New Year's Day 2018 has been a mess at Canadian airports

Between the nationwide deep-freeze, snowfall in Toronto and absent crews, the first day of 2018 was not a happy one for many travelling by air.

Air Canada issued a "travel alert" early in the day and has waived change-fees for those flying from Toronto's two airports, Trudeau Airport in Montreal, MacDonald-Cartier Airport in Ottawa and Calgary International Airport.

The extreme cold weather slowed down operations at many airports since it meant that aircraft had to be constantly de-iced, a highly time-consuming process that can create delays.

As of 6:30pm, 18 flights due to depart this evening from Trudeau Airport were delayed, and three had already been cancelled.  It was even worse in the early afternoon, when delays reached as much as five hours at some of the country's busiest airports.

Complicating matters is snow in the Greater Toronto Area that has slowed operations at Canada's busiest airport.  Nearly 500 flights had been delayed or cancelled at Pearson Airport as of a few hours ago, according to FlightAware.  That is having a cascading effect on flights across the country.

WestJet is also blaming some of its delays on crew issues, offering their "sincere apologies" to all impacted passengers.