Which notional statement about autopilot and autoland power supplies is accurate?

• A. 3 independent power supplies are used (two AC and one DC)
• B. Two AC supplies and two DC supplies
• C. Three DC supplies only
• D. A single, shared power bus is used

Answer: (A)

Redundancy and independent power paths are essential for autopilot and autoland to stay functional even when part of the electrical system fails. The design uses three independent sources: two alternating current supplies from separate generators and a separate direct current supply. This arrangement means that if one AC source drops out, the other can keep the autopilot/autoland powered, and the DC source provides a back-up path to power the critical equipment even if the AC side is unavailable. A single shared power bus would create a single point of failure, and options with three DC sources or only a shared bus don’t provide the same robust, independent redundancy that these critical systems require.