Hm. I've always wondered how they dealt with this situation. I guess those with severe allergies to dog/cat aren't necessarily expecting to find them on a plane. Some carriers don't take pets in the cabin, as I recall, and that may be one way to be sure. (Check carrier's web site for such info.) When they do allow them, there are several rules including a size limit, carrier must fit under seat and a limit of one or two per plane, depending upon airline and plane type. There's also a fee, and it must be reserved well in advance due to the restrictions, particularly the per-plane limit.
I can sympathize with both sides. I have a cat, and if I needed to fly somewhere with her, I'd want to take her in the cabin. I also have allergies, not to cat dander luckily, but to a couple other things, and certainly I know they can be not just uncomfortable but life-threating in some cases. Due to the nature of the reservation and extra fee paid for the pet, I have a feeling that the path of least resistance would be to reaccommodate the allergic person on another flight. That said, I suspect there isn't sufficient info given out about when there is an animal in the cabin. I think it would be a good idea for the airlines to volunteer this info without being asked, but for right now, it seems those with severe allergy are probably going to have to be proactive and ask well in advance. If you can find an airline that doesn't allow them (Southwest is one, though not an option if you're used to F!) you're safe, but I wonder if the others even have a policy for rebooking an allergic person. You may well have to fight for that even.
[This message has been edited by CrazyOne (edited 10-07-2002).]