Proposed features/Aviation Obstacle Light

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Emley Moor Tower by night
Aviation obstacle light
Status: Proposed (under way)
Proposed by: NKA
Tagging: aeroway:light=obstacle
Applies to: node,way,area,relation
Definition: A light indicating the presence of an object which is dangerous to an aircraft in flight.
Drafted on: 2018-02-25
RFC start: 2018-03-06


Proposal

Aviation obstacle lights, also called obstruction lights or aircraft warning lights, are 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.

Per International Civil Aviation Organization (ICAO) obstacle light requirements, all structures exceeding 45 meters above ground level must be appropriately marked with warning lights or paint. FAA and similar bodies may impose more specific national requirements.

This proposal aims to define how warning lights on aviation obstacles could be tagged with the new feature aeorway:light. The proposal also shows how visual markers may be tagged.

The obstacles themselves are tall vertical structures such as buildings, towers, masts, chimneys, bridges etc. They are typically tagged with man_made=*, power=*, building=* etc, or even a aeroway=navigationaid or other aeroway objects. The aeroway:light tags may preferably be put on the node or area which already represents such a structure, so that the supporting structure is also identified. Alternatively, it may be put on a separate node if a special location for the light is required or if the supporting structure is not known.

Although several lights are often required to light a tall structure, only one instance of aeroway:light is needed on each structure. If the structure in question is particularly wide, such as an oil refinery, a chemical plant or a bridge, then one or more extra locations may be tagged with aeroway:light in order to illustrate the horizontal scope of the structure. If an official aviation obstacle database is the source, such as the FAA Digital Obstacle File (DOF), then there will already be a suggestion on which locations to map for these scenarios.

Rationale

Aviation obstacle lights are conspicious features of tall structures. Obstacle lights in OSM may be used by flight simulators. When using external open sources for aviation obstacles for mapping for example communication masts, the structures may get a more complete description using this new key. There is currently no definition on how to tag these warning lights except for seamark tagging for the specific need of nautical charts.

Tagging

The tagging schema is based on the requirements given by ICAO and FAA, and on the Aeronautical Information Exchange Model (AIXM). It is deliberately similar to seamark tagging for lights, which is standardized by IHO/IALA and which has proven flexible for a variety of scenarios. Details of the lights are tagged with the aeroway:light: prefix. The tagging schema has been designed to also be applicable for other aeronautical light objects such as aerodrome beacons.

Key Value Discussion
aeroway:light obstacle There is an obstacle light on the structure. If no other information known then this will be the only tagging. Mandatory for obstacles.
aeroway:light:colour red

white
yellow
blue
green
etc

Colour of the light.

A combination of two colours may be used to denote alternate flashing of these colours, for example white;green.

aeroway:light:character fixed Steady light; a signal light that shows continuously, in any given direction, with constant luminous intensity and colour
flashing Strobe light; a rhythmic signal light alternating between light and darkness
floodlight A broad beam light used to illuminate a structure or area (less common than fixed and flashing)
aeroway:light:intensity high High intensity light as defined by ICAO and FAA, typically 200,000+ candela. Typically added based on external sources rather than measured by mapper.
medium Medium intensity light as defined by ICAO and FAA, typically around 20,000 candela. Typically added based on external sources rather than measured by mapper.
low Low intensity light as defined by ICAO and FAA, typically 2,000 candela or less. Typically added based on external sources rather than measured by mapper.
aeroway:light:icao_type A

B
C
D

Light categories as defined by ICAO (type D is for follow-me vehicles, so not likely to be mapped in OSM)
aeroway:light:multiple * The number of obstacle objects of identical type and with lights of identical character that exists as a co-located group. Optional. Do not use if there is only one obstacle object.
height * Vertical height of the lighted structure (in meters)
ele * Elevation above sea level at the foot/ground level of the lighted structure (in meters)

Use the :conditional suffix to tag dual lights with one colour/intensity etc at night and a different during daylight, e.g. aeroway:light:colour=white@sunrise-sunset and aeroway:light:colour=red@sunset-sunrise.

Use aeroway:light:intensity=* and aeroway:light:icao_type=* only if you happen to know how the light device is specified.

Visual marking on the structure may be tagged in this way:

Key Value Discussion
aeroway:marking obstacle The structure is painted or has other visual markers to warn aircrafts. If no other information known then this will be the only tagging. Mandatory.
aeroway:marking:type paint The obstacle may be painted to make it conspicuous to pilots.
flag Flags are used to mark certain structures or objects when it is technically impractical to use spherical markers or paint. Some examples are temporary construction equipment, cranes, derricks, oil and other drilling rigs.
sphere The spherical marker balls are typically attached to catenary structures/suspended wires. In this case, the way between the two supporting structures may already have been tagged with for example power=line between two power=tower nodes and may get additional tagging according to this table.
aeroway:marking:colour red

white
orange
etc.

Colour of the paint or marker.

A combination of two or more alternating colours may be used, for example white;orange.

aeroway:marking:pattern horizontal The object is marked with horizontal colour bands.
vertical The object is marked with vertical colour bands.
chequered Often referred to as checker plate, where alternate colours are used to create squares similar to a chess or draught board.

Examples

ICAO obstacle light types

The light categories defined by ICAO would be tagged in this way (add aeroway:light=obstacle to all rows):

iCAO intensity type ICAO light type Key/value Comments
Low intensity Type A aeroway:light:colour=red

aeroway:ight:character=fixed

aeroway:light:intensity=low

aeroway:light:icao_type=A

Type B aeroway:light:colour=red

aeroway:light:character=fixed

aeroway:light:intensity=low

aeroway:light:icao_type=B

Type C aeroway:light:colour=yellow (or blue)

aeroway:light:character=flashing

aeroway:light:intensity=low

aeroway:light:icao_type=C

For mobile vehicles, not likely to be mapped in OSM
Type D aeroway:light:colour=yellow

aeroway:light:character=flashing

aeroway:light:intensity=low

aeroway:light:icao_type=D

For follow-me vehicles, not likely to be mapped in OSM
Medium intensity Type A aeroway:light:colour=white

aeroway:light:character=flashing

aeroway:light:intensity=medium

aeroway:light:icao_type=A

Type B aeroway:light:colour=red

aeroway:light:character=flashing

aeroway:light:intensity=medium

aeroway:light:icao_type=B

Type C aeroway:light:colour=red

aeroway:light:character=fixed

aeroway:light:intensity=medium

aeroway:light:icao_type=C

HIgh intensity Type A aeroway:light:colour=white

aeroway:light:character=flashing

aeroway:light:intensity=high

aeroway:light:icao_type=A

Type B aeroway:light:colour=white

aeroway:light:character=flashing

aeroway:light:intensity=high

aeroway:light:icao_type=B

FAA obstruction light types

The light categories defined by FAA in the Digital Obstacle Files (DOF) would be tagged in this way (add aeroway:light=obstacle to all rows):

DOF light code DOF light type Key/value Comments
R Red aeroway:light:colour=red Flashing red light
D Medium intensity White Strobe & Red aeroway:light:colour:conditional=white@sunrise-sunset

aeroway:light:character:conditional=flashing@sunrise-sunset

aeroway:light:intensity:conditional=medium@sunrise-sunset

aeroway:light:colour:conditional=red@sunset-sunrise

Medium intensity flashing white (day) + red (night)
H High Intensity White Strobe & Red aeroway:light:colour:conditional=white@sunrise-sunset

aeroway:light:character:conditional=flashing@sunrise-sunset

aeroway:light:intensity:conditional=medium@sunrise-sunset

aeroway:light:colour:conditional=red@sunset-sunrise

High intensity flashing white (day) + red (night)
M Medium Intensity White Strobe aeroway:light:colour=white

aeroway:light:character=flashing

aeroway:light:intensity=medium

Medium intensity flashing white
S High Intensity White Strobe aeroway:light:colour=white

aeroway:light:character=flashing

aeroway:light:intensity=high

High intensity flashing white
F Flood aeroway:light:character=floodlight The structure is illuminated by a broad floodlight
C Dual Medium Catenary aeroway:light:colour=red

aeroway:light:character=fixed

Dual lighting of power line or other catenary wires
W Synchonized Red Lighting aeroway:light:colour=red

aeroway:light:character=flashing

Flashing red lighting, synchronized with group of lights
N Lighted (Type Unknown) aeroway:light=obstacle The obstacle is lighted but light type is unknown
U Unknown (none) Lighting not known

Please note that the elevation attribute in DOF refers to the top of the vertical structure, while ele=* refers to the ground level, i.e. the foot of the structure, so the height of the structure needs to be subtracted to derive the correct ground elevation.

The mark categories defined by FAA in DOF would be tagged in this way (add aeroway:light=obstacle to all rows):

DOF mark code DOF marking type Key/value Comments
P Orange or Oragne and White Paint aeroway:marking:type=paint

aeroway:marking:colour=orange

The object is painted orange or orange and white.
W White Paint only aeroway:marking:type=paint

aeroway:marking:colour=white

The object is painted white.
M Marked aeroway:marking=obstacle The object is marked, details unknown
F Flag Marker aeroway:marking:type=flag The object is marked with a flag, details unknown
S Spherical Marker aeroway:marking:type=spherical The object is marked with a spherical marker ball.
N None (none) The obstacle is not marked
U Unknown (none) Marking not known


Other national obstacle light types

An import plan is under way for aviation obstacles in Norway, and a small pilot import has been done for the South/East part of Norway.: Aviation obstacle import Norway.

Objects already tagged with aeroway in OSM may be seen here.

Applies to

Aircraft warning light in Changzhou

Obstacle lights could be applied to any tall structure in OSM. Typical objects would be:

man_made=communications_tower

man_made=tower

man_made=mast

man_made=chimney

man_made=crane

man_made=silo

man_made=storage_tank

man_made=water_tower

man_made=bridge

power=generator + generator:source=wind

power=pole

building=* or building:part=*, e.g. a church tower

Rendering

Rendering only likely on maps showing aviation related objects.

Features/Pages affected

The following features have been considered:

  • aeroway=navigationaid - Used to describe approach navigation systems at airports, so not appropriate for obstacle lights. In the future aeroway=navigationaid may be used to describe more types of navaids. The AIXM standard defines navaids and obstacles as two different concepts. The two classes overlap, so a navaid and an obstacle may exist at the same vertical object. In this proposal the obstacle light may belong to a aeroway=navigationaid or any other aeroway object.
  • Seamark lights - The obstacle light information could be used for seamark:light:category=air_obstruction objects, however it would need to be tagged with seamark tags. Obstacles which are close to the sea will often also be tagged as seamarks, so it is convenient to have a similar tagging structure for the lights.
  • Proposed features/Key:light source - This proposal from 2014 has been considered but the tagging structure was not capable of denoting all characteristics for the aviation obstacles. Also, the seamark tagging schema for lights has a much higher usage. On a light mast (man_made=mast + tower_type=lighting) on for example a sports stadium, light_source could be used to describe the floodlight from the mast while aeroway:light could be used to describe the warning light for aircrafts.
  • Proposed features/aeroway obstacle - This abandoned proposal from 2008 attempted to define aviation obstacles (all the structures) including lighting. It was abandoned because man_made and other keys already described these objects. In the discussion for that proposal it was suggested to tag the warning lights only. Those comments have been used when crafting the proposal for aeroway:light.
  • airmark=beacon - The airmark key currently have one value only, namely beacon. On the discussion page it has been commented that the airmark key was introduced without any discussion and should be avoided.


References

ICAO Appendix 14 Volume I 5th Edition - Aerodrome Design and Operations

ICAO Appendix 14 Chapter 6 - Visual Aids for Denoting Obstacles - Excerpt from the previous document

FAA Advisory Circular - Obstruction Marking and LIghting

FAA Digital Obstacle File (DOF) - Please see the readme document for light categories

Aeronautical Information Exchange Model (AIXM)

Comments

Please comment on the discussion page.

Voting on version 1 of this proposal was aborted and the proposal was put back into RFC on 2018-04-02 to accomodate further comments from the voting process. The main change from version 1 is to use the aeroway key instead of airmark. All comments from the voting has been copied to the discussion page.