When Sheffield began threatening about bombs and blowing up the plane, Kennedy said, "We knew it was real."
"Guys were trying to talk him down and it wasn't happening," Kennedy said. "It was getting worse. He said, 'I'm going to take the plane down and you're going to hell with me. I'm going to blow this plane up.'"
Kennedy, who was sitting in the second row in first class, did not know if Sheffield had dynamite on him, he just knew he was moving aggressively toward the door of the cockpit.
"I elected to get unbuckled to take him out, as did the other guys," Kennedy said. "That's the choice we made without talking."
Kennedy stood from his seat and Sheffield threw water on him. Another passenger flashed his wallet at Sheffield as if he were an air marshal, and then a bullrush ensued.
Once Kennedy and seven other passengers restrained Sheffield, they had trouble binding him up. He broke free from a belt that had been wrapped around his wrists, in addition to plastic ties that were used to try and restrain him. Finally, they managed to get him under control using seat belts that flight attendants use for their in-flight demonstrations.
"I had his left arm, trying to pull it out," Kennedy said. "He was strong. I mean, I think I'm sort of strong, but he was strong. I finally got his arm back. Then we held that."
The 20-minute disturbance caused the flight to be rerouted to Albuquerque, N.M., where, according to a report by CNN, it landed at approximately 3:37 a.m.
"We were over El Paso; having managed at Albuquerque, I knew we were close," Kennedy said. "I knew it wouldn't be too long."
After passengers deplaned, Kennedy and the other seven who apprehended Sheffield had their depositions taken by officials, and the plane was screened for bombs.
According to the CNN report, nothing suspicious was found on the flight that landed in Tampa at approximately 9:20 a.m. ET, more than three hours past its scheduled arrival.
"Every one of those guys was great, all seven of them," Kennedy said. "If somebody says they're going to blow up the plane and they're acting irrational, you've got to do something."