Your little one may be perfectly safe snuggled on your lap during story time. But if you fly, that’s a different story.

While the FAA and individual airlines let babies and toddlers under 2 sit in their parent’s lap during the flight and thus fly for free, it’s a risky proposition. As a result, the American Academy of Pediatrics (AAP) urges parents to place all children younger than 2 in a child restraint when they fly, especially during take off, landing and turbulence.

“More near miss events happen during take off and landing than when a plane is in the air,” says Benjamin Hoffman, MD, a member of the AAP’s Council on Injury, Violence & Poison Prevention. In the unlikely event something happens — say, the plane stops abruptly as it’s taxing down the runway — your baby is safest if she is secured.

But that scary bouncing up and down that occurs when the plane hits turbulence is the biggest threat to babies.

“If a plane drops 30 feet because of turbulence, a 10-pound child represents about 450 pounds of inertia,” says Hoffman, professor of pediatrics at Doernbecher Children’s Hospital in Portland, Oregon. “Asking a parent to hold onto something that is being pulled out of his or her arms with that much force is almost impossible even if you are holding onto the child with all your might.”

The result: Your baby becomes a flying object. To play it safe, keep your child restrained throughout the flight — for the same reason your seat belt should be fastened when you’re not moving about the cabin. “In the event of severe turbulence, there is no time to prepare,” says Dr. Hoffman. “You are talking about fractions of a second. A safety restraint keeps your child in the seat so if the plane moves, she moves with it.”

Related: Choosing a Baby Car Seat, Then and Now

The FAA doesn’t require parents to put children under 2 in car seats, reasoning that if it did, some people would drive to their destination, which isn’t as safe as flying, explains Alison Duquette, spokesperson for the FAA. However, the agency “encourages parents to use child restraints on planes,” she adds.

While that means buying an extra seat, some airlines may discount fares for the under-two set, so check with your carrier. Another option: Fly on slow travel days when the chances of snagging an empty seat are good. Just be sure you can get two seats together and use the vacant seat for free.

Other tips for a safe flight with your little ones

As you prepare for your trip, here’s what else you need to know about protecting your tiny flyer:

Read the fine print. Make sure your child safety seat is government approved for use on airplanes. Most car seats are A-okay to use on planes, but it should say that on the seat of the child safety device. If it doesn’t, you’ll need to check it with your luggage. Booster and most harness seats aren’t allowed on planes and must be checked.

Related: A Grandparents’ Guide to Traveling Safely With Your Grandkids

Reserve the right seats. Don’t put your baby’s safety seat in an exit row. And, ideally, install it in a window seat — so your seatmate won’t have to climb over it.

Get out the measuring tape. Make sure your car seat is no wider than 16 inches. If it is, it may not fit the airplane seat.

Weigh your child. Use a rear-facing safety seat if your child weighs less than 20 pounds and a forward facing seat if she weighs 20 to 40 pounds.

Consider a harness for small children. If your child is between ages 2 and 4, weighs 22 to 44 pounds, and is less than 40 inches tall, consider the FAA-approved CARES Airplane Safety Harness, a lightweight alternative to a clunky safety seat.

Here’s how it works: One part of the harness loops over the back of the child’s seat, underneath the tray table, and will fit seats up to 62 inches in circumference. The plane’s seat belt is then threaded through loops at the end of the shoulder straps; and the chest clip is connected. (Good news: Your neighbor can still use his tray table.) For more on CARES, including where to purchase, visit kidsflysafe.com.

Err on the side of safety. Secure your child with the airplane’s seat belt if she weighs more than 40 pounds. But since the AAP maintains that aircraft seat belts don’t adequately protect a child under age 3, err on the side of caution: If your child sits in a car seat when you drive, put him in a safety seat when you fly.

Check with your airline in advance about children over 2 but under 3 years of age: If they won’t allow you to bring a car seat on board, find another airline.

Related: Are You Using Your Child Car Seat Wrong?

Catherine Winters is a freelance writer who specializes in health.