Thanksgiving Eve, 1971. The day Northwest Airlines Flight 305 was hijacked by the notorious Michael Cooper.

Well . . . D.B. Cooper. Michael Cooper was the guy sitting a row ahead. And the similarity in names for a brief time made the Montana high school social-studies teacher the most wanted man in America."Afterwards, it scared the devil out of me," he says now. It was a lesson, Michael Cooper tells students, in how extraordinary things sometimes happen to ordinary people.

Northwest Flight 305 left Missoula at 1:13 p.m. on Nov. 24, 1971. Cooper, a 31-year-old teacher at Missoula Sentinel High School, ducked out of school early for the trip to his hometown of Sequim, Wash., where he now lives and teaches, for a family Thanks-giving.

The Boeing 727 stopped en route in Spokane, then Portland. There, the man known as D.B. Cooper boarded and took a seat in the last row of the aircraft, just behind Michael Cooper.

"At the time, I thought the guy in the back row was making a pass at the stewardess," he said. "All the way from Portland to Seattle, she sat next to him and they seemed to be in deep con-ver-sa-tion."

To Mike Cooper's consternation, the plane overflew Seattle and began circling. After a maddening 21/2 hours, the plane landed, taxied to the end of the runway and parked.

A fuel truck drove to the right side of the airplane. The first-class stewardess came down the aisle with a cream-colored, cotton sack so heavy that it tipped her backward. It was, Cooper said, very clearly a sack of money: $200,000. Next came parachutes, which the hijacker intended to use - and apparently did use - to jump out of the airplane after it flew off again.

Neither the hijacker nor the sack of money has been found in the 25 years since.

On the runway at Seattle, however, the passengers knew nothing of the hijacker's plan. They left the plane through the front door and crossed the runway to an airport bus.

That's when Michael Cooper became entangled with D.B. Cooper.

"FBI agents were waiting for us in the bus and began to take roll of the passengers," Michael Cooper remembered. "The agent called D. Cooper and nobody answered. He called again and again nobody answered.

"Finally, I spoke up and said, `I am M. Cooper, Michael.' And the agent proceeded down the list alphabetically."

Later, Cooper realized that the agent had counted D. Cooper as among the passengers on board the bus, but not M. Cooper. When the roll call ended, only M. Cooper remained unaccounted for - the presumed hijacker.

The busload of passengers went next to a waiting room where each was interviewed by FBI agents. Michael Cooper spoke with three agents, providing them with his Montana driver's license, telling what he had seen of the man in the last row and was then excused.

"My sister was at the airport waiting for me," Cooper said. "We were supposed to go downtown and pick up my car, which had been shipped from Germany where I had been a Fulbright Exchange teacher the year before. But by then, the garage had closed, so my sister dropped me off at her house and went to a party."

Alone in his sister's house, Cooper could scarcely believe the events of the afternoon just past. Or what he saw when he switched on the television for the 10 o'clock news.

"The top news story, of course, was the hijacking," he said. "I was watching the footage, when one of those messages appeared along the bottom of the screen saying that the FBI was seeking Michael Cooper, a high school teacher from Missoula, Mont., in connection with the hijacking."

"This can't be true," Cooper said to himself. "And I just got up and went to bed. It was just too much for me to deal with."

Which was, of course, a mistake.

Back home in Missoula, telephones were ringing and speculation was rising. Newspaper and radio reporters were on the phone to Cooper's wife. Other callers questioned his parents in Sequim. No one had heard from Cooper after the plane landed, as his sister had no telephone.

No, they had to say, they did not know Cooper's whereabouts.

The FBI called school administrators, including Don Harbaugh, then assistant principal at Sentinel. But Cooper had not told Harbaugh or principal Joe Roberts that he was leaving school early. Instead, he had asked another teacher to cover his last class.

Harbaugh remembers the late-night telephone call: "The FBI agent was most emphatic. He said they had positive identification that Mike Cooper had hijacked an airplane between Seattle and Port-land."

"My brain was reeling," Harbaugh said. "I remember thinking, `You mean Mike Cooper checked out of school early to hijack an airplane? Say what?' "

By then, the account was being broadcast over Missoula radio stations, and there was considerable speculation.

"People were talking about how Mike's car was over in Seattle and how someone saw him making a withdrawal at the bank and how he hadn't told us about leaving school early," Harbaugh said.

Within a day, the news reports changed the identity of the hijacker to D.B. Cooper. But there was never a follow-up call or apology, either to school administrators or to Michael Cooper.

"I expected at least a comment about why the error was made," Cooper said. "But I never heard anything."

There was, however, "endless harassing" when Cooper returned to Sentinel the following Monday morning, Harbaugh said. "We had no mercy. For months, we called him `D.B.' "

Cooper began telling the story of Flight 305 while he was still at Sentinel and continued when he moved home to Sequim. In his 20 years at Sequim High School, the storytelling has been an annual event, shared now by two generations of students, parents and children alike.

The tale is also, Cooper said, a cautionary one. "You can't predetermine the things that happen. Every time I get on an airplane, I wonder if something unusual is going to happen."

"Sometimes, kids think that big things happen only to famous people," he said. "But I'm just an ordinary schoolteacher."

With an extraordinary story.