The airline operating a flight from Ottawa to Cuba that was forced to make an emergency landing this morning says de-icing fluid that got into a power vent is to blame for the white vapour that frightened passengers.

In a media release issued later Friday morning, Sunwing Airlines said glycol got into the aircraft through the auxiliary power unit vent, creating a haze of white, odourless vapour in the cabin just five minutes into the flight.

About 170 passengers were on Sunwing flight No. 326 to Varadaro, and the captain decided to turn the Boeing 737-800 around for an emergency landing at the Ottawa airport.

Paramedics got the initial call at about 6:40 a.m. ET, and the plane landed at the airport at about 6:53 a.m.

Two minutes later, firefighters said, the vapour had dissipated. Crews on the scene were checking the brakes on the plane, according to a media release.

An Ottawa Macdonald-Cartier International Airport Authority spokeswoman said all passengers were able to get safely off the plane.

There was no fire in the cockpit, the spokeswoman said, and no one was injured.

Odourless smoke filled cabin

The flight's passengers waited at the airport for several hours while Sunwing arranged a second flight to Cuba, which took off at about 12:35 p.m. ET.

The passengers told the CBC's Stu Mills that white, odourless smoke filled the cabin of the plane.

People started yelling "Fire!" and a flight attendant announced over the PA system that the aircraft would be making an emergency landing.

One passenger, Jamie Page, said he'd never felt an aircraft brake so forcefully before, and that it seemed as though the pilot wanted to get the plane back to the ground quickly.