Southwest Airlines announced today that customers can begin purchasing tickets on June 1 for their dogs or cats, for in-cabin travel on flights starting June 17, 2009. This makes Dog Jaunt happy, since Southwest had been our favorite airline until we began traveling with Chloe.

Here are the highlights of Southwest’s new pet policy: The airline will only accept dogs and cats for in-cabin travel. Call Southwest to make a reservation for your pet, after you have booked your own travel. Up to five carriers are allowed on a flight; a passenger may board with one carrier, containing up to two pets of the same species. The carrier may be soft- or hard-sided and “must be small enough to fit under the seat in front of the Customer and be stowed in accordance with Federal Aviation Administration regulations.” Only cats or dogs are allowed, and they must be over eight weeks old. The cost is $75 each way. Here’s a YouTube video posted by Southwest about the P.A.W.S. (“Pets Are Welcome on Southwest”) program, featuring, yes, an adorable puppy and kitten.

It’s an okay policy, but a couple of things don’t make sense to me. Your pet must be “vaccinated,” the policy states (in the first sentence under the heading “General information on traveling with pets”), but no health certificate is required (FAQ “Do pets require any kind of vaccinations or documentation?”). And you may not move your pet out from under the seat in front of you at any time during the flight. I have no objection to a requirement that my pet remain entirely within her carrier, but I am extremely disappointed to learn that I will not be allowed to sit with her carrier on my lap.

(See Dog Jaunt’s list of U.S. airline pet policies.)