The Red and Green Lights Every Aircraft Carries
If you’ve ever looked up at the night sky and watched an aircraft pass overhead, you’ve probably noticed a red light on one wing and a green light on the other. While they may seem like simple navigation aids for passengers to spot, these coloured lights are actually one of aviation’s oldest and most important safety features.
Known as navigation lights, or position lights, they help pilots instantly determine another aircraft’s direction and orientation, especially during night operations or in poor visibility. Every commercial airliner, business jet and most general aviation aircraft are equipped with them, and their use follows an international standard.
The system is remarkably straightforward. The left wing carries a red light, while the right wing displays a green light. A white light is mounted at the rear of the aircraft, usually on the tail, marking its aft direction. This universal colour scheme has been used for more than a century and was originally adapted from maritime navigation, allowing pilots around the world to interpret another aircraft’s movement at a glance.
These lights do much more than make an aircraft visible. They provide vital information about where it is heading. If you can see both the red and green lights, the aircraft is generally flying towards you. If you can only see the green light, it is crossing from your left to your right. If only the red light is visible, it is moving from your right to your left. And if all you can see is the white tail light, the aircraft has already passed and is flying away from you.
This simple visual language allows pilots to quickly assess another aircraft’s position and direction, helping maintain safe separation in the air and around airports. Air traffic controllers provide instructions and separation, but these navigation lights offer an additional layer of situational awareness that is recognised worldwide.
Although modern aircraft rely on sophisticated radar, satellite navigation and advanced collision-avoidance systems, the humble red, green and white lights remain just as relevant today as they were decades ago. They require no radio communication, no data link and no complex technology—just a clear line of sight.
So, the next time you see an aircraft crossing the evening sky, take a closer look. Those small coloured lights are doing much more than making the aircraft visible. In just a few seconds, they reveal its orientation, direction of travel and place in the sky—proof that sometimes the simplest ideas are also the most enduring in aviation.
Next time you’re at an airport or looking up at the night sky, see if you can tell which direction an aircraft is flying—just by its lights.
Sources
ICAO – Annex 2: Rules of the Air
https://www.icao.int/sites/default/files/postalhistory/annex_2_rules_of_the_air.htm
EASA – Easy Access Rules for Air Operations
AOPA – What Am I? See and Be Seen
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