"There is somebody at the cockpit door trying to get in, and I need some strong men to help!" the pilot said in German. In broken English, he added, "Help, bad passenger, need help!"

Mr. Sommermann, a native of Germany, was already out of his seat.

"It was a gut reaction," he said. "You jump up and run to the front."

There, in the aisle of the first class cabin, Mr. Sommermann witnessed a passenger in front of him tackle a man who was trying to beat down the cockpit door with his fists. "The scary part was the screeching," Mr. Sommermann said. "He was not really in his right mind. They were trying to force him down, and he wouldn't go down. His wife came running toward him. She screamed out, 'Don't hurt him, don't hurt him!' ''

Two other passengers helped pin the man down, and a doctor on board gave him two shots of Valium from the crew's in-flight kit.

The altercation took place Thursday over Colorado as passengers were watching the last 10 minutes of the Steve Martin movie, "Bringing Down the House."

For the remaining two hours of the flight, Mr. Sommermann, along with a U.S. Marine, and an airline crew member were asked to sit with the attacker, who was now handcuffed.

Mr. Sommermann said the man appeared to suffer from claustrophobia or fear of flying and repeatedly shouted, "Assume crash position!" as the plane made its descent into Los Angeles. When the plane landed, Mr. Sommermann said, the man checked himself all over, as if for reassurance that he wasn't injured.

His wife said they had buried his mother in Serbia the day before, and that her husband was under a tremendous amount of stress, Mr. Sommermann said. The couple were traveling with two small children.

"The woman was in shock," Mr. Sommermann said. "She said she had known him since he was 19 and he was not like this."

At LAX, FBI agents boarded the plane and arrested BojanPavkovic, 35, a citizen of New Zealand, on charges of interfering with a flight crew, a felony punishable with up to 20 years in jail upon conviction.

Sitting farther back on the plane, by coincidence, were two other Westmont employees -- David Marten, a chemistry professor, and Nancy Phinney, director of public affairs, both returning to LAX at the end of their vacations, as was Mr. Sommermann.

"We were all a little nervous for a few minutes," Ms. Phinney said. "But it was very interesting to see how quickly men of all ages responded, just racing down the aisle. The passengers dealt with it very well."

According to an FBI complaint filed Thursday in U.S. District Court in Los Angeles, the airline crew said that as Mr. Pavkovic pounded on the cockpit door, he screamed that he needed to talk to the pilots and said, "We all have to die."

In his own statement to the FBI, Mr. Pavkovic said he wanted the captain to announce over the public address system that he, Mr. Pavkovic, loved his wife. He said he thought the pilot might not be in the cockpit, and that he might have to fly the plane himself, though he does not know how to fly. Mr. Pavkovic told the FBI that what he did was stupid, but he wanted to prove to his wife that he loved her.

Mr. Pavkovic was taken to the MetropolitanDetentionCenter and appeared before a U.S. Magistrate Friday. He remained in custody. Another court hearing is scheduled for Tuesday.