on automatic pilot, functioning in an unthinking or reflexive manner.
Origin of automatic pilot
First recorded in 1915–20
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Also called: autopilot a device that automatically maintains an aircraft on a preset course
on automatic pilot informal acting without conscious thought because of tiredness, shock, or familiarity with the task being performed
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012