Image caption The pilot association says a third pilot must be mandated for taxing overnight flights

Fatigue led a pilot to send a passenger plane into a dive over the North Atlantic, injuring 16 people last year, Canadian authorities say.

The drama began when the co-pilot of the Air Canada flight from Toronto to Zurich woke up and wrongly believed the plane was on a collision course.

He mistook the planet Venus for another plane. Passengers without their seat belts on were thrown from their seats.

Pilots are allowed to take short rest periods on overnight flights.

The report said that the pilot had failed to follow procedure for "controlled sleeps" of 40 minutes each, during the January 2011 flight.

'Confused and disoriented'

Canada's Transportation Safety Board also found that none of those injured during the 46-second drama were wearing seat belts, even though the seat-belt sign was on.

I hit the top of the ceiling and fell back to the ground Louisa Pickering , Passenger

According to the investigation, a co-pilot was woken, after a 75-minute nap, by the captain's report of their flight position.

At the time, a US Air Force plane was flying in the opposite direction about 300m (984ft) below them.

The "confused and disoriented" co-pilot heard the standard cockpit warnings from the other plane's approach and thought it was heading directly for his passenger jet.

The pilot pushed the plane into a dive, overriding the auto-pilot, to avoid what he thought would be a collision.

The plane dived 120m before the captain regained control.

Captain Paul Strachan, president of the Air Canada Pilots Association, said the real issue was the need for a mandated third pilot on overnight eastbound flights.

"What if something happens to the other pilot during that 40 minutes?" Capt Strachan told the Canadian Press.

"The only reason there isn't a third pilot on that flight is so they don't have to pay a third pilot."

Louisa Pickering, a passenger on the flight, said she was sleeping when she was thrown out of her window seat and slammed into the ceiling.

"I hit the top of the ceiling and fell back to the ground," she said. "After that it was kind of chaos."

Of the 103 people on board, 14 passengers and two flight attendants were injured.

Seven of those hurt were brought to hospital for treatment when the plane landed in Zurich.