The first glitch came moments before Bock's Car took off from the Pacific island of Tinian.

A fuel selector switch didn't work. About 600 gallons of fuel in a reserve tank would be only dead weight, burning up more of the remaining fuel.

If calculations were correct, the B-29 still had barely enough fuel for the mission. But loss of the reserve left no margin for error.

Bock's Car commander Maj. Charles Sweeney huddled with the 509th Composite Group's commander, Lt. Col. Paul Tibbets.

This run was the destiny the air crew trained for exclusively over the past nine months, they decided. Sweeney and Tibbets agreed to press ahead, and Bock's Car left Tinian at 3:57 a.m.

It was one of the final almost-by-chance decisions that culminated hours later in the destruction of the ancient city of Nagasaki. Subsequently, an upstart village and tent city of scientists, engineers and builders in Eastern Washington would learn their labors helped conclude World War II.

But first, Bock's Car would have to reach the target, laboring across the ocean with its 10,000 pounds of atomic bomb made with Hanford plutonium.

"We had a hell of a time," recalled former Navy Cmdr. Frederick Ashworth, the flight's 32-year-old weaponeer. Ashworth, who now lives in Lincoln, N.M., was a combat veteran who flew torpedo bombers off Guadalcanal.

The crew was young. Sweeney was 25. Fred Olivi, the co-pilot, was 23 and fresh out of flight school when he joined the newly formed 509th.

"We had a lot of rookies," Olivi remembered in a conversation from his home in Chicago. Of the 13 men who flew on the Bock's Car on Aug. 9, seven are still alive.

Although each has told the story of the flight countless times, each recollection is slightly different.

Minutes after takeoff, Ashworth opened a hatch and slid into the bomb bay to fully arm Fat Man - the world's third and only remaining nuclear bomb.

While other crew members worried about the bomb, Ashworth was calm. He had spent months with the Los Alamos scientists who built it. His biggest fear was a catastrophic crash on takeoff. A fire could lead to a low-order radioactive explosion.

From a narrow catwalk, Ashworth noticed someone had pasted a pinup of movie star Rita Hayworth on the bomb's side. Other crew members had scrawled their names on the bomb with messages to the Emperor of Japan.

In less than a minute, Ashworth removed the green plug from the nose of the bomb, which isolated the firing circuit from the fusing signals. He replaced it with a red one.

The bomb was armed.

It was one of the few things to go right during the flight.

* * *

Three B-29s took off from Tinian and flew to the rendezvous point at Yakushima island, just off the southern coast of Kyushu.

One carried the bomb. One carried sensor instruments. The third was the photography plane.

They flew separately to avoid a midair collision as they headed over the Pacific under radio silence without running lights.

The weather was rough at 8,000 to 10,000 feet - the most economical altitudes for fuel consumption.

Sweeney didn't want to jostle Fat Man more than he had to. So he flew at 17,000 feet and burned more fuel.

Static electricity enveloped the B-29's propellers, giving the illusion of blue flames or St. Elmo's fire.

"It was real quiet on board," Raymond Gallagher, the 23-year-old assistant flight engineer, recalled of the flight's first leg to Yakushima.

The radio operator listened closely for any message from Tinian. A secret signal to scrub the mission would be sent if Japan surrendered.

Bock's Car and Great Artiste -flown by Capt. Fred Bock - met at 8 a.m. at 30,000 feet over Yakushima.

They circled the island, burning more precious fuel for 40 minutes.

But the photography plane still didn't show up, so Sweeney waggled his wings and headed to Kokura, the mission's primary target. Bock followed.

Unknown to them, the third plane was waiting above them at 39,000 feet. The captain finally broke radio silence, asking Tinian: "Has Sweeney aborted?"

The message came through: "Sweeney aborted."

No one knew where Bock's Car was.

Thomas Farrell, the general on Tinian in charge of the mission, walked outdoors.

There, he threw up.

* * *

Before Bock's Car was even close to Kokura, a red light on the atomic bomb suddenly blinked on.

It meant a fuse in the bomb apparently activated. Crew members relayed the news to Sweeney.

The question was which fuse.

One fuse was designed to trigger the atomic blast when Fat Man dropped to an altitude of 1,500 feet. A second fuse was activated by barometric pressure. And if all else failed, a third fuse was designed to ignite the bomb when it hit the ground.

Those didn't pose an immediate threat. But a fourth fuse was nothing more than a simple timer, a timer that would set off the bomb in 52 seconds.

And the signal light didn't indicate which fuse switched on.

In the cockpit, Sweeney worried but concentrated on flying the plane as his crew members tried to find the glitch. If he was the nervous type, he wouldn't have been in the cockpit.

A crew member called. A switch was in the wrong position, and all the fuses were still dormant.

"Oh Lord," Sweeney whispered.

* * *

The delay at Yakushima probably doomed Nagasaki.

While Bock's Car circled the rendezvous site for 40 minutes, billowing smoke from a bombing raid on a nearby city was drifting over the previously clear Kokura.

When the two B-29s arrived sometime after 10 a.m., the crews couldn't see the target.

On an ordinary mission, Sweeney might have ordered a radar run. Or he could have used a river as a landmark to bomb by dead reckoning. But his orders were to bomb only if the target could be clearly seen.

He started the first bomb run at 30,000 feet over Kokura, hoping to find a break in the haze. Nothing.

Anti-aircraft fire began to burst around the two B-29s. Sweeney opted for a second run a couple of thousand feet higher to confuse the anti-aircraft gunners.

Again no luck, and Bock's Car kept burning fuel.

The radio man reported increased traffic on frequencies used by Japanese fighter planes. The tail gunner thought he spotted 10 fighters taking off.

Sweeney opted for a third run anyway.

No luck again.

Japanese Zero fighters began to show up.

Sweeney and Ashworth decided to head to Nagasaki. "We had enough problems," Sweeney said.

The route was thick with Japanese fighter bases, and the crew kept a sharp watch for enemy planes.

By now, Sweeney knew, the plane did not have enough fuel to make it back to Tinian or to the backup base at Iwo Jima. He planned to head to Okinawa after taking a crack at Nagasaki.

Bock's Car's flight engineer figured the plane would run out of fuel 50 miles short of Okinawa.

* * *

The sky above Nagasaki was cloudy, and the bomber crew grew increasingly anxious.

It had an armed atomic bomb, but could not see the target to guarantee it could hit it from 30,000 feet - as their orders dictated.

But aborting the mission was not an option in Sweeney's mind. The implicit message he received from his superiors before the mission was the bomb had to be dropped.

"They say now we could have landed and disarmed it," Olivi said. "But I don't think they had practiced that. I'm not sure anyone knew what to do."

Olivi recalls Sweeney said at one point that he might order the crew to bail out and he would dive-bomb the city himself to guarantee hitting the target. (Sweeney remembers saying this during a pep talk before the flight to illustrate the mission's importance.)

But no one was anxious to bail out. Before takeoff, each crewman was given cyanide pills to use if he was forced to bail out and was captured.

"They would have tortured us because of Hiroshima," Olivi said.

Disobeying orders, Ashworth and Sweeney decided to drop the bomb using radar and started the run as soon as Bock's Car reached Nagasaki.

"Our only choice was to drop it," Ashworth said. "I didn't know whether we could make it back to Okinawa hauling around a 10,000-pound bomb."

Ashworth hovered over the navigator's radar scope as the bomb run began.

Just seconds before it was time to release the bomb, a hole opened in the clouds.

"I got it! I got it!" shouted the bombardier, Capt. Kermit Beahan, who turned 27 that day. Beahan quickly synchronized his bombsight as the target approached.

Ashworth calls Beahan the flight's hero. "He held his cool. He had only one shot. He reacted and he did his job."

"He saved our necks," Olivi said. "We would have been in trouble for disobeying an order not to use radar."

The bomb bay doors opened slowly, making the plane begin to wobble because of the drag.

When Beahan released the bomb, the plane abruptly jumped as it lost 10,000 pounds.

Sweeney immediately went into a steep lefthand bank and headed 150 degrees in the opposite direction to outrun the impending radioactive blast cloud.

Crew members donned special goggles and looked into the center of the plane as the bomb exploded about 45 seconds later.

"It got 10 times brighter than the sun ... a white-blue light," Olivi recalled.

Sweeney said the flash covered the sky from horizon to horizon.

The after-mission report described a white smoke ring with a red ball of fire in the middle covering half the target area. A column of smoke a half-mile wide formed and started to funnel up, dark brown at the bottom, amber in the center, white on the top.

Olivi remembered a more colorful sight. He described the mushroom cloud as it rose to 30,000 feet in under two minutes.

"At the stem, it was like a cauldron. Pink, salmon, blues, violets, black, like a churning column of fire and smoke."

Three shock waves, one heavier than expected, slammed into Bock's Car. "It was like someone banging on the bottom of the ship," Gallagher said.

A crewman cried out, "We're going to be hit by the cloud."

But the radioactive cloud by that time was six miles away.

For the first time, Sweeney broke radio silence and sent a coded message: Nagasaki had been bombed.

* * *

The crew's elation and awe changed to apprehension as Bock's Car headed for Okinawa.

Sweeney dug into a grab bag of pilot's tricks to save fuel, including controlled dives and tweaking engine speed.

As the plane approached Okinawa, Sweeney tried to raise the tower for landing instructions.

When he couldn't make contact, he declared a Mayday over the radio. Olivi fired flares out the window and Sweeney cut into the landing pattern ahead of a steady stream of other planes.

Bock's Car came in hot and long, touching down one-third of the way down the runway at more than 150 mph. The plane began to skid toward other craft as Sweeney reversed the props and slammed on the brakes.

As the plane slowed, the No. 2 engine quit. It had run out of gas.

No one on Okinawa knew Bock's Car had dropped the bomb. The crew was ordered to say nothing.

As the plane was refueled, the crew chowed down before heading back to Tinian. Cooks in the mess hall knew another atomic bomb was dropped and were excited the war might end soon.

One cook - not knowing whom he was talking to - told Olivi all about the bombing, claiming a P-38 fighter from Okinawa was involved and the bomb was the size of a golf ball.

"I was just glad it was over," Olivi said. "Just before we dropped the bomb, it flashed through my mind that we would kill a lot of children, elderly and other people. But that was the nature of the beast, and I put it out of my mind quickly."

All of the crew members have thought about it since. Some have visited Nagasaki. But none express any regrets.

"At the time, I didn't think about it," Gallagher said. "Now I think about the people on the ground and how horrible it must have been. But you know, if someone is beating you with a steel bar and you have a gun in your hand, wouldn't you use it?"