Air Canada A330 Makes Emergency Landing in Montreal

Air Canada A330 Makes Emergency Landing in Montreal
Jiaqian AirplaneFan, CC BY 3.0 , via Wikimedia Commons

It has been revealed earlier this week that an Air Canada Airbus A330 bound for Lisbon made a u-turn & an emergency landing in Montreal due to multiple system failures.

Information has been released pertinent to this incident.

Below is what we know so far…

Air Canada AC812 To Lisbon: Emergency Landing in Montreal…

Air Canada A330 Makes Emergency Landing in Montreal
Data provided by

Air Canada flight AC812 is a routine scheduled flight between Montreal and Lisbon, and was the flight involved in the emergency incident.

The aircraft in question operating this flight on May 13 was C-GXZD.

As per data from, C-GXZD is a 10.1 year old Airbus A330-300 that started out life with Singapore Airlines in April 2014.

By June 2020, the aircraft was returned to Dragon Aviation Leasing, before being handed over to Seraph Aviation.

Air Canada took delivery of the aircraft back in May 2023.

Of the A330-300 variant, the airline has 19 of them in the fleet.

Furthermore, of that 19, all but four are in active service, offering an average fleet age of 17.8 years.

Air Canada flight AC812 departed Montreal at 2218 local time on May 13 and headed east towards Lisbon.

Upon reaching St. John’s, the aircraft made a u-turn back to the Canadian airport.

As per The Aviation Herald, it is understood the crew declared a “PAN PAN” due to multiple system failures.

It is understood both autopilots and multiple other systems were lost.

The root cause was the ADIRU #1 being faulty, which caused these system failures.

AC812 landed safely into Montreal without further incident after over four hours in the air.

Why The Aircraft Couldn’t Continue…

Air Canada A330 Makes Emergency Landing in Montreal
Makaristos, Public domain, via Wikimedia Commons

The ADIRU system, or Air Data & Inertial Reference Unit, is an important system on the aircraft.

This system acts as a single fault-tolerant source of navigational data for both pilots of an aircraft.

Such a failure, as we saw on Air Canada flight AC812, means that it couldn’t continue to Lisbon and had to return via an emergency landing into Montreal.

It can also cause the failure of autopilot systems, which is needed for continuous flight too.

With the aircraft also expected to go across the Atlantic Ocean also, it is definitely a risk not worth taking.

A330 Was Grounded for Two Days…

Markus Eigenheer, CC BY-SA 2.0, via Wikimedia Commons

Following the emergency landing by Air Canada flight AC812 into Montreal, the Lisbon-bound flight was cancelled and the aircraft grounded.

Data from RadarBox shows that C-GXZD returned to commercial service on May 15.

Since it’s return to service, it has operated flights to the following destinations:

  • Toronto
  • Bogota

It is expected to operate flights to Bogota again as well as to Casablanca in the next few days.

But for now, the issue remains solved, and everything looks to be in working order on the aircraft.

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By James Field - Editor in Chief 4 Min Read
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