Graphs from online flight monitoring software showed AC549 plummeting from more than 35,000 feet (10,000 meters) to just above 10,000 feet (3,000 meters).
And that's the graphical representation of a 23000 foot rapid descent over the course of 5 minutes. #ac549 #scary pic.twitter.com/cWWks2yhbp
— Paul Karwatsky (@PKarwatskyCTV) January 30, 2016
Business advisor and self-described frequent flyer Milun Tesovic did not lose his nerve, however, and snapped a photo of the scene, showing oxygen masks hanging all across the salon.
"#AC549 @aircanada that sucked. Lost pressure at 36k feet, rapid descend to 10k with masks on," Tesovic tweeted with a picture.
#AC549 @aircanada that sucked. Lost pressure at 36k feet, rapid descend to 10k with masks on pic.twitter.com/188c9xYOGd
— Milun Tesovic (@miluntesovic) January 30, 2016
The flight was diverted to Toronto, where it landed without incident.
#ac549 @flightradar24 #rapiddecompression. Watch altitude, UTC time, and flt path pic.twitter.com/JgcrRPaYIF
— R Sonny Sampayan (@rsonnysampayan) January 30, 2016
Air Canada said that the incident occurred due to a pressurization problem with one of the plane's air-conditioning units. It also confirmed in a tweet that arrangements had been made for passengers trying to make their way to Vancouver.
AC549 landed normally YYZ w/o incident due to pressurization problem w/ AC unit. Arrangements made for customers to continue to YVR asap.
— Air Canada (@AirCanada) January 30, 2016
The author of the photo, who by then had attracted the attention of many Canadian media outlets, later noted that the crew "did a great job," and no one appeared to have been hurt. He added in another tweet saying that his new flight, AC33, was already on its way to Vancouver.
Comment: Last month an Air Canada flight encountered freak turbulence in the skies above Alaska, injuring over 20 people on the Shanghai - Toronto route. Although the cause of the turbulence remains unclear, one Canadian specialist theorized that breaking "gravity waves" were a likely culprit.
Meanwhile, last week an American Airlines plane had to divert to Canada from its Europe-bound flight after encountering severe turbulence over the Atlantic.