ACCORDING to the Air Carrier Access Act, pigs might indeed fly. Technically so might dogs, cats, miniature horses, kangaroos, possums, parrots, hamsters, ducks, turkeys, ferrets, lizards, snakes, turtles and a variety of other animals seldom seen at 35,000 feet. Although individual airlines have policies that bar many of these creatures from boarding, the Air Carrier Access Act, established in 1986, prohibits commercial airlines from discriminating against passengers with disabilities. Differentiating between those with genuine disabilities, who are allowed to travel with service animals, and those seeking a free flight for pets, is the responsibility of airlines.