The JetBlue captain's co-workers tried to calm him as he became more jittery, coaxing him to the back of the plane while making sure - above all - that he didn't get back near the plane's controls.
Then, he sprinted up the cabin's aisle - ranting about a bomb, screaming "They're going to take us down!" and urging confused passengers to pray.
"Nobody knew what to do because he is the captain of the plane," said Don Davis, the owner of a Ronkonkoma, N.Y.-based wireless broadband manufacturer who was traveling to Sin City for a security industry conference.
"You're not just going to jump up and attack the captain," Davis said.
But four men did tackle the pilot, pinning him to the floor for more than 20 minutes while the co-pilot and an off-duty pilot who was aboard landed the plane in Amarillo, Texas.
"Clearly, he had an emotional or mental type of breakdown," said Tony Antolino, a security executive who sat in the 10th row of the plane and tackled the pilot when he tried to re-enter the cockpit.
"He became almost delusional," Antolino said after arriving in Las Vegas from Rick Husband Amarillo International Airport some six hours after schedule.
Josh Redick, who was sitting near the middle of the plane, said the captain seemed "irate" and was "spouting off about Afghanistan and souls and al-Qaida."
The airline described the incident as a "medical situation" involving the captain of JetBlue Airways Flight 191 from New York's John F. Kennedy International Airport. Airline officials said he was taken to a hospital.
"It was a scary situation," said Charlie Restivo, an employee of Davis' who traveled with him and sat in the plane's fourth row.
"It was like a movie, it really was," he said. "It just didn't look real."
The outburst came weeks after an American Airlines flight attendant was taken off a plane for rambling about 9/11 and her fears the plane would crash. An aviation expert could recall only two or three cases in 40 years where a pilot had become mentally incapacitated during a flight.
Gabriel Schonzeit, who was sitting in the third row, said the captain said there could be a bomb onboard the flight.
"He started screaming about al-Qaida and possibly a bomb on the plane and Iraq and Iran and about how we were all going down," Schonzeit told the Amarillo Globe-News.
"A group of us just jumped up instinctually and grabbed him and put him to the ground," Antolino said.
The Federal Aviation Administration said the co-pilot had locked the cockpit.
An off-duty airline captain who was a passenger on the flight entered the flight deck and took over the duties of the ill captain before landing in Amarillo, the airline said in a statement.
Shane Helton, 39, of Quinlan, Okla., said he saw emergency and security personnel coming on and off the plane as it sat on the tarmac in Amarillo.
"They pulled one guy out on a stretcher and put him in an ambulance," said Helton, who went to the airport with his fiancée to see one of her sons off as he joined the Navy.
Authorities interviewed each of the passengers once they had landed and left the plane, said 22-year-old passenger Grant Heppes, of New York City.
"I had no idea it was an employee until it really started happening," Heppes said. "I just assumed it was a passenger who flipped out."
The FBI was coordinating an investigation with the airport police, Amarillo police, the FAA and the Transportation Safety Administration, said agency spokeswoman Lydia Maese in Dallas. She declined to comment on arrests.
The flight left New York around 7 a.m. and was in the air for 3 1/2 hours before landing in Texas. The passengers boarded another plane for Las Vegas several hours later. That plane arrived in Las Vegas about two hours later.
John Cox, an aviation safety consultant and former airline pilot, said incidents in which pilots become mentally incapacitated during a flight are "pretty rare." He said he could only recall two or three other examples in the more than 40 years he has been following commercial aviation.
Airlines and the FAA strongly encourage pilots to assert themselves if they think safety is being jeopardized, even if it means contradicting a captain's orders, Cox said. Aviation safety experts have studied several cases where first officers deferred to more experienced captains with tragic results.
Unruly pilots and crew have disrupted flights in the past.
Earlier this month, an American Airlines flight attendant took over the public-address system on a flight bound for Chicago and spoke for 15 minutes about Sept. 11 and the safety of their plane, saying, "I'm not responsible for this plane crashing," according to several passengers.
Passengers wrestled the flight attendant into a seat while the plane was grounded at Dallas-Fort Worth International Airport; the flight attendant was hospitalized.
In 2008, an Air Canada co-pilot was forcibly removed from a Toronto-to-London flight, restrained and sedated after having a mental breakdown on a flight.
The FAA is likely to review the unidentified captain's medical certificate - essentially a seal of approval that the pilot is healthy. All pilots working for scheduled airlines must have a first-class medical certificate. The certificates must be renewed every six months to a year, depending on the pilot's age. To receive the certificate, the pilot must receive a physical examination by an FAA-designated medical examiner that includes questions about pilot's psychological condition. Pilots are required to disclose all physical and psychological conditions and medications.
Restivo said he thought it was clear that the pilot had suffered a medical episode.
"I don't think when he got up this morning that that's what he was intending to do," he said. "Unfortunately, I just think it happened to him."