WestJet says a Boeing 737 Max that was scheduled to fly from Calgary to Toronto on Friday returned to the gate before taking off due to a warning in the cockpit. A WestJet spokeswoman, Lauren Stewart, said that after the plane’s engines were started, its monitoring system indicated a “potential fault that needed to be verified and reset.”

The process takes time and requires an engine run, which the airline does not perform with passengers on board, Stewart said.

In the interests’ of passengers’ time, WestJet cancelled the flight and booked passengers on the next available flight to Toronto, Stewart said.

The aircraft has since been cleared by maintenance and will return to service as scheduled on Jan. 24, Stewart said.

The Max was cleared to fly in Canadian airspace on Wednesday after it was grounded for nearly two years following deadly crashes in Indonesia and Ethiopia.