Which statement about lighting is true when the engine is running?

• A. Anti collision lights on unless causing vertigo or hazardous condition
• B. Position lights only during daylight
• C. Landing lights always required
• D. Strobe lights never required

Answer: (A)

Anti-collision lighting is used to make the aircraft highly visible to other pilots whenever the airplane is powered and in flight. Keeping these lights on during engine operation greatly reduces the chance of a mid-air encounter by enhancing conspicuity. The only exception—if turning them on would cause vertigo or a hazardous condition for occupants—recognizes a rare comfort or safety trade-off, but the standard practice is to keep them lit whenever practical during flight. This makes the statement true. The other lighting rules don’t apply universally: position lights aren’t limited to daylight only, landing lights aren’t required at all times, and strobe lights are generally required when the aircraft is in flight.