eeyore45 said:
are there any real life experiences with AA?
American is a good airline. Yes, I've had cases where our seat assignments have changed, either because the aircraft has been changed (from a 757 to an MD80, for example) or because the seating was reconfigured (when American reduced their previously generous legroom throughout their fleet).
If you're concerned, check your seats on AA.com. As long as an AAdvantage frequent flyer number is associated with your record and you've registered for AA.com, it's easy to check your future reservations and to pick or change your seats online.)
Regardless of your airline, it's a good idea to look for changes to flight times, flight numbers, aircraft, and seat assignments -- especially if you booked far in advance. If you ever see a change that you don't like, call the airline. My usual experience is that if you're nice to the telephone agents, they'll do their very best to do whatever they can for you.
manning said:
Not even that. They like to over book and if you are the unlucky one to be picked not to fly, you ain't going to get on the plane. The seat will be on another flight.
Yes, most airlines overbook flights. Although tourists with heavily discounted tickets are pretty much tied to specific flights, full-fare business travelers are free to change their plans -- and they often do so.
The airlines are rather sophisticated at knowing which flights can be overbooked, and by how any seats. Usually, overbooking simply means that flights are fairly full, even though a bunch of ticketed passengers didn't show up.
When more passengers show up at the gate than the capacity of the aircraft, the airline asks for volunteers. A typical offer would be a $300 travel voucher per passenger and a reserved seat of a later flight on the same airline or on a different airline. Usually, there are eager volunteers who are thrilled to accept the offer. Voluntary bumping hurts nobody. The airlines win because they can sell more high-fare seats. The volunteers win because they'll have free air travel on their next vacation.
Yes, there can also be cases of involuntary bumping. That's called denied boarding. It's quite rare. In the case of denied boarding, the unlucky passengers are entitled to real money, not just airline vouchers.
Quite frankly, I wouldn't worry about denied boarding. It's never happened to me or to anyone I know. It's not worth losing even a minute of sleep over.
On the other hand, delays and flight cancellations are much more likely to mess up air travel. These can be due to weather, mechanical problems, crew shortages, late aircraft arrival from another city, and air traffic control. Always allow a comfortable time cushion to allow for delays. For example, I would never book a flight to arrive just a few hours before a cruise or a wedding. (For a cruise, we always fly in the prior day.)
It could be my pre vacation jitters, and knowing how Murphy's Law likes to rear its ugly head!! 
I know when I call, they tell me what I want to hear, but I'm curious,
