Aircraft warning lights
Encyclopedia
Aircraft warning lights are high-intensity lighting devices that are attached to tall structures and 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.
Both types were in use in the United Kingdom
until recently, however new regulations stipulate the use of red lamps at nighttime only. Xenon flashers are therefore gradually being phased out.
In the United States
and Canada
, there are several types of lights:
Traditionally, red lamps (or beacons) use incandescent filament bulbs
. In order to improve the otherwise quite short lifespan, they are made with a ruggedised design and are run below normal operating power (under-running). A recent development has been the use of arrays of high-power red LED
s 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 round the clock) 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 nighttime, 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 nighttime. However, white strobes are (sometimes) preferred since they reduce the maintenance cost (i.e. no maintenance of painting, no red side lights) and there are no background lights that would blend with the strobes.
There are 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 candela
s for daytime/twilight, and 2,000 candelas at nighttime.
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 does not provide 360˚ 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 nighttime.
Dual lighting is a system in which a structure is equipped with white strobes for daytime use, and red beacons/strobes for nighttime 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 nighttime. In the United States and Canada, red beacons are slowly being withdrawn from service 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".
, water tanks located on high elevation, electricity pylons, chimney
s, tall buildings
, cranes
and wind turbine
s. 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.
lights in either red, white, or both colors in an alternating pattern. In such a case red is employed at night, while a white strobe is usually used during daylight hours.
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
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
until recently, however new regulations stipulate the use of red lamps at nighttime only. Xenon flashers are therefore gradually being phased out.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, 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
Incandescent light bulb
The incandescent light bulb, incandescent lamp or incandescent light globe makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated. In a halogen lamp, a chemical process...
. In order to improve the otherwise quite short lifespan, they are made with a ruggedised design and are run below normal operating power (under-running). A recent development has been the use of arrays of high-power red LED
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s 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 round the clock) 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 nighttime, 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 nighttime. However, white strobes are (sometimes) preferred since they reduce the maintenance cost (i.e. no maintenance of painting, no red side lights) and there are no background lights that would blend with the strobes.
There are 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 candela
Candela
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function . A common candle emits light with a luminous intensity of roughly one candela...
s for daytime/twilight, and 2,000 candelas at nighttime.
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 does not provide 360˚ 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 nighttime.
Dual lighting is a system in which a structure is equipped with white strobes for daytime use, and red beacons/strobes for nighttime 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 nighttime. In the United States and Canada, red beacons are slowly being withdrawn from service 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".
On aircraft
Aircraft use collision avoidance lighting systems to warn other aircraft of their presence. These lights include landing lights, red or white flashing beacons, wingtip strobes, and wingtip navigation lights. The wingtip navigation lights are required to consist of a red light on the left wingtip and a green light on the right wingtip. Landing lights are used during the descent and approach to landing, and at other times if deemed necessary by the flight crew or operator.Use and positioning
These lights can generally be found attached to any tall structure such as broadcast masts and towersRadio masts and towers
Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. They are among the tallest man-made structures...
, water tanks located on high elevation, electricity pylons, chimney
Chimney
A chimney is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the...
s, tall buildings
Skyscraper
A skyscraper is a tall, continuously habitable building of many stories, often designed for office and commercial use. There is no official definition or height above which a building may be classified as a skyscraper...
, cranes
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
and wind turbine
Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...
s. 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
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
's Belmont mast
Belmont transmitting station
The Belmont transmitting station is a broadcasting and telecommunications facility, situated next to the B1225, one mile west of the village of Donington on Bain in the civil parish of South Willingham, near Market Rasen and Louth in Lincolnshire, England . It is owned and operated by Arqiva.It has...
(the tallest construction in the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
) has nine clusters of red lamps spaced equally along the full height of the mast.
Non-standard aircraft warning lights
On some tall structures there are or were non-standard aircraft warning lights installed.- The mast of Deutschlandsender Herzberg/ElsterDeutschlandsender Herzberg/ElsterThe Deutschlandsender Herzberg/Elster was a 500 kilowatt long-wave transmitter at Herzberg/Elster, which was in service from 1939 to 1945. It used a 337 metre high guyed steel lattice mast of triangular cross section. This was used as a mast radiator and was therefore mounted on a 0.75 metre high...
had no aircraft warning lamps installed. It was instead lit by skybeamers mounted on small masts near the tower. This method was chosen as the mast was a mast radiatorMast radiatorA mast radiator is a radio mast or tower in which the whole structure itself functions as an antenna. This design is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically...
insulated against ground and for feeding the lamps on the mast otherwise special devices like Austin transformerAustin transformerAn Austin transformer is a special type of an Isolation transformer used for feeding the air-traffic obstacle lamps and other devices on a mast radiator antenna insulated from ground. As the electrical potential difference between the antenna and ground is high , feeding the lamps directly is...
s would be required. - Stuttgart TV TowerFernsehturm StuttgartThe Fernsehturm Stuttgart is the world's first TV tower built from concrete ....
carries rotating lamps like used on lighthouses. Such lamps were also used on other towers in earlier days. - BlosenbergturmBlosenbergturmThe Blosenbergturm is a transmitting tower in Beromünster, Canton of Lucerne, Switzerland, built in 1937 for the German language radio station DRS and radiating at an AM frequency of 531 kHz marking the bottom end of the official mediumwave broadcasting range. The Blosenbergturm has a height of...
in Beromünster has a rotating lamp above the cabin. In opposite to Stuttgart TV Tower it is less bright and only operated at dawn. - The main masts of Mühlacker radio transmitter and the former Konstantynów Radio MastWarsaw radio mastThe Warsaw radio mast was the world's tallest structure until its collapse on 8 August 1991. It is the second tallest land-based structure ever built, being surpassed as tallest by the Burj Khalifa, completed in 2010....
also have aircraft warning lights at the outermost bases of their anchor guys. - Conductor marking lightsConductor marking lightsConductor marking lights are a particular type of non-standard aircraft warning lights designed for overhead power lines.-Background:Power distribution on overhead wires, often suspended to widely spaced masts, represents an almost invisible obstacle to low flying aircraft, requiring the...
and BalisorBalisorBalisor is a system of illuminated beacons for high voltage power lines using a cold-cathode low-pressure neon lamp .-Description:High voltage power cables, particularly those close to airports, need to be visible day and night. During the day, brightly coloured balls positioned along the length of...
s are sometimes used for marking power lines. - The Obstacle Collision Avoidance SystemObstacle Collision Avoidance SystemThe Obstacle Collision Avoidance System is designed to alert pilots if their aircraft is in immediate danger of flying into an obstacle. OCAS uses a low power ground based radar to provide detection and tracking of an aircraft's proximity to an obstacle such as a power line crossing, telecom...
allows the standard lights to remain off until an aircraft is within a given radius, allowing for a significant decrease in light pollution. The OCAS system also provides audio warnings.
Aircraft warning paint
Aircraft warning paint usually consists of red and white paint at equal lengths on the antenna tower or mast. This paint scheme is usually required on towers over 300 feet tall, but may vary from state to state and near airports internationally. Because such a paint scheme is expensive to apply, antenna towers and masts are often built to heights just below the level of requirement. Antenna towers and masts often also have other aircraft warning features located at equal distances along their height and at their tops. These may include high powered strobe lights or LEDLEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
lights in either red, white, or both colors in an alternating pattern. In such a case red is employed at night, while a white strobe is usually used during daylight hours.
External links
- The Transmission Gallery: Close up of LED warning lamp array on the Membury mast
- The Transmission Gallery: Belmont mast - includes night shot showing the nine sets of warning lamps
- Obstacle Collision Avoidance System (OCAS) - Enhanced Standard Lighting by eliminating unnecessary light pollution
- Aircraft warning lights gallery
- Aircraft warning lights video and models: LIOL-B (L810), MIOL-B (L864), MIOL-A (L865)