A Porter Airlines pilot has been taken to hospital for assessment after being forced to turn his plane around because he lost consciousness. (Adrian Wyld/Canadian Press)

A Porter Airlines plane was forced to turn around Saturday morning after leaving Halifax for St. John's.

The pilot briefly lost consciousness shortly after the 10:30 a.m. takeoff, according to Porter Airlines president Robert Deluce.

"At 11:16 this morning, our control tower received a call from Porter flight number 243 that the pilot required medical attention," said Ashley Barnes, spokeswoman for the Halifax International Airport Authority.

It's unclear what was causing his condition, she said. "We just don't know at this point. It's still being investigated."

The co-pilot took over the plane before the pilot passed out, and it landed safely at the Halifax airport around 11:45 a.m.

The pilot managed to walk off the plane and into a waiting ambulance on the runway, Barnes said. He was taken to hospital for assessment.

Barnes could not say how many passengers were on the plane, but it seats 70 people.

All of the passengers remained on the plane while a replacement crew was found to resume the flight, which got underway again at about 2:30 p.m.

The 39-year-old pilot has 7,000 hours of flying experience, Porter's president said.

Deluce said his thoughts are with the pilot's family and friends. He also apologized to the flight's passengers for the delay.

Porter Airlines introduced St. John's as its newest destination on Oct. 5, as part of expanded service in Atlantic Canada.

It offers four daily round-trip flights between St. John's and Halifax, with service continuing onward to Ottawa and Toronto from Halifax.

Porter operates a fleet of 70-seat Bombardier Q400 turboprop aircraft.