CALGARY

The medical issue that caused an Air Canada pilot in flight to scream for help and demand off his plane was a previously undiagnosed ailment, says the airline.

The pilot was in control of Flight 584 from Calgary to Newark, N.J., last Thursday when passengers felt the plane jolt and saw him emerge from the cockpit holding onto a flight attendant while screaming for help and demanding to get off the plane.

He had to be restrained in a first-class chair until the plane, which was diverted to Toronto, landed and he was met by paramedics.

Air Canada could not provide specifics on the nature of the pilot's medical condition, citing privacy.

"I can say that it was an unforseen, previously undiagnosed physical ailment and he is currently on leave," spokeswoman Angela Mah said.

"All Air Canada pilots undergo regular medical checks as per Transport Canada requirements."

In fact, airline pilots receive mandatory checkups every six months once over the age of 40, and once every year before that, said president of the Air Canada Pilots Association Capt. Craig Blandford, who called the incident rare.

"We are a very, very healthy group -- in fact ... we live longer than most Canadians and partly because we live healthy lives and we get monitored by medical staff more," he said.

All pilots and air traffic controllers are also seen by a medical practitioner prior to receiving a medical certificate from Transport Canada, spokeswoman Kelly James said.

And every two years they undergo rigorous testing including heart monitoring and blood work, Brandford said.

"It's in the public's interest to make sure that those people operating the airplanes are healthier, safer than the average person," Brandford said, adding a peer program exists for pilots to address mental health issues, addictions and stress.

"By regulation and by law we have an obligation not to fly if we don't feel we are fit to fly."

However, pilots work long days while eating and sleep habits can be strained, which is why the association supports changing flight and duty times, he said.

The Transportation Safety Board is aware of the incident but not pursuing it.

katie.schneider@sunmedia.ca

On Twitter: @SUNKSchneider