If you get to the gate within the check-in limit and you're told the flight is full, remind the gate agent that they are obligated to board the aircraft and ask for volunteers before they deny you your seat. Domestic bumping minimums are set by the U.S. Department of Transportation and stringently observed by the airlines. International travel is a little more complicated. International flights departing from the United States require the same compensation, but the airlines get a little more latitude. If you're bumped on a flight departing from abroad, you're subject to a web of rules that vary by country.
Airlines flying from many other countries offer far less.
Some offer nothing at all. Generally, the compensation holds value for one year. These are general policies, but keep in mind that most gate agents are allowed to use some discretion in what is offered. Vouchers can be issued in anyone's name and that person may reassign the value to another person at a later date. Tom Parsons is editor of Best Fares Magazine .