public class Airplane implements Flyer 
{
  public void takeOff() 
  {
    // accelerate until lift-off
    // raise landing gear
  }
  public void land() 
  {
    // lower landing gear
    // decelerate and lower flaps until touch-down
    // apply breaks
  }
  public void takeOff() 
  {
    // keep those engines running
  }
}