Standard & Runway
Rule note
Governs which maximum spacing table applies. Never default to FAA values for a non-FAA project.
Rule note
ICAO Annex 14, 5.3.9 — 100 m max for non-instrument runways, 60 m max for all instrument categories. This selection also drives the suggested threshold/runway-end group count (visual = 3, instrument = 4 for MIRL). For FAA and project bases it does not change the spacing maximum.
Rule note
Lighting-intensity system. It does not change the spacing maximum, but together with the runway classification above it sets the suggested threshold/runway-end group count.
Length & Display
Rule note
Threshold-to-threshold, or the applicable calculation segment length.
Rule note
Output units, decimal precision, and configurable min/max plausible length (in metres) — used only to flag likely data-entry errors such as 24500 instead of 2450. Never blocks calculation.
Threshold / Runway-End & Conditions
Rule note
Auto-suggested from edge-light system + runway classification; override here if the project calls for a different count.
Threshold and runway-end lights form their own transverse arrangement — counted separately from longitudinal edge lights, never added into N + 1.
Existing-Installation Check (optional)
Rule note
If checking an installed runway, enter the count per side to verify achieved spacing against the maximum. Uses the runway length and design basis from the Calculate tab.
Check result
Report details
Quantity schedule
Runway Edge & Threshold/Runway-End Fixture Quantity
| Item | Quantity |
|---|---|
| Left side edge lights | — |
| Right side edge lights | — |
| Longitudinal edge lights (both sides) | — |
| Threshold/runway-end combination fixtures | — |
| Total preliminary quantity | — |
Preliminary only. Threshold/runway-end combination fixture counts assume the same configuration at both ends — the final quantity, and any asymmetry between ends, must be verified against the approved lighting layout drawing before use as a bill-of-quantities figure.
Layout diagram
Schematic, not to scale in width. Light positions are drawn at the calculated uniform spacing; threshold and runway-end groups are shown at each end.
Build-up
How This Calculator Works
The engineering basis behind each result, kept visible so the numbers are auditable rather than a black box.
Core spacing calculation
For a uniform section of design length L against a maximum permitted interval Smax, the number of intervals is found by rounding up — never ordinary rounding, since any excess over the maximum is a non-compliance:
Where a light position is defined at both ends of the section, positions per side are N + 1, and both sides together give the nominal longitudinal count 2(N + 1). This is labelled nominal because it assumes a simple uniform layout — it is not automatically the final bill-of-quantities figure.
Threshold / runway-end lights are separate
FAA AC 150/5340-30 treats threshold/runway-end lights as their own transverse arrangement — perpendicular to the runway axis, on their own spacing rule, not the 2–10 ft edge-light offset. The planning quantities used here are 3 per group for visual operation and 4 per group for instrument operation; confirm them against the threshold-lighting tables of the AC edition in force (currently AC 150/5340-30J). Two symmetrical groups at each of the two ends give 12 or 16 combination fixtures in total. They are counted as one combined threshold/runway-end set, and kept out of the longitudinal N + 1 total to avoid double-counting. The suggested count follows edge-light system and runway use: LIRL → 3; MIRL → 3 (visual) or 4 (instrument); HIRL → 4; manual override always allowed.
Existing-installation check
For field verification, enter the number of positions actually installed per side. The achieved spacing is back-calculated and compared to the applicable maximum:
A PASS/FAIL result follows directly from whether that achieved spacing sits within Smax.
Special conditions are flagged, not folded in
Displaced thresholds and runway intersections both change the lighting arrangement in ways a simple formula shouldn't silently absorb. A displaced threshold shows red edge lights toward the approach ahead of the threshold; an intersection may use irregular spacing or omitted positions where pilot guidance remains adequate. Both are surfaced as review flags rather than recalculated automatically.
Standard maximum-spacing database
| Basis | Runway type | Max interval |
|---|---|---|
| ICAO Annex 14 | Instrument | 60 m |
| ICAO Annex 14 | Non-instrument | 100 m |
| FAA AC 150/5340-30 | Standard edge lighting | 200 ft / 60.96 m |
| Project | Project-specific | User-defined |
This database is a working reference, not a substitute for the standard itself. The ICAO 60/100 m values and FAA 200 ft criterion above should be independently checked against the exact edition of Annex 14 and AC 150/5340-30 applicable to your project before this calculator is relied on as a standards-based reference.
Validation examples
| Runway | Basis | N | Actual |
|---|---|---|---|
| 1,000 m | ICAO 60 m | 17 | 58.82 m |
| 2,450 m | ICAO 60 m | 41 | 59.76 m |
| 2,000 m | FAA 60.96 m | 33 | 60.61 m |
| 3,000 m | FAA 60.96 m | 50 | 60.00 m |
| 3,000 ft | FAA 200 ft | 15 | 200.00 ft |
Indian / AAI & DGCA projects
For an Indian airport project, treat the design-basis hierarchy as: project specification / approved drawing → applicable DGCA requirement → ICAO Annex 14 where adopted → FAA only where the project specification explicitly calls for it. Select Project-Specific above and enter the approved criterion rather than assuming an ICAO or FAA default applies.