WHAT IS ICAO ANNEX 14?
ICAO Annex 14 – Aerodromes holds the Standards and Recommended Practices (SARPs) for aerodromes. Volume I covers aerodrome design and operations (physical characteristics, obstacle limitation surfaces, visual aids, technical services); Volume II covers heliports. For runway and taxiway AGL, Volume I is the primary reference.
Memory
- Chapter 5 = LIGHT (what the pilot sees)
- Chapter 8 = POWER (how it keeps working)
- Chapter 10 = MAINTENANCE (how it stays serviceable)
- Appendix 2 = PHOTOMETRY (how output is defined)
| Chapter | Subject | AGL relevance |
|---|---|---|
| 2 | Aerodrome data | Visual-aid information |
| 3–4 | Physical characteristics, obstacles | Geometry, approach-light environment |
| 5 | Visual aids | Primary AGL chapter |
| 6–7 | Obstacles, restricted-use areas | Obstacle lighting, closed runway lighting |
| 8 | Electrical systems | AGL power |
| 10 | Maintenance | AGL serviceability |
| Appendix 2 | Light characteristics | Isocandela diagrams, colour |
Shall is a Standard; should is a Recommended Practice. Always read the full paragraph, including notes and exceptions.
CHAPTER 5: APPROACH LIGHTING AND PAPI
Chapter 5 splits into markings (5.2), lights (5.3) and signs (5.4), designed as one visual guidance system. Approach lighting gives alignment, runway identification, transition from instrument to visual guidance, and visual reference.
| System | Key points |
|---|---|
| CAT I precision approach | Centreline row, wherever possible over 900 m from threshold, with a 30 m crossbar at 300 m; a shorter system can bring operational limits |
| CAT II/III | Centreline, two side rows, crossbars at 150 m and 300 m; side rows to 270 m (240 m alternative if serviceability is demonstrated); 900 m overall where possible |
| PAPI / APAPI | Vertical path guidance: white and red combinations show above, on or below slope. Engineer it as a system: optics, aiming, siting, obstacle protection, photometry, supply, control |
The approach-light system should lie as nearly as practicable in the horizontal plane through the threshold; no object other than specified ILS/MLS antennas should protrude through it, and the pattern should not be screened from an approaching aircraft.
CHAPTER 5: RUNWAY LIGHTING
| Light | Colour / rule |
|---|---|
| Edge | Variable white; the section at the remote end (from where the take-off run starts), 600 m or one-third of runway length whichever is less, shows yellow; red between the runway start and a displaced threshold, in the approach direction |
| Threshold | Green (wing bars where applicable) |
| Runway end | Red |
| Centreline (RCL) | Required on CAT II/III; about 15 m spacing, 30 m permitted for RVR ≥ 300 m if serviceability objectives are demonstrated; on the centreline or uniformly offset by no more than 0.60 m; variable white to 900 m from the runway end, alternating red and white from 900 m to 300 m from the end, then red over the last 300 m; on runways shorter than 1,800 m the alternating section starts at the midpoint of the runway usable for landing (differs from the FAA 3,000/1,000 ft pattern) |
| Touchdown zone (TDZ) | CAT II/III; paired barrettes (at least three lights each), fixed, unidirectional, variable white, extending 900 m from the threshold (not beyond the runway midpoint on runways under 1,800 m) |
| Rapid exit indicator | Recommended for low-RVR and heavy-traffic runways |
Compare the FAA values in Note 19 and Note 21.
Remember
- Threshold = GREEN, runway end = RED
- Check runway direction before deciding which end is the "remote end"
- PAPI aside, a pilot sees one pattern, not one lamp
CHAPTER 5: TAXIWAY, STOP BARS AND GUARD LIGHTS
Taxiway centreline lights are required on specified taxiways, de-icing facilities and aprons intended for RVR below 300 m. Straight sections: not more than 15 m. Curves need tighter spacing.
| Curve radius | Spacing (guidance) |
|---|---|
| ≤ 400 m | 7.5 m |
| 401–899 m | 15 m |
| ≥ 900 m | 30 m |
Runway turn-pad lights (RVR below 300 m) guide a 180° turn onto the centreline. Where no stop bar exists, intermediate holding-position lights are required at positions used below 300 m RVR. Road-holding-position lights are required for low-RVR operations and recommended at higher RVR; take the exact thresholds from the current Annex text.
| Feature | Stop bar | Runway guard light |
|---|---|---|
| Colour | Red | Yellow |
| Message | STOP | Runway-entry warning |
| Location | Runway holding position, across the taxiway | Runway holding position, beside or in the taxiway |
| Control | ATS, interlocked with centreline lead-on | System-dependent |
Interlock: stop bar ON means red and stop; clearance switches the bar OFF and the lead-on centreline guidance ON, so the lights never give conflicting indications. Design so that one common fault cannot extinguish a whole stop bar.
AMENDMENT 18: 350 m BECOMES 300 m
Amendment 18 harmonized many low-visibility lighting thresholds from 350 m to 300 m: taxiway centreline lights, rapid exit indicators, turn-pad lights, intermediate holding-position lights, the 30 m runway centreline spacing limit (now RVR 300 m or more) and the serviceability criterion for taxiway centreline lights. Rapid exit, centreline, turn-pad and intermediate holding-position lights are now tied to RVR below 300 m, which is CAT III conditions, rather than CAT II. It also covers CAT II lighting harmonization, main-beam average intensity, threshold marking, closed runway lighting, unserviceability signs and runway distance remaining signs (300 m spacing where provided; the technical specification does not by itself require installation).
| Item | Date |
|---|---|
| Annex 14 Vol. I | 9th Edition, July 2022 |
| Amendment 18 adopted by ICAO Council | 28 March 2025 |
| Amendment 18 effective | 4 August 2025 |
| Design and visual-aid applicability | 27 November 2025 |
| Ground handling / obstacle limitation surfaces applicability | 26 November 2026 / 21 November 2030 |
| Corrigenda listed in the ICAO store (22 Oct 2026) | No. 2 (18 Mar 2026), No. 3 (8 Jun 2026): read the current consolidated text |
CHAPTER 8: ELECTRICAL SYSTEMS AND SWITCH-OVER
Chapter 8 asks how lighting stays powered when the normal supply fails. Secondary power applies to approach, runway and taxiway lighting in the applicable configurations. Architecture depends on category, lighting type, national rules and the approved design.
| Facility (CAT II/III) | Max switch-over |
|---|---|
| Inner 300 m approach | 1 s |
| Other approach lighting | 15 s |
| Threshold, runway end, centreline, TDZ | 1 s |
| Stop bars | 1 s |
| Runway edge, essential taxiway | 15 s |
A generator alone may not meet a 1 s load: use UPS or fast transfer for critical loads and the generator for sustained backup. Annex 14 states the operational need; the CCR must still deliver correct current, steps and monitoring (typically 6.6 A series circuits, from the approved design). Closed runway lighting must be supplied and controlled independently of the normal runway lighting.
CHAPTER 10: MAINTENANCE AND SERVICEABILITY
A light is deemed unserviceable when its main-beam average intensity is below 50% of the applicable specified value (the higher design value where one applies). This is an individual-light test, not permission for 50% of the airport to fail.
| CAT II/III element | Objective |
|---|---|
| Inner 450 m approach, RCL, threshold, edge | 95% |
| TDZ | 90% |
| Approach beyond 450 m | 85% |
| Runway end | 75% |
CAT I: at least 85% for approach, threshold, edge and end lights, with continuity of guidance. Below 300 m RVR: no more than two stop-bar lights unserviceable and no two adjacent; no two adjacent taxiway centreline lights unserviceable.
Why percentage is not enough
- Two failures side by side hurt the pattern more than two apart
- Ask: how many are serviceable, where are the failures, is the pattern kept?
- A light can be electrically healthy yet photometrically deficient
| Criterion | Source | Purpose |
|---|---|---|
| Below 50% of specified/design value | ICAO Annex 14 | Light deemed unserviceable |
| About 70% of minimum output at maximum intensity | FAA AC 150/5340-26C | Maintenance targeting for in-pavement lights |
APPENDIX 2: PHOTOMETRY AND COLOUR
Appendix 2 holds the isocandela diagrams: intensity depends on direction, so "1000 cd" alone means little. For each critical fixture ask how bright, where it points and how far the beam extends. Measure with an approved method and geometry, and compare before and after cleaning (for example 68% before, 91% after shows contamination, not a failed fixture).
| Colour | Typical use |
|---|---|
| White | Runway and approach guidance |
| Green | Threshold, taxiway centreline |
| Red | Runway end, stop bar |
| Yellow | Holding, guard lights, remote runway end |
| Blue | Taxiway edge |
Check each use against the Annex paragraph and figure. A trend such as 96% (2024), 89% (2025), 76% (2026) should trigger inspection before failure. Frangibility applies to elevated lights, signs, PAPI units and approach structures.
CONTROL, LVP AND STANDARDS HIERARCHY
ATC commands go through ALCMS/PLC/SCADA to CCRs, stop bars and monitoring. Selective switching lights only the needed taxi route, useful for low-visibility taxiing, stop bars and lead-on guidance. As visibility falls, lighting outweighs marking, and power, control and monitoring become critical.
LVP is not Annex 14 alone
Add certification, AIP, SMGCS/A-SMGCS, ATC procedures, RVR and navigation aids.
Do not blend standards
ICAO Annex 14, FAA AC 150-series and Indian regulation use similar ideas but different classes, photometry and criteria.
A BOQ line "runway light as per ICAO" is not enough: define application, type, photometry, colour, intensity, electrical input, environment, connector, transformer, standard, tests and documents. Annex 14 gives the aerodrome-level requirement; it is not a product specification.
INSPECTION, COMMISSIONING AND FAULT-FINDING
Inspection
Identify, visual, electrical, optical, alignment, serviceability. For circuits follow CCR, cable, transformer, connector, fixture.
Commissioning
Design verification, installation, electrical, CCR, control, power failover, functional, photometry, alignment, serviceability, documents.
FAT / SAT
FAT at the factory (CCR, panels, ALCMS, UPS, fixtures, signs); SAT on site (location, orientation, intensity, control, interlocking, transfer, photometry).
Maintenance mix
Preventive (cleaning, IR tests, connectors), corrective (replace, repair), predictive (photometric and CCR trends, fault history).
"On" is not "healthy": contamination, misalignment or water ingress can leave electrical output normal and optical output low. Keep as-builts, schedules, photometric, IR and commissioning reports, calibration certificates and fault history. See Note 14 and Note 15.
QUICK REVISION
Critical numbers
- 900 m: precision approach lighting length where possible
- 300 m: Amendment 18 low-RVR harmonization point
- 15 m / 30 m: RCL spacing; 0.60 m maximum offset
- 50%: individual-light unserviceability
- 95 / 90 / 85 / 75%: CAT II/III serviceability objectives
- 1 s: critical CAT II/III switch-over
EXAM / INTERVIEW QUESTIONS
Which chapter is most important for AGL?
Chapter 5, Visual Aids for Navigation.
Which chapters cover power and maintenance?
Chapter 8 (electrical systems) and Chapter 10 (aerodrome maintenance).
Where are photometric characteristics specified?
Appendix 2, Aeronautical Ground Light Characteristics.
What colour is a stop bar, a runway guard light and a threshold?
Red, yellow and green.
What is the CAT II/III runway centreline requirement?
Centreline lights, about 15 m spacing; about 30 m permitted for RVR of 300 m or more when serviceability objectives are demonstrated.
What is the 50% criterion?
A light with main-beam average intensity below 50% of the applicable specified or design value is unserviceable. It is not the share of airport lights allowed to fail.
What changed in Amendment 18?
Many low-visibility thresholds moved from 350 m to 300 m.
Why is Chapter 8 vital for CAT II/III?
Several critical elements have 1 s switch-over requirements.
Why does failure location matter?
Adjacent failures break the visual pattern even when overall serviceability looks high.
Is Annex 14 a transformer specification?
No. It sets the aerodrome-level visual-aid requirement; product specs come from equipment standards, the project and national rules.
FINAL STUDY TAKEAWAY
Annex 14 defines the visual-aid system the pilot must receive, the electrical reliability behind it and the maintenance needed to keep it working.
Do not ask "is the light on?" Ask whether the right aid is in the right place, with the right colour, intensity, beam, alignment, power, control and serviceability.
ENGINEERING & EXPERT NOTES
Distinguish Standards From Recommendations
TerminologyThe wording decides what is mandatory and what is advisory. Read it carefully before quoting it.
Cite the Amendment You Used
CurrencyAnnex content is amended. State the edition or amendment in any design or compliance note.
Remember the National Layer
AuthorityStates implement and may differ. Check the national regulation for the aerodrome in question.
Support Compliance With Measured Evidence
VerificationPhotometry and colour data strengthen a compliance statement more than assumption.
REFERENCES & FURTHER READING
These notes are a study aid. Verify every figure against the current primary sources.
| # | Source | Use it for |
|---|---|---|
| 1 | ICAO Annex 14 Vol. I, 9th Edition (July 2022), as amended up to Amendment 18 (effective 4 August 2025) and later corrigenda | Chapters 5, 8, 10 and Appendix 2 |
| 2 | ICAO Aerodrome Design Manual Doc 9157, Part 4 – Visual Aids; Part 5 – Electrical Systems | Visual-aid layout guidance and electrical systems |
| 3 | ICAO Airport Services Manual Doc 9137, Part 9 – Airport Maintenance Practices | Maintenance practice and inspection guidance |
| 4 | ICAO State Letter SL 2025/23 – Adoption of Amendment 18 to Annex 14, Volume I | Adoption, effective and applicability dates |
| 5 | FAA AC 150/5340-26C | FAA maintenance targets (comparison only) |
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