Obstacles and restricted-use areas
Learning objectives
- Identify the colours and patterns used to mark fixed obstacles, and explain which pattern fits which kind of object.
- Identify obstacle lights from their colour and flash behaviour, including the wire-tower sequence and the day/night dual system.
- Explain what closed markings, unserviceability markers and lights, side stripes and pre-threshold chevrons mean, and what you do when you meet them.
- Calculate the band width on a marked mast and the number of markers needed along a wire span.
The idea
Some things on and near an aerodrome can hurt you: a mast in your climb-out, a wire across a valley, a runway full of workmen, a patch of pavement that will not carry your weight. Most are hard to see in time. So each hazard wears a code: bold colours and patterns by day, lights by night, crosses on ground that is shut. Learn the code once, and a glance tells you "keep away", "go around" or "not here".
Where these rules apply
The EU aerodrome rules cover aerodromes in EU territory that are open to public use, serve commercial air transport and have a paved instrument runway of 800 m or more; all three conditions must be met. Smaller fields follow national rules, so you may meet different markings there, or none.
The marking and lighting specifications describe what the operator provides, not what you must do, and they apply only to the area under the operator's control. Expect unmarked obstacles outside it.
An obstacle is a fixed or mobile object that sits on a surface where aircraft move, or sticks up through a surface that protects aircraft in flight, or stands outside those surfaces but has been assessed as a hazard. A marker stands above the ground, like a flag or sphere; a marking is a symbol on the surface, like a cross.
The specifications on which objects are marked or lit apply only to the area under the control of the aerodrome operator.
Marking and lighting only make an obstacle visible. They do not remove any approach or take-off limitation the obstacle causes.
Which objects get marked
Not every tall thing is marked. A fixed object is marked, and lit if the runway or aerodrome is used at night, when it sticks up through a take-off climb, approach or transitional surface within 3 000 m of the inner edge, or through the horizontal surface around the aerodrome. An object shielded by another fixed obstacle is exempt. Objects close to a taxiway or stand taxilane centre line are marked too, and lit if the taxiway is used at night. So are objects above the protection surface of a visual glide-slope indicator.
Outside those surfaces, an object 150 m or more above ground counts as an obstacle unless a safety assessment says otherwise, and it is marked and lit. Wires over a river, valley or highway, and objects beside visual routes, are marked if an assessment finds them hazardous.
Marking fixed objects: colour first
The logic is "stand out against sky and ground": orange or red, paired with white, does that best. Colour the object if practicable; if not, put markers or flags on it. An object that is already conspicuous by shape, size or colour needs nothing extra.
The pattern depends on the object's shape:
- Chequered pattern for big, unbroken surfaces at least 4.5 m across in both directions, such as a water tank. The corner squares take the darker colour.
- Alternating bands for an unbroken object with one dimension over 1.5 m and the other under 4.5 m, and for lattice (skeletal) structures with a dimension over 1.5 m. Bands run across the longest dimension, each about one seventh of it or 30 m, whichever is less. Orange and white are the default, and both end bands, top and bottom of a mast, are the darker colour. That gives an odd number of bands.
- A single colour, orange or red, for small objects under 1.5 m in both dimensions.
Describe this figure
Three objects stand side by side on the ground. The wide tank on the left carries a three-by-three chequer with dark corners and a dark centre, for unbroken surfaces of 4.5 m or more in both directions. The tall slim mast in the middle has seven horizontal bands, dark at the top and at the bottom, which gives an odd number of bands; it stands for narrow or lattice objects. The small box on the right is plain orange, for objects under 1.5 m in both directions. A key says dark is orange or red and light is white.
The figure shows a wide tank with a dark-cornered chequer, a tall mast with bands dark at top and bottom, and a small plain orange box.
Where painting is impractical, expect flags or markers. Flags are orange, or two triangles of orange and white or red and white. Markers are provided so they can be recognised in clear weather from at least 1 000 m in the air and 300 m on the ground.
Scan the circuit and low-level VFR routes for orange and white bands or chequers, flags, and white flashing lights by day. Small or off-aerodrome objects may carry no marking at all.
Obstacle lights: reading the code
Lit objects use low-, medium- or high-intensity lights, or a mix, arranged so the object shows from every direction, with one light as close to the top as practicable.
The code in plain words:
- Low intensity. Types A and B are fixed (steady) red. Type C, for vehicles, flashes yellow or blue; Type D, the follow-me vehicle, flashes yellow; both flash 60 to 90 times a minute. Type E flashes red and is used on wind turbines. Types A and B work at night only.
- Medium intensity. Type A flashes white, Type B flashes red, Type C is fixed red. Type A and B flash 20 to 60 times a minute. Only Type A also works by day and twilight.
- High intensity. Types A and B both flash white, 40 to 60 times a minute. They work by day as well as at night.
By day the flash you see is white. At night it may still be white, or it may be red where a dual system or a Type B or C light is fitted. Lights on one structure that are high-intensity Type A or medium-intensity Type A or B flash at the same moment.
| Type | Colour and flash | Day / twilight / night | Used on |
|---|---|---|---|
| Low A | red, steady | – / – / 10 cd | fixed objects, not extensive |
| Low B | red, steady | – / – / 32 cd | fixed objects, not extensive |
| Low C | yellow or blue, flashing, 60 to 90 a minute | – / 40 / 40 cd | vehicles (blue: emergency or security) |
| Low D | yellow, flashing, 60 to 90 a minute | – / 200 / 200 cd | follow-me vehicle |
| Low E | red, flashing, same rate as the nacelle light | – / – / 32 cd | wind turbines |
| Medium A | white, flashing, 20 to 60 a minute | 20 000 / 20 000 / 2 000 cd | objects from 45 m, extensive objects |
| Medium B | red, flashing, 20 to 60 a minute | – / – / 2 000 cd | objects from 45 m, extensive objects |
| Medium C | red, steady | – / – / 2 000 cd | objects from 45 m, extensive objects |
| High A | white, flashing, 40 to 60 a minute | 200 000 / 20 000 / 2 000 cd | tall structures |
| High B | white, flashing, 40 to 60 a minute | 100 000 / 20 000 / 2 000 cd | towers carrying wires |
Describe this figure
The table has one row for each of ten light types: low-intensity A to E, medium-intensity A to C, and high-intensity A and B. Low A and B are steady red and work at night only. Low C and D flash yellow, or blue for emergency vehicles, at 60 to 90 flashes a minute, and low E is the flashing red light of wind turbines. Medium A flashes white and works by day, twilight and night, while medium B flashes red and medium C is steady red, both at night only. High A and B flash white at 40 to 60 flashes a minute and work in all light, high B being for towers that carry wires.
The figure is a lookup table: one row per light type, with colour, steady or flashing, flash rate, and whether it works by day, twilight or night.
The dual system
A bright white flash near an aerodrome at night can dazzle. Where that is a concern, within roughly 10 000 m of the aerodrome or for environmental reasons, the same mast shows white lights by day and twilight and red medium-intensity lights at night.
Height bands
Taller structures get more light levels:
- Under 45 m: low-intensity Type A or B where the object is not extensive. Medium- or high-intensity lights are used if low would be inadequate or early warning is needed. A group of buildings counts as extensive.
- 45 m to under 150 m: medium-intensity lights, with extra levels added so that levels are no more than 105 m apart for Type A and no more than 52 m apart for Types B and C.
- Above 150 m: high-intensity Type A where a safety assessment says they are essential for recognition by day, levels no more than 105 m apart. If medium-intensity lights are used instead, the same spacings apply.
Describe this figure
Four masts rise from the ground in increasing height. The shortest, under 45 m, has one steady red light at the top. The second, from 45 m to under 150 m, has a flashing red light at the top and two more levels below it, the middle one steady, spaced 52 m or less apart. The third, over 150 m, is shown by day with three flashing white levels at most 105 m apart. The fourth is the same mast at night, with five flashing red levels at most 52 m apart, as in a dual system.
The figure shows masts of increasing height: one steady red light at the top, then more levels, and finally the tallest mast in its white-by-day and red-by-night forms.
Some wind farms switch their lights on only when an aircraft approaches. Do not rely on seeing a light to know an obstacle is there.
Wind turbines
Wind turbines that count as obstacles are painted white on the blades, nacelle and upper two-thirds of the mast, unless a safety assessment finds another colour safer. A wind farm is one extensive object: lights mark its perimeter, flashing lights flash together, and noticeably taller turbines inside are lit too.
Describe this figure
The upper panel shows a wind farm from above. Eight turbines mark a dashed perimeter and each carries a flashing light; one taller turbine in the middle is lit as well. The lower panel shows a turbine of 150 m to 315 m in side view. Its blades, nacelle and upper two-thirds of the mast are white, the lower third is not. A flashing light sits on the nacelle, and a ring of flashing red lights circles the mast at half the nacelle height.
The figure shows a wind farm from above and the side: lights on the perimeter turbines, one taller inner turbine lit too, and a ring of red lights on a larger turbine.
Wires and their towers
A wire is thin and nearly invisible, so it is the real danger. The supporting towers are coloured with chequers or bands, and that colouring can be omitted if the towers carry high-intensity lights by day. Wires that need marking carry spherical markers at least 60 cm across, alternating white and red or white and orange, one colour per sphere. Spacing, marker to marker or marker to tower, normally does not exceed 30 m for 60 cm spheres, 35 m for 80 cm spheres and 40 m for spheres of 130 cm or more.
If markers cannot go on the wires, or a safety assessment says lights are essential, the towers carry high-intensity Type B lights, flashing white, at three levels: the top, the lowest point of the wire sag (the catenary), and about midway between.
The three lights flash in sequence, not together: middle, then top, then bottom, with gaps of about 1/13, 2/13 and 10/13 of the cycle. A single mast flashes all its lights at once. That rippling order tells you wires span between towers.
Describe this figure
Two striped towers stand on the valley sides with a wire sagging between them. White and red spheres alternate along the wire. Each tower carries three flashing white lights: at the top, at the level of the lowest point of the wire, and midway between. The timing strip below shows one cycle: the middle light flashes first, the top light 1/13 of the cycle later, the bottom light 2/13 after that, then a pause of 10/13 before the middle light starts again.
The figure shows two towers across a valley, spheres along the wire, and a timing strip: middle, top, bottom, then a long pause.
Treat any tower on a low-level route as a possible wire anchor, and look for the next tower.
Vehicles on the movement area
Vehicles and other mobile objects on the movement area are marked with conspicuous colours or chequered flags. If vehicles and the aerodrome are used at night or in low visibility they also carry lights. Emergency and security vehicles show flashing blue. Other vehicles, including follow-me, show flashing yellow. Objects of limited mobility, such as aerobridges, show fixed red. The follow-me vehicle shows a brighter flashing yellow (Type D).
Closed runways and taxiways
If a runway or taxiway, or part of one, is closed, it shows a closed marking: a cross. It is white on a runway and yellow on a taxiway. The runway cross is long and narrow, centred on the centre line. The taxiway cross is small, with arms at right angles to each other and at 45 degrees to the centre line.
On a closed runway the cross appears at each end of the closed part and again so that crosses are never more than 300 m apart. On a closed taxiway it appears at least at each end of the closed part.
Three details:
- Lighting on a closed runway or taxiway is not operated, except for maintenance. An unlit runway may therefore be closed rather than merely unlit.
- Where a usable runway or taxiway used at night crosses a closed area, steady red unserviceability lights are placed across the entrance in addition to the crosses, no more than 3 m apart.
- A short temporary closure may carry no marking if air traffic services give adequate warning. A permanently closed taxiway may carry only lights and markers at its entrance.
Markings of a permanently closed runway or taxiway are physically removed, never painted over, because dark paint can reflect sunlight and wear through, and so mislead crews.
Describe this figure
A runway runs down the page with white crosses at each end and one in between, never more than 300 m apart. Its edge lights are drawn as empty circles because they are not operated. A taxiway joins from the left and carries a small yellow cross. A row of steady red lights, 3 m apart or less, lies across the taxiway where it meets the closed runway.
The figure is a plan view: white crosses at each end of the closed runway section with dark edge lights, a smaller yellow cross on a taxiway, and fixed red lights across the entrance where a usable taxiway meets the closed area.
Unserviceable areas
Cones and lights mark local hazards, such as a hole or a patch under repair, that aircraft can still safely go around. They are not used when part of a runway or most of a taxiway's width is unusable; that is closed and gets closed markings.
By day you see upstanding devices: cones, flags or marker boards. A cone is at least 0.5 m tall. A flag is at least 0.5 m square. Each is red, orange or yellow, or one of those combined with white. A marker board is at least 0.5 m high and 0.9 m long, with vertical stripes of red and white or orange and white.
At night on a movement area you see unserviceability lights. They are steady red, never less than 10 cd. For a temporary area, lights mark the extremities: at least four, or three for a triangle, and at least one per 7.5 m of perimeter.
Describe this figure
Two panels show the same hatched patch on an apron. In the day panel, cones, flags and a vertical-striped marker board stand around its edge. Cones and flags are at least 0.5 m, and the board at least 0.5 m by 0.9 m. In the night panel, steady red lights replace them, at every corner and between corners: at least four lights, and at least one per 7.5 m of perimeter.
The figure shows an apron patch outlined by cones, flags and a striped board by day, and by fixed red lights at night.
Non-load-bearing surfaces
Some pavement, such as a taxiway shoulder, looks usable but cannot carry an aircraft. A taxi side stripe marking fences it off: two solid yellow lines, each 15 cm wide and 15 cm apart.
Describe this figure
The plan shows a T-junction of taxiways on dark pavement. A double solid yellow line runs along every taxiway edge, including the curved corners. Outside the lines is the shoulder, which looks like pavement but is not load-bearing. A close-up box shows the two lines enlarged: each is 15 cm wide and the gap between them is 15 cm.
The figure shows a double yellow line along each edge of a taxiway junction.
Holding positions belong to the runway and taxiway markings page (010-09-03).
Pre-threshold chevrons
If the paved surface before a threshold is longer than 60 m and is not suitable for normal aircraft use, its entire length is marked with chevrons. They point towards the threshold, are conspicuous and preferably yellow, and have a stroke width of at least 0.9 m. As drawn, each arm sits at 45 degrees to the centre line, with apexes every 30 m.
Describe this figure
A runway is seen from above with its centre line dashed. Six yellow chevrons sit on the centre line before the white threshold bar, all pointing towards the runway. Each arm is at 45 degrees to the centre line and each chevron is at least 0.9 m wide in stroke. The apexes are 30 m apart. The first chevron is cut off by the start of the area, and the last stops short of the threshold.
The figure shows yellow arrow-heads on the centre line before a threshold, all pointing towards the runway.
A displaced threshold is marked with arrows instead; see the runway markings page (010-09-03).
Treat a closed marking, chevrons, red fixed lights across a pavement, or cones, flags and boards on a taxiway as "do not use this surface". If unsure, stop and ask. Read the NOTAMs and ATIS before flying to any aerodrome, and re-check after a change of destination. This content is educational and does not replace ATO instruction or your aircraft's POH/AFM. For where closures are published, see the page on aeronautical information (010-08-01).
Worked examples
Band width on a mast. Given: a lattice mast, longest dimension 21 m. Method: band width is about one seventh of the longest dimension, or 30 m, whichever is less. Working: 21 / 7 = 3 m, which is less than 30 m. The number of bands is 21 / 3 = 7, which is odd, so the top and bottom bands are both the darker colour. Answer: bands of 3 m, 7 bands in total.
Markers on a wire span. Given: a span of 90 m between two towers, 60 cm spheres. Method: spacing, including sphere to tower, normally does not exceed 30 m for 60 cm spheres. Working: 90 / 30 = 3 intervals. Three intervals between two towers need 3 − 1 = 2 spheres. Answer: 2 spheres in between.
In the real world
At night, during runway works at London Stansted on 12 November 1998, the crew of a Gulfstream IV, VP-BHG, misread the ATIS and the temporary lighting and landed on the closed half of the runway, stopping about 100 m short of the far threshold. The closed section had cones with red lights across it and covered edge lights, but some light leaked and the red wing bars were taken for a visual approach slope indicator. Read the ATIS, the NOTAM and the visual aids together; dimmed or covered lights do not mean "usable".
After a diversion on 13 March 2018, the pilot of a PA-28, G-BTAW, did not check NOTAMs or obtain prior permission and landed on a runway closed at Castle Kennedy for tethered-kite trials. A flat cross-shaped closure marker at the threshold was seen only during the flare and taken for a flag. It was a small unlicensed airfield, so its marker was not to the EU standard. The closure marker is the last line of defence; pre-flight information, re-checked after a change of plan, is the first.
Exam traps
"Closed markings are yellow everywhere", or "white everywhere". They are white on a runway and yellow on a taxiway.
"Unserviceability lights flash, or are amber." They are steady red.
"Obstacle lights are always red." Medium-intensity Type A and all high-intensity lights are flashing white, and they work by day.
"All lights on a mast flash in sequence." Lights on one structure flash together; the middle-top-bottom sequence belongs to towers carrying wires.
"Blue flashing means follow-me." Blue is emergency or security; follow-me is flashing yellow.
"Every closure is marked on the ground." A short temporary closure may rely on an ATS warning, so read the NOTAM and ATIS.
Explain it back
On a low-level route you see a tower with three white lights flashing in rippling order, and a second tower across the valley. Explain, without notes, what this tells you, why the wire is the real hazard, and what you do next.
Self-check
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A slim lattice radio mast, 2 m wide and 40 m tall, is to be marked by painting. Which treatment is specified?mcq · easy
Show answer
Lattice structures with a dimension over 1.5 m are banded, orange and white by default, with the darker colour on both end bands, which gives an odd number of bands. A chequer is for large unbroken surfaces at least 4.5 m across in both directions. A single colour is for objects under 1.5 m in both dimensions. Red and white bands with white at the ends would break the rule that the ends are the darker colour.
Reference: CS ADR-DSN.Q.845(b)
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At dusk, flying low along a valley, you see a tower with three white lights that flash one after another in a rippling order: middle, then top, then bottom, repeating. What does this tell you?mcq · medium
Show answer
High-intensity Type B lights at the top, the lowest point of the wire sag and midway flash in sequence to signal wires between towers. Wind-farm flashing lights flash together, not in sequence. A dual system changes colour with the light level and does not ripple. Height decides the number of light levels but does not produce a sequence, because lights on one ordinary mast flash at the same moment.
Reference: CS ADR-DSN.Q.846; GM1 ADR-DSN.Q.846; CS ADR-DSN.Q.852(d)
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At night, in the beam of your landing light, you see a runway with all its edge lights off and a white cross at its end. What does this mean?mcq · medium
Show answer
A closed runway carries white crosses, and the lighting on it is not operated except for maintenance, so an unlit runway may be closed rather than merely unlit. A cross is not a landing-direction signal. Yellow is the colour of a closed taxiway cross, not a runway one. Fixed red lights are added across the entrance where a usable pavement crosses a closed area, in addition to the crosses, and dark lights never mean open.
Reference: ADR.OPS.B.071(a); ADR.OPS.B.071(d); CS ADR-DSN.R.855
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Two towers are 140 m apart. The wire between them carries 80 cm spheres, and the normal maximum spacing for that size, including sphere to tower, is 35 m. What is the minimum number of spheres needed between the towers?mcq · hard
Show answer
140 / 35 = 4 intervals, which need 4 - 1 = 3 spheres between the towers. Two spheres would leave intervals of about 47 m, over the limit. Four and five spheres would also meet the limit but are more than the minimum.
Reference: CS ADR-DSN.Q.852(c)(3)
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Taxiing at night, you follow a vehicle showing a bright flashing yellow light. Beside your lit taxi route, a ring of steady red lights outlines part of the apron. What is the correct reading?mcq · medium
Show answer
The follow-me vehicle shows a brighter flashing yellow, whereas emergency and security vehicles show flashing blue. Steady red lights of at least 10 cd outline an unserviceable area at night, such as a patch under repair, which aircraft keep clear of. Flashing yellow is not the emergency vehicle colour (blue), and a runway closure is shown by crosses, so the first option fails. Security vehicles show blue, not yellow, and the red lights are steady, not flashing obstacle lights, so the second fails. Steady red is a warning, not permission to park, so the fourth fails.
Reference: ADR.OPS.B.080(a); AMC1 ADR.OPS.B.070(c)(5); CS ADR-DSN.R.870
Key concepts
Written with ASD-STE100 writing principles: short sentences, one topic per sentence, active voice, one word for one meaning.
Closed marking
A closed marking is a cross that shows a closed runway, a closed taxiway, or a closed part of either.
It is white on a runway and yellow on a taxiway.
The lights on a closed pavement do not operate, except for maintenance.
Rule: ADR.OPS.B.071(a)
Do not: use a runway or taxiway that shows a closed marking.
Obstacle marking pattern
A fixed obstacle gets its colour first, where that is practicable.
The pattern depends on the object shape.
Chequers suit large unbroken surfaces, bands suit lattice structures and slender objects, and one colour suits small objects.
Rule: CS ADR-DSN.Q.845(a)
Obstacle light code
Low-intensity Type A and B lights show fixed red at night only.
Medium-intensity Type A and high-intensity lights flash white, and they also work by day.
A dual obstacle lighting system shows white lights by day and red lights at night near an aerodrome.
Rule: CS ADR-DSN.Q.846(b)
Wire markers and tower lights
A wire that needs marking has spherical markers at least 60 cm across.
Spacing between 60 cm markers normally does not exceed 30 m.
If markers cannot go on the wires, each tower carries three high-intensity Type B lights that flash middle, top, then bottom.
Rule: CS ADR-DSN.Q.852(c)
Do: treat a tower on a low-level route as a possible wire anchor.
Unserviceable area
An unserviceable area is a local hazard, such as a hole in a taxiway, that aircraft can still safely go around.
By day, cones, flags or marker boards mark it.
At night, steady red lights of at least 10 cd outline it.
Rule: AMC1 ADR.OPS.B.070(c)(5)(a)(1)
Do: go around an unserviceable area only when it is safe to do so.
Taxi side stripe marking
A taxi side stripe marking is two solid yellow lines, each 15 cm wide and 15 cm apart.
It marks the edge of the load-bearing pavement.
Beyond it, the non-load-bearing surface can damage an aircraft.
Rule: CS ADR-DSN.R.860(a)
Pre-threshold chevrons
A paved pre-threshold area longer than 60 m, and unsuitable for normal aircraft use, carries chevrons along its full length.
The chevrons point towards the threshold, and each stroke is at least 0.9 m wide.
The preferred colour is yellow.
Rule: CS ADR-DSN.R.865(a)
Vehicle lights
Emergency and security vehicles show flashing blue when the aerodrome operates at night or in low visibility.
Other vehicles, such as the follow-me vehicle, show flashing yellow.
Objects of limited mobility, such as aerobridges, show fixed red.
Rule: ADR.OPS.B.080(a), (b)
Do not: read flashing blue as the follow-me light.
Flashcards
Print them: A6 landscape cards (PDF, front and back) · 4 cards per A4 landscape sheet (PDF, cut lines) · Key figures deck (PDF, 41 figures)
Print double-sided, flip on the short edge.
010-09-06-01What colour is the closed marking on a runway, and on a taxiway?
White on a runway, yellow on a taxiway. The closed marking is a cross.
010-09-06-02Are the lights on a closed runway or taxiway operated?
No. They stay off, except for maintenance.
010-09-06-03How far apart can closed markings be on a closed runway?
No more than 300 m apart, with a marking at each end of the closed part.
010-09-06-04What lights cross the entrance to a closed area used at night?
Unserviceability lights, no more than 3 m apart, across the entrance.
010-09-06-05What is the first choice for marking a fixed obstacle?
Colour the object, where that is practicable. Use markers or flags only if it is not.
010-09-06-06Which pattern marks a large unbroken surface, such as a water tank?
A chequer, for surfaces at least 4.5 m across in both directions.
010-09-06-07Which objects get alternating bands instead of one colour?
Unbroken objects over 1.5 m in one dimension and under 4.5 m in the other, and lattice objects over 1.5 m.
010-09-06-08How wide is each band on an object?
About 1/7 of the longest dimension, or 30 m, whichever is less.
010-09-06-09What are the default band colours, and which bands are darker?
Orange and white. The top and bottom bands are the darker colour.
010-09-06-10Which objects are marked with one colour, not bands?
Objects under 1.5 m in both dimensions. Use orange or red.
010-09-06-11How far away must a marker be recognisable in clear weather?
At least 1 000 m from the air, and at least 300 m from the ground.
010-09-06-12Which colours can a flag on a fixed object use?
Orange, or two triangles of orange and white, or red and white.
010-09-06-13What colour and flash do low-intensity Type A and B lights show?
Fixed red. They work at night only.
010-09-06-14Which medium-intensity obstacle light flashes white?
Type A, at 20 to 60 flashes per minute. It also works by day and twilight.
010-09-06-15Which medium-intensity obstacle light flashes red?
Type B, at 20 to 60 flashes per minute. It works at night only.
010-09-06-16What do high-intensity Type A and B obstacle lights show?
Flashing white, at 40 to 60 flashes per minute, by day and by night.
010-09-06-17How fast does a follow-me vehicle light flash?
60 to 90 flashes per minute, flashing yellow.
010-09-06-18How far from an aerodrome does a dual obstacle lighting system apply?
Roughly 10 000 m, where white lights could dazzle pilots at night. White by day, red at night.
010-09-06-19Which lights mark a fixed object under 45 m high, if it is not extensive?
Low-intensity Type A or B lights.
010-09-06-20Which lights mark a fixed object 45 m to under 150 m high?
Medium-intensity lights, with levels no more than 105 m apart for Type A and 52 m for Types B and C.
010-09-06-21When are high-intensity Type A lights used on a fixed object above 150 m?
Where a safety assessment shows they are essential for recognition by day.
010-09-06-22Which part of a wind turbine mast is painted white?
The upper two-thirds, plus the blades and nacelle, unless a safety assessment finds another colour safer.
010-09-06-23What size and colour are wire markers?
Spheres at least 60 cm across, one colour each, alternating white and red or white and orange.
010-09-06-24What is the normal maximum spacing of wire markers?
30 m for 60 cm spheres, 35 m for 80 cm, and 40 m for at least 130 cm.
010-09-06-25If markers cannot go on the wires, how many lights does each tower carry?
Three high-intensity Type B lights: at the top, at the lowest point of the catenary, and midway.
010-09-06-26In what order do the three wire-tower lights flash?
Middle, then top, then bottom. A tower with this sequence means wires span between towers.
010-09-06-27What fractions of the cycle separate the wire-tower flashes?
1/13 from middle to top, 2/13 from top to bottom, and 10/13 from bottom to middle.
010-09-06-28What is an unserviceable area?
A local hazard, such as a hole in a taxiway, that aircraft can still safely go around.
010-09-06-29Which devices mark an unserviceable area by day?
Upstanding cones, flags or marker boards.
010-09-06-30What are the minimum sizes of unserviceability cones, flags and marker boards?
Cone at least 0.5 m tall. Flag at least 0.5 m square. Board at least 0.5 m high and 0.9 m long.
010-09-06-31What colour and minimum intensity do unserviceability lights show?
Steady red, never less than 10 cd.
010-09-06-32How many unserviceability lights mark a temporary area at night?
At least four, or three for a triangle, and at least one per 7.5 m of perimeter.
010-09-06-33What does a taxi side stripe marking show?
Two solid yellow lines, each 15 cm wide and 15 cm apart, at the edge of load-bearing pavement.
010-09-06-34What lies beyond a taxi side stripe marking?
A non-load-bearing surface, which can damage an aircraft.
010-09-06-35When does a pre-threshold area get chevrons?
When the paved area is longer than 60 m and not suitable for normal aircraft use.
010-09-06-36Which way do the chevrons point, and what is their minimum stroke width?
Towards the threshold. The stroke width is at least 0.9 m.
010-09-06-37What angle do chevron arms make with the centre line, and how far apart are the apexes?
45 degrees to the centre line, with apexes every 30 m.
010-09-06-38What light do emergency or security vehicles show?
Flashing blue, when the aerodrome operates at night or in low visibility.
010-09-06-39Does a flashing blue vehicle mean follow-me?
No. Follow-me vehicles show flashing yellow, brighter than other vehicles.
010-09-06-40Can a short temporary closure go without a closed marking?
Yes, if air traffic services give adequate warning.
Sources
- Easy Access Rules for Aerodromes (Regulation (EU) No 139/2014), March 2026 revision, including CS ADR-DSN Issue 7 (Chapters J, Q and R and associated GM1, Tables Q-1 and Q-4, Figures Q-1, Q-2, R-1, GM-R-1 and R-2) and ADR.OPS.B.070, B.071, B.075, B.080, C.015 and ADR.OR.B.065 with AMC/GM (EASA).
- Regulation (EU) 2018/1139 (Basic Regulation), Article 2, consolidated text of 2 August 2026 (EUR-Lex).
- ICAO Annex 14, Volume I, Aerodrome Design and Operations, 9th edition (July 2022), consolidated to Amendment 18, Chapters 6 and 7.
- AAIB Bulletin 4/99, Gulfstream IV VP-BHG, London Stansted, 12 November 1998 (ref. EW/C98/11/2). https://assets.publishing.service.gov.uk/media/5422f411e5274a13170004e5/dft_avsafety_pdf_500176.pdf
- AAIB Bulletin 6/2018, Piper PA-28-161 G-BTAW, Castle Kennedy, 13 March 2018 (ref. EW/G2018/03/05). https://assets.publishing.service.gov.uk/media/5afac2a5e5274a25dbface9a/Piper_PA-28-161_Cherokee_Warrior_II_G-BTAW_06-18.pdf
This page is educational. It does not replace instruction at your ATO or your aircraft's POH/AFM. Rules change: check the regulation in force.