Washington, Oct 6 (IANS): An American Airlines pilot died of a heart attack during flight, prompting the co-pilot to make an emergency landing of the aircraft with 152 people on board, the media reported on Tuesday.

Captain Michael Johnston, 57, was flying the plane on Monday from Phoenix to Boston when he fell ill, CNN reported.

The Airbus 320 had to be diverted to Syracuse.

Crew members "took extraordinary care of Mike, each other and our customers," airline chief Doug Parker said in a statement.

"We couldn't be more proud of the teamwork this crew showed during an extremely difficult time."

An autopsy and preliminary toxicology tests "showed that the death was the result of natural diseases," the medical examiner's office in Onondaga county, New York, said.

The pilot's wife said he had a double bypass surgery in 2006. She said she was told that he would likely die of a heart attack.

Those on board knew something was wrong when a woman's "quivering" voice came over the intercom, alerting them the pilot was sick, a passenger said.

"If it wasn't for the co-pilot using a cool head," the passenger said, "it might have been more disastrous."