The only inkling passengers had that something was wrong on the Continental Airlines flight over the Atlantic Ocean was when an announcement came over the loudspeaker asking if there was a doctor on board.
Otherwise, flight attendants continued to serve snacks. Passengers read magazines and watched movies. And the flight kept on its schedule.
But in the cockpit, the 60-year-old captain had died of a suspected heart attack and two co-pilots took over the controls. The 247 passengers aboard did not learn what had happened until the flight from Brussels landed safely Thursday and was met by fire trucks, emergency vehicles and dozens of reporters.
"I was shocked," said Dora Dekeyser of Houston. "Nobody knew anything."
"We weren't panicking. I never thought it was something as serious as this. We were relaxed," said Dekeyser's granddaughter, Stephanie Mallis, 18, of Lansdale, Pa.
After the crew of the Boeing 777 asked if there were any doctors aboard, several passengers approached the cockpit, including a doctor who said the pilot appeared to have suffered a heart attack.
Dr. Julien Struyven, 72, a cardiologist and radiologist from Brussels, examined the pilot in the cockpit and tried to revive him using a defibrillator. But it was too late.
"He was not alive," Struyven said. There was "no chance at all" of saving him.
The dead pilot was based in Newark and had worked for Continental for 32 years, the airline said. His name was not immediately released.
Tom Donaldson, a former leader of the Continental pilots' union who currently flies Boeing 767 jets for the airline, said pilots must pass an extensive physical every six months to remain qualified to fly. The exam includes an electrocardiogram, blood pressure check and a vision test.
For long routes such as trans-Atlantic flights, a third pilot is aboard to permit the captain or first officer to take rest breaks.
Donaldson said there is no specific training on how to react if a crew member becomes incapacitated, but any one of the three pilots is fully qualified to operate the jet.
"Clearly you want another set of eyes watching when you're going down a checklist, but you're capable of flying the airplane yourself," he said. "You can put the gears down, put the flaps down and carry out your other duties by yourself in an emergency."
Air France pilot Hugues Duval, 29, said his co-pilot training included an exercise in which he had to take off and land without a captain.
"It's not a drama. If the captain is ill or incapacitated, you make sure he isn't blocking any controls or the wheel," Duval said in Le Bourget, France, where he was attending the Paris Air Show.
"After you ask for priority to land, you can also ask in the cabin if there is another pilot on board. In case you need help reading the checklist or taking the radio. I did it in a simulator," said Duval, who flies the Boeing 777 but was at the air show to do stunt flying.
On Thursday's flight, Martha Love of Greenwich, N.J., was sitting in the first row of the plane. She said passengers were not told what was going on.
"No one knew," she said. She only became concerned after the plane landed, when she saw emergency vehicles lined up along the runway.
Simon Shapiro, a passenger from the Brooklyn region of New York City, was also unaware. "I didn't hear anything or see anything," Shapiro said. "I was wondering why there were so many cops."
Passenger Kathleen Ledger, 45, of Bethlehem, Pa., said she learned about what happened when her cell phone rang after landing.
"My husband called me and told me," she said.
She was impressed with the way the flight crew handled themselves and did not think passengers needed to be informed of the death during the flight.
"They did an incredible job," she said. "I would have done the exact same thing."
In 2007, another Continental pilot died at the controls after becoming ill during a flight from Houston to Puerto Vallarta, Mexico. It landed safely with a co-pilot at the controls after being diverted to McAllen, Texas.