Question

What does the outer loop of an autopilot do?

(a) Generate commands to the inner flight control loop

(b) Access the flight control surfaces to control the pitch and roll of the aircraft

(c) Access the flight control surfaces to control the altitude and heading of the aircraft

(d) Generate commands for the pilot to follow

This question was posed to me at a job interview.

My doubt stems from Autopilots, Height Control and Heading Control in division Autopilots and Flight Management Systems of Avionics

Answer 1

The correct answer is (a) Generate commands to the inner flight control loop

Easy explanation: The autopilot exercises a guidance function in the outer loop and generates commands to the inner flight control loop. These commands are generally attitude commands which operate the aircraft’s control surfaces through a closed flight control loop system so that the aircraft rotates about the pitch and roll axes until the measured pitch and bank angles are equal to the commanded angles. The changes in the aircraft’s pitch and bank angles then cause the aircraft flight path to change through the flight path kinematics.