(CNN) -- Many frequent flyers can tell at least one story about running through the airport and barely making it on board their plane in time for takeoff. But, how late is really too late when it comes to air travel?

What many flyers don't know is that airlines can give your seat away if you don't check in 10 to 20 minutes before your flight departure time.

Passengers also get confused about when it is that you are actually "checked-in" for a flight.

"One common mistake that people make is they think that they're checked-in for the flight if they've simply checked their bags and that's not always the case," said Chris McGinnis, CNN business travel consultant.

It's best to find out the airline's requirements before your flight departs. Some airlines want flyers to check in at the front desk, while others say it's OK to check in at the gate, said Karen Cure, a spokeswoman for Fodor's Travel Publications.

If you arrive late and your seat has been given away, the airline will usually try to book you on its next flight.

"Go to the nearest telephone and call your travel agent or call the airlines and try to get yourself on the next flight. It may be that you can do it inexpensively (but) you may have to pay a premium," Cure said.

Airlines don't have to compensate you if you violate their rules by showing up late for your flight.

If you're so late that your reservation has been canceled, the airline may owe you a refund, but they can tack on cancellation fees. And, if your ticket is non-refundable, in most cases you are just out of luck.

In addition, remember that there are ripple effects: If the airline cancels one portion of your reservation, it may cancel the next leg or the return trip as well.

Based on a report from CNN's Business and Travel and Beyond. The segment appears weekdays on Early Edition at 7 AM (ET) and on Morning News at 10 AM (ET).