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Safety-critical technical reference — read before use. Independent educational guidance for qualified AGL and aerodrome personnel. It is not an approved procedure, design, specification or regulatory instruction and does not replace your aerodrome’s permit-to-work, isolation/LOTO procedures, the approved design or the manufacturer’s instructions. Series-circuit AGL equipment can carry lethal voltages. Read the full disclaimer ↓
THE AGL ENGINEERING CENTRE by Precision AGL Academy · EASA CS-ADR-DSN · Issue 7 · Aerodrome Design

EASA CS-ADR-DSN & AGL COMPLIANCE

A deep dive into European Aerodrome Design Requirements for Airfield Ground Lighting — how EASA CS-ADR-DSN, Certification Specifications and Guidance Material for Aerodrome Design, is translated through approved design, selected equipment, verified installation, electrical performance and monitoring into defensible EASA compliance evidence.

Requirement → Design → Visual Aid → Electrical System → Installation → Testing → Monitoring → Maintenance → Evidence
Start Reading ICAO Annex 14
01 · Core Principle

CS-ADR-DSN Is a Certification Framework, Not a Parts List

EASA CS-ADR-DSN, Certification Specifications and Guidance Material for Aerodrome Design, is one of the key European references for aerodrome design. For Airfield Ground Lighting engineers, it is particularly important because the specification contains detailed provisions relating to visual aids, aerodrome lighting, runway/taxiway/approach lighting, PAPI, signs, markings, obstacle lighting, electrical systems, secondary power, lighting system design, monitoring, serviceability and installation-related requirements.

The current EASA publication is CS-ADR-DSN Issue 7, issued through ED Decision 2025/004/R.

Visual AidsRunway LightingTaxiway LightingApproach LightingPAPISignsMarkingsObstacle LightingElectrical SystemsSecondary PowerMonitoringServiceability
The Engineering Chain
REQUIREMENT
DESIGN
VISUAL AID
ELECTRICAL SYSTEM
INSTALLATION
TESTING
MONITORING
MAINTENANCE
EVIDENCE
02 · Definition

What Is CS-ADR-DSN?

CS-ADR-DSN means Certification Specifications and Guidance Material for Aerodrome Design. It is EASA's aerodrome design certification specification framework.

It addresses the design of aerodrome infrastructure and visual aids required for safe aircraft operations.

03 · Relevance

Why CS-ADR-DSN Matters to AGL

AGL is not an isolated electrical installation — it is part of the aerodrome's visual navigation system. The AGL system must provide appropriate guidance, identification, alignment, position information, runway/taxiway delineation, approach guidance, operational warnings and obstacle identification. AGL design must therefore be considered together with the aerodrome layout and operational purpose.

GuidanceIdentificationAlignmentPosition InformationRunway/Taxiway DelineationApproach GuidanceOperational WarningsObstacle Identification
04 · Current Baseline

Current EASA Baseline & Regulatory Structure

As of 2026, the current published CS-ADR-DSN baseline is Issue 7, published 19 May 2025 and issued through ED Decision 2025/004/R. EASA subsequently replaced the file on 16 June 2025 to incorporate corrections, including a correction identified on page 312. EASA explains that some provisions of operational nature previously contained in CS-ADR-DSN had been transferred to the AMC and GM associated with Part-ADR.OPS, to improve consistency between aerodrome design requirements and operational requirements.

Issue 7

CS-ADR-DSN — published 19 May 2025

16 Jun 2025

File replaced with corrections, incl. page 312

ED 2025/004/R

Decision issuing Issue 7

Mar 2026

Easy Access Rules for Aerodromes incorporate Issue 7

Part-ADR.OPS

Operational provisions transferred here from CS-ADR-DSN

The March 2026 Easy Access Rules for Aerodromes incorporate ED Decision 2025/004/R and other regulatory changes. Engineers should not rely on an old CS-ADR-DSN PDF without checking the current EASA publication.
05 · Regulatory Hierarchy

CS vs Regulation vs AMC/GM

This distinction is important, and EASA describes Certification Specifications as non-binding technical standards indicating means to demonstrate compliance with the applicable regulatory framework.

InstrumentFunction
RegulationProvides the legally applicable regulatory framework.
Certification Specification (CS)Provides technical specifications used as a means of demonstrating compliance.
AMCProvides acceptable means of compliance.
GMProvides guidance and explanatory material.
06 · Scope

Not an Equipment Catalogue — Compliance Is System-Based

CS-ADR-DSN should not be treated as a list of AGL products. It establishes aerodrome design requirements; the engineer still needs to determine Requirement → Equipment → Installation → Electrical Interface → Testing.

An AGL system should not be evaluated only by asking "Does this light meet the specification?" The better question is "Does the complete visual aid system satisfy the applicable aerodrome design requirement?"

EquipmentLocationConfigurationAlignmentIntensityColourElectrical SupplyControlMonitoringInstallationMaintenance
07 · Chapter M — Visual Aids for Navigation, Lights

General, Elevated & Surface Light Requirements

One of the most important parts of CS-ADR-DSN for AGL engineers is Chapter M, Visual Aids for Navigation, Lights. The March 2026 EASA Easy Access Rules identify Chapter M provisions covering visual navigation lights and associated systems. AGL fixtures must be considered in relation to their operational environment — elevated fixtures, surface fixtures, approach lights, runway lights, taxiway lights and other visual navigation lights — and the installation must preserve the required operational and physical characteristics.

Elevated Lights

EASA requirements address physical characteristics: elevated runway, stopway and taxiway lights are required to be frangible, with height sufficiently low to preserve aircraft clearance. This is a design issue, not simply a product issue.

Surface Lights

Inset fixtures in runways, stopways, taxiways and aprons must be designed and fitted to withstand aircraft wheel loading without damage to the aircraft or the light itself: Fixture → Base → Pavement → Drainage → Installation → Mechanical Loading.

Frangibility

Particularly important for elevated equipment — fixture construction, supporting structure, mounting, height, aircraft clearance, location and structural behaviour should be considered at design review, procurement and installation inspection.

08 · Approach Lighting

Approach Lighting Systems & Categories

Approach lighting is a major component of the EASA visual-aid framework. EASA states that the safety objective of an approach lighting system is to provide alignment and roll guidance and limited distance-to-go information to support a safe approach. The applicable arrangement depends on the runway type and operational category — CS-ADR-DSN provisions address non-instrument runways, non-precision approach runways, Precision Approach Category I, and Precision Approach Categories II and III. The applicable design must be determined from the runway classification and approved aerodrome design.

Approach Lighting Engineering Chain
RUNWAY TYPE
APPROACH CATEGORY
REQUIRED VISUAL GUIDANCE
LIGHTING CONFIGURATION
EQUIPMENT
INSTALLATION
VERIFICATION

Same scale, approach heading towards the threshold: Category I against Category II and III.

ICAO CAT II / III · 900 M white centreline + red side rows FAA ALSF-2 · 2,400 FT standard for Cat II and III ICAO CATEGORIES decision height and RVR APPROACH DIRECTION RUNWAY CENTRELINE white, every 30 m 300 M CROSSBAR 30 m long RED SIDE ROWS barrettes to 270 m 150 M CROSSBAR fills gap to side rows INNER 300 M centreline in barrettes THRESHOLD green 900 M RUNWAY FLASHERS 1,000 ft outward BARRETTES white, every 100 ft 1,000-FT BAR 21 lights, ~100 ft wide RED SIDE ROWS inner 900 ft 500-FT BAR 4 lights each side THRESHOLD green 2,400 FT CAT I DH not lower than 60 m (200 ft) RVR not less than 550 m CAT II DH 30 to 60 m (100-200 ft) RVR not less than 300 m CAT IIIA DH below 30 m (100 ft) or none RVR not less than 175 m CAT IIIB DH below 15 m (50 ft) or none RVR 50 m to under 175 m CAT IIIC no DH no RVR limit bar length = RVR floor Cat I: 900 m, one crossbar, no side rows. Cat II/III add side rows + 150 m crossbar. ICAO · ANNEX 14 900 m, 30 m spacing, red side rows crossbars at 150 m and 300 m FAA · ALSF-2 barrettes, 1,000-ft and 500-ft bars red side rows over the inner 900 ft ICAO · CATEGORIES DH and RVR fall from Cat I to IIIC national minimums follow the procedure
Figure 2. Approach lighting for Category I and for Category II and III, with the category chart.
AGL Visual Encyclopedia: Category II and III approach lighting Category I approach lighting
Airmen replacing a flush-mount approach light on a flight line
Photo 2. Airmen replace a flush-mount approach light from the flight line.Credit: U.S. Air Force photo by Airman 1st Class Jonathan McElderry (VIRIN 171010-F-IY281-0006). Public domain (U.S. Government work). Source page
09 · Runway & Taxiway Lighting

Runway Lighting & the Taxiway Guidance System

Runway Lighting

A core part of the visual navigation system. Engineering considerations include runway edge, runway centreline, threshold, runway end, touchdown zone where applicable, approach lighting, runway designation and markings, and control and monitoring.

Taxiway Lighting

Taxiway visual aids support safe aircraft movement on the aerodrome surface — depending on the applicable design, this can involve centreline lights, edge lights, stop bars, runway guard lights, signs, markings and control systems.

A taxiway should not be evaluated by looking at the centreline lights alone. The operational guidance environment is integrated: Centreline + Edge + Signs + Markings + Stop Bars + Control + Monitoring.

Runway pattern as the pilot sees it on landing.

TOP VIEW — THE COMPLETE PATTERN (AIRCRAFT LANDING LEFT TO RIGHT) THRESHOLD + WING BARS: GREEN TDZ BARRETTES EDGE LIGHTS: WHITE EDGE: YELLOW CENTRELINE: WHITE RED / WHITE RED RUNWAY END ROW: RED FAR-END COLOUR ZONES — LAST 1000 M (INSTRUMENT RUNWAY) 900 M 600 M 300 M RUNWAY END CENTRELINE LIGHTS EDGE LIGHTS CENTRELINE: WHITE, THEN ALTERNATING RED AND WHITE, THEN RED. EDGE LIGHTS: YELLOW IN THE LAST 600 M OR ONE-THIRD OF THE RUNWAY, WHICHEVER IS LESS. SCHEMATIC: NOT TO SCALE. ZONE DISTANCES ARE MEASURED FROM THE RUNWAY END.
Figure 3. Runway lighting pattern for an aircraft landing left to right.
AGL Visual Encyclopedia: Runway lighting pattern Runway lighting layout

Every light of a complete taxiway lighting system, in plan.

COMPLETE TAXIWAY LIGHTING SYSTEM RUNWAY A B → BLUE EDGE LIGHTS · OMNIDIRECTIONAL SIGNS GREEN CENTRELINE LIGHTS INTERMEDIATE HOLDING POSITION LIGHTS STOP BAR · RED RUNWAY GUARD LIGHTS · YELLOW EXIT LIGHTS · GREEN / YELLOW AIRFIELD LIGHTING CONTROL SYSTEM · SELECTIVE SWITCHING · STOP-BAR INTERLOCK · MONITORING EDGE CIRCUITBLUE EDGE LIGHTSCENTRELINE CIRCUITSSWITCHED BY SECTIONSTOP-BAR CIRCUITINTERLOCKEDHOLDING & GUARD CIRCUITYELLOW LIGHTSSCHEMATIC · LAYOUT, SPACING AND CIRCUIT COUNT ILLUSTRATIVE · NOT TO SCALE
Figure 4. A runway, link taxiway and parallel taxiway with their lights.
AGL Visual Encyclopedia: Complete taxiway lighting system Taxiway lighting layout
10 · PAPI

PAPI: More Than Selecting a Light Unit

PAPI is another important visual navigation aid. PAPI design involves more than selecting a suitable light unit — engineering considerations include location, elevation, alignment, azimuth, vertical aiming, unit relationship, approach geometry and visual performance.

A PAPI can be electrically functional while still providing incorrect guidance. Therefore: Electrical ON ≠ Correct PAPI Guidance. PAPI verification must consider its optical and geometric performance.

Four visual glide-slope systems side by side.

FOUR SYSTEMS · SAME JOB, DIFFERENT SIGNALS FOUR-UNIT PAPI one wing bar ONE BAR OF FOUR ON SLOPE: 2 WHITE, 2 RED four units, five signals one bar beside the runway units set at four angles TWO-BAR PAPI a bar each side RUNWAY SAME SIGNAL BOTH SIDES a second bar of four units opposite side of the runway where the design requires it TWO-UNIT APAPI abbreviated PAPI ONE BAR OF TWO ON SLOPE: 1 WHITE, 1 RED two units, three signals one bar beside the runway only where the standard allows VASI older slope indicator NEAR / FAR BARS ON SLOPE: RED OVER WHITE light bars, not a split beam red over white means on slope largely replaced by PAPI
Figure 5. Visual glide-slope systems in schematic. A PAPI is more than a choice of light unit.
AGL Visual Encyclopedia: Different PAPI systems PAPI system overview PAPI alignment
11 · Photometric Performance

Photometry, Colour & Beam Alignment

AGL photometry is fundamental to visual-aid verification. Depending on the applicable visual aid, performance may involve light intensity, beam characteristics, colour, alignment, coverage, uniformity and operational visibility. The applicable requirement must always be identified before establishing the acceptance criteria — a runway centreline light, taxiway light, approach light and PAPI do not automatically have identical photometric requirements.

IDENTIFY FIXTURE/SYSTEM
APPLICABLE REQUIREMENT
MEASUREMENT CRITERIA
MEASURE
COMPARE
REPORT

Colour is an operational parameter — incorrect colour can affect the interpretation of a visual aid. Light intensity alone does not guarantee correct performance: a fixture can produce sufficient output but direct the beam incorrectly. Intensity + Colour + Alignment + Coverage may all be relevant to visual performance.

Angle on the axes, intensity inside the contours.

THE DIAGRAM · ANGLE GRID curves of equal candela around the beam axis READING IT · BANDS AND SPACING between two curves, close or wide apart 50 % OF PEAK 10 % OF PEAK LEFT RIGHT UP HORIZONTAL AND VERTICAL ANGLE FROM THE BEAM AXIS P 1 2 3 4 PEAK 50 % 10 % P LIES BETWEEN 10 % AND 50 % OF PEAK read from the two curves around it 6 CLOSE steep fall WIDE gentle fall 5 1ANGLE GRIDhorizontal across, vertical up, beam axis at centre 2CURVE OF EQUAL CANDELAevery direction on it has the same intensity 3PEAK ON THE AXIShighest intensity, centre of the rings 4READ A DIRECTIONfind its angles, see the two curves around it 5CURVE SPACINGclose curves mean a quick change in intensity 6COMPARE WITH THE STANDARDmeasured against the required diagram CORRECT READINGBY ANGLE, THEN BETWEEN TWO CURVESDirection in, intensity band out WRONG READINGTHE PEAK VALUE ONLYSame peak, very different beams SCHEMATIC · ILLUSTRATIVE LEVELS · NOT A STANDARD DIAGRAM · SEE ICAO ANNEX 14 VOL. I, APP. 2
Figure 6. An isocandela diagram, used to check the intensity distribution of a light.
AGL Visual Encyclopedia: Isocandela diagram Beam measurement
12 · Chapter S — Electrical Systems

Electrical Systems, Secondary Power & Low Visibility Design

AGL performance depends on the electrical system supporting the visual aids — primary power, secondary power, CCRs, series circuits, cables, isolating transformers, connectors, control systems, monitoring, protection, and earthing and bonding.

CS ADR-DSN.S.885 states that where runway visual range is less than 550 m, the electrical systems for power supply, lighting and control included in the relevant table should be designed so that an equipment failure does not leave the pilot with inadequate visual guidance or misleading information. This is a major AGL engineering principle.

Secondary power is particularly important for critical visual aids — the objective is not simply "Provide a generator." The system must provide the required level of continuity and operational availability. Where duplicate feeders are used for secondary power, the provisions address physical and electrical separation to ensure the required availability and independence — redundancy should not simply mean two cables; it should mean an appropriately engineered independent supply arrangement.

CS ADR-DSN.S.885 also addresses interlocking where a runway forms part of a standard taxi route and runway and taxiway lighting are provided: the lighting systems should be interlocked to prevent simultaneous operation of both forms of lighting. This connects directly with control logic, safety, human factors, ALCMS and fail-safe design.

Normal operations, preparation, LVP in force, stand-down and back to normal.

NORMAL TO LVP AND BACKNORMALStep follows the step tableStop bars as ATC needs themCAT II/III-only lights maybe off or at a low stepPREPARATIONATC declares preparationLamps, circuits, interlockschecked and read backStandby power made readyLVP IN FORCEFull CAT II/III pattern litStop bars on where in useCentreline off beyond a lit barStep follows the RVR tableSTAND-DOWNVisibility better: margin + delayATC cancels LVPStop bars back to normal useSteps return; state confirmedTRIGGERCHECKEDCANCELBACK TO NORMALDOWNGRADE, WHILE IN FORCEIf serviceability falls below the minimum, the category or minima are reduced and ATC is told.
Figure 1. Lighting modes for low visibility: the electrical and control systems must support every change of mode.
AGL Visual Encyclopedia: Mode changeover sequence LVP lighting configuration Single-point-of-failure analysis
Airfield lighting contractors preparing a job site on a flightline
Photo 1. A base operations team prepares a flightline job site to update the primary electric line connected to the approach runway lights.Credit: U.S. Air Force photo by Airman 1st Class Bailee A. Darbasie (VIRIN 190606-F-FM571-001). Public domain (U.S. Government work). Source page
13 · Chapter S — Monitoring

Monitoring Under CS ADR-DSN.S.890

Monitoring is explicitly addressed by CS ADR-DSN.S.890 — a system of monitoring should indicate the operational status of lighting systems. Where lighting systems are used for aircraft control purposes, the provisions call for automatic monitoring capable of indicating faults that may affect control functions, with the information automatically relayed to the air traffic service unit. This is highly relevant to stop bars, control systems, ALCMS and safety-critical visual aids.

2 sec

Indication for a stop bar at a runway-holding position

5 sec

Indication for other types of visual aids

CS ADR-DSN.S.890 specifies response-time provisions for changes in operational status — this demonstrates why ALCMS monitoring cannot be treated merely as a display feature.
Fault-to-ATC Response Time — S.890

The clock starts at the change of status, not at the moment someone notices the display

CHANGE OF OPERATIONAL STATUS AUTOMATIC detection & monitoring RELAYED TO ATS air traffic service unit INDICATED Total time from status change to indication: 2 SECONDS — STOP BAR 5 SECONDS — OTHER VISUAL AIDS Relative bar length is illustrative, not to a fixed time scale
14 · ALCMS Relationship

Field Reality vs Control-System Status

An ALCMS may provide command, status, alarm, fault indication, circuit monitoring, equipment monitoring and event logging. However, the ALCMS display must not automatically be assumed to represent the actual optical condition of every field fixture.

A control system may indicate LIGHTING ON while a field condition may actually be: fixture failed, lens damaged, incorrect colour, beam misaligned, reduced intensity, cable fault, or water ingress. Therefore: Command Status ≠ Complete Visual Performance Verification.

15 · Safety-Critical Visual Aids

Stop Bars, Runway Guard Lights, Centreline Lighting & Signs

Stop Bars

Safety-critical: location, configuration, red light, control, interlocking, monitoring, fail-safe operation, taxiway centreline relationship and ATC interface.

Runway Guard Lights

Provide conspicuous visual warning associated with runway access — effectiveness depends on correct location, configuration, visibility, control, electrical supply, maintenance and operational procedures.

Taxiway Centreline

Guidance along taxi routes requires attention to geometry, fixture spacing, curves, intersections, stop bars, runway crossings, control logic and low-visibility requirements.

Signs

Part of the visual navigation system: message, location, orientation, visibility, illumination, power, control, mounting and maintenance.

Markings and lighting work together — a visual navigation system combines different information channels: Marking defines surface information, Sign provides identification/instruction, Lighting provides visual guidance. The three should be considered together.

A taxiway meeting a runway, with the control chain below.

RUNWAY STOP BAR · RED · ON CENTRELINE · OFF HOLDS SHORT 1 · STOP BAR ON — HOLD RUNWAY STOP BAR · OFF CENTRELINE · GREEN CLEARED TO CROSS 2 · STOP BAR OFF — PROCEED ATCCLEARS ATC CONTROLLERTOWER PANEL · A-SMGCSSENDS ON / OFF COMMAND ALCMSINTERLOCK LOGICLINKS BAR TO CENTRELINE FIELD CONTROLLERSWITCHING UNITSWITCHES THE RIGHT BAR STOP BAR CIRCUITSEPARATELY SWITCHEDFEEDS ONE BAR ONLY LIGHTS ON TAXIWAYBAR + CENTRELINEPILOT SEES THE RESULT STATUS FEEDBACK · BAR LIT OR OFF · LAMP FAULTS → CONTROLLER DEFAULT: BAR ON, CENTRELINE OFF · CLEARANCE SWAPS THEM · BAR RETURNS AFTER CROSSING
Figure 7. Stop bar control: the lights are only part of the system.
AGL Visual Encyclopedia: Stop bar control Stop bar monitoring

Flashing yellow guard lights on each side of the taxiway.

TAXIWAY / RUNWAY INTERSECTION RUNWAY RUNWAY CENTRELINE (SECONDARY) RUNWAY EDGE LIGHTS (SECONDARY) TAXIWAY CENTRELINE LIGHTS (SECONDARY) TAXIWAY DIRECTION OF TAXI → TOWARD RUNWAY RUNWAY HOLDING POSITION MARKING RUNWAY GUARD LIGHTS PAIR ON EACH SIDE · FLASHING SCHEMATIC VIEW OF A TAXIWAY/RUNWAY INTERSECTION · FIXTURE COUNT AND SPACING ILLUSTRATIVE · NOT TO SCALE
Figure 8. Runway guard lights at a runway holding position. Flashing lights are shown lit.
AGL Visual Encyclopedia: Runway guard lights
16 · Chapter Q — Visual Aids for Denoting Obstacles

Obstacle Marking & Obstacle Lighting

CS-ADR-DSN also contains provisions for visual aids used to denote obstacles. The current EASA material includes Chapter Q, Visual Aids for Denoting Obstacles. The requirements address objects within obstacle limitation surfaces and include provisions for objects near taxiways and other aerodrome movement areas. Exact applicability depends on the object, location, height, aerodrome environment, obstacle limitation surface and operational conditions.

The EASA material also addresses marking of elevated aeronautical ground lights and signs where required to make them conspicuous by day, and specifies that obstacle lights should not be installed on elevated ground lights or signs in the movement area — an important detail that should not be overlooked during obstacle-lighting design.

Three structures of increasing height and the class of light each needs.

CHOOSE THE CLASS BY HEIGHT ~45 m ~150 m GROUND AIRCRAFT LOW-INTENSITY FIXED RED · TYPES A / B BUILDINGS LOW MASTS · CRANES MEDIUM-INTENSITY FLASHING WHITE / RED · FIXED RED MASTS · CHIMNEYS WIND TURBINES · TALL BUILDINGS HIGH-INTENSITY FLASHING WHITE · DAY AND NIGHT VERY TALL TOWERS STACKS · LONG SPANS SCHEMATIC · HEIGHTS, LIGHT POSITIONS AND TIERS ILLUSTRATIVE · HEIGHT BANDS ARE A GUIDE · NOT TO SCALE
Figure 9. Obstacle lighting by structure height. Flashing lights are shown lit.
AGL Visual Encyclopedia: Obstacle lighting overview Obstruction light monitoring
Airfield electrical technician climbing a tall ramp-light tower
Photo 3. A technician climbs a 100-foot ramp-light tower. Elevated lighting structures need working-at-height arrangements.Credit: U.S. Air Force photo by Senior Airman Julianne Showalter (VIRIN 080225-F-5957S-011). Public domain (U.S. Government work). Source page
17 · Compliance Dimensions

Electrical, Visual & Mechanical Compliance Are Different

An AGL installation can be electrically compliant — the circuit operates correctly — but visually non-compliant, with incorrect intensity, colour, alignment or location, or damaged optics. Therefore Electrical Test + Visual/Photometric Verification are complementary, not interchangeable.

Mechanical compliance can involve fixture mounting, frangibility, height, pavement integration, structural integrity, aircraft clearance, fasteners, bases and drainage. A complete compliance review must therefore cover: Electrical + Optical + Mechanical + Geometric.

Environmental Considerations
RainWater IngressDustRubber ContaminationChemicalsTemperatureCorrosionJet BlastSnow/IceAircraft Wheel Loading
A common field problem is water entering the fixture, base, connector, transformer, junction or cable system — resulting in insulation failure, intermittent faults, optical deterioration, corrosion and repeated fixture failure.
18 · Installation & Commissioning

Installation Quality, Commissioning & Type vs Site Testing

Correct installation should verify Location → Level → Orientation → Mounting → Cable → Connector → Drainage → Electrical → Optical. Commissioning should verify the complete system rather than simply energising the circuit.

Commissioning Sequence
INSTALLATION INSPECTION
ELECTRICAL TEST
ENERGISATION
FUNCTIONAL TEST
MONITORING TEST
PHOTOMETRIC/VISUAL
ACCEPTANCE
StageWhat It Verifies
Type Testing (Factory)Electrical, environmental, mechanical, optical and material characteristics of the product itself — does not automatically prove correct site installation.
Site Acceptance TestingThe actual installed system: installation inspection, electrical measurements, functional tests, control tests, monitoring tests, photometric measurements, alignment verification and defect/rectification records.

Static checks first; power goes on only after the hold point.

PRE-COMMISSIONING · STATIC CHECKS BEFORE POWER DE-ENERGISED · CCR LOCKED OUT · NO LIVE TESTS 1 DOCUMENTS As-built drawings Circuit schedules Permit & test plan RECORD: documents 2 INSTALLATION Fixtures aligned Torque & seating Labels & cleanliness RECORD: inspection 3 CABLES Loop continuity Insulation resistance Joints & connectors RECORD: cable log 4 EARTHING Earth resistance Bonding continuity Earth pits RECORD: earth log 5 EQUIPMENT CCR & controls Transformers & lamps Settings recorded RECORD: settings HOLD POINT READINESS SIGN-OFF · RECORDS REVIEWED 6 OPEN ITEM RECTIFY · RE-TEST CLEARED READY FOR ENERGIZATION SCHEMATIC · CHECK LISTS SHORTENED · NOT TO SCALE
Figure 10. Pre-commissioning sequence: documents, installation, cables, earthing and equipment, then a hold point.
AGL Visual Encyclopedia: Pre-commissioning Final acceptance
19 · Serviceability & Maintenance

Serviceability Is Not Only a Commissioning Issue

A system must remain serviceable during operation: Design → Installation → Commissioning → Operation → Maintenance → Reverification. Maintenance should preserve light output, colour, alignment, mechanical condition, electrical integrity, control functionality, monitoring and availability.

Routine Visual InspectionCleaningFixture InspectionConnector InspectionTransformer InspectionCable InspectionCCR InspectionControl-System InspectionFunctional TestingPhotometric VerificationDocumentation

How far a light can fall before it counts as unserviceable.

ICAO SERVICEABILITY LEVEL WHAT COUNTS AS A SERVICEABLE LIGHT, AND HOW MANY MUST BE ONE LIGHT: SERVICEABLE OR NOT 100% as designed 62% still serviceable 38% unserviceable 50% OF SPECIFIED VALUE ONE SYSTEM: WHICH LIGHTS ARE OUT SPREAD APART: GUIDANCE HOLDS 18 of 20 serviceable (90%) SIDE BY SIDE: GUIDANCE LAPSES 18 of 20 serviceable (90%) Same count, different result. Where the outages sit matters as much as how many there are. HOW THE LEVEL IS SET AND HELD Operation served Category, visibility, take-off minima Level required % of lights serviceable, no adjacent outages Maintenance holds it Inspect, clean, replace before it slips SCHEMATIC · ILLUSTRATIVE VALUES · NOT TO SCALE
Figure 11. The ICAO serviceability level concept.
AGL Visual Encyclopedia: Serviceability level concept Minimum serviceable lamp percentages
20 · Failure Management

Failure Management & Field Troubleshooting

When a visual aid fails: Detect → Identify → Isolate → Diagnose → Rectify → Test → Verify → Record. The objective is not simply to restore illumination — the objective is to restore the required operational function.

One Taxiway Light Failed

Investigation

  • Fixture
  • Secondary connector
  • Isolating transformer
  • Primary circuit & cable
  • CCR
  • Physical damage / water ingress
  • Verify the repaired fixture

Multiple Lights Failed

Investigation

  • CCR → Primary Circuit
  • Control → Cable
  • Transformers → Fixtures
  • Investigate common elements first
  • Do not automatically replace individual lights

Stop Bar Fault

Investigation

  • Command & feedback
  • Interlocking & monitoring
  • ATC interface
  • Field operation
  • Fail-safe response
  • Event/alarm record

PAPI Guidance Problem

Investigation

  • PAPI location & elevation
  • Azimuth & vertical aiming
  • Unit relationship
  • Approach geometry
  • Optical condition

Make safe first, then isolate the fault step by step.

FAULT-ISOLATION FLOWCHART · SYMPTOM, TYPE, SECTIONFIRSTTELL ATC · SWITCH OFF AND ISOLATE THE CCR · LOCK OFF · AUTHORISED PERSONNEL ONLYALL LIGHTS OUTCCR open-circuit alarm, no currentOPEN CIRCUITa break in the loopTEST CONTINUITY BY SECTIONFault is where it failsCCR TRIPSEarth-fault or overcurrent alarmEARTH FAULTinsulation to earth is lowTEST INSULATION RESISTANCE BY SECTIONLow reading marks the sectionSOME LIGHTS OUTCCR normal, circuit runningLOCAL FAULTfixture, connector or transformerCHECK THE DEVICE ITSELFLight, secondary connector, transformerNARROW DOWN BY HALF-SPLITTEST: GOOD · SET ASIDEBAD · SPLIT AGAINfault sectionTHEN1 Repair the faulty part2 Retest section and circuit3 Restore, run, confirm status4 Record results, tell ATC
Figure 12. Fault isolation for a series circuit.
AGL Visual Encyclopedia: Fault-isolation flowchart Series circuit troubleshooting
21 · Two Diagnostic Traps

Electrically ON, Operationally FAIL

A fixture may illuminate, draw current and respond to CCR control, but still fail because the beam is misaligned, intensity is inadequate, colour is incorrect, the fixture is damaged, or installation geometry is incorrect. Therefore: Electrical Function ≠ Complete AGL Compliance.

Similarly, an ALCMS may show normal status while the actual fixture has optical degradation — monitoring should be understood according to what it actually monitors. Command monitoring is not necessarily the same as Photometric performance monitoring.

22 · Documentation & Traceability

Documentation Evidence Chain & Requirement Traceability

A strong EASA-related project record can include the applicable regulation, CS-ADR-DSN revision, requirement matrix, approved drawings, equipment datasheets, certificates, type-test reports, installation records, electrical/functional/monitoring/photometric test reports, inspection records, NCRs, rectification and retest reports, final acceptance records and maintenance records.

RequirementCS ReferenceDesignEquipmentInstallationTestEvidence
Runway lightingApplicable CSLayoutFixtureSiteFunctional/visualReport
Approach lightingApplicable CSALS designFixturesSiteAlignment/photometryReport
PAPIApplicable CSPAPI layoutPAPISiteAlignmentReport
Taxiway lightingApplicable CSLayoutFixturesSiteFunctional/visualReport
Stop barApplicable CSControl logicFixture/controlSiteInterlock/monitoringReport
Obstacle lightingApplicable CSObstacle studyObstacle lightsSiteFunctional/visualReport
Electrical systemApplicable CSElectrical designCCR/powerSiteElectrical testReport
EASA REQUIREMENT
PROJECT SPECIFICATION
APPROVED DESIGN
EQUIPMENT
INSTALLATION
TEST PROCEDURE
MEASURED RESULT
ACCEPTANCE
RECORD
If one link is missing, the compliance argument becomes weaker. Every important requirement should have a traceable evidence path: Requirement → Implementation → Verification → Evidence.

Trace each requirement from source to proof.

TRACE EACH REQUIREMENT FROM SOURCE TO PROOF 1 REQUIREMENT 2 SOURCE DOCUMENT 3 SPEC CLAUSE & TEST 4 EVIDENCE Runway edge light colour and intensity ICAO Annex 14 Vol I and DGCA requirements Photometric test against the specification Photometric report Inset fixture construction and durability FAA AC 150/5345-46 IS 11071 Type tests, such as leakage and load Type test certificate CCR for a 6.6 A series circuit IEC 61822, FAA AC 150/5345-10, IS 12291 Factory acceptance test Signed test record Series transformer isolation IEC 61823 IS 12290 Transformer tests per named standard Signed test record Installed circuit insulation IEC 60364-6 verification Insulation resistance test on site Commissioning record EVERY REQUIREMENT NEEDS A SOURCE, A CLAUSE, A TEST AND A RECORD EXAMPLES ONLY · CHECK EDITIONS AND CLAUSES AGAINST YOUR GOVERNING SPECIFICATION
Figure 13. Requirement mapping: requirement, source, clause or test, and evidence.
AGL Visual Encyclopedia: Requirement mapping Compliance matrix
23 · The Golden Rule

Never Write "EASA Compliant" Without Defining It

The phrase "EASA compliant AGL" is too broad by itself. Instead identify the applicable CS, paragraph, issue/revision, equipment, installation, test, acceptance criterion and evidence.

A stronger engineering statement is: "The applicable EASA aerodrome design requirements were identified, incorporated into the approved design, verified against the installed system, and supported by documented inspection and test evidence."

24 · CS-ADR-DSN in Context

EASA vs ICAO Annex 14 vs FAA vs National Requirements

Manufacturer instructions — installation, torque, cable connection, base, alignment, sealing and maintenance — remain important and should be reviewed together with the applicable aerodrome design requirement. Project specifications can introduce additional requirements: EASA → Authority → Airport → Project Specification → Approved Design → Manufacturer. The project-specific governing framework must always be established.

FrameworkRelationship to CS-ADR-DSN
ICAO Annex 14EASA aerodrome requirements should not simply be treated as a copy of Annex 14 — there are relationships and common aviation objectives, but the documents have different regulatory structures and applicability. For an EASA-regulated project, the applicable EASA regulatory framework must be followed.
FAA AC 150/5340 seriesEASA CS-ADR-DSN ≠ FAA AC 150/5340. FAA Advisory Circulars belong to the FAA regulatory and technical framework; CS-ADR-DSN belongs to the EASA aerodrome certification framework. A project should not mix requirements without identifying why each reference applies.
Indian Projects (DGCA/AAI)For an Indian airport project, EASA CS-ADR-DSN should not automatically be treated as the governing regulatory standard. The applicable framework may instead include DGCA requirements, AAI requirements, ICAO provisions, Indian Standards, project specifications and airport-specific requirements. EASA requirements may be relevant where the project or contract specifically adopts them.

One global baseline, several regulators.

ONE BASELINE, THREE ROUTESICAO ANNEX 14 VOLUME IBASELINEStandards and Recommended PracticesStates notify differences under Article 38TRANSPOSEDGENERALCONFORMANCEFOLLOWS NUMBERINGEASAEUCS-ADR-DSN with GM paragraphs;Regulation (EU) 139/2014, Part-ADR.OPSFAAUSAdvisory Circulars, L-numbered fixtures;14 CFR Part 139 airport certificationDGCAINDIACAR Section 4 Series B Part I;AIP India and airport supplementsWHERE EACH RECORDS ITS DIFFERENCESCertification basis agreed withthe competent authorityFAA AIP, GEN 1.7Lists differences from Annex 14AIP India, GEN 1.7Filed on ICAO EFOD and publishedSAME LIGHTS IN SUBSTANCE. DIFFERENT LEGAL ROUTE, VOCABULARY, UNITS AND EDITION DATES.
Figure 14. ICAO, EASA, FAA and DGCA: one baseline, several regulators.
AGL Visual Encyclopedia: Regulator comparison EASA vs ICAO Annex 14 Filed differences
25 · AGL Photometry Under EASA

Photometry Workflow & Report Structure

For a photometry engineer, the correct workflow is: Identify Visual Aid → Identify Applicable CS Requirement → Identify Performance Criteria → Select Measurement Method → Measure → Evaluate → Report. Do not use a generic photometric pass/fail criterion for every visual aid.

Project & Equipment

Airport, runway/taxiway and location; fixture type and manufacturer.

Test Equipment & Requirement

Photometer and calibration information; applicable EASA/project reference.

Measurements & Acceptance

Recorded results, requirement versus measured value, PASS/FAIL, corrective action if required, retest after rectification.

26 · Monitoring & Low-Visibility Verification

Verifying Monitoring & Low-Visibility Readiness

Monitoring should be tested separately from illumination: Field Condition → Detection → Controller → ALCMS → Alarm/Status → ATC/Operator Indication. Create a controlled fault, then verify it occurs, is detected, changes alarm/status, correctly locates, reaches the appropriate interface within the applicable response time, is recorded, and that the system returns to normal after rectification.

For systems supporting low-visibility operations, verify lighting availability, power supply, secondary power, control, monitoring, interlocking, failure response, serviceability and required visual guidance. The objective is to prevent a failure from leaving the pilot with inadequate or misleading visual guidance.

27 · AGL Safety Model

What Makes a Reliable AGL Safety Function

Visual GuidanceElectrical AvailabilityControlMonitoringInstallationMaintenance

Visual Guidance + Electrical Availability + Control + Monitoring + Installation + Maintenance = Reliable AGL Safety Function. A reliable AGL system requires correct design, correct equipment, correct installation, reliable power, correct control, effective monitoring and proper maintenance.

28 · Common Mistakes

Ten Mistakes That Undermine EASA Compliance

01

Using an old CS-ADR-DSN revision.

02

Ignoring the March 2026 EASA Easy Access Rules.

03

Treating CS-ADR-DSN as an equipment catalogue.

04

Checking only fixture certification.

05

Ignoring installation geometry.

06

Testing only electrical operation.

07

Ignoring monitoring.

08

Ignoring secondary power.

09

Ignoring interlocking.

10

Claiming "EASA compliant" without traceable evidence.

Remember the most important engineering distinction: Equipment compliance ≠ Installation compliance, and Installation compliance ≠ Complete system compliance. A complete compliance demonstration should connect Requirement + Design + Equipment + Installation + Testing + Monitoring + Maintenance.

29 · Design Review Checklist

EASA AGL Design Review Checklist

Regulatory

  • Applicable EASA framework identified
  • Current CS-ADR-DSN revision checked
  • Applicable AMC/GM identified
  • Project requirements reviewed

Design

  • Aerodrome reference code checked
  • Runway classification checked
  • Taxiway configuration checked
  • Approach category checked
  • Visual-aid requirements identified

Equipment

  • Correct fixture type
  • Applicable equipment specification
  • Manufacturer documentation
  • Certification/type-test evidence

Installation

  • Location, spacing, orientation
  • Alignment & height
  • Frangibility
  • Pavement integration
  • Cable connection

Electrical

  • Primary & secondary supply
  • CCR & series circuit
  • Isolating transformers
  • Cable & connectors
  • Earthing/bonding

Control & Verification

  • Control logic & interlocking
  • Monitoring & alarm
  • ATC interface where applicable
  • Functional / electrical / visual tests
  • Photometric & monitoring tests
  • Emergency/secondary power test
30 · The Eight-Level Compliance Model

AGL Compliance Model (This Guide's Framework)

LEVEL 1

Regulatory Requirement — What EASA requirement applies?

LEVEL 2

Design — How is the requirement implemented?

LEVEL 3

Equipment — Does the selected equipment satisfy the required characteristics?

LEVEL 4

Installation — Was it installed correctly?

LEVEL 5

Performance — Does the system actually perform correctly?

LEVEL 6

Monitoring — Can failures be detected?

LEVEL 7

Maintenance — Can performance be maintained?

LEVEL 8

Evidence — Can compliance be demonstrated through records?

The Eight Levels as a Stack

Monitoring and maintenance sit above performance — this guide's model treats fault detection and upkeep as their own compliance levels, not part of "installation"

8 · EVIDENCE 7 · MAINTENANCE 6 · MONITORING 5 · PERFORMANCE 4 · INSTALLATION 3 · EQUIPMENT 2 · DESIGN 1 · REGULATORY REQUIREMENT
31 · Current EASA Reference Map

CS-ADR-DSN Issue 7 — The Chapters That Matter Most

Chapter M

Visual Aids for Navigation, Lights.

Chapter Q

Visual Aids for Denoting Obstacles.

Chapter S

Electrical Systems.

These chapters are particularly relevant to AGL engineering. The March 2026 EASA Easy Access Rules provide the current integrated reference environment.
32 · Change Management

Change Management & Modification Compliance

Any major aerodrome change should trigger a compliance review — runway extension or rehabilitation, taxiway modification, new taxiway, new holding position, PAPI relocation, approach lighting modification, new stop bar, ALCMS modification, secondary power modification, obstacle introduction or new sign.

A modification should follow: Existing Requirement → Proposed Change → Design Review → Approval → Installation → Testing → Operational Verification → Documentation. Do not treat a modification as simply replacing equipment.

33 · Final Principle

The Final Engineering Principle

CS-ADR-DSN should not be treated as simply another AGL equipment standard. It is an aerodrome design certification framework that establishes requirements affecting the environment in which AGL operates.

For AGL engineers, the correct approach is: Understand the Aerodrome → Identify the Visual Aid → Identify the Applicable CS → Check the Current Issue → Design → Select Equipment → Install → Test → Verify → Monitor → Maintain → Document.

The most important question is not "Is this light EASA compliant?" The better question is: "Which EASA aerodrome design requirement applies to this visual aid, how has it been implemented in the approved design, and what objective evidence demonstrates that the installed system satisfies the applicable requirement?"

Final Workflow
01

Understand

Start with the aerodrome and the requirement, not the product.

02

Identify

Identify the visual aid and the applicable CS-ADR-DSN requirement.

03

Check Current Issue

Verify the current EASA publication and the March 2026 Easy Access Rules.

04

Design

Incorporate the requirement into the approved aerodrome design.

05

Specify

Select equipment against the approved design.

06

Install

Install fixtures, cabling and equipment on the airfield.

07

Power & Control

Verify primary/secondary power, CCR, series circuits and control logic.

08

Monitor

Verify monitoring against CS ADR-DSN.S.890 response-time provisions.

09

Measure

Quantify optical and electrical performance against acceptance criteria.

10

Verify

Carry out operational verification of the complete system.

11

Document

Compile the compliance file and objective evidence.

12

Maintain

Ongoing inspection, testing and corrective action.

13

Reassess

Revisit the requirement after any aerodrome, standard or equipment change.

From understanding the aerodrome to documenting the result.

LIFECYCLE ENGINEERING ENGINEER THE ASSET FOR ITS WHOLE LIFE, FROM THE FIRST DRAWING TO THE LAST RENEWAL THE BATHTUB CURVE · WHAT FAILS, AND WHEN failure rate against operating time for a repairable asset FAILURE RATE TIME EARLY LIFE USEFUL LIFE WEAR-OUT faults show up steady rate: MTBF applies ageing: renew ENGINEERING THROUGH THE LIFE 1 DESIGN FOR THE LIFE duty, environment and required service 2 BUY ON WHOLE-LIFE COST price, energy, upkeep and downtime 3 INSTALL AND PROVE IT joints, seals and tests catch early faults 4 OPERATE AND MAINTAIN inspection, spares and planned work 5 RENEW BEFORE WEAR-OUT act on condition, before failures climb 6 FEED BACK THE RECORDS failures and costs improve the next design THE METHOD 1 DEFINE THE REQUIRED LIFE 2 ESTIMATE WHOLE-LIFE COST 3 DESIGN FOR REPAIR 4 COMMISSION AND PROVE 5 TRACK CONDITION 6 RENEW AND FEED BACK SCHEMATIC · SHAPE ILLUSTRATIVE · REAL CURVES COME FROM RECORDED FAILURES AND CONDITION DATA
Figure 15. The engineering chain behind the principle: each stage depends on the one before.
AGL Visual Encyclopedia: Lifecycle engineering Design requirement flow
Go Deeper

The EASA CS-ADR-DSN AGL Knowledge Hub

This page connects directly with the detailed engineering resources below — covering EASA, ICAO and FAA standards, photometry, design, installation and the individual lighting systems CS-ADR-DSN governs.

ICAO Annex 14 AGL Requirements

The parallel global SARPs framework for aerodrome visual aids.

Open ICAO Annex 14 →

FAA AC 150/5340 Series Explained

The FAA's parallel technical framework for airport visual aids.

Open FAA AC 150/5340 →

AGL Photometry

Quantitative verification of optical performance.

Open AGL Photometry →

AGL Design & Electrical Engineering

Series circuits, CCR sizing, transformers, cable design and control.

Open Design Engineering →

AGL Installation & Commissioning

From delivered equipment to a verified system.

Open Installation & Commissioning →

PAPI Engineering Guide

Siting, alignment and photometric commissioning.

Open PAPI Guide →

Approach Lighting Systems

Visual guidance leading toward the runway.

Open Approach Lighting →

Runway Lighting Systems

Edge, centreline, threshold, end and touchdown zone.

Open Runway Lighting →

Taxiway Lighting Systems

Centreline, edge, stop bars and guard lights.

Open Taxiway Lighting →

All About AGL

The complete AGL guide, end to end.

Open All About AGL →

Have an EASA CS-ADR-DSN compliance project?

Available for AGL compliance support, technical documentation and EASA aerodrome design engineering review.

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Ask which standard applies before asking whether a light complies.

STANDARD-SELECTION FLOWCHART · THE REGULATOR COMES FIRST ASK IN ORDER · THEN CHOOSE BY SCOPE 1 ITEM REGULATOR NAMES a standard? 2 CONTRACT NAMES a standard? 3 NO NO 4 CHOOSE BY SCOPE YES YES USE REGULATOR'S Mandatory standard, as named, at its edition USE CONTRACT'S Required by client; also meet regulator if stricter ICAO / FAA Layout, intensity, colour and signs IEC Electrical safety and circuits BIS / IS National product specifications 5 BEFORE YOU USE IT Confirm the edition and national differences  ·  record the choice and its source in the compliance matrix IN DOUBT · ASK THE REGULATOR OR CLIENT SCHEMATIC · EXAMPLE FLOW ONLY · NOT TO SCALE
Figure 16. Selecting a standard for an AGL item.
AGL Visual Encyclopedia: Standard-selection flowchart Applicable standard identification
Keyword Reference

EASA Aerodrome Lighting Requirements

EASA aerodrome lighting requirements

EASA aerodrome lighting requirements are set out in the certification specifications for aerodrome design, CS-ADR-DSN, with related rules and guidance. They cover approach, runway and taxiway lighting, PAPI, colours, intensity, secondary power and monitoring. Always check the current issue and the acceptable means of compliance used by your aerodrome and authority.

AGL Engineering Hub

Explore the AGL Engineering Knowledge Hub

Fundamentals

All About AGL How Airfield Lighting Works Physics of AGL AGL Components Airfield Lighting Colour Codes LED Airfield Ground Lighting LED Benefits, Lifespan & Energy Savings Solar AGL (SAGL) Portable AGL (PAGL) Advantages & Disadvantages by System Type Sustainability in AGL

Standards & Compliance

ICAO Annex 14 AGL Requirements ICAO Aerodrome Lighting Requirements FAA AC 150/5340 Series EASA CS-ADR-DSN Compliance NOTAMs

Runway, Taxiway & Approach Lighting

Runway Lighting Systems Taxiway Lighting Systems Airport Approach Lighting Systems Approach Lighting Systems Apron Lighting & Stand Guidance Apron Floodlighting Design & Lux Levels VDGS: Visual Docking Guidance Obstruction Lighting & Marking Airfield Signage & Guidance Signs Markings & Signage Integration

Surface Movement & Safety

Follow the Greens Runway Guard Lights & Stop Bars Runway Incursion Prevention & SMGCS A-SMGCS ALCMS

PAPI

How Does PAPI Work? PAPI Engineering Guide ICAO PAPI Requirements PAPI Installation & Aiming PAPI Calibration & Alignment PAPI Alignment & Maintenance PAPI Maintenance Checklist

Electrical Engineering & Power

AGL Design & Electrical Engineering Diagrams, Schematics & Wiring CCR Working Principle CCR Deep Dive AGL Isolating Transformers Airport Isolating Transformer Junction Box & Transformer Housing Cables & Connector Engineering Electrical Architecture & Redundancy Emergency Backup Power Emergency Power & Lighting Systems Surge Protection & Lightning Mitigation Lightning & Surge Protection for Circuits

Photometry & Testing

AGL Photometry Photometric Testing Guide Photometric Testing Procedure Runway Lighting Photometry Taxiway Lighting Photometry AGL Testing & Inspection Installation & Commissioning Testing & Commissioning Guide

Maintenance, Inspection & Safety

Preventive & Corrective Maintenance Maintenance Schedule & Checklist Inspection, Maintenance & Audit Checklists How to Inspect & Replace Airfield Lights Common Failure Causes & Fixes Outage Response & Runway Closure Maintenance Work Safety: LOTO, Permits, PPE

Resources, Documentation & Careers

Datasheets, Catalogues & PDF Guides Project Documentation: ITP, As-Built, O&M Engineer & Technician Job Description / Salary
FAQ

Frequently Asked Questions

Q1What is EASA CS-ADR-DSN?

CS-ADR-DSN means Certification Specifications and Guidance Material for Aerodrome Design. It is EASA's aerodrome design certification specification framework, addressing the design of aerodrome infrastructure and visual aids required for safe aircraft operations.

Q2What is the current CS-ADR-DSN baseline according to this page?

The page records CS-ADR-DSN Issue 7, published 19 May 2025 and issued through ED Decision 2025/004/R, with the file replaced on 16 June 2025 to incorporate corrections. It notes that the March 2026 Easy Access Rules for Aerodromes incorporate Issue 7, and that engineers should not rely on an old PDF without checking the current EASA publication.

Q3Why does CS-ADR-DSN matter for airfield ground lighting?

AGL is part of the aerodrome's visual navigation system, and CS-ADR-DSN contains detailed provisions on visual aids, aerodrome lighting, runway, taxiway and approach lighting, PAPI, signs, markings, obstacle lighting, electrical systems, secondary power, monitoring and serviceability. AGL design must be considered together with the aerodrome layout and operational purpose.

Q4Is CS-ADR-DSN a list of approved AGL products?

No. It is a certification framework, not a parts list or equipment catalogue. The better question is not whether a light meets the specification but whether the complete visual aid system satisfies the applicable aerodrome design requirement, following the chain of requirement, equipment, installation, electrical interface and testing.

Q5What is the difference between a Certification Specification, a regulation, AMC and GM?

Regulation provides the legally applicable framework. A Certification Specification provides technical specifications used as a means of demonstrating compliance, and EASA describes CSs as non-binding technical standards. AMC provides acceptable means of compliance, and GM provides guidance and explanatory material.

Q6What is Chapter M of CS-ADR-DSN?

Chapter M, Visual Aids for Navigation, Lights, is described on the page as one of the most important parts of CS-ADR-DSN for AGL engineers. It covers visual navigation lights and associated systems, including elevated fixtures, surface fixtures, approach lights, runway lights and taxiway lights.

Q7What do the requirements say about elevated and inset lights?

Elevated runway, stopway and taxiway lights are required to be frangible, with height sufficiently low to preserve aircraft clearance. Inset fixtures in runways, stopways, taxiways and aprons must be designed and fitted to withstand aircraft wheel loading without damage to the aircraft or the light itself.

Q8How does CS-ADR-DSN treat approach lighting?

EASA states that the safety objective of an approach lighting system is to provide alignment and roll guidance and limited distance-to-go information. The provisions address non-instrument runways, non-precision approach runways, Precision Approach Category I, and Precision Approach Categories II and III, so the applicable design depends on the runway classification and approved aerodrome design.

Q9Does a working PAPI mean the PAPI is compliant?

No. PAPI design involves location, elevation, alignment, azimuth, vertical aiming, unit relationship, approach geometry and visual performance. A PAPI can be electrically functional while still providing incorrect guidance, so electrical ON does not equal correct PAPI guidance and verification must consider optical and geometric performance.

Q10Why were some operational provisions moved out of CS-ADR-DSN?

EASA explains that some provisions of operational nature previously contained in CS-ADR-DSN were transferred to the AMC and GM associated with Part-ADR.OPS, to improve consistency between aerodrome design requirements and operational requirements.

Field Insight

Engineering & Expert Notes

RS
By Rahul Sharma
Airfield Ground Lighting Specialist
Know What Is Binding and What Is Guidance
Framework

Distinguish certification specifications from acceptable means of compliance and guidance material before citing them.

Cite the Current Edition
Currency

Requirements are amended. Check the current text and any applicable amendment before claiming compliance.

Compliance Is a System Property
Scope

Meeting individual product specifications does not alone prove that the installed system meets requirements.

Verify Photometry and Alignment on Site
Verification

Document measured values and aiming for lights that require them.

Check Secondary Power Requirements
Power

Confirm switch-over arrangements and time requirements against the applicable text.

Keep Evidence for Audits
Records

Retain design basis, test reports and inspection records in a form an auditor can follow.

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