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.

Emotional-support animals are defined as companion animals which, on the determination of a medical professional, provide benefit for an individual with a psychological disorder. These benefits include helping to calm people with post-traumatic stress or providing a sense of security for those suffering from anxiety. Unlike service animals, which provide an actual service such as guiding the blind, being ears for the deaf or alerting and protecting an epileptic on the verge of a seizure, the need for emotional support is harder to judge and therefore easier to fudge.

To fly with an emotional-support animal, a passenger needs a letter from a mental-health professional describing the emotional benefit the animal provides. These can be obtained cheaply and speedily online through a variety of websites that promise to send them overnight, along with certificates, collars, harnesses, vests and other paraphernalia proclaiming “emotional support animal”. After an incident earlier this year in which a woman flying from Newark Liberty Airport to Los Angeles attempted to board a United Airlines flight with her emotional-support peacock (they were denied passage), certain airlines, including United, now also require passengers to provide health and vaccination forms from veterinarians, as well as confirmation that their animals have been trained to behave properly in a public setting, which they do not always do.

Between 2016 and 2017, Delta Air Lines reported an 84% increase in animal incidents, most of which involved urination, defecation or aggressive or threatening behaviour by a support animal. A survey released on September 12th by the Association of Flight Attendants echoes these findings. Sixty-one percent of the attendants surveyed say they have worked on a flight where an emotional-support animal caused disruption in the cabin.

Passengers seated next to emotional-support animals have been put on oxygen because of allergic reactions to the creatures, flight attendants have been bitten when attempting to put drinks on tray tables and veterinarians have been summoned because the animals meant to be managing the anxiety attacks of their handlers have had anxiety attacks themselves. In an attempt to save the honour of her dog, which had relieved itself mid-flight, one passenger instead claimed that she herself had had an accident in the aisle.

“We want to ensure the safety and comfort of all of our passengers,” says Sara Nelson, president of the Association of Flight Attendants. “But the widespread abuse of the system ruins it for people with a legitimate need. Now anyone bringing an animal on board is being looked at with greater scrutiny.” Even so, the popularity of travelling with support animals is growing. Last year the number of support animals on United Airlines flights increased from 43,000 to 76,000. For many of those who are very attached to their pets, the perk of being able to fly with their animal (as opposed to sending it in cargo), and to pay nothing for it (a benefit extended to service and support animals under federal regulations), is worth fibbing for.

Celebrities from Miley Cyrus and Kim Kardashian to Oprah Winfrey and Bradley Cooper have praised their emotional-support animals. Jane Fonda, an actress, is rarely seen without her dog, nor is Ivana Trump, the former wife of President Donald Trump, who made headlines when she tried to pass off her six-pound Yorkie as a service animal, so that it could dine with her in an upscale Manhattan restaurant.

Under the Americans with Disabilities Act, emotional-support animals are not granted the same public-access rights as service animals, which is why they are seldom seen at the opera or on the laps of lunching billionaires. The Disabilities Act does entitle them to live in otherwise pet-free accommodation, a frequent source of tension with landlords, and to stay in hotels without their handlers having to pay extra deposits. But their public access is otherwise restricted. For now, at least, the sky really is the limit.