Make sure the airline as comprehensive information and guidelines for traveling pets. They should have a phone number specifically dedicated to owners with flying pets. Continental, for example, has a dedicated phone line for pet travelers.
Get an appropriately sized, airline approved dog carrier. Dog carrier specifications include proper ventilation; no wire kennels; a dog carrier large enough for the dog to sit, stand, turn around and lie down comfortably; no wheels on the dog carrier; two empty food dishes in the dog carrier; absorbent material on bottom of the dog carrier, such as a blanket; properly closing dog carrier (no locks).
Consider weather conditions – You need a backup for in case the airline determines that weather conditions are too extreme for pet travel.
Your dog’s veterinarian will need to issue a Health Certificate within ten days of departure.
Flying can be very stressful to your pet. You have probably considered tranquilizers for your pet, but I have found that veterinarians do not recommend this except in extreme circumstances. A tranquilized pet can not pant in hot weather (panting helps cool them down) or shiver in cold weather (shivering helps warm the body). If you think your dog will be too stressed for flying, try to find an alternative.
Although there are very strict regulations about animals flying, bad things can still happen. I heard a story on the Bonnie Hunt Show, where the dog in the kennel was left exposed to the pouring rain as the luggage was being put in. As a result, the dog was wet, the blanket was wet, everything was wet for the entire plane ride as the dog rode in cold terror in the baggage compartment of the plane. Thankfully, the dog was okay, but very very stressed.