Nav Canada has confirmed that its flight data processing system went down in Edmonton at about 8:35 a.m. Thursday, temporarily grounding flights in Edmonton and Calgary.
A "ground stop" was put in place, meaning no flights were allowed to take off, though those arriving were still allowed to land.
Ron Singer, a spokesperson for Nav Canada, said the flight data processing system was back up and running about an hour later, at around 9:40 a.m.
The ground stop has ended, he said, and now airports are dealing with a backlog as they catch up to get delayed flights moving.
There was no safety issue, Singer said, since air traffic controllers were still able to see and communicate with aircraft.
Earlier Thursday, some airline passengers in Calgary and Edmonton reported that their flights had been temporarily grounded.
"Calgary airport at a standstill," Ian Austen, the New York Times reporter for Canada, wrote in a tweet Thursday morning. "Air Canada says that air traffic control system in Edmonton has failed and is being 'rebooted'."
"Our pilot has informed us Edmonton Airport is having major computer issues with air traffic [control] and no planes leaving #YEG #YCC," Stephanie Carvin, an assistant professor Carleton University, said in a tweet from Edmonton.
Calgary airport sent out a tweet at 11 a.m. that confirmed Nav Canada systems were back online.
The airport advised travellers to continue to check flight times with their airlines, as the system gets back to 100-per-cent operation.