Can the Maestro Sport be used on an airplane, and if so, how?

Yes, but only when used with the 5-point harness — it cannot be used in booster mode on aircraft. To install, place the seat forward-facing on the aircraft seat (in the fully upright position), route the aircraft seat belt through the belt path, fasten it as tightly as possible, and secure your child in the harness. Check with your airline before departure to confirm the restraint meets their requirements. (Pages 17, 47–48)