It helps to place a wall of Arcos along the border of your city. You can increase the chance of trapping a plane if you place your airport near this wall of Arcos.

Warning! Make sure disasters are off or else you'll lose some of your Arcos when planes crash into them! It is possible to catch planes with any type of Arco (Plymouth, Darco, Forest, Launch). It is also possible to trap all of your planes so none can land.

See an airplane trapped between Arcos