What an Airfield Lighting Compliance Audit Actually Looks For

Airfield ground lighting can look acceptable at night while still having serious compliance issues.

A runway may appear evenly lit to the naked eye, but fittings can still be below the required intensity, misaligned, the wrong colour, poorly levelled, or affected by ageing cabling and water ingress.

That is why a proper AGL compliance audit measures and verifies the system. It does not just observe whether the lights turn on.

Why audits happen

Most AGL audits are triggered by one of four things:

• A periodic compliance check against CASA Manual of Standards Part 139, Defence requirements, or the aerodrome’s own maintenance obligations.
• Due diligence before a capital works project, so the airport understands the true condition of the existing system before setting the scope.
• Handover of a completed project, where the operator wants independent confirmation that the works have been delivered correctly.
• Repeated faults, outages or pilot reports that suggest a broader system issue.

The trigger matters because it determines how deep the audit needs to go.

What gets checked

Lighting performance

The visible fittings are the starting point, but they should not be assessed by appearance alone.

A good audit checks the relevant runway, taxiway, apron, signage and wind indicator systems for:

• light output and photometric performance;
• colour and lens condition;
• alignment, level and rotation;
• damaged fittings, bases, gaskets or lenses;
• water ingress, corrosion and pavement damage around inset fittings;
• sign legibility, luminance and correct inscriptions; and
• serviceability of illuminated wind direction indicators.

The aim is to identify whether the system is compliant, reliable and presenting the correct visual information to pilots.

Field circuits and below-ground infrastructure

Many of the most important findings are below the surface.

An audit should review the condition of primary cabling, isolating transformers, connectors, secondary leads, pits, ducts and circuit identification.

Insulation resistance testing is particularly useful because it can identify ageing cables, moisture ingress and weak circuits before they fail completely.

Pits and ducts also need attention. Water, silt, damaged lids, poor cable management and overcrowded ducts can all shorten asset life and increase the cost of future works.

Equipment room and controls

The Airfield Lighting Equipment Room is the heart of the system.

An audit should check constant current regulators, circuit selector equipment, control panels, AGL control system functions, monitoring, standby power, labelling, ventilation, water ingress, cable management and spare parts.

Where an AGL control system is installed, the audit should confirm that switching, intensity selection, fault reporting and failure behaviour match the intended operating modes.

Records and maintenance evidence

A lighting system can appear physically sound but still be difficult to defend if the records are poor.

The audit should review maintenance procedures, inspection records, test results, fault history, as-constructed drawings, equipment schedules, control system settings and configuration records.

This is often where simple but important gaps appear. Incomplete drawings, missing test results or unclear equipment records can make future maintenance and upgrade works harder than they need to be.

What makes an audit report useful

The value of an audit is not just in the inspection. It is in the report.

A useful report should:

• separate non-compliances, defects, risks and observations;
• prioritise findings by safety, operational impact and urgency;
• include clear locations, photographs and test results;
• explain the likely cause of each issue where possible;
• identify practical corrective actions; and
• support future budgeting and capital works planning.

A weak report gives the airport a long list of comments. A strong report gives the airport a clear action plan.

When to audit

There is no single audit interval that suits every aerodrome.

As a practical rule, an AGL audit is valuable before major upgrade works, after significant project handover, and periodically during the life of the system. Older installations, recurring faults, poor records or original cabling are all reasons to audit more closely.

The simplest test is this:

Could you produce current, measured evidence of your AGL compliance tomorrow?

If not, an audit is the fastest way to understand where the system stands, what needs attention, and what should be planned before the next failure or capital works project.