If one wing tip navigation light bulb fails, how do you switch to the secondary bulb?

• A. The pilot must manually switch to the secondary bulb
• B. The navigation light system automatically switches to the secondary bulb
• C. The system cannot switch to a secondary bulb
• D. Replacement bulb must be installed

Answer: (B)

Redundancy with automatic failover is what this tests. Wing-tip navigation lights are wired so a spare bulb can take over without any pilot action. If the primary bulb fails, a failover path (via a relay or parallel wiring) automatically energizes the secondary bulb and the light stays on. This design keeps the light operational and reduces pilot workload, which is why the automatic switch to the secondary bulb is the correct behavior. Manual switching isn’t required in normal operation, and maintenance would address bulb failures as needed rather than in-flight switching.