Bill Foster knows why Bo Rein was on that plane to nowhere.

He knows why a football coach would fly into a thunderstorm. You have to. Losing eats you up and you want to win. You need to win.

So if you're recruiting, or scouting, or Lord only knows what else you're doing in the mad dance with your demon, it is no big deal to get in a little airplane and fly into a thunderstorm. I gotta get there, dammit, let's fire 'er up.

Bo Rein's little plane went down in the ocean. He had been the Louisiana State football coach barely a month. At 34, he was on the rise in his career, up to LSU from North Carolina State. It was to be a 57-minute flight from Shreveport, where he made his sales pitch to a teen-age kid who might help make LSU a big winner -- a 57-minute flight to Baton Rouge, where Rein lived with his assistants and film projectors and recruiting lists until his family moved down from Raleigh.

The thunderstorm sent Reins's little plane north instead of south, north toward Memphis, where it made a turn east -- for some reason on automatic pilot now, the pilot sand the coach unconscious. It passed through the night over North Caroline, over Raleigh, a ghost ship flying 40,000 feet over the coach's children asleep.

Bill Foster, the basketball coach at Duke, has been on airplanes when he knew better. Or should have known better. Rein's death hurts Foster, not because they were buddies; they were casual acquaintances here, driven men working 25 miles apart. Rein's death hurts Foster because it is a reminder of mortality. It is the ultimate cost that a man possessed might be asked to pay someday.

It was January or February maybe 10 years ago when Foster wanted to get to Buffalo. He needed to get to Buffalo. Up from little Bloomsburg (Pa.) State, Foster then was the coach at Rutgers, where success would move him to Utah and on to Duke, where a man can build the basketball team of his dreams. At Rutgers, Foster needed to get to Buffalo to scout his next opponent.

"My flight on Eastern was canceled because the Buffalo airport was closed down with snow," Foster said today. "So I'm running around, I,m telling the girl, 'I gotta get there, the train's not running, I can't get a bus, I gotta get there.' I'm running around, it's like I'm a crazy man.

"So the girl finds a Mohawk Airlines flight. It's going to Buffalo! I get on. We get up in the air and it's snowing a blizzard. I look around in the plane. There's only four of us on the thing.

"Suddenly, I realize how crazy it is. If Eastern isn't flying to Buffalo, what's Mohawk doing? We made it, but it was bumpy and terrible. The Buffalo airport was filled with people who couldn't get out.

"It was crazy. Mohawk Airlines.

"But you do it."

Bill Foster, 49, is a tall, lean man, all sharp angles. His face is a wound spring. His brow is furrowed, eyebrows pinched down, mouth tight. This is, of course, a game day. And not just any game day. Cursed North Carolina is here, visiting from Chapel Hill, 10 miles up Highway 54.

It is noon and Foster's face tells the truth. He is tight. At a Durham civic club luncheon yesterday, Foster told the people he wouldn't be good company. "I'm here, but, one, I'm really concerned that we lost to Clemson (Wednesday). The second thing is my preparation for Carolina. The third thing is the Bo Rein tragedy."

It is noon here, three hours before tipoff, and already 2,000 students are in Cameron Indoor Stadium. Some slept at the door overnight. Some had slept at the door since Tuesday. It's first come, first served for seats. They love basketball here, bastetball at first made wonderful by Vic Bubas and Art Hayman and Jeff Mullins, as lately made wonderful by Foster and Jim Spanarkel and Mike Gminski.

In 1978, Foster's fourth Duke team lost in the NCAA championship game to Kentucky. Because most of the players from that team were back last season, expectations were raised to a level that bothers Foster.

He wonders if he is the same person he used to be.

"People say I'm not as humorous as I used to be," Foster said. "Somebody once said I was whimsical. But now, even when we win, I immediately hop on to the next game. After we won the Big Four (tournament, six weeks ago), and it was my 300th coaching victory, I must not have looked too happy. A friend said, Geez, Bill, enjoy it.'"

The problem is that Foster wants to win a national championship.

"Just wanted to win the national championship, and yet keep everything else in perspective --that's tough," he said.

When Duke met Kentucky in the 1978 NCAA final much was made of Kentucky's "joyless" approach to the game. Foster's team, in contrast, was a bundle of jokes, all smills at having done such an unexpected thing as reaching the NCAA final.

"I can really see how unfair that was to Kentucky," Foster said. "You have to be serious. We saw it last year."

After that Cinderella year, Duke in the 1978-79 season was ranked No. 1 early but stumbled at a 22-8 season. no more jokes at Durham.

It is noon, three hours before the game, and already Bill Foster is thinking about how much it will hurt to lose today. Not that that he expects to lose. But all driven coaches know tha t fear of losing. Adolph Rupp, in his 48th year f coaching at age 70, said the prospect of losing bothered him so much that before games "my gut burns like I'd just swallowed a gallon of Ivy."

"I'm not a good loser, I take it out on myself," Foster said. "That's why I don't schedule anything for after a game. I've always been one to take each loss personally. I think about what I could have done to win, what I should have and could have but didn't.

"Luckily, I'm smart enough to not take it out on my family or my assistants. I just go driving around. I'll drive on the interstate and listen to country-and-western music. Sometimes I'll come back into my office."

How late does he stay?

"Oh, my goodness, I'd hate to tell you. Very late."

Then, a smile.

"But I haven't been doing it much lately. We're winning."