Overbooking is regrettably the long standing practice of Air Canada.
Missing a holiday of a lifetime is really unfortunate. We’ve nearly experienced more dire circumstances travelling with small children when Air Canada attempted to bump us when we were connecting overseas from a codeshared flights.
Dan Gardner is right to profile his experience. I especially appreciate his underscoring that no matter how many steps he took as a customer - early online checkin 24 hours before the flight, arrival and in person checkin the airport well in advance, he and his son were still mysteriously taken off the flight at the gate at boarding with no explanation. The blithe disrespect that the staff at the checkin and gates have towards the travellers in such situations is one of the things that make flying with Air Canada so incredibly stressful.
Once upon decades ago, Air Canada used to offer vouchers for free additional flights as an incentive for travellers to agree to take a later flight. Now Air Canada feels it has the right to impose significant financial and personal cost on it customers without compensation, recourse or explanation.