Have you ever wondered what all those lights are for on an aircraft at night (or at times of the day)? Well, it turns out that each one has a very important role to play in keeping the plane, and its passengers, safe and sound.
Read on to find out how.
What are the different lights on aircraft used for?
And so, without further ado, here are some of the most common types of lights, and their purpose, on aircraft. The following list is far from exhaustive and is in no particular order.
1. Logo lights are some of the most obvious of aircraft lights
The most obvious type of external lights you'll see on an aircraft at night are its logo lights. Usually mounted on the horizontal stabilizer of the plane, they are used to light up the aircraft's vertical fin.
Sometimes mounted on an aircraft's wingtips, the sole purpose of these lights is to, well, make sure the carrier's logo can be seen in low light levels. These are not required by law, but are a common sight and are used as a form of advertising.
They do, of course, help make the aircraft that little bit more visible, which is always a bonus. As the vertical fin is a fairly major part of the aircraft's outline, illuminating it definitely helps other pilots spot the aircraft on the ground or in the air.
They can also help air traffic controllers identify, and keep track, of aircraft on taxiways.
2. Wing inspection lights are aptly named
Another common kind of lighting on aircraft are the wing inspection lights. As the name suggests, these lights are used to illuminate the wings for ease of inspection in low light levels.
They are typically mounted on the side of the aircraft's fuselage forward of the main wings. These lights are also angled in such a fashion as to enable the leading edge and tops of the wings to be illuminated.
The main purpose of the lights is to allow the ground crew and maintenance personnel to inspect the wings for ice and snow build-up, or damage. They also have a secondary purpose of increasing an aircraft's overall visibility to help reduce the chance of collision.
3. Red anti-collision lights (beacon lights) help keep the plane and ground crew safe
Anti-collision lights, as you might expect, are specifically designed to help prevent collisions in the air. They are vitally important, especially near airports, where there can be many aircraft in the air at the same time.
For this reason, it is incredibly important for pilots to be able to see one another's planes from a distance -- either in the air or on the ground. These lights can make aircraft observable from several miles away.
Also called beacon lights, or rotating beacons, one tends to be located on top of the fuselage, with another on the bottom of the fuselage. They are super bright and constantly flash to really grab people's attention -- and for good reason.
These lights tend to be turned on before pilots start up the aircraft's engines are used, in part, to inform the ground crew that the engines will be turned on very shortly. They can also be activated by the maintenance crew when testing hazardous components like landing gear and the parking brake.
They are only turned off once the aircraft has parked up and the engines have been turned off. For this reason, they also act as a visual aid to the ground crew that it is safe to now approach the plane.
Historically, these lights used to consist of motorized rotating reflectors or xenon arc lamps to create the flashing effect, but more modern aircraft use super bright LEDs.
4. White anti-collision lights (strobe lights) make planes visible from a great distance
Similar in purpose to red anti-collision lights, white ones are also intended to increase the aircraft's visibility from a distance. Typically mounted on the wingtips, these bright flashing white lights are also called "strobes".
They can also be found on the tail of some aircraft too.
These lights are some of the most obvious, especially whenever you look at an aircraft in the air. When an aircraft is taxiing, these lights tend to be turned off as they are very bright and can easily distract (or blind) other pilots.
Pilots tend to activate these just before takeoff and then turn them off immediately after landing. Some aircraft, like those built by Airbus, automatically activate and turn off these lights, using a special "weight-on-wheels" switch that breaks the circuit whenever the landing gear bears the weight of the plane.
These used to also be xenon arc lamps but tend to be LED today.
4. Position lights have a naval origin
Position lights are the red and green lights you'll see on the wingtips of aircraft. The red light is always on the left wing (port) and the green always on the right (starboard).
Aircraft may also have other white positioning lights on the rearward side of wingtips and/or on the back of the tail.
They are sometimes known as "navigation" or "nav" lights, although this is something of a misnomer as they are not used as navigational aids -- at least in aircraft. This kind of colored lighting system was first used in shipping way back in the 1800s.
Collisions were far too common in busy shipping lanes, so lighting was introduced to help ships see each other at night. The system proved very effective and dramatically reduced accidents at sea.
The same system was later adopted by the aircraft industry in the 20th-century. These lights must be activated at all times, no matter the time of day.
When pilots see the white positioning lights they know immediately that the other plane must be moving away from them. If they see the red and green lights, they know an aircraft is on an approach vector.
The lights help pilots, tower, ground controllers, and ground support personnel determine aircraft position and direction – thus the name “position lights.”
5. Alternating landing light system (ALLS)
ALLS or alternating landing light system is a relatively new form of aircraft lighting that was introduced to help make aircraft more visible. This system consists of alternating pulses of the left and right landing lights to create a very obvious lighting display, day or night.
ALLS is operated by the pilot using a three-position switch and are generally turned off during flight. During the descent, the lighting system is set to "pulse" around 200 feet (61 m) above the runway. The idea of using this lighting system is to help avoid collisions with other aircraft, birds, ground collision, and to also increase the lifespan of incandescent bulbs of the landing lights (if used).
6. Landing lights are very powerful lights indeed
Landing lights are the most powerful, brightest lights you will find on an aircraft. They are typically mounted on the wings, landing gear, or beneath the fuselage.
They are designed to have a very narrow beam angle that works similar in fashion to a floodlight. These lights tend to be angled slightly downwards so that they can light up the runway during takeoff and landing.
During an approach, these lights tend to begin to illuminate the runway when the aircraft is roughly 200 feet (61 m) above ground level.
These lights are very, very bright, and tend to use 600-watt bulbs. This is around ten times the strength of typical car headlights.
Both pilots and groundcrew take great care when using or testing these lights -- especially at night time. For this reason, these lights are only activated when ground personal are well clear of the aircraft, to prevent blinding them!
7. Runway turnoff and taxi lights are very important
Generally speaking, runway turnoff and taxi lights are installed on the nose gear strut and/or the front parts of the aircraft's wings. As their name suggests, these lights are used to illuminate the way in front of an aircraft while it moves around on the apron and taxiways of an airport.
In this sense, the work in a similar fashion to the headlights on your car.
Taxi lights need to be bright enough to light up the taxiway several feet in front of the plane so that the pilot can safely maneuver the aircraft when natural light levels are low. Aircraft like the Boeing 757 and 767 tend to have these lights mounted installed on the nose gear.
Runway turnoff lights can also be installed on the nose gear strut, or at the wing roots. These lights are angled slightly to the left and right of the nose.
Runway turnoff lights are used to illuminate high-speed runway exits as the aircraft decelerates during the landing rollout. The lights are also useful when making tight turns on taxiways.
And that, as they say, is a wrap. So, next time you visit an airport at night why not see how many different kinds of aircraft lights you can see?