Niki, a private pilot from Kansas, writes: So… I’m wondering where we get the colors for our nav lights: Red on the left, green on the right, and white on the tail. I’m sure it’s been this way forever, but why was this arrangement originally selected?
Because it was the law. And had been since 1838. Now, wait a minute. You say there weren’t any airplanes in 1838?
The whole scheme for navigation lights, a.k.a. position lights or running lights, comes to us from boats. By the time airplanes were being lit, the system of using a red light on the port side of a ship, a green light to starboard, and a white light to stern was well-established. More than well-established. It was codified in international law.
So it only made sense for our aviation forefathers to adopt the existing standard and take it up a notch (in altitude).
The history of boat lighting, on the other hand, isn’t quite so well illuminated.
Here’s what’s known for sure: In 1838, the U.S. Congress passed a law requiring steamships that ran from dusk to dawn to have lights, but the law was moot on the issues of the colors and the positions of the lights.
What followed was a period of aquatic anarchy in which different steamship companies adopted different color schemes — and the same thing was happening throughout the seven seas.
Finally, in 1847, the British Admiralty said enough is enough, and standardized the green light on the right and the red on the left.
Was there a (then) logical advantage for our current scheme over the other schemes? Was it simply a matter of adopting what was most commonly in use? Was there influence from well-connected people in the industry?
I wasn’t able to find out.
But once the Big Kahuna of the world’s oceans established a protocol, the rest of the world — recognizing the benefit of a global standard — basically shrugged its shoulders, and said, yeah, fine, whatever. We’re on board.
Pardon the pun.
As to the selection of the colors, which are arguably a poor choice given that red-green color blindness is the most common kind, that’s another mystery.
Some commentators think that the colors came from the railroads, but I’m skeptical about that. The rails were just starting to grow at this time in history, and it’s hard for me to believe that the nascent rail industry had much of an impact on a group as hide-bound as the British Admiralty.
Perhaps it was something as simple as red and green glass were more commonly available, or less expensive, than other colors.
But back to airplanes. Of course, night flight pre-dates aircraft lighting, but not by much. And not too surprisingly, the Dayton Boys were the first to both parties.
An airplane from the Wright flying school in Alabama was the first documented fixed wing night flyer, making a moonlit flight in May 1910.
But by August of the same year, three planes from the Wright exhibition team were equipped with port and starboard position lights for a group nocturnal ascension at an airshow in Asbury Park, New Jersey.
The New York Times reported that automobile horns were also attached to the machines, “so that they may honk each other out of the way if two of them happen to occupy the same air lanes at any given time.”
I guess I’ll have to look into the history of our current right-of-way rules some other day.
Meanwhile, our current position light scheme — inherited from ships of old — is going to yet new heights: Both Orbital Sciences’ Cygnus cargo spacecraft and the SpaceX Dragon capsules have the same nav lights we do.
And speaking of new heights, next time on Questions from the Cockpit I answer a question that takes us to the top of the sky.
William E. Dubois is a commercial pilot, ground instructor, and doesn’t fly at night because his airplane isn’t equipped with an automobile horn.