Be sure the shoulder straps are properly adjusted and fasten the airplane seat belt around the CRS as tightly as possible.
Always follow the manufacturer's instructions when using a CRS. The FAA recommends that a child weighing:
* Less than 20 pounds use a rear-facing CRS
* From 20 to 40 pounds use a forward-facing CRS
* More than 40 pounds use an airplane seat belt
While booster seats and harness vests enhance safety in vehicles, FAA prohibits passengers from bringing these types of devices on airplanes for use during taxi, take-off and landing. These devices should be checked as baggage. Also, supplemental lap restraints or "belly belts" are not approved for use in both airplanes and vehicles in the United States.