Autopilot is the automatic pilot: a system that flies a plane, or steers a ship, so the human pilot does not have to hold it every second. On a long flight, the plane is often on autopilot. The person is still there; the machine is holding the path. Though actually, everyday English stole the word. “I’m on autopilot this morning” means you are doing the usual things — wash, train, desk — without really thinking, because your body already knows the path. That loose use is now as common as the plane use, maybe more common in ordinary talk. It feels technical when you talk about aircraft, and informal, a little tired or funny, when you talk about people. Some car makers also use Autopilot as a product name for driving help, which is why younger speakers may picture a car first. In careful talk, a plane on autopilot still has a pilot in the seat; it is not an empty plane flying itself.