Ask a Pilot with Spencer: The Lights on a Plane

In our Ask a Pilot series, pilot Spencer Marker answers one of your aviation-related questions each week. See past installments here and submit your own to Whitney@johnnyjet.com.

The question

Hi Spencer. The last time I flew, some airplanes were using their lights during the daytime. I’ve seen this at night, but why is it necessary during the day?

—Karen

The answer

Hi Karen! At night, an airport is lit up like a Christmas tree! Flashing lights of seemingly endless colors blend into soft blue of the taxiway lights and white runway lights. Even after all my time in the industry, I’m still amazed by the beauty of an airport at night.

While the airport lights are mostly shut off during daylight hours, pilots will continue using the lights on the airplane. This is because many of the lights pilots use on an airplane aren’t just for simple illumination. They are there to convey information to other pilots and workers on the ground. I’ll explain.

Bright white lights
Let’s start with the simplest airplane lighting system, the landing lights. These bright white lights are used to illuminate the runway while an aircraft takes off or lands. Just like a car’s headlight. Some are retractable into the body of the plane, while others are embedded in the wing.

These lights come on once the pilots have received clearance for takeoff and stay on until the airplane passes 10,000 feet. This increases the visibility of the airplane to other pilots as the airplane departs the busy airspace around the airport. Similarly, they come on again as the airplane descends through 10,000 feet and are used until the airplane has taxied off the runway. Additionally, a taxi light located on or near the nose landing gear helps pilots guide the airplane around the airport. Again, just like a headlight.

White lights are also mounted to the body of the airplane, illuminating the wing and engines for easy inspection. Like with many of the other lights on the airplane, we use these for anti-collision purposes, as well.

And since airlines spend good money painting their logos on the tail of their airplanes, it’d be a shame to lose all that branding after the sun sets. Luckily manufacturers have built logo lights for just this use. These white bulbs illuminate the colors on the airplanes tail, making sure the airline’s brand is visible, even at night.

Red and white flashing lights
One of the most important lights on modern airplanes is what we call the beacon. This flashing red light is turned on any time the engine is running, or about to start running. Pilots will turn this light on just prior to pushback and switch it off just after the parking brake is set and the engines are shut down at the end of a flight.

While the beacon is helpful in identifying an airplane while it’s flying, its main occupation is to warn anyone near the aircraft that an engine is or could start running. This advises everyone to stay clear.

Airplanes also have a set of white flashing lights located on the wing tips and, in some cases, on the tail cone. These are called anti-collision lights, or strobes. These lights are used to identify the aircraft in flight, so the plane is more visible to other pilots. These lights are switched on as the aircraft takes the runway (there are a few exceptions) and are finally turned off after the aircraft has landed and taxied clear of the runway. Pilots will also use these lights when crossing runways as a way to highlight their presence for any traffic that may be on approach or lined up to take off.

Steady red, green and white lights
Aviation takes many cues from its ancestral ties to the Navy and seafaring in general. This includes the uniforms, the word “Captain,” and as you’ve probably already guessed, the way we use lights on our airplanes.

Looking at the wingtips of any airplane, observers will see a red light on the left wing, and a green light on the right. Looking at the back of the airplane, they’ll either see a white light on the tail, or one on each wingtip, facing rearward. They are illuminated any time the aircraft has power. These are called our navigation lights and believe it or not, a quick glance provides pilots of other aircraft some very important information.

You see, Karen, these navigation lights are used to determine the orientation of another aircraft in relation to yours, depending on the lights you see. Sailors use the exact same lights for the same purpose. If you see a red and white light, the other airplane is passing from right to left. Green and white means left to right. Do you see both green and red? The airplane is pointing toward you. And finally, if you see only white, the airplane is going the same direction as you, or pointing away.

All this information just by looking at the lights.

To sum up
Thanks, Karen, for the great question. Pilots are indoctrinated in the use of the lights equipped on the airplane for not just simple illumination, but to convey information, to warn others of potential danger (a running engine), and to keep other pilots aware of their presence. The next time you’re on a flight, see if you can notice what lights the pilots turn on and when. While the illumination may seem random, your pilots are making use of every available tool to ensure you have a safe flight!

Thanks again, Karen. Do you have any stories about airplane lights? Post to the comments below. If anyone has a burning aviation question or something you would like cleared up, drop us a line at Whitney@johnnyjet.com to get your question featured in an upcoming Ask a Pilot column.

Tailwinds,

—Spencer