FAA car seat rules on planes & TSA breast milk/formula rules (2026)

Whether you are flying domestically across the United States on Delta, United, American, Southwest, JetBlue, or Alaska Airlines or flying into the US from the UK or Canada, two federal agencies set the ground rules for your baby's gear and milk: the Federal Aviation Administration (FAA) governs car seats and child restraints on board, and the Transportation Security Administration (TSA) governs breast milk, formula, ice packs, and strollers at airport security.

Here is the plain-English guide to every FAA and TSA rule for babies and toddlers — including the exact red lettering flight attendants check on your car seat, why your car seat must go in a window seat, airplane seat widths by airline, and how to bring unlimited breast milk or formula through TSA checkpoints (checked October 2026).

Quick answers: FAA car seat & TSA baby rules

1. The mandatory FAA approval label (and what UK/European parents can use)

When you board a US airline with a car seat to use in a purchased airplane seat, the flight attendant is trained to check the side or base of the shell for the official certification sticker before pushback:

• US Car Seats (FMVSS 213): Look for the printed statement (almost always in red lettering):

> "This restraint is certified for use in motor vehicles and aircraft." (Watch out: "rotating" 360-degree convertible car seats sold in the US — such as the Nuna Revv or Evenflo Revolve360 — are frequently NOT FAA-approved for aircraft because their permanently attached rotation base cannot be installed tightly with an airplane 2-point lap belt! Always check the sticker on your specific seat before heading to the airport.)

• UK, European & Canadian Car Seats on US Airlines: Under FAA guidance (Advisory Circular 120-87C) and major airline tariffs (Delta, United, American, Air Canada, British Airways), US airlines also accept foreign child restraint systems that carry:
• The Canadian CMVSS 213 / 213.1 aircraft approval mark, OR
• A United Nations (UN) ECE R44/04 or R129 (i-Size) label accompanied by the TÜV Rheinland "For Use in Aircraft" qualification sticker (for example, the Maxi-Cosi Pebble 360 Pro² and CYBEX Cloud T — see our lightest infant car seats for travel).
• What if your car seat is NOT FAA-approved? Every single US airline still lets you check it for free at the gate or ticket counter! You only need the FAA aircraft label if your baby is sitting in the car seat inside the aircraft cabin.

2. Will your car seat fit the airplane seat? (Economy widths by US airline)

The FAA recommends choosing a car seat with a base no wider than 16 inches (40.6 cm) so it fits inside the armrests of any narrowbody regional jet, though most mainline Airbus A320/A321 and Boeing 737 seats measure 17 to 18 inches between armrests (and on most rows except bulkhead Rows 1–2, you can raise the middle armrest while installing the seat):

• Tip for installing a rear-facing infant seat on a plane: Leave the heavy ISOFIX / LATCH car base at home (or pack it in your checked suitcase) and install the infant carrier shell directly on the airplane seat using the European belt path / lap belt guides printed on the shell. It weighs half as much in the airport and installs in 15 seconds!

3. Your rights if a flight attendant questions an FAA-approved car seat

According to the FAA's official Child Safety on Airplanes rules:

• If you bought a ticket for your child and your car seat has the red FAA certification label, the airline must permit you to use it (provided it is not in an exit row or blocking the aisle).
• What if the car seat is wider than the armrests? FAA regulations state that if your FAA-approved CRS does not fit in your assigned seat, the airline is responsible for accommodating the CRS in another seat in the same class of service (for example, moving you to a row with movable armrests or a wider seat pitch).

4. The CARES aviation harness: when you can (and can't) use it

For toddlers who have outgrown their infant carrier and don't need a car seat at their destination (for example, visiting Walt Disney World by motorcoach or New York City by train), the AmSafe CARES (Child Aviation Restraint System) harness is the only harness-type device approved by the FAA:

• Weight & height limits: Approved for children at least 1 year old weighing 22 to 44 lbs (10 to 20 kg) and up to 40 inches (100 cm) tall who have their own purchased airplane seat.
• Beware of cheap online knock-offs: Flight attendants on Delta, United, American, and Southwest are explicitly trained to check for the white AmSafe "FAA Approved in Accordance with 14 CFR 21.8(d), Approved for Aircraft Use Only" label on the chest strap. Uncertified blue or black straps sold on online marketplaces without the AmSafe FAA label will be rejected on board.

5. TSA security rules for breast milk, formula, ice packs & strollers

At every US airport security checkpoint, TSA's "Traveling with Children" exemptions override the standard 3-1-1 liquid rule:

• Breast milk, formula, water & baby food over 3.4 oz (100 ml): You may bring breast milk, infant formula, pre-mixed liquid formula, bottled water for mixing formula, toddler drinks, and baby food purée pouches in quantities greater than 3.4 oz (100 ml) in your carry-on bag, and they do not need to fit inside a quart-sized zip-top bag. (You do not even need to have your child with you if you are a pumping mother flying solo!)
• Ice packs, freezer packs & gel packs: Freezer packs, frozen gel packs, and slushy ice packs used to keep breast milk or formula cool are 100% allowed through TSA, even if they are partially melted or slushy.
• How to speed through the TSA X-ray lane:
• Separate your milk/formula/pouches into one easy-to-grab cooler bag and place it in its own bin before the X-ray belt, telling the TSA officer: "I have breast milk / baby formula to declare."
• What if TSA wants to test your liquid breast milk? TSA officers will usually screen clear bottles in a contactless Bottle Liquid Scanner (BLS) in 10 seconds. If a container is opaque or triggers an alarm, you have the right to ask the officer not to open the container or X-ray it; instead, TSA will conduct additional screening of you and your carry-on property (such as a quick hand-swab for explosives residue) while your milk stays sealed!
• How TSA screens strollers and car seats:
• Folded compact strollers (like the Bugaboo Butterfly 2, Joolz Aer+, and Joie Pact Lite — check them in our Cabin Size Stroller Checker) fit right through the standard TSA X-ray tunnel on the conveyor belt!
• Wide or full-size strollers and wide convertible car seats that don't fit through the X-ray tunnel are wheeled through the walk-through gate and given a quick visual/swab inspection by a TSA officer while you hold your baby through the walk-through metal detector (children 12 and under keep their shoes on and never go through the full-body scanner alone).

Related flying & car seat guides

• Car Seats on Planes: Rules for 19 US, UK & Global Airlines Compared
• Lightest Infant Car Seats for Travel
• Cabin Pushchair & Travel Stroller Size Checker
• Delta, United, American Airlines, Southwest, JetBlue, Alaska Airlines & Air Canada baby rules
• Car Seat Rules in Europe

FAQs

Sources

• Federal Aviation Administration (FAA): Flying with Children & Child Restraint Systems (CRS)
• TSA: Traveling with Children — Formula, Breast Milk, Juice, Strollers & Car Seats
• American Academy of Pediatrics (AAP) / HealthyChildren.org: Flying with Baby

Last checked and updated: 30 October 2026 · Kiddieko · How we check facts