Bobby Cervantes at the Amarillo Globe News gives two passengers' graphic description, including that a lot of passengers were going to--no joke--a security convention:

[....] The aircraft was carrying people bound from New York to Las Vegas, Nev., for a security convention, passengers said. The pilot went to a restroom, then emerged, “shouting, ‘Iraq, al-Qaida, terrorism, we’re all going down.’"

"It seemed like he went crazy,” said Gabriel Schonzeit, of New York City, who was seated in the third row and traveling to the security convention [....]

The crew kicked the pilot out of the cockpit, and he turned unruly, attempting to use the intercom system, which had been disabled, said Josh Redick, 41, of New York. The pilot later attempted to re-enter the cockpit, but his security code appeared to have been changed, Schonzeit said.

When the pilot began pounding on the cockpit door, a former prison security guard grabbed him by the neck and choked the captain until he collapsed, Schonzeit said. “We all knew in the front rows if he got back in the cockpit, we were going down,” Schonzeit said. The captain started pounding on the door when another passenger, a former prison security guard, grabbed the pilot by the neck and choked him until he collapsed.

“The pilot was a very large man, bigger than me,” said Schonzeit, who stands 6 feet, 3 inches and weighs 250 pounds. A flight attendant was elbowed in the ribs during the struggle to keep the captain subdued, Schonzeit said. The passengers tried to bind the captain’s wrists behind his back with a zip tie, but he broke it, Schonzeit said. “I couldn’t have broken those,” Schonzeit said.

Passengers handed over their belts to bind the pilot’s arms, Schonzeit said [....]

And Manny Fernandez at the NYT reminds us about Jet Blue that:

The captain’s behavior was reminiscent of another embarrassing moment for the airline involving a crew member, when a flight attendant named Steven Slater opened a plane’s emergency chute, grabbed a beer from the beverage cart and slid down to the tarmac at Kennedy Airport in New York in August 2010 after getting into a dispute with a passenger who stood up before the seat belt light had been turned off.