Changing the Light Bulbs
By: Faa Safety Briefing
Tags: Lighting, Faasteam, Airports, Led, Aviation

“If you want a quick and easy way to save money, change your lightbulbs to LEDs.”

I received these words of wisdom from countless adults when I was looking for ways to make ends meet in my first apartment. Back then, light emitting diodes (LEDs) “lit up” the consumer marketplace as the longer lasting, more energy-efficient, eco-friendly alternative to traditional incandescent bulbs. The initial investment was quite steep, but with 80% less energy usage than Edison bulbs, the long-term, in-pocket savings offset the upfront cost.

With all that benefit buzz, I decided to give the lightbulb switch a try. What sounded good in theory was harder in practice, as I wandered up and down the lighting aisle of my local hardware store, desperately trying to figure out what the watt is an LED lumen, and will this oddity replace my existing 60 watt bulbs? Who knew that changing the light bulbs could be so complicated! Skeptical, I reluctantly purchased a box of 60 watt equivalent LEDs, and although it took me a while to “warm up” to the light, I haven’t looked back. I don’t have to change them, they don’t burn a hole in my wallet, and I’m doing my part to protect the environment.

Navigating Change 💡

“Change can be hard, even when the benefits are obvious,” says Donald Lampkins, FAA Visual Guidance Lighting Systems Technical Lead. Lampkins and his team are leading the effort to convert incandescent lamps used in airport approach lighting systems to LEDs. While the switch may seem like a natural next step in cost and energy savings, Lampkins’ team has had to invest considerable effort in ensuring buy-in from pilots and technicians in the field. “As is the case with any new technology,” he continues, “you have to be prepared for hesitation or even skepticism.”

In 2007, the Energy Independence and Security Act mandated improved light bulb efficiency. As a result, LED-based lighting began to replace traditional incandescent lights at U.S. airports. Apart from the mandate, four influential factors promoted the switch to LEDs: lamp life, lamp cost, reliability, and maintenance costs. LED technology greatly outperforms traditional light systems using a fraction of the power, with an expected life of 50,000 hours versus 2,000 hours for incandescent lamps. They’re non-hazardous, recyclable, digital, and very precise in how they produce constant, uninterrupted light. Despite their higher upfront price, the return on investment is realized in substantial savings. This is especially attractive to airports across the country.

“LEDs are replaced less often and cost less to maintain. Airfields no longer have to close their runways incrementally each night just to change out lamps for maintenance,” says Matthew Harmon, Aviation Safety Inspector in the FAA’s Flight Operations Group. “At a busy airfield that’s a really big deal,” he explains.

But at the end of the day, the switch to LEDs has proven to be safe and effective. They’ve been researched continuously for over a decade by both the FAA and industry and they are the same, if not better than the familiar incandescents. “The research bears that out, and the aviation community overall is pleased with LED lighting,” says Harmon.

Flipping the Switch 💡

Across the board, both large and small airports are transitioning to LEDs, to the point where LED-based lighting has largely replaced incandescent technology on runways and taxiways, with approach lighting systems (ALS) soon to follow. Since ALS plays a safety-critical role in ground-based navigation, particularly at night and in reduced-visibility conditions, any transition has to be safe or safer than the system in use today.

Early on, prior to installation, some of the common concerns about LEDs were related to brightness, glare, and depth perception. Anecdotal pilot reports suggested that LEDs were perceived as brighter than incandescents at the same intensity, and tests confirmed this was true.

Prior to introducing the technology into the National Airspace System (NAS), the FAA conducted extensive photometric testing to determine how LED lights affect a pilot’s visibility and perception. LEDs have different visual, infrared, and thermal characteristics from incandescents, due to the dissimilar ways in which they generate light. The saturated color of LEDs makes them appear brighter than their less saturated, incandescent counterparts.

To resolve the issue, the FAA revised and re-defined the dimming curves for LED runway lighting, effectively lowering the light intensity. After making these changes, pilots are now beaming over the improved clarity, resolution, and better ability to distinguish colors on the airfield.

💡 The FAA requires airports to convert to LED lights on a single runway or taxiway at the same time to avoid any visual perception differences to pilots.

The U.S. Department of Transportation’s Volpe Aviation Weather Research Center compared incandescent lamps to LEDs in a wide variety of real-world weather and challenging visibility conditions. “Testing and analysis has convincingly shown that in all weather conditions, the pilot will see and recognize LED lights before incandescents,” says Steve McArthur, FAA Visual Guidance Lighting Systems Manager. Check out this video to see the side-by-side comparison on approach (the video contains no audio):

There’s LED lighting options for aircraft too that have some good benefits. More on that in a future article.

Oh Say Can You See 💡

In 2015, the FAA assembled a Significant Safety Issues (SSI) team and Safety Risk Management Panel (SRMP) to study the integration of LED lighting into the aviation system. “There were some initial safety concerns identified with LEDs that we’ve since mitigated; namely, compatibility with night vision goggles (NVGs), and loss of sight issues with high intensity runway edge lights,” says Robert Bassey, electronics engineer in the FAA’s Office of Airports. Legacy NVGs were built to detect the infrared (IR) emission of incandescents. That presents a problem with LEDs, given their limited IR. The FAA found that some pilots using NVGs were unable to acquire red-colored, LED obstruction lights. The agency adopted performance specifications in 2020 to add IR emitters to red LED obstruction lights. “Pilots need to know these lights are now compatible with NVGs,” says Bassey, “and the red obstruction lights are being built to those standards.” Work is ongoing to upgrade the circuitry that powers airport light fixtures so they’ll support LED voltage, with plans to introduce new standards specific to LEDs.

💡 LEDs are compatible with night vision goggles.

When LED conversion was initially considered, the FAA had a restriction on the use of LED high intensity runway edge lights (HIRL). After rigorous testing, the SSI team and SRMP concluded that LEDs meet the standards set for lighting performance in both approach and runway lighting systems. As a result, the restriction on LED HIRL was lifted in 2019.

💡 There are plans to change the Terminal Procedures Publication to identify LED lighting on airfields.

Some pilots also reported an inability to recognize the shape of the runway closure marker, based on LED intensity and the size of the runway closure marker. “We issued a technical report, and we’re doing some validation testing that would ultimately allow us to modify those parameters to make LED runway closure markers more easily recognizable by pilots — that’s coming down the pike,” says Bassey.

Pilots who use Enhanced Flight Vision Systems (EFVS) can continue to use their devices safely, and in the same manner, but the requirement to have an electronic means to see approach lights if you can’t see them with your naked eye, will not change (Title 14 Code of Federal Regulations (14 CFR) section 91.176 (a) and (b)). EFVS users have asked to know, prior to departure, if an airfield has LED lighting. “There are plans to change the Terminal Procedures Publication (TPP) to identify LED lighting on airfields, with emphasis on HIRLs, and any LED approach lighting systems as they change over,” says Harmon.

Cleared for Approach 💡

It is estimated that by 2024, LEDs will start to replace incandescent lamps in ALS across the United States. “The conversion is happening at a rapid pace not only because of the obvious benefits, but also because several manufacturers have stopped making incandescents suitable for airport lighting systems,” says Lampkins. Outside of ALS testing sites, there are currently no LED ALS in use at any U.S. airport. The FAA has determined the most economical approach to replace incandescent lamps is to use the existing ALS infrastructure of 950 Medium Intensity Approach Lighting Systems (MALSRs). As commercial LED lamps are unable to meet the intensity requirements of the current MALSR design, the FAA has validated the requirements for a special LED lamp.

Since 2016, Lampkins and his team have installed LED Precision Approach Path Indicator (PAPI) systems at 52 airports throughout the U.S., such as Flagstaff, Ariz.; Vero Beach, Fla.; Rochester, N.Y.; Harlingen, Texas; Atlanta, Ga.; Newport News, Va.; and Tri-Cities, Tenn., to name a few.

In 2018, they installed LEDs in the MALSR at Juneau International airport in Alaska (KJNU) to collect operations data during low visibility and/or degraded weather conditions. The team received glowing feedback from pilots stating that LEDs are brighter, and easier to distinguish and see.

ALS environmental testing and flight evaluation is ongoing at Savannah/Hilton Head International airport (KSAV), with initial positive feedback from pilots and airport management. Plans are in place to install LEDs at three additional airport test sites: Memphis (KMEM), Columbus (KCMH), and McCarran (KLAS).

“We’ve looked at these lights as a replacement for incandescents for over a decade, and we haven’t found any safety case not to install them,” says Lampkins. “With a much longer life and a more consistent, even light, LEDs are the new beacon of safety on approach.”