How much time do you have for those cats to diet?

Seriously, my 16.5 lb Maine Coon can not fit into a carrier approved for in-cabin use: we took him to PetCo and tried out a couple. He was too cramped and quite miserable, even though he likes to sleep in very small containers at home - cats!

Anyhow, the rules on DL's website state that the cat "must fit comfortably" which seems to be change from the old "must be able to stand up in the carrier" rule. Check with Delta by phone to see exactly what carrier specs they use now, but I doubt 20 lb'ers will make it, especially for what will be a 15 hour or more trip, by the time you figure in check-in, security, waiting to board, flying, arrival, etc.

The web page on pets also has 2 other warnings you might want to check into: (sorry I can't link to the page, it didn't show a direct url)

1. Business Elite - due to the new flat bed design, many planes can no longer take pets in BE so if you want to bring a pet you must consult Delta in advance to find out the configuration of the plane before booking for the pets

2. pets in cargo - no snub-nose or pug animals, which means no Persians, no Himalayans. Our British Shorthair would definitely not be able fly cargo - the way her nose is, she wheezes at sea level, forget 30,000 ft in the cargo hold.

If the cats are compatible, you might be able to group them together in one kennel in cargo, but I personally would be reluctant to do so. I just don't see a way to put cats of that size in carriers under a seat.

Good luck!