Have you ever noticed the colored lights used on the wingtips of airplanes? Although there are exceptions, most commercial airplanes have colored lights on their wingtips. You’ll often see either a green or red light on their wingtips that flashes in the night sky. Unbeknownst to most passengers, though, there’s a reason why airplanes use red and green lights.

The Basics of Navigation Lights

The red and green lights found on the wingtips of airplanes are known as navigation lights. They are designed to increase the airplane’s visibility to other pilots, as well as air traffic controllers on the ground, to minimize the risk of collision. Navigation lights don’t emit any signals. Rather, they simply illuminate the airplane during the nighttime hours so that other pilots and air traffic controllers can see it more easily.

Most commercial airplanes have a green light on one of their wings and a red light on the opposite wing. The red light is located on the airplane’s left wing, whereas the green light is located on the airplane’s right wing. They two lights will flash simultaneously to increase the airplane’s visibility.

Reasons for Red and Green Navigation Lights

The use of red and green navigation lights makes airplanes easy to spot. If airplanes only had green lights — or if they only had red lights — pilots or air traffic controllers may mistake them for other aircraft, such as drones or weather balloons. But only airplanes use a combination of red and green lights, so they are distinguishable from other airborne objects.

Airplanes are designed with red and green navigation because it’s the same configuration used in boats. During the 19th century, mariners discovered that adding red and green flashing lights to their boats lowered the risk of collisions. Therefore, aviation experts applied this same configuration to airplanes. Red and green light navigation lights make airplanes more visible, which in turn creates a safer flying experience by lowering the risk of collision.

Of all the colors on the visible spectrum, red and green are among the most distinguishable to the human eye. The human eye, in fact, is most sensitive to green than any other color. With that said, red works particularly well as a navigation light for both airplanes and boats because it contrasts with the color of the ocean and the sky.