Aircraft and development of its system seems to be a never ending process. One of great achievements of in aviation technology is Autopilot. Now a days modern airliners are 20% flown by pilots while the rest of 80% is done by Autopilot. Today’s Autopilot system is so advance that it helps pilots to land in low visibility, and even has capability to land if Runway is equipped with ILS CAT-III (Instrument Landing System), which is really amazing. From after take off till landing the aircraft is totally flown by Autopilot! While human pilots are just monitoring instruments isn’t it Amazing?
Usually when aircraft takes off the Autopilot is engaged at 400 Feet. Autopilot is devided into Three main parts(There are more sub parts, but they are derived from following three) which control different areas of aircraft.
The L NAV (Lateral Navigation) : Allows aircraft to fly the route from departure airport to arrival airport, that has been fed into its FMC (Flight Management Computer).
The V NAV (Vertical Navigation): Controls climb, cruise , descent path and speed of aircraft.
APP (Approach): Lands aircraft if runway has ILS CAT-III.
The Autopilot is configured from FMC being Pre-flight and then you dont need to fly aircraft , because Autopilot is doing it!