automatic pilot 
noun
A device for keeping an aircraft on a set course without the intervention of the pilot.Disengage the automatic pilot and contact the control tower for clearance....
- The speed valves control the rate at which the automatic pilot reacts to bring the airplane back on its course.
- After climbing out and disappearing from sight above the clouds, the pilot switched on the automatic pilot and sat back, the story goes.
Phrases
on automatic pilot