For years, travelers with the right certification have been allowed to fly with animals that provide emotional support and alleviate mental distress.

But, for the airlines, it’s been anything but a smooth ride.

They’ve heard thousands of complaints from other passengers who don’t want to sit near animals on their flight. And airline executives believe many of the pets, flying at no extra charge because of their designation, aren’t there to provide any therapeutic benefits at all. A cottage industry has emerged to sell certification to travelers who are trying to avoid paying extra fees.

Under a new federal rule announced Wednesday, emotional support animals will no longer receive special access to airplane cabins. Neither will service animals — those specially trained to perform a task to help someone with a disability — that aren’t dogs.

The proliferation of animals on planes prompted backlash from other passengers. For years, the U.S. Department of Transportation required that emotional support animals be recognized as service animals for passengers with disabilities who are protected from discrimination under the Air Carrier Access Act. The DOT has received more than 15,000 comments submitted online, by mail, fax, hand delivery or courier on the proposed rule.

More than 10,000 of the comments concerned emotional support animals. Some came from airline industry groups and thousands of individuals who want them to be treated as pets instead of service animals. But more than 6,000 commenters wanted emotional support animals to continue to be recognized as service animals or as a separate accommodation for those with disabilities.

The new DOT rule will recognize only dogs as service animals, not exotic animals like peacocks and rabbits.

That wouldn’t preclude airlines from allowing passengers to travel with uncertified animals as pets. But Atlanta-based Delta Air Lines charges $125 each way to bring a pet in the cabin, and it must be in a carrier that fits under the seat. Southwest, the second-largest carrier in Atlanta, charges a $95 pet fare each way. Delta and other carriers have not yet announced what their new policies will be under the new rule.

But Delta has been vocal about its concerns about emotional support animals on flights after several incidents, including an emotional support dog mauling a passenger. The passenger filed suit. The airline applauded the DOT for acknowledging concerns it and others had raised.

Delta, Southwest and other airlines over the past few years have put new restrictions on emotional support animals and service animals on flights in response to the problems and complaints.

“This rule will allow airlines to put safety first for all of our customers and employees, while protecting the rights of customers who have disabilities and need to travel with trained service animals,” Delta said in a written statement.

Delta said it is reviewing the new rule and will work with its advisory board on disability to implement it. “At this time, there are no changes to Delta’s current service and support animal policies,” the statement said.

Industry group Airlines for America said the number of passengers traveling with emotional support animals has skyrocketed in recent years, and that the misbehavior of some emotional support animals “has ranged from mauling and biting to urinating and defecating.”

The DOT’s definition of a service animal now will more closely align with the definition in the Americans with Disabilities Act. While untrained emotional support animals will lose special access, trained psychiatric service dogs still will be treated the same as other service animals.

The DOT also in the final rule confirms that airlines are prohibited from refusing to transport a service animal “solely based on breed.”

Delta is in violation of that rule, since it does not accept pit bull type dogs as service animals. Delta put in place its ban on pit bulls as service or support animals in 2018 after two employees were bitten by a passenger’s emotional support dog. The airline declined to comment on the DOT’s prohibition on breed bans.

Delta’s pit bull ban prompted opposition from the American Kennel Club, which has said in statements “it’s the deed, not the breed.”

The DOT agreed. “If the carrier determines that the animal is a pit bull, that fact, standing alone, would not be considered a proper basis on which to make an ‘individualized assessment’ of any threat that the animal poses. Instead, the carrier would be required to base its assessment on observable, objective factors such as its behavior and health,” the new rule states.

A DOT spokesperson said in a written statement that the agency investigates all disability-related complaints it receives about airline service, including complaints from passengers alleging an airline refused to carry their service dog based on the animal’s breed.

The changes will take effect 30 days after it is published.

Under the new rule, airlines also are prohibited from requiring that passengers with service animals check in at airports in person.

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