You can put your dog, cat, or other animal “under the plane.” Some types of aircraft have a pressurized cargo hold that maintains the same conditions as the cabin, where you'll be sitting. This involves booking in advance, as there are limited spaces, and paying a fee determined by the airline.
Depending on the airline, you can either bring your pet to the check-in counter to be taken away like a regular bag (this is an option on American and Alaska, among others), or take them to a separate cargo drop-off in a location separate from the airport, which you have to do if flying with your pet on United or Delta.
For each airline, you will need a health certificate from your vet from within 10 days of departure (for each flight—so if your trip is longer than 10 days, you'll need to get another certificate at your destination).
Alaska: You can either check or ship your pet as cargo. The airline claims they may refuse an animal if there are “extreme outdoor temperatures,” though no hard limits are listed.
American: You can fly with your pet as checked baggage on certain non-Airbus planes for $200 each way. The ground temperature cannot be below 45 degrees Fahrenheit (except with a letter from your vet), or above 85 degrees.
Delta: You can ship your dog or cat as cargo. The ground temperature cannot be below 20 or above 80 degrees Fahrenheit.
United: You can ship your dog or cat as cargo by taking them to a separate cargo location. It costs $338 per trip. Your pet and its crate must meet certain requirements. There are also location restrictions during certain months due to outdoor temperatures.
Be sure to check with your airline before flying for further restrictions that may apply to your specific flight.
The benefit of going through this process is that there is no weight limit–you can fly with your Great Dane as long as he's in a crate he can sit, stand, and turn around. There are no support requirements, meaning your animal does not have to be working in a service capacity to fly with you. You can also check any type of pet (except snub-nosed dogs like French bulldogs).
The obvious downside is the cost and convenience factor, especially if you have to go to an entirely separate location, away from the airport, to ship your animal.
The second option is to take your pet on the plane, under the seat in front of you. On some major airlines, such as Southwest and JetBlue, this is your only option—these airlines don't allow pets in the cargo hold at all. As long as your pet can stand up and turn around in a plane-approved carrier that fits under the seat in front of you, your buddy can travel with you. In some cases, pet and carrier must weigh a combined 20 pounds. Some airlines have restrictions for first and business class seats on particular types of planes, so check with your airline first before booking your ticket.
Note that you will usually need to schedule your pet's travel with the airline 14 days in advance, as there are only a certain number of pet slots per plane. Most airlines charge between a hundred to two hundred dollars to carry your pet on the plane.
The clear downside to this option is that the animal must be very small; many full-grown cats and even some small dogs are too large to fit under the seat.
There are also risks involved with flying with your pet. In one recent high-profile case, a snub-nosed dog died in the overhead bin when it was placed there instead of underneath the seat. Many carriers already restrict the breed of dog that can be checked in the cargo hold; now some are adding restrictions to dogs that can be carried on the plane because of safety concerns.
Individuals with service animals, such as blind passengers who need a service dog to walk and find their seats, are generally welcome to bring their animals on the plane as they perform a life-saving function.
To avoid the fee and inconvenience of checking an animal, airline passengers will often register their pets as “emotional support animals”, or ESAs. To do this, passengers need a letter from a mental health professional saying the pet performs a necessary function for its owner, though many companies have emerged that claim to simply sell ESA letters online.
As ESAs become more common, issues have arisen with their behavior. Until recently, no formal training was required and no species restrictions were in place for ESAs, so many animals, from ducks to pigs, have boarded with their owners, and in some cases have caused disruptions.
In some cases, untrained “emotional support” animals have caused issues by attacking service animals who are performing a life-saving function, leading advocates for people with disabilities to call for restrictions on untrained animals. Consequently, some airlines now ask patrons to sign a training verification, including Delta. Legislation was also introduced in 2018 that would require airlines to align their definition of a service animal more closely with that of the Americans with Disabilities Act.
In January 2018, United announced they would be restricting Emotional Support Animals to dogs and cats above four months of age, and banned ESAs from flights longer than eight hours, citing a rise in incidents.
United joins Delta, Spirit, and Alaska in announcing these restrictions. The three airlines also require three forms (the vet certificate, a letter from a mental health professional, and a liability waiver from the passenger) and 48 hours' notice before an ESA can be brought on the plane.
If your pet does not perform a life-saving function or weighs more than 20 pounds, your best best is to check your pet or ship it via cargo. Be sure to travel outside of times (or airports) where extreme temperatures are expected, and get a vet's letter right before you travel. And if you are ever in doubt, call your airline before booking tickets to make sure you can bring your pet on your flight with you.