Which response occurs when one wing tip navigation light bulb fails?

• A. The system automatically switches to the secondary bulb
• B. The pilot must manually switch to the secondary bulb
• C. The lighting remains on only the non-failed side
• D. The entire navigation lights system must be replaced

Answer: (A)

Wingtip navigation lights are designed with redundancy so a single bulb failure doesn’t leave a wing dark. In many installations, the fixture contains a primary bulb and a backup bulb wired so that if the primary fails, the circuit automatically switches to the secondary without pilot input. This seamless transition keeps the light visible and maintains compliance with lighting requirements.

That automatic handover is preferred because it reduces pilot workload and ensures continuous visibility to other aircraft. Manually switching to a secondary bulb isn’t expected in normal operation, and leaving the light off on the failed side or replacing the entire system for a single burnt bulb would not align with how these lights are designed to operate.