FAA Standards and Photometric Testing

Photometric testing is critical to ensuring the operational safety and compliance of airport lighting systems in the United States. This article covers Photometric Testing and related FAA standards.

The FAA Advisory Circular (AC) 150/5340-26C, titled Maintenance of Airport Visual Aid Facilities, provides clear guidelines for maintaining the performance of airport lighting systems through photometric measurements.

Department of Transportation Federal Aviation Administration building in Washington D.C.

What are the FAA Standards for Airfield Lighting System Photometric Measurement?

FAA requires photometric measurements to be conducted as a part of monthly checks, as well as before and after airfield lighting maintenance. Also, it is required when the airfield lights are identified as a potential suspect in an aircraft accident.

This section summarizes the relevant AC 150/5340-26C articles (5.3.2.1.2, 5.3.4.1.3, 3.7 and Appendix A), paraphrasing some items.


Monthly Checks for Runway and Taxiway Elevated Edge Lighting Systems

  1. Check the orientation of all lenses. Make this check by viewing the lights at night or performing photometric testing. Misaligned light units will appear dimmer or brighter than properly aligned ones.

  2. Photometric Testing     

  3. For high-intensity runway edge lighting (HIRL), Regular photometric measurements are the only practical way to determine if the lights emit the specified amount of light and to determine misalignment errors.

  4. Regularly using photometric measurements identifies light fixture issues early and can save time and resources.

  5. The frequency of photometric measurements varies by facility, runway, traffic levels, and fixture age. Over time, intervals can be adjusted to suit operational needs.

  6. Photometric testing for precision approach runways should occur at least twice a year, considering traffic density, pollution, equipment reliability, and measurement results. Testing should be done:

    • Before cleaning, re-lamping, or realignment to assess maintenance needs.

    • After maintenance to verify its effectiveness. Persistently low-output lights should be removed and serviced.

Runway edge lights with output below 70% of the required minimum (per AC 150/5345-46) should be maintained, as they are ineffective in low visibility or high background brightness conditions.


Monthly Checks for Runway and Taxiway In-pavement Lighting Systems

  1. Cleaning:
    In-pavement lights need frequent cleaning to maintain performance, with frequency depending on location, weather, and airport traffic.

  2. Rubber deposits and de-icing fluids significantly reduce light output. Clean fixtures when output falls below 70% of the required minimum (per AC 150/5345-46), as they become ineffective in low visibility and high brightness conditions.

  3. Photometric Testing:
    Initially, busy facilities may require monthly or weekly checks until a regular schedule is established. For precision approach runways, measurement frequency should consider traffic, pollution, equipment reliability, and results but must occur at least twice a year.

  4. Regular photometric measurements ensure lights meet specified output and identify misalignments. Targeted maintenance saves time and resources while ensuring compliance and consistent lighting for clear pilot visual cues. Measurement frequency depends on traffic and fixture age.

  5. Inspection schedules can be adjusted with experience. Runway centerline lights may need weekly checks due to rubber deposits. This is especially true for CAT II and CAT III runways.

  6. In-pavement lights with output below 70% of the required minimum (per AC 150/5345-46) are ineffective in low visibility and should be cleaned or maintained. Photometric testing should be done:

    • Before cleaning, re-lamping, or realignment to assess maintenance needs.

    • After maintenance to verify its effectiveness. Persistently low-output lights should be removed and serviced.


Testing After Aircraft Accidents

When the FAA declares a lighted navigational aid out of service due to suspicion in an aircraft accident, the airport sponsor/owner/operator is required to immediately inspect the affected facility and record all functional parameters as found per the appropriate table of Appendix A, Standards and Tolerances, of AC 150/5340-26C.

Supposing the accident happened on a runway, all related runway lights’ photometrics are to be measured to provide evidence.


Standards and Tolerances

AC 150/5340-26C outlines tolerances for unserviceable lights, which airports must meet to maintain operational levels. For instance, if only 90% of a CAT II runway’s edge lights meet photometric standards, ILS CAT II approaches cannot continue.

A simplified version of the related table is shown below. Please see AC 150/5340-26C Appendix A Table A-8 Runway and Taxiway Lighting Systems for the original table.


Runway Lights

Threshold Lights 75% ON for VFR and non-precision IFR runways
End Lights 75% ON
Edge Lights 85% ON, except CAT II and CAT III runways require 95% serviceable
Centerline Lights 95% serviceable
Touchdown Zone Lights 90% serviceable

Taxiway Lights

Edge Lights 85% ON
Centerline Lights 90% ON
Elevated Runway Guard Lights No more than one light in a fixture unserviceable
In-pavement Runway Guard Lights No more than three lights per location unserviceable, nor two adjacent lights unserviceable
Runway Stop Bar Lights No more than three lights per location unserviceable, nor two adjacent lights unserviceable

Notes for the tables:

  • To maintain guidance continuity, unserviceable lights must not disrupt the lighting pattern or be adjacent, except in barrettes or crossbars where two adjacent unserviceable lights are allowed. Lights are considered adjacent if consecutive laterally (in a barrette or crossbar) or longitudinally (in a row of edge lights or barrettes).

  • Threshold lights for precision runways are part of the approach lighting system and are not included in this table.


FAA’s Letter to Airports on Maintenance of Visual Aids

In September 2023, the FAA sent a letter to airports highlighting the importance of maintaining airport-owned approach lighting systems and visual aids. This communication reminds airport sponsors of their responsibility to adhere to the maintenance standards outlined in AC 150/5340-26C, which includes the requirement for regular photometric testing.

The FAA emphasized that neglecting these requirements can lead to operational inefficiencies and potential safety risks, particularly when visual aids are implicated in aircraft incidents or accidents. In such cases, airports must immediately inspect affected facilities, including conducting photometric testing, to verify compliance with Appendix A, Standards and Tolerances, of AC 150/5340-26C. Proper record-keeping and prompt maintenance ensure navigational aids remain functional and meet required performance standards.


River Island and Photometric Testing

At River Island, we specialize in airfield lighting and photometric testing, offering unparalleled expertise to ensure compliance, safety, and efficiency for airports. Our partnerships with industry leaders, such as Argos Ingegneria, and our team’s experience in the world’s largest and most advanced airfield lighting systems position us as a trusted resource for all your photometric needs.

Whether addressing regulatory requirements, planning system upgrades, or optimizing your maintenance processes, we are here to provide tailored solutions backed by experience and innovation.


References
https://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5340-26
https://www.faa.gov/airports/airport_safety/maintain_airport_approach_lighting_systems_visaids


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