If you've already purchased tickets on Air Canada, you may be eligible for same-day standby status. In other words, if you show up at the airport early on the day of your flight, you can stand by for open seats on earlier flights to the same destination, or stand by for an upgraded seat on your original flight. Whether you'll pay a fee for that opportunity – and in one case, whether it's available at all – depends on the type of fare you've purchased.

No-Fee Standby Tickets

Regardless of whether you're flying within Canada or to the U.S., full-fare tickets entitle you to same-day standby status at no charge. Full-fare ticket classes include Economy Latitude, Premium Economy (flexible) and Business Class (flexible) or, if you're traveling on Air Canada's low-fare Rouge planes, Premium Rouge.

Some Discount Fares Allowed

Even if you purchased a discounted fare, there are a few conditions under which you can still get free same-day standby status. If you're flying within Canada, same-day standby is complimentary on Rapidair commuter routes and on Air Canada flights between Calgary, Alberta; Edmonton, Alberta; and Vancouver, British Columbia. If you're traveling to the U.S., same-day standby is free for flights between Toronto Pearson and JFK, LaGuardia and Newark airports. Discounted fare classes include Economy Tango, Economy Flex, Premium Economy (flexible) and Business Class (flexible).

Stand by for a Fee

If you purchased a discounted fare class and don't fit the previous exception, you'll have to pay a fee for exercising the same-day standby option. Here's another catch you should be aware of: On Rouge flights, same-day standby is only available for premium fare classes. It simply isn't an option for the lower fare classes.

Things to Keep in Mind

Air Canada's standby service is available on the same day as your flight – not starting a strict 24 hours before, as is sometimes the case for other airlines. You can't fly standby if you've already checked your bags, and, in fact, the type of flexibility standby flights require is much easier if you can manage with only carry-on luggage. And, of course, standby seats and upgrades are subject to availability. Ultimately, your best tools in getting one are to show up as early as you can, pack lightly, join the Aeroplan loyalty program to show your value as a customer, and be pleasant and polite to the customer service agents you deal with.