EASA CS-ADR-DSN and ADR.OPS.C.015: Aerodrome Lighting Rules

Four layers of EU text

European aerodrome lighting is governed by a stack of documents, and each layer has a different legal weight.

At the top sits Regulation (EU) 2018/1139, the Basic Regulation, which sets the essential requirements and the scope. Under it sits Commission Regulation (EU) No 139/2014, the implementing rule for aerodromes. It is binding in its entirety and directly applicable in every Member State, and it carries the rule that matters most for lighting maintenance, ADR.OPS.C.015. Next to the rule EASA publishes Acceptable Means of Compliance (AMC) and Guidance Material (GM), which the regulation itself defines as non-binding. Finally there is CS-ADR-DSN, the certification specifications for aerodrome design, now in Issue 7. That is where the photometric and colour requirements for each light live.

Every EU clause on this page was read in the March 2026 revision of EASA’s Easy Access Rules for Aerodromes, which carries CS-ADR-DSN Issue 7 as introduced by ED Decision 2025/004/R of 16 May 2025, with an applicability date of 24 May 2025.

Who it applies to

CS ADR-DSN.A.001 applies the specifications to aerodromes that fall within the scope of the Basic Regulation. Article 2(1)(e) of the Basic Regulation covers aerodromes open to public use that serve commercial air transport and have a paved instrument runway of 800 m or more, or that serve helicopters exclusively with instrument procedures. Under Article 2(7) a Member State may exempt an aerodrome that handles no more than 10,000 commercial air transport passengers and no more than 850 cargo movements a year. The guidance to the same clause adds a detail that often surprises people. If such an aerodrome has more than one runway, only one has to meet the Basic Regulation criteria, but the CS and GM apply to the other runways as well, including short, unpaved or non-instrument ones.

Within Regulation (EU) No 139/2014, Annex II binds the competent authorities and Annexes III and IV bind the aerodrome operators. ADR.OPS.C.015 sits in Annex IV, so it binds the operator, and the national authority checks it through continuing oversight.

How a CS becomes binding at one aerodrome

The regulation defines certification specifications as technical standards adopted by EASA indicating means to show compliance, which an organisation can use for certification. On their own they oblige nobody. They gain force through the certification basis.

Under ADR.AR.C.020 the competent authority establishes and notifies each aerodrome’s certification basis. It consists of the CS the authority finds applicable to that aerodrome’s design and type of operation, effective on the date of application, plus any provision for which an equivalent level of safety has been accepted, plus any special condition. ADR.OR.B.025 then obliges the operator to demonstrate compliance with that notified basis and to declare it. From that point a CS clause is as enforceable for that aerodrome as the regulation itself.

The regulation provides three routes for a site that does not meet a CS as written.

Equivalent level of safety (ELOS). The operator proposes a different solution and shows it is no less safe. GM1 ADR.AR.C.020(b) asks the authority to check the proposal against the intent of the CS.

Special conditions. Under ADR.AR.C.025 the authority prescribes its own detailed specifications where the CS are inadequate or inappropriate. That applies when physical or topographical limits make the CS impossible to meet, when the aerodrome has novel or unusual design features, or when experience shows safety may be endangered.

Deviation Acceptance and Action Document (DAAD). Article 7 let authorities accept deviations that existed before the regulation, did not qualify as ELOS or special conditions, and were backed by a safety assessment. The evidence is compiled in a DAAD attached to the certificate, with a validity period set by the authority. Since the 2024 amendment, new applications could only be accepted until 31 December 2024. An existing DAAD must still be kept valid, and is amended, suspended or withdrawn if its conditions stop being met.

AMC works differently. ADR.OR.A.015 lets an operator use an alternative means of compliance instead of EASA’s AMC, but only with the authority’s prior approval and a full description showing the rule is still met. AMC is not mandatory, but departing from it takes paperwork.

ADR.OPS.C.015, clause by clause

The rule has seven points, and (a) to (c) carry most of the lighting work.

(a) Electrical systems. A preventive and corrective maintenance programme to keep the electrical systems serviceable and power available to all necessary facilities.

(b) Lights. A preventive and corrective maintenance programme to ensure the serviceability of individual lights and the reliability of the lighting systems, so that guidance to and control of aircraft and vehicles is continuous. The numbers follow, set for each system.

(c) Unserviceable. The definition every percentage depends on.

(d) Markings and signs. The same kind of programme for the marking and sign system.

(e) Works under low visibility. No construction or maintenance near aerodrome electrical systems while low-visibility procedures are in effect.

(f) Inspections. The programmes under (a), (b) and (d) must include inspections and checks of each element and of each system, done to established procedures and at defined intervals appropriate to the intended operation and system. Defects must be corrected.

(g) Records. The operator keeps records of the maintenance done.

Serviceability, system by system

Point (b) does not give one figure for “the lights”. It gives objectives per system and per type of operation, and every one is phrased the same way. During the relevant operations, the objective is that all the lights are serviceable, and the percentages are the floor that must hold in any event.

GM1 to ADR.OPS.C.015(b) repeats these figures in a summary table, and the table is broader than the rule. It shows 85 % for runway centreline lights under CAT I and under take-off at 550 m RVR or more, and 85 % for touchdown zone lights under CAT I where they exist. The rule text does not list those elements. GM is non-binding, so where the two differ, plan to the rule and treat the extra columns as advice.

Pattern and adjacency

The percentages are not enough on their own. Under (b)(2), the lights allowed to fail on a CAT II or III runway must not alter the basic pattern of the system. Under (b)(3), no unserviceable light may sit next to another, except that two adjacent lights may fail in a barrette or crossbar. The CAT I and take-off objectives carry their own adjacency limits. GM3 explains what adjacent means. For barrettes, crossbars and edge lights, two lights are adjacent if they are consecutive laterally in the same barrette or crossbar, or longitudinally in the same row of edge lights or barrettes.

A runway can be above 95 % edge light serviceability and still miss its objective because two dark lights sit side by side. A failure count cannot show that. A map can.

What unserviceable means

Point (c) gives two triggers. The first is photometric. A light is unserviceable when its main beam average intensity is below 50 % of the value in the certification specifications, or 50 % of the design value where the unit is designed to exceed the CS. The second is colour. A missing or damaged filter, or a light that does not produce the correct colour, also makes it unserviceable.

The first trigger cannot be checked by eye, since a dim light still looks lit. That is why the AMC asks for measurement, and why GM1 to ADR.OPS.C.015(b) and (c) suggests two thresholds in the maintenance programme. A maintenance level, always above 50 %, warns that a unit is drifting and lets the repair be scheduled. The 50 % unserviceability level is where it has failed operationally.

What the AMC and GM add

The rule says “defined intervals”. AMC1 to ADR.OPS.C.015(b) and (f) is where the numbers are.

Daily ground checks. The lighting systems should be checked at least for light failures, breakage, gross misalignment and correct operation of the intensity control.

Photometric measurement on every runway. Irrespective of runway type, the operator should ensure serviceability by conducting photometric measurements at appropriate intervals. The AMC sets no number for runways other than CAT II and III.

CAT II and III. The programme should include visual inspection and in-field measurement of the intensity, beam spread and orientation of approach and runway lights, measurement of the electrical characteristics of each circuit, and a check of the intensity settings used by air traffic control. All lights should be measured as far as practicable against the relevant figure in CS ADR-DSN.U.940, with a measuring unit accurate enough to analyse individual lights. The frequency should rest on traffic density, local pollution, equipment reliability and the trend of past results, but should not be less than twice a year for in-pavement lights and once a year for other lights.

PAPI and APAPI. Alignment is checked at defined intervals, and errors over one minute of arc should be corrected. A unit of three or more lights counts as unserviceable when more than one light has failed, and a unit of fewer than three when any light has failed. Lights behind a faulty red filter should be switched off until it is fixed. More on what that means for the angle check is on the PAPI page.

Flight checks. Approach, runway and taxiway lighting, the visual approach slope indicators, the aerodrome beacon and the intensity control should be flight checked at regular intervals, at least yearly. Extra checks are due after major maintenance, after changes and before new systems are commissioned.

GM2 to ADR.OPS.C.015(b) warns that LED output falls and its colour shifts over time, so a lit unit can be outside its specification. Long life, it says, is not a reason for “install and forget”.

Chapter M and Chapter U: what the lights must be

The maintenance rule measures against design values, and those live in CS-ADR-DSN. Chapter M, Visual aids for navigation (lights), runs from CS ADR-DSN.M.615 General to M.771 No-entry bar. It covers beacons, approach lighting for each category, PAPI and APAPI, and runway lighting element by element: edge , threshold, wing bar and end , centreline and touchdown zone. Taxiway lights, stop bars, runway guard lights, apron floodlighting and docking guidance follow.

Chapter U holds the numbers a photometer is checked against. CS ADR-DSN.U.930 sets the colours for aeronautical ground lights, and U.940 carries the isocandela diagrams, Figures U-5 onwards, one per type of light. The collective notes to Figures U-5 to U-15 matter for maintenance too. The figures show minimum allowable intensities, the main beam average is the arithmetic mean over a grid of points inside the main beam ellipse, and each unit should be aligned within half a degree. The notes also say the average should never fall below 50 % of the figure.

Part of the intensity data in those diagrams is printed inside the figure rather than in the text, so read the rendered page, not a text extract, before quoting a value.

Chapter S closes the loop on monitoring. CS ADR-DSN.S.890 asks for automatic monitoring of lighting systems used for aircraft control. For runways used below 550 m RVR, the systems in Table S-1 should alert maintenance when any element falls below the serviceability level in ADR.OPS.C.015(b)(1) to (b)(7). Under GM1 ADR-DSN.S.890, the level below which operations should not continue is set by the competent authority.

CS-ADR-DSN and ICAO Annex 14

CS-ADR-DSN is the EU’s transposition of ICAO Annex 14 Volume I for aerodrome design, and ADR.OPS.C.015 tracks Annex 14 section 10.5 closely. In the 9th edition, 10.5.1, the 50 % unserviceability definition, and 10.5.2, preventive maintenance of visual aids, are Standards. The CAT II and III checks, the measurement of all lights and the twice-a-year and once-a-year frequency in 10.5.3 to 10.5.6 are Recommendations. The EU put the Standards into the binding rule and moved the Recommendations into AMC1. The EU also dropped one word. Annex 14 10.5.5 recommends a mobile measuring unit, while AMC1 asks for an appropriate measuring unit of sufficient accuracy.

AMC1 ADR.AR.C.020(b) and (c) tells authorities that, when deciding an ELOS or a special condition, they may consider whether the CS in question corresponds to an ICAO Standard or a Recommended Practice. The ICAO distinction still matters inside the EU system, even where EU law no longer prints it.

The two texts are not in step right now. Annex 14 Amendment 18 was adopted on 28 March 2025 and has applied since 27 November 2025, with some provisions from 26 November 2026 and 21 November 2030. EASA has not yet transposed it into CS-ADR-DSN, and the transposition is in consultation as NPA 2026-01. Until a new issue is adopted, an EU aerodrome is certified against Issue 7, and some of its text may differ from the current Annex. The Annex 14 paragraph numbers on this page were read in the July 2022 9th edition, and Amendment 18 may have changed them.

The United Kingdom after Brexit

The UK left the EASA system and kept the structure of Regulation (EU) No 139/2014 in its domestic law. The UK CAA now adopts its own CS, AMC and GM for UK Regulation (EU) 139/2014 by CAA decision, starting with UK-EU Transition Decision No. 1 in December 2020. CAP 168, Licensing of Aerodromes, is a separate document, with aeronautical ground lighting in Chapter 6. EASA amendments made after the UK left, CS-ADR-DSN Issue 7 among them, do not flow into UK law automatically. A UK aerodrome should read the CAA’s documents, not this EU stack.

Where drone measurement fits

None of these texts names an instrument platform, and none of them requires or approves drones. What the rule and the AMC ask for is evidence: that each system meets its serviceability objective, that no two failed lights sit side by side, that no light has dropped below half its specified output or shows the wrong colour, and that the measurement was done at defined intervals.

TarmacView inspects airfield lighting by drone, flown between movements in coordination with the tower, without booking a closure. Each light gets a record of whether it is lit, whether its colour matches its position, its output relative to its neighbours and to the commanded dimming step, and its RTK-surveyed position. That answers the adjacency and pattern questions in ADR.OPS.C.015(b) and flags units drifting towards the maintenance level. Absolute candela against a U.940 figure needs a calibrated anchor. The survey also measures PAPI transition angles.

It does not measure constant current regulator output, insulation resistance, standby power switch-over or anything underground, and it does not replace the yearly flight check. Flight inspection checks the approach and runway lights as well as the PAPI. For runways working towards the low-visibility objectives, the low-visibility serviceability page covers what that means in practice.