My wife and I want to return early from Mexico. Can we show up at the airport - cancun - for american airlines a few days early and get a standy seat. The airline wouldn{t lose any money. thx

call american airlines.

Not usually - the same day, yes.

Fares on American Airlines to Cancun do not allow standby.Nor do Continental,Delta and probably most carriers.You can change the tickets as ong as there seats available usually for $100 each plus any fare differential.Mexico is international.Yes, they've got your money.But, more is better.

Same day standby does carry an official fee, but often on any number of carriers they will waive that fee. Agree it might be different for international travel, but for other than same day, you will have to pay.

No. Not possible on international flights.

Update: called our American Airlines Vacations number and they changed our flight for $100/ticket but upon arrival at the airport the check-in agent said we had not been charged. I'll believe that when I check my credit card statements.

Anyway, we didn't try the no-notice standby thing, but I don't see why that wouldn't work in theory. Maybe they charge you a fee, but it's probably no more than changing the ticket and it gives you the flexibility to hop on an earlier flight. In our case, we were giving up higher demand seats for lower demand seats (Sunday and Thursday respectively).

It might be they will decide not to charge you.
In general you are right: the airline does not loose any money as they take you to the same place in the same way but on another date !
What makes the difference is that flexibility on airfares is expensive and those who have a flexible or open ticket have already paid more at the beginning.
With some airfares you are even not allowed to change flight dates even by paying a fee: they are so restrictive and also so much cheaper that if you do not fly that day you loose all you money as not refundable !
This does not mean that you can anyway try at the airport and see what happens. Rules are not flexible but human beings are !