To properly secure a baby in their own ticketed seat, the FAA and international safety boards recommend using a hard-backed, FAA-approved Child Restraint System (CRS), which is essentially a car seat certified for aircraft use. You should look for a sticker on the seat that states, "This restraint is certified for use in motor vehicles and aircraft." The seat is secured by threading the airplane's lap belt through the designated path on the CRS. Infants should remain rear-facing as long as possible, following the manufacturer's weight and height limits. For toddlers weighing between 22 and 44 pounds, an FAA-approved CARES harness is a popular, lightweight alternative that attaches directly to the plane seat's back and uses the lap belt to create a four-point harness. Avoid using "booster seats" or "vest-style" restraints, as these are not certified for use during takeoff or landing.