Story : 1956 Grand Canyon mid-air collision, 1986 Cerritos mid-air collision, Avianca Flight 52, Gol Transportes Aéreos Flight 1907, Überlingen mid-air collision. This special looked at the role of air traffic controllers in the airline industry, and took a look at the Next Generation Air Transportation System, a new technology meant to eliminate mid-air collisions by reducing overall dependence on radar and radio, as well as delegating some of the air traffic controllers' tasks to computers on board each plane.