When a flight instructor hands the airplane to a student, the exchange takes three steps. The instructor says, “You have the flight controls.” The student answers, “I have the flight controls.” The instructor repeats, “You have the flight controls.”
Pilots also repeat what air traffic control tells them. The FAA’s Aeronautical Information Manual asks them to read back the parts of a clearance that contain altitude assignments, vectors or runway assignments. The readback lets both sides check each other.