Navigation light

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Basic lighting configuration. 2, a vessel facing directly towards observer; 4, vessel facing away from the observer Propmec50.PNG
Basic lighting configuration. 2, a vessel facing directly towards observer; 4, vessel facing away from the observer
Red and green navigation lights on an F-22 Raptor Raptors refuel 140926-F-ML224-004.jpg
Red and green navigation lights on an F-22 Raptor
Red and green bottom navigation lights on SpaceX Dragon Dragon approaches the ISS (32238998824).jpg
Red and green bottom navigation lights on SpaceX Dragon

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. [1] 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).

Contents

A common misconception is that marine or aircraft navigation lights indicate which of two approaching vessels has the "right of way" as in ground traffic; this is never true. However, the red and green colours are chosen to indicate which vessel has the duty to "give way" or "stand on" (obligation to hold course and speed). Consistent with the ground traffic convention, the rightmost of the two vehicles is usually given stand-on status and the leftmost must give way. Therefore a red light is used on the (left (port)) side to indicate "you must give way"; and a green light on the (right (starboard)) side indicates "I will give way; you must stand on". In case of two power-driven vessels approaching head-on, both are required to give way.

Marine navigation

In 1838 the United States passed an act requiring steamboats running between sunset and sunrise to carry one or more signal lights; colour, visibility and location were not specified.

In 1846 the United Kingdom passed the Steam Navigation Act 1846 (9 & 10 Vict. c. 100) enabling the Lord High Admiral to publish regulations requiring all sea-going steam vessels to carry lights. [2] The admiralty exercised these powers in 1848 and required steam vessels to display red and green sidelights as well as a white masthead light whilst under way and a single white light when at anchor. [3]

In 1849 the U.S. Congress extended the light requirements to sailing vessels.

In 1889 the United States convened the first International Maritime Conference to consider regulations for preventing collisions. The resulting Washington Conference Rules were adopted by the U.S. in 1890 and became effective internationally in 1897. Within these rules was the requirement for steamships to carry a second mast head light.

The international 1948 Safety of Life at Sea Conference recommended a mandatory second masthead light solely for power-driven vessels over 150 feet (46 m) in length and a fixed sternlight for almost all vessels. The regulations have changed little since then. [4]

The International Regulations for Preventing Collisions at Sea (COLREGs) established in 1972 stipulates the requirements for navigation lights required on a vessel.

Basic lighting

Watercraft navigation lights must permit other vessels to determine the type and relative angle of a vessel, and thus decide if there is a danger of collision. In general, sailing vessels are required to carry a green light that shines from dead ahead to 2 points (22+1⁄2°) abaft [note 1] the beam on the starboard side (the right side from the perspective of someone on board facing forward), a red light from dead ahead to two points abaft the beam on the port side (left side) and a white light that shines from astern to two points abaft the beam on both sides. Power driven vessels in addition to these lights, must carry either one or two (depending on length) white masthead lights that shine from ahead to two points abaft the beam on both sides. If two masthead lights are carried then the aft one must be higher than the forward one.

Small power-driven vessels (under 12 metres (39 ft)) may carry a single all-round white light in place of the two or three white lights carried by larger vessels, they must also carry red and green navigation lights. Vessels under 7 metres (23 ft) with a maximum speed of less than 7 knots (13 km/h; 8.1 mph) are not required to carry navigation lights, but must be capable of showing a white light. [5] Hovercraft at all times and some boats operating in crowded areas may also carry a yellow flashing beacon for added visibility during day or night.

Lights of special significance

In addition to red, white and green running lights, a combination of red, white and green mast lights placed on a mast higher than all the running lights, and viewable from all directions, may be used to indicate the type of craft or the service it is performing. See "User Guide" in external links.

Aviation navigation

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  1. Navigation lights
  2. Aft light
  3. Anti-collision strobe lights
  4. Logo light

Aircraft are fitted with external navigational lights similar in purpose to those required on watercraft. [6] These are used to signal actions such as entering an active runway or starting up an engine. Historically, incandescent bulbs have been used to provide light, however recently light-emitting diodes have been used.

Aircraft navigation lights follow the convention of marine vessels established a half-century earlier, with a red navigation light located on the left wingtip leading edge and a green light on the right wingtip leading edge. A white navigation light is as far aft as possible on the tail or each wing tip. [7] High-intensity strobe lights are located on the aircraft to aid in collision avoidance. [8] Anti-collision lights are flashing lights on the top and bottom of the fuselage, wingtips and tail tip. Their purpose is to alert others when something is happening that ground crew and other aircraft need to be aware of, such as running engines or entering active runways.

In civil aviation, pilots must keep navigation lights on from sunset to sunrise, even after engine shutdown when at the gate. High-intensity white strobe lights are part of the anti-collision light system, as well as the red flashing beacon.

All aircraft built after 11 March 1996 must have an anti-collision light system (strobe lights or rotating beacon) turned on for all flight activities in poor visibility. The anti-collision system is recommended in good visibility, where only strobes and beacon are required can use white (clear) lights to increase conspicuity during the daytime. For example, just before pushback, the pilot must keep the beacon lights on to notify ground crews that the engines are about to start. These beacon lights stay on for the duration of the flight. While taxiing, the taxi lights are on. When coming onto the runway, the taxi lights go off and the landing lights and strobes go on. When passing 10,000 feet, the landing lights are no longer required, and the pilot can elect to turn them off. The same cycle in reverse order applies when landing. Landing lights are bright white, forward and downward facing lights on the front of an aircraft. Their purpose is to allow the pilot to see the landing area, and to allow ground crew to see the approaching aircraft.

Civilian commercial airliners also have other non-navigational lights. These include logo lights, which illuminate the company logo on the tail fin. These lights are optional to turn on, though most pilots switch them on at night to increase visibility from other aircraft. Modern airliners also have a wing light. These are positioned on the outer side just in front of the engine cowlings on the fuselage. These are not required to be on, but in some cases pilots turn these lights on for engine checks and also while passengers board the aircraft for better visibility of the ground near the aircraft. While seldom seen, the International Code of Signals allows for the exclusive use of a flashing blue lights (60 to 100 flashes/minute) and visible from as many directions as possible, by medical aircraft to signal their identity. [9]

Spacecraft navigation

In 2011, ORBITEC developed the first light-emitting diode (LED) system for use as running lights on spacecraft. Currently, Cygnus spacecraft, which are uncrewed transport vessels designed for cargo transport to the International Space Station, utilize a navigational lighting system consisting of five flashing high power LED lights. [10] The Cygnus displays a flashing red light on the port side of the vessel, a flashing green on the starboard side of the vessel, two flashing white lights on the top and one flashing yellow on the bottom side of the fuselage.[ citation needed ]

The SpaceX Dragon and Dragon 2 spacecraft also feature a flashing strobe along with red and green lights.

See also

Notes

  1. ↑ abaft: to the rear/closer to stern/'aft'

Related Research Articles

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.

<span class="mw-page-title-main">Belisha beacon</span> Design of lamp

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<span class="mw-page-title-main">Landing</span> Transition from being in flight to being on a surface

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<span class="mw-page-title-main">Instrument landing system</span> Ground-based visual aid for landing

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<span class="mw-page-title-main">Strobe light</span> Device producing regular flashes of light

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".

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<span class="mw-page-title-main">Sector light</span> Man-made pilotage and position fixing aid

A sector light is a man-made pilotage and position fixing aid that consists of strictly delineated horizontal angle light beams to guide water-borne traffic through a safe channel at night in reasonable visibility. Sector lights are most often used for safe passage through shallow or dangerous waters. This may be when leaving or entering harbour. Nautical charts give all the required information.

<span class="mw-page-title-main">Emergency vehicle lighting</span> Visual warning lights fitted to a vehicle

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<span class="mw-page-title-main">Emergency vehicle equipment</span> Equipment used by emergency vehicles

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<span class="mw-page-title-main">Aerodrome beacon</span> Beacon installed at an airport

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<span class="mw-page-title-main">Approach lighting system</span> Runway lighting installed on the approach end which extends beyond the runway

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<span class="mw-page-title-main">Airway beacon</span> Rotating light assembly mounted atop a tower

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<span class="mw-page-title-main">Aviation obstruction lighting</span> Aircraft obstacle avoidance systems

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.

<span class="mw-page-title-main">Landing lights</span> Aircraft lights

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References

  1. ↑ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 200. ISBN   9780850451634.
  2. ↑ 9th and 10th Vic. c. 100: "An act for the regulation of steam navigation, and for requiring sea-going vessels to carry boats, pp. 623–624, retrieved 6 July 2019
  3. ↑ "Steamers' lights – to prevent collision". The London Gazette . No. 20876. 11 July 1848. p. 2606.
  4. ↑ Handbook of the Nautical Rules of the Road Llana and Wisneskey
  5. ↑ "Amalgamated International & U.S. Inland Navigation Rules: Part C - Lights and Shapes". United States Coast Guard Navigation Center. Retrieved July 18, 2022.
  6. ↑ "AC 20-30B - Aircraft Position Light and Anticollision Light Installations – Document Information". www.faa.gov. Retrieved 6 April 2018.
  7. ↑ "14 CFR 25.1385, "Position light system installation"". Archived from the original on 2017-09-20. Retrieved 2012-12-09.
  8. ↑ "14 CFR 23.1401, "Anticollision light system"". Archived from the original on 2017-09-20. Retrieved 2012-12-09.
  9. ↑ http://www.seasources.net/PDF/PUB102.pdf page 146
  10. ↑ "ORBITEC Delivers First-Ever LED Lighting System for Orbital Science's Cygnus Module Spacecraft Navigation Lighting". Archived from the original on 2013-08-20. Retrieved 2013-04-13.
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