Planes are equipped with a variety of lights that are used for navigation, safety, and to improve visibility during flight or when taxiing on the ground.
The external lights on aircraft fall into two general categories. The first is navigation lights or beacons that are always illuminated while the aircraft is in operation.
A second type includes takeoff and landing lights that are used to improve visibility when the plane is close to or on the ground.
Navigation lights: All aircraft are equipped with a steady light near the leading edge of each wingtip. When facing forward from the perspective of the pilot, the light on the right wingtip is green while that on the left wing is red. The different colours make it possible for an outside observer, such as the pilot of another aircraft, to determine which direction the plane is flying. These navigation lights are most useful at night when it is more difficult to tell the direction the plane is going without them.
Navigation or Position lights: In addition to the red and green lights, most planes are also fitted with other steady white navigation lights in various locations. Large airliners, in particular, will often have such lighting on the trailing edge of each wingtip. These lights are also sometimes placed along the trailing edges of the horizontal tail. Another popular location is at the very rear of the fuselage or at the top of the vertical tail. One of these latter lights placed along the aircraft centreline is especially common on smaller airliners and commuter planes. Whatever the location, the purpose of these steady white lights is to improve the plane's visibility from behind the aircraft.
Anti-Collision Beacon lights: Two beacon lights are fitted to aircraft near the centre of the fuselage. One is located on top of the fuselage and the other on the bottom. These lights are coloured reddish orange and rotate to produce a flashing effect. The beacons are turned on just before the engines are started and they remain active until the last engine is shut down. The beacons help to serve as a safety warning to ground personnel that the engines are operational.
Strobe lights: High-intensity strobe lights that flash a white-coloured light are located on each wingtip. Most smaller planes are only equipped with one of these strobes near the leading edge just behind the red or green navigation light. Larger airliners may be equipped with an additional strobe at the trailing edge as well. These flashing lights are very bright and intended to attract attention during flight. They are sometimes also used on the runway and during taxi to make the plane more noticeable.
Logo lights: These lights are not required but are common on most commercial aircraft. The lights are usually located on the surface of or at the tips of the horizontal stabilizer. The steady white lights are used to illuminate the company's logo painted on the vertical tail. While useful for advertising, the primary purpose of these lights is safety since the bright lights help to make the plane more visible.
Wing lights: Many airliners feature lights along the root of the wing leading edge that can be used to illuminate the wing and engine pylons in flight. These lights may be used to make the plane more visible during takeoff and landing or to inspect the wings for damage in flight. Pilots can also use the wing lights to inspect the wings and slats for any ice accretion that might build up when flying through clouds.
Taxi lights: A bright white lamp is located on the nose landing gear strut of most planes. This light is typically turned on whenever the aircraft is in motion on the ground for greater visibility during taxi, takeoff, and landing.
Landing lights: Bright white landing lights are usually fitted to most planes for enhanced visibility during the landing approach. These lights can also be used to illuminate the runway at poorly lit airports. They are often required for night landings but also commonly used during the day as well to make the plane more noticeable. While the usage of these lights is common, their location can vary from plane to plane. Landing lights may be located in the wing root, in the outboard wing, or somewhere along the forward fuselage. Some aircraft are equipped with multiple sets of landing lights in more than one of these locations.
Explanation of the lights used on the MD-11 Explanation of the lights used on the MD-11
Runway Turnoff lights: Usually located in the leading edge of the wing root, these bright white lamps are intended to provide side and forward lighting during taxi and when turning off the runway. These lights are most useful at poorly lit airports but are usually unnecessary. The lights can also be used in flight if greater visibility is required.
Wheel Well lights: Some planes are equipped with additional lights in the nose and main gear wheel wells. These lights are provided primarily to assist ground personnel in making pre-flight inspections of a plane at night.
Taxi, landing, and turnoff lights visible on the Boeing 777
Taxi, landing, and turnoff lights visible on the Boeing 777
Runway lighting
The first runway lighting appeared in 1930 at Cleveland Municipal Airport (now known as Cleveland Hopkins International Airport) in Cleveland, Ohio. A line of lights on an airfield or elsewhere to guide aircraft in taking off or coming in to land or an illuminated runway is sometimes also known as a flare path.
Technical specifications
Runway lighting is used at airports which allow night landings. Seen from the air, runway lights form an outline of the runway. A particular runway may have some or all of the following.
Runway End Identification Lights (REIL) - unidirectional (facing approach direction) or omnidirectional pair of synchronized flashing lights installed at the runway threshold, one on each side.
Runway end lights - a pair of four lights on each side of the runway on precision instrument runways, these lights extend along the full width of the runway. These lights show green when viewed by approaching aircraft and red when seen from the runway.
Runway edge lights - white elevated lights that run the length of the runway on either side. On precision instrument runways, the edge-lighting becomes yellow in the last 2,000 ft (610 m) of the runway, or last half of the runway, whichever is less. Taxiways are differentiated by being bordered by blue lights, or by having green centre lights, depending on the width of the taxiway, and the complexity of the taxi pattern.
Runway Centreline Lighting System (RCLS) - lights embedded into the surface of the runway at 50 ft (15 m) intervals along the runway centreline on some precision instrument runways. White except the last 3,000 ft (914 m), alternate white and red for next 2,000 ft (610 m) and red for last 1,000 ft (305 m).
Touchdown Zone Lights (TDZL) - rows of white light bars (with three in each row) on either side of the centreline over the first 3,000 ft (914 m) (or to the midpoint, whichever is less) of the runway.
Taxiway Centreline Lead-Off Lights - installed along lead-off markings, alternate green and yellow lights embedded into the runway pavement. It starts with green light about runway centreline to the position of first centreline light beyond holding position on taxiway.
Taxiway Centreline Lead-On Lights - installed the same way as taxiway centreline lead-off Lights.
Land and Hold Short Lights - a row of white pulsating lights installed across the runway to indicate hold short position on some runways which are facilitating land and hold short operations (LAHSO).
Approach Lighting System (ALS) - a lighting system installed on the approach end of an airport runway and consists of a series of light bars, strobe lights, or a combination of the two that extends outward from the runway end.
According to Transport Canada's regulations, the runway-edge lighting must be visible for at least 2 miles (3 km).
The edge lights must be arranged such that:
the minimum distance between lines is 75 ft (23 m), and maximum is 200 ft (61 m);
the maximum distance between lights within each line is 200 ft (61 m);
the minimum length of parallel lines is 1,400 ft (427 m);
the minimum number of lights in the line is 8.
Control of Lighting System
Typically the lights are controlled by a control tower, a Flight Service Station or another designated authority. Some airports/airfields (particularly uncontrolled ones) are equipped with Pilot Controlled Lighting, so that pilots can temporarily turn on the lights when the relevant authority is not available. This avoids the need for automatic systems or staff to turn the lights on at night or in other low visibility situations. This also avoids the cost of having the lighting system on for extended periods. Smaller airports may not have lighted runways or runway markings. Particularly at private airfields for light planes, there may be nothing more than a windsock beside a landing strip.
Aircraft warning lights
Aircraft Warning Lights http://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Emley_Moor_Tower_by_night.jpg/250px-Emley_Moor_Tower_by_night.jpg
These are high-intensity lighting devices that are attached to tall structures that are used as collision avoidance measures. Such devices make structures more visible to passing aircraft and are usually used at night, although they may be used during the day as well. These lights need to be of sufficient brightness in order to be visible for miles around the structure.
Lamp types
The lights generally come in two forms:
Red lamps that are either constantly illuminated or turn on and off slowly in a cycle of a few seconds.
White xenon discharge flashers.
Both types were in use in the United Kingdom until recently, however new regulations stipulate the use of red lamps at night time only. Xenon flashers are therefore gradually being phased out.
In the United States and Canada, there are several types of lights:
Obstruction lights (that are constantly illuminated)
Red Beacons/Red strobes
High Intensity White (Strobe) Lights
Medium Intensity White (Strobe) Lights
Traditionally, red lamps (or beacons) use incandescent filament bulbs. In order to improve the otherwise quite short lifespan, they are made with a ruggedized design and are run below normal operating power (under-running). A recent development has been the use of arrays of high power red LEDs in place of incandescent bulbs, which has only been possible since the development of LEDs of sufficient brightness. LED based lamps have a significantly longer lifespan than incandescent bulbs, thus reducing maintenance costs and increasing reliability. Several manufacturers have also developed medium intensity white strobes based on LED technology to replace Xenon.
Xenon flashers, whilst more visually impressive, tend to require frequent replacement and so have become a less favoured option. However, with the advent of LEDs, white strobes are still somewhat desired.
It is common to find structures with white xenon flashers/white strobes during the daytime, and red lights at night. Red lights are commonly found to be used in urban areas, since it is easier for pilots to spot them from above. White strobes (that flash 24/7) may also be used in urban areas. However, it has been recommended that flashing white strobes should not be used in densely populated areas; the lights usually merge with background lighting at night time, making it difficult for pilots to spot them and thereby aggravating the hazard. In addition, residents near the lit structure will complain of light trespass.
In rural areas, red beacons/strobes may also be used during night time. However, white strobes are sometimes preferred since it reduces maintenance cost (i.e. no maintenance of painting, no red side lights) and there are no background lights that would blend with the strobes.
For white strobes, there is a medium intensity white strobe and a high intensity white strobe. Medium Intensity White Strobes are usually used on structures that are between 200-500 feet (61-152.4 meters). If a medium white strobe is used on a structure greater than 500 feet (152.4 meters), the structure must be painted.
The common medium white strobe flashes 40 times in a minute, at an intensity of 20,000 candelas for daytime/twilight, and 2,000 candelas at night time.
A high intensity white strobe light is used on structures that are greater than 500 feet (152.4 meters). These lights provide the highest visibility both day and night. Unlike a medium strobe, a high intensity strobe doesn't provide 360Ëš coverage; this requires the use of at least 3 high strobes at each level. On the other hand, it reduces maintenance costs (i.e. no painting). If the structure has an antenna at the top that is greater than 40 feet, a medium intensity white strobe light must be placed above it rather than below.
The common high white strobe flashes 40 times in a minute, at an intensity of 270,000 candelas for daytime, 20,000 candelas at twilight, and 2,000 candelas at night-time.
Dual lighting is where a structure is equipped with white strobes for daytime use, and red beacons/strobes for night time use. In urban areas, these are commonly preferred since it usually exempts a structure from the requirement of having to be painted. One advantage to the dual system is that when the uppermost red lights fail, the lighting switches onto its Backup lighting system, which uses the white strobes (at its night intensity) for night time. In the United States and Canada, red beacons are slowly going out of commission and being replaced with red strobes. In addition, some medium strobes are equipped to flash the white light for daytime and red light for night in a single strobe (unlike the old type which had two different lights).
For high tension power lines, the white strobes are equipped to flash 60 times per minute, using the same intensities as stated above. Unlike the common white strobes, these strobes are specified not to flash simultaneously. The flash pattern should be middle, top, and bottom to provide "a unique system display".
Use and positioning
These lights can generally be found attached to any tall structure such as broadcast masts and towers, water tanks located on high elevation, electricity pylons, chimneys, tall buildings, cranes and wind turbines. Shorter structures that are located close to airports may also require lighting. The International Civil Aviation Organization (ICAO) sets standards, usually adopted worldwide, for the performance and characteristics of aviation warning lamps.
Lights are usually arranged in clusters of two or more around the structure at specific heights on the tower. Frequently there will be a set at the top, and then one or more sets equally spaced down the structure. England's Belmont mast (the tallest construction in the European Union) has nine clusters of red lamps spaced equally along the full height of the mast.
Navigation light
http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Winglet_and_nav_light_arp.jpg/220px-Winglet_and_nav_light_arp.jpg
A navigation light is a coloured source of illumination on an aircraft, spacecraft, or waterborne vessel, used to signal a craft's position, heading, and status. Commonly, their placement is mandated by international conventions or civil authorities.
Navigation lighting systems include:
Right-of-way lights - On ships, aircraft and manned spacecraft, a red light will be mounted on the left or port side of the craft and a green on the right or starboard side. These help two craft on a collision course determine who has right-of-way: if a pilot sees a craft on a path crossing his own, he will see either its red running light or green running light. If he sees green, he is to the impinging craft's starboard and has the right of way. If the pilot sees the red light, he knows that the approaching craft has the right-of-way, and he is required to deviate from his course to avoid the collision.
http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/Ba_b757-200_g-bpei_closeup_arp.jpg/220px-Ba_b757-200_g-bpei_closeup_arp.jpg
A British Airways Boeing 757-200 lands. The port wing tip carries a red navigation light.
Strobe lights - On aircraft primarily, strobe lights flash a high-intensity burst of white light, to help other pilots recognize the aircraft's position in low-visibility conditions.
Aviation navigation lights
High-intensity strobe lights are located on the aircraft to aid in collision avoidance. Navigation lights in civil aviation are required to be turned on from sunset to sunrise. The anti collision light system is required for all airplanes built after March 11, 1996 for all flight activities in poor visibility, and recommended in good visibility, where only strobes and beacon are required. An example of this would be just before push back, (push and start) the beacon lights are required, to notify ground crews that the engines are about to be started. These beacon lights will stay on for the duration of the flight. While taxiing, the taxi lights are activated. When coming onto the runway, the taxi lights are deactivated and the landing lights and strobes are activated. When passing 10000 feet (or FL100) the landing lights are no longer required, and can be turned off at the pilots discretion. The same cycle works when landing, but in reverse order.
Regulations
The Federal Aviation Administration (FAA) has implemented regulations concerning warning light requirements for night time flying. Night time flying presents safety hazards because structures can present optical illusions when seen at varying altitudes.
Plane Light Position
For night time flying, FAA regulations mandate an anti-collision lighting system consisting of flashing or rotating lights placed on the plane's left and right wingtips. The lighting system aims to provide other pilots with information concerning a plane's flight position.
Anti-Collision Lights
FAA regulations mandate that anti-collision lights meet requirements for colour and intensity. Anti-collision lights must be industry standard red or white and also meet light intensity specifications.
Airport Lights
Most airports use a rotating beacon light for night time identification. A civilian land airport typically uses an alternating white and green beacon light. Military airports also use an alternating white and green beacon light distinguishable by its quick white flash.
Pre-flight Light Check
FAA regulations mandate a pre-flight light check of all airplane lights. If a check indicates a loose light connection, the light must be inspected before departure. Also before departure, pilots must note prominently lighted points along the flight path.
Exterior aircraft lights are essential aircraft components that are regulated by the Federal Aviation Administration (FAA). The proper use of lighting allows pilots to see other airplanes and determine the direction that they are travelling.
Source of Regulations
Regulations concerning the use of civil aircraft lighting are detailed under Part 91, Section 209 of the Code of Federal Aviation Regulations (FAR 91.209), as well as in "Use of Aircraft Lights," Chapter 4, Section 3, paragraph 23 of the Aeronautical Information Manual (AIM 4-3-24). Both of these are available on the FAA's website.
Anti-collision Lights
Aircraft equipped with anti-collision lights must use them when the aircraft is operating regardless of the time of day. Anti-collision lights may either be an "aviation red" rotating beacon, often located on the top and bottom of the fuselage, or "aviation white" strobe lights located on the wing tips and on the tail.
Position Lights
Aircraft must be equipped with operating "lighted position lights" when operating between sunset and sunrise. Airplane position lights use the same three-coloured lighting system found on maritime vessels. These lights help other pilots determine the direction an aircraft is travelling. Position lights consist of three steady lights, green on the right wingtip, red on the left wingtip and white on the tail.
Parking or Moving at Night
If an aircraft is parked or moved between sunset to sunrise, it must be clearly illuminated. It must also either be "in an area that is marked by obstruction lights" or have "lighted position lights." The FAA does not define "clearly illuminated," but a taxi or landing light combined with a rotating beacon (if installed) is a good rule of thumb.
Sunset and Sunrise
The sun rises and sets at different times each day. The AIM defines sunset and sunrise as "when the upper edge of the disk of the sun is on the horizon." Official times assume a flat horizon, so in mountainous regions, the sun may be behind an obstruction prior to official sunset or after official sunrise.
Compliance
Depending on the nature of the violation, individuals who fail to comply with FAA regulations are subject to fines of up to $50,000 and suspension of their certificates.
