Calgary-based WestJet has chartered two aircraft — including a Boeing 747 jumbo jet — to clear the backlog of stranded passengers in Toronto.

The 747 will pick up 400 passengers and 1,100 pieces of luggage from Toronto's Pearson airport Thursday before returning to Calgary.

The airline is also adding 14 extra flights to its Thursday schedule.

Spokesman Robert Palmer says at one point WestJet had as many as 22,000 stranded passengers.

"We have not seen a backlog like this for many, many years," he said. "(It's) one of the more challenging weeks in recent memory for us."

The backlog was caused by poor weather in eastern North America that resulted in a temporary closure of Toronto's Pearson airport earlier this week.