How Flying Works
What Autopilot Actually Does (And Doesn’t)
On 18 June 1914, 21-year-old Lawrence Sperry flew a Curtiss C-2 biplane fifty feet above the River Seine in front of a Paris crowd. Then he stood up in the cockpit with both hands over his head. His mechanic, Émile Cachin, climbed out and walked along the wing to balance on the tip. The aircraft kept flying straight and level with nobody in the pilot’s seat. The pair had just shown off what is widely called the world’s first practical autopilot, and they won a 50,000-franc prize for it (roughly $10,000 at the time). Sperry had built the device two years earlier by connecting his father’s gyroscopic instruments to the rudder and elevators. It’s a direct ancestor of the system flying every airliner today. More than a century later, the crowd’s misunderstanding is still common: that switching the autopilot on means nobody is flying the plane. Mentour Pilot’s video “How Does Autopilot Work? A Pilot Explains What It Can and Can’t Do” was made to correct exactly that. The autopilot carries out instructions; it doesn’t make decisions. It does precisely what it’s told, more consistently than a human hand-flying for hours could, and nothing more.
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What it does
- Holds a commanded altitude, heading, speed and vertical rate with far more precision than continuous manual flying could over hours.
- Flies a programmed lateral and vertical route from the flight management system, including complex arrival and departure procedures.
- On a CAT III-equipped aircraft and runway, can fly and execute the entire approach and landing itself, tracking the ILS beams more precisely than a human could in zero visibility.
- Reduces crew workload on long sectors specifically so pilots can dedicate more attention to monitoring systems, weather and traffic — not so they can stop paying attention.
What it doesn’t
- Decide where to go, when to climb, or what to do about an unexpected situation. Every instruction it follows was set by a pilot, and it does exactly and only that.
- Handle every phase of every flight. Many airlines require autopilot to be off below a set altitude on takeoff and, without CAT III certification, below a set altitude on approach.
- React to something it wasn't told to react to. If air traffic control or weather changes the plan, a pilot has to notice and reprogram it — autopilot doesn't improvise.
- Substitute for a pilot's judgment in an abnormal or emergency situation. The first action in nearly every real in-flight emergency checklist is still a human decision, often followed by deliberately disconnecting the autopilot to fly manually.
The strip across the top of the screen: reading the modes
“The autopilot is on” is not a complete sentence to a pilot. The real question is which modes it’s in.
The automatic flight system has separate jobs. The autothrottle controls speed or thrust. One part of the autopilot controls direction, the roll axis. Another controls climb and descent, the pitch axis. Each can work in several modes: hold a heading or follow the planned route; climb at a set speed or at a set vertical rate.
All of this is shown in the Flight Mode Annunciator, or FMA, a row of boxes across the top of each pilot’s main flight display. There is one column for thrust, one for roll and one for pitch. Active modes usually show in green. Modes that are armed, waiting to take over at the right moment, show in white or blue.
Pilots are trained to read the FMA after every change and call it out loud. Pressing a button is not proof the aircraft is doing what was intended. The FMA is. Many training programmes treat “check your modes” as one of the most important habits in automated flying.
From wing-walking stunt to CAT III autoland
Sperry’s gyroscope could only hold an aircraft level. It couldn’t navigate, land, or react to anything it wasn’t already correcting for. Each decade since has added a layer. First came heading hold, then altitude hold, then the ability to lock onto a radio beam for an approach. Then came full flight management systems that can fly a whole route programmed before departure. The last big leap, CAT III certification, lets a modern autopilot fly and land the aircraft in weather too poor for a human to see the runway. Getting from a biplane over the Seine to that point took roughly fifty years, and the basic principle never changed: the system carries out the plan, and the pilots make the decisions.
The role it actually frees up
The real value of the autopilot isn’t that it replaces pilots. It takes the repetitive, precise work of straight-and-level flight off their hands. That frees their attention for things automation can’t do: watching weather build ahead, cross-checking instruments, talking to air traffic control, and being ready to step in the moment a human decision is needed. On a long-haul flight, that’s the difference between a tired crew hand-flying for ten hours and a crew that’s alert for the parts of the flight that matter most.
Try it
Follow the beams: an ILS approach in fog
Two radio beams guide the aircraft: the glideslope sets a steady 3° descent and the localiser lines it up with the centreline. Each category lowers the decision height, the point where the crew must see the runway or go around, and the minimum visibility (RVR). CAT IIIB: decision height below 50 ft or none, visibility down to about 50 m. In CAT III the autopilot flies all the way to touchdown, flaring at roughly 30 to 50 ft. Vertical scale exaggerated; ICAO category values.
Sources & Further Reading
Common Questions
Frequently Asked Questions
Can a plane really land itself with no pilot input?
Yes, if the aircraft, runway and crew are all certified for CAT III. It’s a real capability, used routinely for landing in fog and poor visibility. Even then, pilots must actively monitor every stage and be ready to take over or go around at any sign of a fault.
Do pilots fly by hand much?
On a typical airline flight, hand-flying is usually limited to the first minute or so after takeoff and the last stretch before landing. The autopilot handles the rest, which cuts fatigue and errors on repetitive, precise tasks the automation does more consistently.
Is it true a plane can fly itself with no one in the cockpit?
Not in any commercial sense today. Autopilot requires a pilot to set and continuously supervise it; it has no independent decision-making authority, and current airliner certification assumes an actively monitoring flight crew at all times.
What happens if the autopilot itself fails?
It disconnects, usually with a warning sound and light, and the pilot flying takes over by hand. Every airline pilot trains for this and is regularly tested on it in the simulator.
Last reviewed: October 2026. Facts that change, such as fleets, airspace and airline ownership, are re-checked on a schedule. Spotted an error? Email contact@skyplus.news and we’ll fix it. See how we check facts.