Navigation light

A Navigation light is a coloured source of specular illumination (a point source) on an aircraft, spacecraft, or waterborne vessel. Commonly, their placement is mandated by international conventions or civil authorities. They are used to signal a craft's position in low visibility, and to communicate basic information about the craft, primarily its position, heading, and status.

Some common 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.

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.

Marine navigation lights

Basic lighting

To avoid collisions, vessels mount navigation lights that permit other vessels to determine the type and relative angle of a vessel, and thus decide if there is a danger of collision. For example, almost all vessels mount a green light on the starboard (right), a red light on the port (left), and a white light facing astern. The lights have defined quadrants throughout which they must be clearly visible, and outside of which they are invisible.

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 "Quick Guide" in external links.

Large "steamers" must mount red lights on major masts.
Ships at anchor hoist a single bright white light (the anchor light).
Boats classed as "small" are not compelled to carry navigation lights and may make use of a handheld torch

Aviation navigation lights

Navigation lights are the small lights located on each wingtip of an aeroplane, there is one red light on the left wingtip, and one green light on the right wingtip, they are there so that other planes and air traffic control can know whether the pilot is coming or going. They also improve visibility.

Sources

Admiralty Manual of Seamanship ISBN 0117726966

External links

Nautical terms | Aerospace engineering