Definition
An obstruction lighting system that combines red lights for nighttime use with high-intensity white strobe lights for daytime and twilight use on the same structure, such as a tall tower or antenna. The system automatically switches between the two light types based on ambient light levels.
Plain English
A tall obstacle, like a radio tower, lit with two types of lights: white flashing lights during the day and red lights at night. The lights switch automatically as it gets dark or light.
Context Anchor
Seen in discussions of obstruction lights on towers, antennas, buildings, cranes, and other objects near flight paths.
Derivation
Dual comes from the Latin word duo, meaning two. In this term, it points to two lighting modes used for the same object: one for daylight conditions and one for night.
Why Pilots Care
Allows a single installation to mark hazards safely both day and night, reducing mid-air collision risk.
Intuition Check
Dual lighting does not mean the object is simply twice as bright. Here, dual means two different lighting modes: white for daytime or twilight, and red for night.
Example Sentence 1
The 1,200-foot broadcast tower uses dual lighting, so we'll see white strobes if we pass it during the day and red lights after sunset.
Example Sentence 2
During the preflight briefing the pilot confirmed the wind turbines ahead had dual lighting installed.