If your child is big enough to do so (around 4 years and 40 lbs), you can have them sit buckled on the airplane seat.

Yes, a 5-year-old can—and in 2026, legally must—sit in their own assigned airplane seat. By age five, children are well past the "lap child" age (which ends at age two) and require a full-fare ticket. While they are physically large enough to sit directly in the aircraft seat using only the standard lap belt, the FAA and airlines strongly recommend using a government-approved Child Restraint System (CRS), such as a forward-facing car seat, for children weighing under 40 pounds to provide maximum safety during turbulence. However, most 5-year-olds exceed this weight and are perfectly safe using just the seatbelt. It is important to note that booster seats are strictly prohibited for use during taxi, takeoff, and landing because they require a shoulder belt to function, which planes do not have. To stay grounded and helpful: if your 5-year-old is small for their age, consider a CARES harness, which is an FAA-approved belt-and-buckle device that provides extra upper-body support without the bulk of a full car seat. This makes the flight more supportive for their small frame and provides you with peace of mind.