An Air Canada Boeing Co 737-8 Max en route between Arizona and Montreal with three crew members on board suffered an engine issue that forced the crew to divert the aircraft to Tucson, Arizona, the Canadian airline company said in an emailed statement on Friday.

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Shortly after the take-off, the pilots received an “engine indication” and “decided to shut down one engine,” an Air Canada spokesman said.

“The aircraft then diverted to Tucson, where it landed normally and remains.” The incident took place on Dec 22.

Modern aircraft are designed to operate with one engine and our crews train for such operations.

Air Canada

The crew received a left engine hydraulic low pressure indication and declared a PAN PAN emergency before diverting the flight, Belgian aviation news website Aviation24.be here reported.

“Modern aircraft are designed to operate with one engine and our crews train for such operations”, the Air Canada statement added.

In a response to a Reuters request for comment, a Boeing spokeswoman referred to Air Canada for information on the incident and did not provide any additional comment.

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Boeing and operators are bracing for heightened scrutiny as the MAX returns from a 20-month safety grounding, but safety experts say such glitches are common and usually go unnoticed.

The MAX was grounded following two crashes linked in part to flawed cockpit software. The engines were not implicated.

The United States lifted a 20-month-old flight ban on the 737 MAX last month, with the US Federal Aviation Administration outlining details of the software, system and training upgrades Boeing and airlines must complete before carrying passengers.