A pilot with Canadian low-budget airline Sunwing was arrested after he was allegedly found passed-out from alcohol prior to take-off.

The male pilot was said to have boarded the Boeing 737 flight - scheduled to have flown between Calgary and Cancun in Mexico - on Saturday, with 99 passengers and six crew on board.

But prior to departure, both gate staff and crew members indicated the pilot was acting strangely.

Police allege the co-pilot found the pilot passed out in the cockpit.

A Calgary Police press statement read: "Prior to departure, gate crew and crew aboard the flight noticed that the pilot was behaving oddly before he became unconscious in the cockpit.

"The pilot was escorted from the aircraft at which point he was taken into custody by Calgary police."

The statement added that initial tests showed the pilot was "severely impaired" by alcohol.

Police believe the pilot was anything up to three times over the legal alcohol limit.

A Sunwing spokeswoman confirmed the incident and praised the rest of the crew for handling what she called a "very unfortunate matter".