Pakistan International Airlines flight PK-782 had to return and make an emergency landing in Toronto, Canada, on December 7.
The Boeing 777-200, bound for Karachi, Pakistan, had to return after the pilot reported that the cabin was not pressurizing properly.
The plane landed uneventfully and was taken for examination.
The aircraft had first attempted to depart from Toronto on December 5 but returned immediately due to cabin pressurization issue. The technicians at Air Canada Hangers conducted maintenance after which it was cleared to take off again 2 days later.

Air Canada flight 549 made an emergency landing in Toronto, Canada, on January 29.
Copa Airlines flight CM-156 had to divert and make an emergency landing in Mexico City, Mexico, on October 18th.