Gadling

I recently retired from flying (after 18 years) and this is one of the problems I don't miss. Agents have told me that if a passenger is over 300 pounds and can not sit in just one seat they are supposed to pay for the second seat. Most carriers offer that second seat if it is availible for half price as they do for parents requesting to use an Infant seat. It is hard to discriminate against someone because he or she is "Fat" but it is also a safty issue. People who are too large to fasten a standard seat belt are not allowed to sit at window exits where the FAA will not allow seat belt extensions to be used. I had one passenger at a window seat who would have been blocked by the very large man next to him. In an emergency there was no way he could have gotten past him. I had to move him for safty sake.
About first class. We just can't give those seats away unless it is a true problem like the door is shut and we are ready to go. Delays cost the airlines more money than the public could ever imagin. Agents that have unusual numbers of delays can even loose their positions. All problems need to be solved before "Push-Back" and as quickly as possible and sometimes moving someone up is the only solution. Flight Attendants and Ground Agents will try to "reward" their Frequent Fliers first but when the time is short they usually move up the person who was the most accomidating and greatful. Winning through intimidation and bullying will almost always get you stuck in the worst seat in the back. Remember in just a few minutes F/As have to please about 100-300 people as fast and saftly as possible.

Sue,

That's really tough. I spent about 4 years commuting weekly by air and it happened a couple times where I was wedged next to someone too large for a seat. Once I was able to move to an open seat...Which is itself is an embarassing exchange..."Umm...I'm going to find another seat because you need both of these". The other time there I sat contorted and in discomfort for about 2 hours. I didn't bother the flight attendents because I've seldom seen a problem fixed by demanding they defy the laws of physics.

Complain to the airline after your flight or while you are still on the ground. Maybe you can get a different flight or at least a big chunk of miles.

While I understand they are busy and it is a touchy subject gate agents really should look to reseat those folks where they'll cause the least problems or ask them to take a less crowded flight.