Three Porter Airlines flights and an Air Canada flight were all forced to make emergency landings over the past 24 hours.

Porter Airlines flight PD539 left Toronto's Billy Bishop City Airport at 7:30 p.m. Sunday en route to Sudbury but was diverted to Pearson Airport after the crew detected smoke in the aircraft.

Brad Cicero, a spokesperson for Porter Airlines, said that there was no indication of a fire.

"One of the two engines was shut down using standard procedures and the aircraft landed safely," Cicero said in an email. "Passengers were bused to the terminal."

Medical personnel attended to two passengers for suspected anxiety, Cicero said, adding that hotel accommodation was being arranged for the 74 passengers on board till the next available flight.

A Porter flight from Thunder Bay to Toronto was also diverted to Pearson Airport as a "precaution" based on something the captain noticed in the cockpit. Cicero said the circumstances surrounding this emergency landing were unrelated to flight PD53. 

Smoke was also detected on board a Porter flight from Toronto to Washington D.C. on Sunday morning, causing the flight to be diverted to Williamsport, Pennesylvania. Again, no injuries among the 66 passengers on board were reported.

Air Canada also experienced some trouble Monday morning. A plane from Calgary to London's Heathrow Airport was diverted to Toronto as an "abundance of caution" after an electric-related smell was detected in the cabin, according to Air Canada spokesperson Angela Mah. There were approximately 200 people on board the Boeing 767 and no injuries were reported.

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