I'm going to have trouble reading through all the posts in this thread because of my print disability. I see some issues coming up which might or might not already have been addressed, but in case not, I'll chime in.
1. Not all airlines or all flights permit pets in cabin. Some do, probably most do not. Those that do permit them require that they fit in carriers of certain dimensions. These dimensions will vary from airline to airline depending on how their seats are constructed and how fussy the airline is. They do not have to permit pets, so they can set whatever rules they want and you either accept them, leave the pet at home, or choose another airline.
Pets flying in cabin must remain in their carriers and under the seat throughout the flight. Every single airline policy I've read has specified that.
Some airlines will require ESAs and SDs to remain on the floor during take-off and landing. This is REASONABLE. This is a safety issue, just like buckling the seatbelt. In an emergency a dog can become an airborne projectile just like a purse or brief case. The dog is safer and better protected on the floor during take-off and landing and other passengers are safer from the dog, should the plane experience an emergency. Not all airlines do this, but many do. They are allowed to because it is a safety issue, just like they can make you take a window seat so you don't block another passenger from being able to escape in an emergency.
2. Annual letters for SDs are
required by regulation only for invisible disabilities (specifically for psychiatric disabilities), but not necessarily for those disabilities that are readily apparent. This is regardless of whether the animal is a PSD or ESA. 48 hours advanced notice is required by regulatory law for both PSDs and ESAs. Advanced notice for other SDs is not required, but is just plain good common sense because it avoids a lot of confusion and hassles. The DOT (who writes the regulations for the ACAA) does not distinguish between PSDs (task trained) and ESAs (not task trained) but does distinguish between PSDs/ESAs and all other kinds of SDs. They don't care. Yes, it is discrimination. Again, they've been told and they don't care. (Arguing with me about it being unfair won't change it, because I already agree, but that's the way it is so that's the way I report it.)
3. ESAs are permitted to ride in the cabin, even on flights that don't ordinarily permit pets, but must be under control. They are not required to be a certain size or to ride in a carrier, so long as they fit within the foot space assigned to the passenger. (The same is true of service dogs.) If the dog is observed at the gate not behaving appropriately, it can be barred from the flight.
NOTE: If your gear and credible verbal assurances aren't considered credible, they CAN ask any person with any disability and any sort of service dog for written documentation. Legally, they are allowed to. They tend to err on the side of being permissive, but don't count on it. The regs say that gear is an indicator, but it does not say that they must absolutely accept any dog that shows up in gear:
(1) Carriers shall accept as evidence that an animal is a service animal identification cards, other written documentation, presence of harnesses or markings on harnesses, tags, or the credible verbal assurances of the qualified individual with a disability using the animal.
(my emphasis)
"Evidence," not "proof." Evidence is, "A thing, a document, or the testimony of a person that bears on the truth or falsity of an assertion made in litigation..." If you're evidence sucks in a court of law, you lose. Doesn't matter that you have evidence, just how convincing it is. A cape on an unruly dog isn't very convincing evidence that the dog is a service dog. An unusual breed, and in particular a toy breed might automatically be suspect because of the high number of fakers.
4. Fitting in footspace:
If the service animal does not fit in the assigned location, you should relocate the passenger and the service animal to some other place in the cabin in the same class of service where the animal will fit under the seat in front of the passenger and not create an obstruction, such as the bulkhead. If no single seat in the cabin will accommodate the animal and passenger without causing an obstruction, you may offer the option of purchasing a second seat, traveling on a later flight or having the service animal travel in the cargo hold. As indicated above, airlines may not charge passengers with disabilities for services required by part 382, including transporting their oversized service animals in the cargo compartment. (69 FR 64393)
If your dog doesn't look or act professional, it can get you stopped. As with the ADA, they are ALLOWED to ask you what the dog is trained to do. If your explanation doesn't make sense, then they are allowed to insist on seeing documentation as a condition of letting you board. Regardless of disability. If you have documentation, this is a time to carry a photo copy with you as insurance. If you have a psychiatric disability, regardless of whether your dog is a PSD or ESA, you must carry documentation and must notify them at least 48 hours in advanced of scheduled departure of your intent to fly with a PSD or ESA. No it isn't fair! Yes, it is discrimination. But that's the way it is. That's the way regulatory law governing the access of PWDs to planes is written. It is the law. Sometimes laws suck too (consider taxes...). Why did this unfair change get made to the regulations? FAKERS. Too many fakers claiming their pets as ESAs or PSDs. And people think fakers don't hurt anyone.
All of that said, I've flown many times without a problem, without even a question other than what my dog does for me. Yes, I have an invisible disability (TBI with atypical seizures). I always have a very professional service dog with excellent training and behavior, I mark my service dog clearly (with a cape) and I use a traditional breed. I have had friends with non-traditional breeds stopped. I'm not trying to scare anyone, just prepare everyone. The goal is to reach your destination. If you are well prepared, you stand a better chance of achieving that goal in a timely manner than if you are not. If you have a non-traditional breed, you have even more reason to carry documentation. Just in case.