First findings: Sunwing Diversion Due to Fumes not fire
Re: Preliminary findings regarding the Sunwing Flight 326 at 6:32 from Ottawa to Varadero with 170 passengers
The smoke passengers saw coming from the air vents of the Boeing 737 was vapor from excess de-icing fluid. The smell described by the passengers was similar to engine coolant. Oxygen masks did not deploy.
The pilot returned to the runway at 7:00 a.m. No smoke or fire was found (obviously) because the vapor was not smoke at all, but evaporating coolant that had gotten into the plane via a vent.
The investigation is ongoing.