Which AFCS level corresponds to Digital SAS (autopilot on - trim motors off)?

• A. Unstabilized
• B. Back-up SAS
• C. Digital SAS (autopilot on - trim motors off)
• D. Autopilot (attitude retention)

Answer: (C)

AFCS levels describe how much automated stabilization and control is active. Digital SAS is the mode where stabilization is handled by a digital control loop while the autopilot is engaged, but the trim motors are kept off. Keeping trim motors off prevents trim inputs from fighting the autopilot, so the aircraft is stabilized entirely by the digital stabilization system and the autopilot commands. This matches the description given, making it the correct choice. The other options represent different states: no stabilization, only basic stabilization in a degraded mode, or a full autopilot mode with attitude retention that isn’t the same as the Digital SAS setup.