The captain of a Continental Airlines flight en route from Brussels to Newark died during the trip, but the flight landed safely with two co-pilots at the controls.
A doctor who examined the pilot said he likely died of a heart attack.
Dr. Julien Struyven, a cardiologist, said he responded Thursday to an announcement made on board Continental Flight 61 asking for doctors.
He examined the captain, who was already dead, and concluded that heart failure likely killed him. Struyven said there was "no chance at all" of saving the pilot, though he did use a defibrillator to try to resuscitate him.
Continental Airlines would say only that the pilot died of natural causes Thursday on the flight from Belgium to New Jersey.
Two co-pilots took over flying the Boeing 777, said FAA spokesman Les Dorr.
The plane with 247 passengers aboard landed on time just before noon at Newark Liberty International Airport. It left Brussels at 9:45 a.m.
Passengers weren't told of the pilot's death in flight. About midway through the trip, an announcement was made asking if any doctors were aboard, and several passengers approached the cockpit.
There were two first officers aboard the flight who flew the plane after the captain died.
Continental Airlines released a statement saying the deceased Newark-based pilot was 60 years old, had 32 years of service with the company and died in flight of natural causes.
"The crew on this flight included an additional relief pilot who took the place of the deceased pilot," Continental said. "The flight continued safely with two pilots at the controls. The company has been in touch with his family and we extend our deepest sympathies."
FAA spokeswoman Arlene Salac said the airline alerted federal authorities around 10:30 Thursday morning that Flight 61 was being flown by two co-pilots.
Martha Love, a passenger who was sitting in the first row of the plane, said passengers weren't told exactly what was going on in the cockpit.
"No one knew," she said.
She only became concerned when after the plane landed, she saw fire trucks and emergency vehicles lined up along the runway.
Simon Shapiro, another passenger, was also unaware of the drama.
"I didn't hear anything or see anything," Shapiro said. "I was wondering why there were so many cops."
As a precaution, the airport's emergency crews were sent to meet the plane.
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-Miller International Airport.
The Associated Press contributed to this report.