An Air Canada flight from Toronto was forced to make an emergency landing approximately two-and-a-half hours into its journey after the flight crew noticed an electrical odour on the aircraft. 

According to the Aviation Herald, the Boeing 787-9 — which was performing flight AC824 — departed from Toronto Pearson International Airport at 3:09 a.m. on Dec. 2, and was due to arrive in Madrid roughly seven hours later. 

With 177 passengers on board, the aircraft was en route to the destination when the flight crew noticed a "burning electrical odour," which was soon followed by a "recirculation fan upper" caution indication on the plane. 

Following the indication, the crew declared PAN-PAN and landed in St. John's, Newfoundland, at 7:28 a.m. NST. The Transportation Safety Board of Canada (TSB) reported that the recirculation fan had a "failed bearing," and the fan was eventually replaced. 

Pan-Pan, which is short for "possible assistance needed," is an international radio distress signal, which is of less urgency than a mayday signal, and is used to communicate an urgent, but non-emergency situation to air traffic control. 

This might involve a situation where an aircraft requires rerouting or landing at a nearby airport, with the flight crew being able to handle the issue assisted with priority from air traffic control. 

In contrast, Mayday communication is urgent and requires immediate attention to an issue that threatens the lives of those onboard the aircraft. 

blogTO reached out to Air Canada for more information regarding the flight but did not receive a response in time for this article's publication.