returned from the raid. He said the trip out to the target was uneventful. The bomb was released by direct vision. "We dropped the bomb at exactly 9 15 a.m. Japanese time," he continued, "and got out of the target area as quickly as possible to avoid the full effect of the explosion. A tremendous cloud of smoke arose which completely blotted out Hiroshima. When we felt the explosion it was like flak bursting close by. We stayed over the target area for two minutes.

Although they were ten miles away the crew of the Super-Fortress from which the first atomic bomb was dropped on Japan likened the concussion to the bursting of an anti-aircraft shell close to the 'plane. The members of the Super-Fortress crew told their stories to press correspondents in Guam early this morning. Reconnaissance reports on the raid are expected to be released later to-day. Japanese statements have not been able to conceal the serious nature of the destruction caused by the bomb. They say the bomb was attached to a parachute and exploded in the air. Tokio broadcasts have contained violent attacks on the Americans for using such a weapon. It is believed in Washington that the Allies may issue a second surrender ultimatum to Japan, and that there may be an interval before a full-scale atomic bomb attack is launched.

Captain Parsons, who went in the 'plane to observe the effects of the bomb, said: "The whole thing was tremendous and awe-inspiring. After the missile had been released I sighed and stood back for the shock. When it came the men aboard with me gasped 'My God,' and what had been Hiroshima was a mountain of smoke like a giant mushroom."

"We were at least ten miles away, and there was a visual impact, even though every man wore coloured glasses for protection. We had braced ourselves, when the bomb had gone, against the shock, and Tibbits said 'Close flak.' It was just like that - a close burst of ack-ack fire.

"A thousand feet above the ground was a great mass of dust, boiling, swirling, and extending over most of the city. Soon afterwards small fires sprang up on the edge of the town, but the town itself was entirely obscured. We stayed around for two or three minutes and by that time the smoke had risen to 40,000ft. As we watched the top cone of white smoke broke off, but another soon formed."

Asked if the men in the Super-Fortress knew what their mission was, Captain Parsons replied: "They knew they were in on something big, but no more. They were, however, told to expect a blinding flash and were issued with black goggles. Only three of us in the 'plane, Colonel Tibbits, Bombardier Major Thomas Ferebee, and myself, knew what type of bomb was being dropped."

We dispatched an aircraft to check the weather. There was an alert in Hiroshima when the aircraft arrived. Then it turned away and the "All Clear" signal was given in the town. And then we arrived. I have never regretted it or been ashamed; I thought at the time I was doing my patriotic duty in carrying out the orders given to me.

Studs Terkel: You got the go-ahead on August 5.

Paul Tibbets: Yeah. We were in Tinian [the US island base in the Pacific] at the time we got the OK. They had sent this Norwegian to the weather station out on Guam [the US's westernmost territory] and I had a copy of his report. We said that, based on his forecast, the sixth day of August would be the best day that we could get over Honshu [the island on which Hiroshima stands]. So we did everything that had to be done to get the crews ready to go: airplane loaded, crews briefed, all of the things checked that you have to check before you can fly over enemy territory.

General Groves had a brigadier-general who was connected back to Washington DC by a special teletype machine. He stayed close to that thing all the time, notifying people back there, all by code, that we were preparing these airplanes to go any time after midnight on the sixth. And that's the way it worked out. We were ready to go at about four o'clock in the afternoon on the fifth and we got word from the president that we were free to go: "Use 'em as you wish." They give you a time you're supposed to drop your bomb on target and that was 9.15 in the morning , but that was Tinian time, one hour later than Japanese time. I told Dutch, "You figure it out what time we have to start after midnight to be over the target at 9am."

Studs Terkel: That'd be Sunday morning.

Paul Tibbets: Well, we got going down the runway at right about 2.15am and we took off, we met our rendezvous guys, we made our flight up to what we call the initial point, that would be a geographic position that you could not mistake. Well, of course we had the best one in the world with the rivers and bridges and that big shrine. There was no mistaking what it was.

Studs Terkel: So you had to have the right navigator to get it on the button.

Paul Tibbets: The airplane has a bomb sight connected to the autopilot and the bombardier puts figures in there for where he wants to be when he drops the weapon, and that's transmitted to the airplane. We always took into account what would happen if we had a failure and the bomb bay doors didn't open: we had a manual release put in each airplane so it was right down by the bombardier and he could pull on that. And the guys in the airplanes that followed us to drop the instruments needed to know when it was going to go. We were told not to use the radio, but, hell, I had to. I told them I would say, "One minute out," "Thirty seconds out," "Twenty seconds" and "Ten" and then I'd count, "Nine, eight, seven, six, five, four seconds", which would give them a time to drop their cargo. They knew what was going on because they knew where we were. And that's exactly the way it worked, it was absolutely perfect.

After we got the airplanes in formation I crawled into the tunnel and went back to tell the men, I said, "You know what we're doing today?" They said, "Well, yeah, we're going on a bombing mission." I said, "Yeah, we're going on a bombing mission, but it's a little bit special." My tailgunner, Bob Caron, was pretty alert. He said, "Colonel, we wouldn't be playing with atoms today, would we?" I said, "Bob, you've got it just exactly right." So I went back up in the front end and I told the navigator, bombardier, flight engineer, in turn. I said, "OK, this is an atom bomb we're dropping." They listened intently but I didn't see any change in their faces or anything else. Those guys were no idiots. We'd been fiddling round with the most peculiar-shaped things we'd ever seen.

So we're coming down. We get to that point where I say "one second" and by the time I'd got that second out of my mouth the airplane had lurched, because 10,000lbs had come out of the front. I'm in this turn now, tight as I can get it, that helps me hold my altitude and helps me hold my airspeed and everything else all the way round. When I level out, the nose is a little bit high and as I look up there the whole sky is lit up in the prettiest blues and pinks I've ever seen in my life. It was just great.

I tell people I tasted it. "Well," they say, "what do you mean?" When I was a child, if you had a cavity in your tooth the dentist put some mixture of some cotton or whatever it was and lead into your teeth and pounded them in with a hammer. I learned that if I had a spoon of ice-cream and touched one of those teeth I got this electrolysis and I got the taste of lead out of it. And I knew right away what it was.

OK, we're all going. We had been briefed to stay off the radios: "Don't say a damn word, what we do is we make this turn, we're going to get out of here as fast as we can." I want to get out over the sea of Japan because I know they can't find me over there. With that done we're home free. Then Tom Ferebee has to fill out his bombardier's report and Dutch, the navigator, has to fill out a log. Tom is working on his log and says, "Dutch, what time were we over the target?" And Dutch says, "Nine-fifteen plus 15 seconds." Ferebee says: "What lousy navigating. Fifteen seconds off!"

Studs Terkel: Did you hear an explosion?

Paul Tibbets: Oh yeah. The shockwave was coming up at us after we turned. And the tailgunner said, "Here it comes." About the time he said that, we got this kick in the ass. I had accelerometers installed in all airplanes to record the magnitude of the bomb. It hit us with two and a half G. Next day, when we got figures from the scientists on what they had learned from all the things, they said, "When that bomb exploded, your airplane was 10 and half miles away from it."

Studs Terkel: Did you see that mushroom cloud?

Paul Tibbets: You see all kinds of mushroom clouds, but they were made with different types of bombs. The Hiroshima bomb did not make a mushroom. It was what I call a stringer. It just came up. It was black as hell, and it had light and colours and white in it and grey colour in it and the top was like a folded-up Christmas tree.

Studs Terkel: Do you have any idea what happened down below?

Paul Tibbets: Pandemonium! I think it's best stated by one of the historians, who said: "In one micro-second, the city of Hiroshima didn't exist."

Studs Terkel: You came back, and you visited President Truman.

Paul Tibbets: We're talking 1948 now. I'm back in the Pentagon and I get notice from the chief of staff, Carl Spaatz, the first chief of staff of the air force. When we got to General Spaatz's office, General Doolittle was there, and a colonel named Dave Shillen. Spaatz said, "Gentlemen, I just got word from the president he wants us to go over to his office immediately." On the way over, Doolittle and Spaatz were doing some talking; I wasn't saying very much. When we got out of the car we were escorted right quick to the Oval Office. There was a black man there who always took care of Truman's needs and he said, "General Spaatz, will you please be facing the desk?" And now, facing the desk, Spaatz is on the right, Doolittle and Shillen. Of course, militarily speaking, that's the correct order: because Spaatz is senior, Doolittle has to sit to his left.

Then I was taken by this man and put in the chair that was right beside the president's desk, beside his left hand. Anyway, we got a cup of coffee and we got most of it consumed when Truman walked in and everybody stood on their feet. He said, "Sit down, please," and he had a big smile on his face and he said, "General Spaatz, I want to congratulate you on being first chief of the air force," because it was no longer the air corps. Spaatz said, "Thank you, sir, it's a great honour and I appreciate it." And he said to Doolittle: "That was a magnificent thing you pulled flying off of that carrier," and Doolittle said, "All in a day's work, Mr President." And he looked at Dave Shillen and said, "Colonel Shillen, I want to congratulate you on having the foresight to recognise the potential in aerial refuelling. We're gonna need it bad some day." And he said thank you very much.

Then he looked at me for 10 seconds and he didn't say anything. And when he finally did, he said, "What do you think?" I said, "Mr President, I think I did what I was told." He slapped his hand on the table and said: "You're damn right you did, and I'm the guy who sent you. If anybody gives you a hard time about it, refer them to me."

Studs Terkel: Anybody ever give you a hard time?

Paul Tibbets: Nobody gave me a hard time.

Studs Terkel: Do you ever have any second thoughts about the bomb?

Paul Tibbets: Second thoughts? No. Studs, look. Number one, I got into the air corps to defend the United States to the best of my ability. That's what I believe in and that's what I work for. Number two, I'd had so much experience with airplanes... I'd had jobs where there was no particular direction about how you do it and then of course I put this thing together with my own thoughts on how it should be because when I got the directive I was to be self-supporting at all times.

On the way to the target I was thinking: I can't think of any mistakes I've made. Maybe I did make a mistake: maybe I was too damned assured. At 29 years of age I was so shot in the ass with confidence I didn't think there was anything I couldn't do. Of course, that applied to airplanes and people. So, no, I had no problem with it. I knew we did the right thing because when I knew we'd be doing that I thought, yes, we're going to kill a lot of people, but by God we're going to save a lot of lives. We won't have to invade (Japan).

The 60th anniversary of the dropping of the first atomic bomb. The occasion will be marked by a torrent of prose from those who regard the destruction of Hiroshima and of Nagasaki three days later as "war crimes", forever attaching shame to those who ordered them.

By contrast, there will be a plethora of dismissive comment from pundits who believe the nuclear assault saved a million allied casualties in 1945, by causing Japan to surrender without an invasion of its mainland.

Plentiful evidence is available to both schools. In the spring of 1945, Americans fighting in the Pacific were awed by the suicidal resistance they encountered. Hundreds of Japanese pilots, thousands of soldiers and civilians, immolated themselves, inflicting heavy US losses, rather than accept the logic of surrender.

It was well-known that the Japanese forces were preparing a similar sacrificial defence of their homeland. Allied planning for an invasion in the autumn of 1945 assumed hundreds of thousands of casualties. Allied soldiers - and prisoners - in the far east were profoundly grateful when the atomic bombs, in their eyes, saved their lives.

On the other side of the argument is the fact that in the summer of 1945 Japan's economy was collapsing. The US submarine blockade had strangled oil and raw-materials supply lines. Air attack had destroyed many factories, and 60% of civilian housing. Some authoritative Washington analysts asserted that Japan's morale was cracking.

Intercepts of Japanese diplomatic cables revealed to Washington that Tokyo was soliciting Stalin's good offices to end the war. The Americans were also aware of the Soviets' imminent intention to invade Japanese-occupied China in overwhelming strength.

In short, the 2005 evidence demonstrates that Japan had no chance of sustaining effective resistance. If America's fleets had merely lingered offshore through autumn 1945, they could have watched the Japanese people, already desperately hungry, starve to death or perish beneath conventional bombing. Oddly enough, Soviet entry into the war on August 8 was more influential than the atomic explosions in convincing Japanese leaders that they must quit.

Just after 8.15am Japanese time, on August 6 1945, six miles above Hiroshima, a Boeing B29 bomber, the Enola Gay, commanded by Colonel Paul Tibbets, who has died aged 92, carried out the world's first atomic attack. Of 320,000 people in that city that morning, 80,000 died immediately or were badly wounded by the A-bomb, nicknamed "Little Boy". The site of the explosion reached a temperature of 5,400°F. Days later, thousands of incinerated, blackened cadavers still adhered to the streets.

In the aftermath of the bomb's release, Tibbets flung the huge B29 into a 155° turn to avoid destruction. Shock and horror swept over the 12-strong crew, he recalled. "Fellows," he had said, "you have just dropped the first atom bomb in history." Only Tibbets and US navy captain William "Deke" Parsons - who completed the assembly, and armed Little Boy en route to Japan - had been privy to the secret of the Manhattan Project, the US atomic bomb programme.

Three days after Hiroshima, Nagasaki was A-bombed, with up to 40,000 killed. On August 14 1945, the Japanese emperor broadcast to his people that they must "bear the unbearable" and surrender. The causal link between Tibbets' mission and Hirohito's announcement remained a hotly debated issue. The controversy surrounding the raid has never ended and the only presidential invitation Tibbets ever received was from the man who ordered the bombing, Harry Truman....

Until Enola Gay's arrival over Hiroshima, the most taxing part of the flight had been the takeoff, when Tibbets had held 65 tons of B29 on the runway for two miles before pulling it into the air. He had been given cyanide pills for the crew - in case they came down over Japan - and anti-flash goggles for the A-bomb itself. "My teeth told me more emphatically than my eyes of the Hiroshima explosion," Tibbets wrote: there was a tingling sensation, as his fillings interacted with the radioactivity.

In the city, wrote Richard Rhodes in his definitive The Making of the Atomic Bomb, "birds ignited in mid-air. Mosquitoes and flies, squirrels, family pets crackled and were gone. The fire balls flashed an enormous photograph of the city at the instant of its immolation fixed on the mineral, vegetable and animal surfaces of the city itself."

The mushroom cloud over the stricken city was still visible from Enola Gay at 10 that morning. By 3pm, the B29 had touched down at Tinian. The crew was decorated - Tibbets with a distinguished service cross - on landing. Back home Tibbets' local paper called him "Florida's Buck Rogers".

That September, together with Ferebee and Van Kirk, he went to Hiroshima. Soon afterwards, he went to the air war college in Alabama to write about the use of A-bombs. He was infuriated when denied a key role in the 1946 Bikini Atoll A-bomb tests, partly blaming machinations by Norstad, and went on to test the B47 atom bomber.

In 1952, Robert Taylor played Tibbets, with Eleanor Parker as his wife Lucy in Above and Beyond, billed as the "love story behind the billion dollar secret". But two years later, the marriage ended in divorce and in 1956, while posted to Nato in Paris, he married Andrea Quattrehomme.

Tibbets never reached the top echelon in the cold-war US air force; he retired with the rank of brigadier-general. Soon after serving with the US supply mission in India (1964-66) - where the Indian Communist party labelled him the "world's greatest killer" - he quit and joined an executive jet company in Ohio.