The aircraft was on its final approach to Pearson airport when the pilot told air traffic control that he had to abandon the planned landing because of "flight control" issues.
Police were alerted at 6:30 a.m. ET., and set up a staging area with officers and ambulances on standby, according to Const. Fiona Thivierge with Peel Regional Police.
The plane circled over Lake Ontario until it determined it was safe to land.
"They landed without incident, fortunately,” Thivierge said.
Thivierge said she did not know the specific problems with the Airbus 320 plane.
None of the 93 people on board were injured, the airline and police said.
Flight AC1174 left Edmonton at 1:10 a.m. MT and arrived in Toronto at 7 a.m. ET.
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