A Heathrow worker, who wished to remain anonymous, told The Sun: "I've never seen anything like this in my life. There is no way the plane would have taken off in Canada without someone doing the final checks on it and they would have noticed if a wheel was missing.
"The proper checks could not have been carried out because these wheels are worth around £10,000 ($18,000) each and they don't simply just fall off.
"None of the passengers knew what had happened and neither did the pilot, he was in shock when he landed and was told about the wheel.
"Heathrow and Air Canada will try and keep this to themselves but that isn't right, they should inform the public because this could have been fatal."
The aircraft, which was due to be cleaned to provide a service back to Montreal at 1pm, was grounded and it is unlikely to be used for another three days.
A spokesman for Canada Air confirmed the incident and added that losing the wheel had "no impact on the safe operation of the flight".
