Yes, cat carriers are allowed on planes.

A cat backpack is one type of cat carrier.

Important:

1. check the size of carry-on baggage for your airline.
   For example, in Europe, for most airlines, the size of carry-on baggage, and therefore the backpack, should not exceed 55 x 35 x 25 cm
   Place the cat backpack under the seat in front of you.
2. The weight of the animal together with the carrier should not exceed 8 kg.

1. When traveling by car, make sure your cat is securely locked in a carrier or crate. This will protect it from injury or loss in the event of an emergency or unexpected move.
2. Also, do not allow your cat to roam around the car, as this poses a danger to both the cat and the driver.

It's crucial to prepare! Your cat requires a variety of things to travel well, including to feel at ease in their carrier and, if you're driving, in the car. Prior to embarking on your journey together:

• Select the appropriate carrier.
  Your cat will require a comfortable carrier to ride in for the duration of the trip. Make sure your cat is properly fit for the carrier; it shouldn't be too small to restrict their movement or too large to cause them to feel exposed and jostled.

• Cat should be introduced to their carrier early. Prior to your trip, make sure your cat is comfortable in their carrier. A little before your scheduled departure, introduce them to it and encourage them to explore—with the door open—by putting their favorite toys and blankets inside. When it comes time to travel, your pet will feel more at home and content in their carrier.
  
• Make travel plans ahead of time. To allow your cat to get out of the crate for brief periods of time to stretch their legs, use their litter box, and cuddle up with you, plan your route and be sure to include plenty of stopping spots.
  
• For added safety, wear a lead and harness. Adding a cat harness is a terrific way to increase safety a bit. Your pet will be much more secure on a harness and lead as you can be sure they won't be able to escape the carrier even if you reach in to comfort them. This is especially crucial while traveling by public transportation.

• When you stop at rest areas, you can take your cat out of the car with a lead so they can stretch their legs. Naturally, not every cat is fond of leads or harnesses, so be sure to acquaint your feline before your trip.
  
• Get your cat a microchip. Having your cat microchipped is a smart idea, especially if you plan on traveling, in case they manage to escape.
  
• Carry a litter tray with you. If the trip is lengthy, your cat could need a rest! For lengthy trips, a litter pan filled with easily disposed of litter is essential. Your cat can then dispose of this in an appropriate container while you travel by placing it in a handy location for them to take a break throughout their travels.
  
• As you depart, don't give your cat food! Give your cat food 5-6 hours before leaving. This will lessen the likelihood of motion sickness and make the trip less enjoyable for everyone!
  
• Think about where you're going. If you are going on vacation, pick a pet-friendly destination and make sure it has safe amenities that will help your cat feel at home.
  
• Bring home comforts for cat. Bring along anything that will help your kitty companion feel at home, such as bedding, toys, water and food bowls, and even their favorite scratching post.