Station generation, centreline/crossbar/side-row/SFL quantity, geometry validation and compliance dashboard for an approach lighting system (ALS).
This calculator does not maintain an ALS type database — it does not select ALSF-2, MALSR, SSALR, or a specific ICAO configuration for you, and it does not derive required length or station spacing from approach category alone. Those numbers are figure- and system-specific and must come from the applicable approved specification. What this calculator does is take the station spacing, required/available length, and per-station component pattern you enter, and turn them into a validated station schedule, quantity summary, and compliance dashboard — the same generic station-and-shared-fixture discipline as the earlier calculators, applied to a longer and more complex system.
This calculator does not mix ICAO and FAA geometry internally — it doesn't compute either one. This selection only labels the report; all geometry below is entered directly.
ALS-A and ALS-B are separate systems and are never assumed identical. Selecting "Both" flags that this calculator computes one system per session — run it again with Threshold B's parameters for ALS-B.
This calculator does not infer ALS requirement from category or RVR alone — select the status per the approved project specification / regulatory requirement.
This calculator does not maintain a database of ALS type geometries — entering a type name here does not auto-populate length, spacing, or component counts. All geometry below must be entered from the approved specification for the named system.
Per the applicable approved ALS type specification — not derived from category here.
Physically constructible length given site/land constraints. Stations are generated up to the lesser of the required and available lengths, so surplus land is never counted as lit.
Standard-specific — never use an arbitrary universal tolerance; confirm against the applicable specification.
Total lights per crossbar = 2 × this value (symmetrical about centreline).
One flashing unit per listed station — reported separately from steady-burning lights.
| Component | Quantity |
|---|---|
| Centreline lights | — |
| Crossbar lights | — |
| Side-row lights | — |
| Sequenced flashing lights | — |
| Total steady-burning | — |
| Total flashing | — |
| Total physical optical units | — |
Calculated / Nominal Quantity — not a Final BOQ Quantity. Steady-burning and flashing units are kept separate since they have different equipment, control circuits and serviceability requirements.
Checks each interval against the nominal spacing ± tolerance above.
The key design principle: this calculator does not compute ALS quantity from approach length alone. Different ALS configurations have different geometry and component counts, and this tool does not maintain a database of those configurations — it turns whatever station pattern you specify into a validated schedule and quantity summary.
Stations are generated across the available (physically constructible) length, referenced to the runway threshold at d = 0 — the same coordinate convention used in Calculator #05, so the two calculators' threshold references stay consistent.
A crossbar is not one fixture — it is a station property containing multiple lights (2 × lights-per-side here). Side-row lights apply only across the configured station range and side-row mode. Sequenced flashing lights are never merged into the steady-burning count, since they use different equipment, control circuits, and serviceability logic.
The calculator never assumes a shortened available length is equivalent to the full nominal system. If available length is less than required length, the configuration is flagged for review rather than silently treated as compliant.
ALS-A and ALS-B are separate systems and are never assumed identical, even on the same runway. This calculator computes one direction per session by design — running it twice, once per threshold, keeps that separation explicit rather than silently copying one system's geometry onto the other.
It does not select an ALS type (ALSF-1, ALSF-2, MALSR, SSALR, an ICAO Annex 14 precision/simple approach lighting configuration, or any other named system) from approach category. It does not derive required length, station spacing, or crossbar dimensions from that selection. Those are figure-specific values that must come from the approved specification for the named system — entering a label in "ALS Type / Designation" is documentation only.
Marking the approach area "Restricted" never produces an automatic approval or a modified geometry — it always returns an engineering-review flag. This calculator does not independently approve an obstacle-limited ALS design.
Three independent checks, each optional: longitudinal spacing (interval-by-interval against tolerance), centreline alignment (single measured offset against a standard-specific tolerance you supply), and crossbar symmetry (|DL − DR| against tolerance, per crossbar). None of these tolerances are hard-coded — this calculator does not assume a universal value across standards.
ALS geometry sits outward from the threshold; runway threshold/runway-end lighting sits at and beyond it. Both calculators use the same d = 0 threshold reference so a combined layout schedule stays internally consistent.
Quick answers on station generation, quantities and validation for an approach lighting system.
It takes the station spacing, required and available length, and per-station component pattern that you enter, and turns them into a validated station schedule, a quantity summary and a compliance dashboard. It does not maintain an ALS type database. It does not select ALSF-2, MALSR, SSALR or a specific ICAO configuration for you, and it does not derive required length or station spacing from approach category alone.
Those numbers are figure- and system-specific and must come from the applicable approved specification. The design standard selection and the ALS type name only label the report. The tool does not mix ICAO and FAA geometry internally, and it does not infer whether an ALS is required from category or RVR.
Station positions are the first station distance plus the station number times the spacing, measured from the threshold at distance 0. The number of stations is the available length minus the first station distance, divided by the spacing, rounded down, plus one. Stations are generated up to the lesser of the required and available lengths, so surplus land is never counted as lit.
The total is the centreline lights, plus the crossbar lights, plus the side-row lights, plus the sequenced flashing lights. A crossbar is a station property with two times the lights per side, symmetrical about the centreline. Side-row lights apply only across the configured station range and side-row mode. Steady-burning and flashing units are kept separate, because they have different equipment, control circuits and serviceability requirements.
If the available length is less than the required length, the configuration is flagged for review and a length deficit is shown, and it is never silently treated as compliant. Marking the approach area Restricted never produces an automatic approval or a modified geometry, and always returns an engineering-review flag.
ALS-A and ALS-B are separate systems and are never assumed identical, even on the same runway. The calculator computes one direction per session, so run it again with the other threshold's parameters. The threshold reference is the same as in Calculator #05, so a combined layout schedule stays consistent.
There are three optional checks. Longitudinal spacing is checked interval by interval against the nominal spacing plus or minus a tolerance, centreline alignment compares one measured offset against a tolerance you supply, and crossbar symmetry compares the left and right extents of each crossbar against a tolerance. None of these tolerances is hard-coded, because they are standard-specific.
No. It gives calculated nominal quantities and not a final BOQ quantity. Final approach-lighting design must be verified against the approved aerodrome lighting layout, applicable regulatory requirements, obstacle limitations and project specifications.
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