Materials have don't corrode and plans for speedier boarding. >> taking a plane could be as simple as taking the subway. >> in the future we could think about city center check-in and actually transport little pods to the airport where the passengers are already in, and just get with the pod, slide it into the airplane, in order to have a seamless experience of flight. >> reporter: cheaper flights have driven the growth, and with air traffic predicted to rise by more than 4% a year, the prospect of free flights is on the horizon. >> the airlines may not take the money from the passenger direct...