Air travel is a meaningfully bigger undertaking than car travel for a cat, with real risks and airline-specific requirements that are worth understanding well before you book.
In-cabin versus cargo: this decision matters enormously
Whenever possible, book your cat as in-cabin carry-on rather than checked cargo. Cargo hold travel carries genuinely higher risk — temperature extremes, less monitoring, and documented incidents of animals lost, injured, or worse during cargo transport. Most airlines allow a small number of in-cabin pet spots per flight, which fill up early, so book the pet spot as soon as you book your own ticket, not afterward.
Carrier requirements are airline-specific
Under-seat dimension limits vary by airline and sometimes by aircraft type on the same airline — check the specific airline's current pet policy rather than assuming a carrier that worked for one airline will be accepted by another. Soft-sided carriers that compress slightly to fit under a seat are generally more forgiving of size variation than rigid hard-sided carriers.
Health certificate timing
Most airlines and destinations require a health certificate from a licensed vet issued within a specific window before travel — often 10 days for domestic travel, sometimes shorter for international. International travel can involve considerably more complex requirements, including rabies titer testing that must be done well in advance (sometimes months, for certain countries), so research destination-specific requirements as early as possible in your planning, not close to departure.
Sedation is generally not recommended for flying
Unlike car travel, sedating a cat for a flight is generally discouraged by veterinary and airline guidance, since sedation can affect breathing and blood pressure at altitude in ways that are harder to monitor and respond to in an aircraft cabin. If anxiety is a significant concern, discuss non-sedating options (like gabapentin, which reduces anxiety without the same respiratory concerns) with your vet well before the flight date.
Microchipping and ID before any travel
Ensure your cat is microchipped with current contact information before any travel, air or otherwise — a cat that escapes a carrier in an unfamiliar airport is a genuine, if uncommon, risk, and a microchip is the most reliable way to be reunited if this happens.
Consider whether the trip is actually necessary for the cat
For cats with significant travel anxiety, or for older cats with health conditions that make air travel riskier, boarding with a trusted sitter or cattery may genuinely be the better choice over bringing the cat along, even if that means missing out on having them present for the trip. This is a legitimate, common decision, not a failure of preparation.