If the main wing tip navigation bulb fails, how is the backup provided?

• A. The system will automatically switch to the secondary bulb.
• B. The pilot must manually switch to the secondary bulb.
• C. All navigation lights shut down until maintenance.
• D. The secondary bulb remains off until reset.

Answer: (A)

Redundancy in wing tip navigation lighting is designed so a failed primary bulb doesn’t leave you without position lights. When the main bulb stops working, the system automatically switches to the secondary bulb. A fault detector and relay logic senses the failure and reroutes power to the backup, keeping the nav light on without pilot intervention. This automatic switchover avoids loss of visibility to other aircraft and complies with regulations that require navigation lights during flight. Manual switching isn’t typically required because the system is intended to maintain operation automatically; waiting for a manual action or reset would defeat safety. The backup is ready to take over and remains available, not permanently off.