Aviation obstruction lighting is used to enhance the visibility of structures or fixed obstacles which may conflict with the safe navigation of aircraft. Obstruction lighting is commonly installed on towers, buildings, and even fences located in areas where aircraft may be operating at low altitudes. In certain areas, some aviation regulators mandate the installation, operation, color, and/or status notification of obstruction lighting. For maximum visibility and collision-avoidance, these lighting systems commonly employ one or more high-intensity strobe or LED devices which can be seen by pilots from many miles away from the obstruction.
The lights generally come in two forms:
Both types were in use in the United Kingdom until recently. New regulations stipulate the use of red lamps at nighttime only. Xenon flashers are 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. 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 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. With the advent of LEDs, white strobes are still somewhat desired.[ citation needed ]
It is common to find structures using 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) (60 per minute for flashing marking "a unique signal that pilots should interpret as a warning that catenary wires are in the vicinity of the lights") may also be used in urban areas. It has been recommended that flashing white strobes should not be used in densely populated areas, as the lights usually merge with background lighting at nighttime, making it difficult for pilots to spot them, 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. 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.[ citation needed ]
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 and 500 feet (61 and 152 meters). If a medium white strobe is used on a structure greater than 500 feet (150 meters), the structure must be painted. The common medium white strobe flashes 40 times per minute, at an intensity of 20,000 candelas for daytime/twilight, and 2,000 candelas at nighttime.
A high-intensity white strobe is used on structures that are taller than 700 feet (210 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 per minute, at an intensity of 270,000 candelas for daytime, 20,000 candelas at twilight, and 2,000 candelas at nighttime. [1]
Dual lighting is a system in which a structure is equipped with white strobes for daytime use, and red lights for nighttime use. In urban areas, these are commonly preferred since it usually exempts a structure from painting requirements. 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 US and Canada, red incandescent beacons are slowly being withdrawn from service and being replaced with red strobes or red LEDs.
For high-tension power lines, white strobes are equipped to flash 60 times per minute, using the same intensities as stated above. Unlike common white strobes, these strobes are specified not to flash simultaneously. The FAA-mandated flash pattern is middle, top, and bottom to provide "a unique signal that pilots should interpret as a warning that catenary wires are in the vicinity of the lights." [2]
On electric transmission towers, lights may be energized either from the electric field surrounding the energized conductor, or the magnetic field produced by current through the conductor.[ citation needed ] The first approach takes advantage of the high electric potential gradient around conductors. The second approach is based on Faraday's law of induction involving magnetic flux flowing through a circuit which energizes the warning light.
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; an example of such is the south scoreboard at Lambeau Field in Green Bay, Wisconsin built in 2013, which is the tallest structure in the general area of nearby Austin Straubel International Airport. 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. The United Kingdom's Belmont mast has nine clusters of red lamps spaced equally along the full height of the mast.
Conductor marking lights are sometimes used (in conjunction with overhead wire markers) to make overhead power lines more visible. Because power lines are often suspended between widely spaced masts, they present a particularly grave hazard to low flying aircraft. A simple and cost-effective solution to this problem is installing marking lights directly on the wires, but there are significant technical difficulties to low-cost power extraction from a distribution system which carries high voltages and wide-range AC current.
The ideal warning light must be able to power itself while clamped to a single wire of the line. Lights may be powered either from the electric field surrounding the energized wire, or the magnetic field produced by current through the wire. The first approach takes advantage of the high electric potential gradient between conductors, but a strong enough capacitive coupling is requested to allow capacitive extraction of the power required from the warning light. This means that long conductors must be suspended parallel to the line using glass/ceramic isolators: in fact several meters of suspended conductor are generally required, total length being inversely proportional to the line voltage. The second approach is based on Faraday's law of induction involving magnetic flux flowing through a circuit which powers the warning light.
On some tall structures there are or were non-standard aircraft warning lights installed.
Aviation laws also require towers and masts to be painted with equal length stripes of international orange and white paint along their length to improve daytime visibility. This paint scheme is usually required on towers over 200 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 LED 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. [2] [3]
Warning lights on ground-based towers and buildings contribute to both light pollution and towerkill of birds [4] .
A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which draws attention to a fixed point that can be used to navigate around obstacles or into port. More modern examples include a variety of radio beacons that can be read on radio direction finders in all weather, and radar transponders that appear on radar displays.
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid for maritime pilots at sea or on inland waterways.
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek στρόβος (stróbos), meaning "act of whirling".
A navigation light, also known as a running or position light, is a source of illumination on a watercraft, aircraft or spacecraft, meant to give information on the craft's position, heading, or status. Some navigation lights are colour-coded red and green to aid traffic control by identifying the craft's orientation. Their placement is mandated by international conventions or civil authorities such as the International Maritime Organization (IMO).
Bicycle lighting is illumination attached to bicycles whose purpose above all is, along with reflectors, to improve the visibility of the bicycle and its rider to other road users under circumstances of poor ambient illumination. A secondary purpose is to illuminate reflective materials such as cat's eyes and traffic signs. A third purpose may be to illuminate the roadway so that the rider can see the way ahead. Serving the latter purposes require much more luminous flux and thus more power.
A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. It consists of either a rotating disk with slots or holes or a lamp such as a flashtube which produces brief repetitive flashes of light. Usually, the rate of the stroboscope is adjustable to different frequencies. When a rotating or vibrating object is observed with the stroboscope at its vibration frequency, it appears stationary. Thus stroboscopes are also used to measure frequency.
A precision approach path indicator (PAPI) is a system of lights on the side of an airport runway threshold that provides visual descent guidance information during final approach. It is generally located on the left-hand side of the runway approximately 300 metres (980 ft) beyond the landing threshold of the runway.
Radio masts and towers are typically tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: guyed and self-supporting structures. They are among the tallest human-made structures. Masts are often named after the broadcasting organizations that originally built them or currently use them.
A motor vehicle has lighting and signaling devices mounted to or integrated into its front, rear, sides, and, in some cases, top. Various devices have the dual function of illuminating the road ahead for the driver, and making the vehicle visible to others, with indications to them of turning, slowing or stopping, etc., with lights also indicating the size of some large vehicles.
Emergency vehicle lighting, also known as simply emergency lighting or emergency lights, is a type of vehicle lighting used to visually announce a vehicle's presence to other road users. A sub-type of emergency vehicle equipment, emergency vehicle lighting is generally used by emergency vehicles and other authorized vehicles in a variety of colors.
Emergency vehicle equipment is any equipment fitted to, or carried by, an emergency vehicle, other than the equipment that a standard non-emergency vehicle is fitted with.
Round Island Lighthouse, in the Isles of Scilly was designed by William Tregarthen Douglass for Trinity House and completed in 1887. At the time of building it was one of three lights in the Isles of Scilly, the others being the Bishop Rock and St Agnes lighthouse. The light was modernised in 1966, automated in 1987 and the island designated as a Site of Special Scientific Interest (SSSI) in 1995. It is now managed by the Isles of Scilly Wildlife Trust, and except for the maintenance of the Grade II listed lighthouse, landing is not allowed.
An aerodrome beacon, airport beacon, rotating beacon or aeronautical beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night.
An approach lighting system (ALS) is a lighting system installed on the approach end of an airport runway and consisting of a series of lightbars, strobe lights, or a combination of the two that extends outward from the runway end. ALS usually serves a runway that has an instrument approach procedure (IAP) associated with it and allows the pilot to visually identify the runway environment and align the aircraft with the runway upon arriving at a prescribed point on an approach.
An Air traffic obstacle is a tall structure which can endanger air traffic. Air traffic obstacles have to be marked in most cases with red and white colored markings and with aircraft warning lights at night. On larger structures blinking lights are required. An example of an air traffic obstacle is the air traffic control tower.
Landing lights are lights, mounted on aircraft, that illuminate the terrain and runway ahead during takeoff and landing, as well as being used as a collision avoidance measure against other aircraft and bird strikes. Landing lights must be activated when the aircraft is under 10,000 feet in altitude.
Hoyt Radio Tower is the tallest man-made structure in Colorado and one of the tallest structures in the world. Hoyt Radio Tower is a 608.1-metre (1,995 ft) tall guyed mast near Hoyt, Colorado.
Anti-collision lights, also called beacon lights or strobe lights, are a set of lights required on every aircraft to improve visibility to others, as well as collision avoidance measures by warning other pilots. Historically they have used incandescent light bulbs, but recently LED lamps have been used.
An Austin ring transformer is a special type of isolation transformer with low capacitance between the primary and secondary windings and high isolation.
Heligoland Lighthouse is located on Germany's only offshore island, Heligoland. Constructed during World War II as an anti-aircraft tower, it was turned into a lighthouse in 1952. It features the strongest light on the German North Sea coast with a range of 28 nautical miles (52 km) so that it can be seen as far as on the East Frisian or the North Frisian islands and Halligen. The lighthouse is operated by the Tönning water and shipping authority.