One airline is betting that passengers will pay extra to sit away from babies and young children. Corendon Airlines says that it will sell an adults-only zone — no one under 16 allowed — on flights between Amsterdam and Curacao starting in November. The airline announced last week that it will set aside about 100 seats for adults on its Airbus A350 jets and will charge passengers an extra reservation fee of $49 for the no-kids zone, rising to $109 for one of the extra-legroom seats.