Power savings, reduced maintenance and better performance are the supposed benefits of using light-emitting diodes (LEDs) for airfield lighting. But their uptake has been hampered by both the existing infrastructure and the licensing authorities.
For the past 15 years trials have been run to test the use of LEDs on airfields and around five years ago LED lights slowly began to replace incandescent bulbs in traditional airfield lighting systems.
"LEDs are the hot item in lighting these days, both due to their energy saving properties and also the expected long life of the light source," says David N Rainey, vice president of Navaid Lighting Associates. Having worked for Memphis International airport for 25 years as a senior airfield electrician, Rainey formed Navaid Lighting to provide worldwide consulting, training and testing services to the airfield lighting industry. Despite these benefits, however, Rainey says that the technology is still not being used to its fullest potential.
Highlights and holdbacks
The purpose of airfield and runway lighting is to act as a marker instead of providing typical illumination in the conventional sense. According to the study 'Power Distribution for an All-LED Circuit', produced by Rainey and his colleague Seward Ford, an all-LED circuit provides a number of benefits when the full potential of LEDs are unleashed. These include longer lamp life, reduction in airport energy costs and a reduction in power supplies.
In addition, Richard Farmer, development manager at ATG Airports, a company that also provides lighting solutions, says that a primary benefit of LED lights is the lack of maintenance required once they are installed. "When you consider a major hub like Heathrow, they have a very small window for maintenance and many tasks. It is a safety critical area and it is hard for them to get out and do maintenance so anything that can provide improvements brings a lot of benefits."
But these advantages can be negated by the expensive infrastructure that often needs to be updated and through legislation that dictates LED fixtures need also be applicable for more traditional lighting methods.
"The development of LED lighting for airfield uses has required [via Federal Aviation Administration standards] that the LED light fittings be able to be interchangeable with their incandescent counterparts requiring extra electronics added to the light which, in turn, consumes power, making the light source less efficient than it could be," says Rainey.
"Incandescent lamps dim on a curve in relation to the amount of power that is provided to the lamp while LEDs dim in a linear fashion, i.e. 50% power in equals 50% light output."
A further problem associated with LEDs when they are used as the only lighting solution is related to the new enhanced flight vision system (EFVS) technology that is being installed in some aircraft – most notably FedEx's Express fleet which was first off the mark to get FAA approval.
"The problem with EFVS is that while it is primarily for use in low-visibility conditions, it always looks for infrared radiation that is typically emitted by the incandescent lamps,"
"LEDs on the other hand, have no infrared radiation signature. This is why they are so efficient. Instead of converting up to 90% of the power into heat, it is all used to generate light. That is why incandescent lights are so inefficient."
While these problems are being addressed, LEDs are still being integrated into thousands of airfield lighting systems all around the world. Farmer says that it was the aviation authorities in the US and the UK who were the first ones to investigate the benefits of LED technology. The conformity of the industry to the conventions and practices of the International Civil Aviation Organisation should enable the technology to be propagated throughout the world in the coming years.
Lighting up green
As a versatile lighting alternative for temporary runways, remote airfields without grid access, or as an emergency-response application, solar-powered LED lights offer distinct advantages. "Self-contained, portable and wireless solar LED lights can be installed and operational in a matter of hours to provide bright and reliable lighting," says Chris Zegger-Murphy, manager, Middle East and Africa for Carmanah Technologies.
Dubai-based aviation distributor PTLSolar's recent $1.2m acquisition of solar-powered lights from Carmanah demonstrates how the use of stand-alone solar LEDs is growing due to their speedy implementation, reliability, durability and performance.
In addition, Carmanah's solar-powered aviation lights are designed to endure challenging conditions such as extreme temperatures, sandstorms, flooding and poor solar conditions. A built-in energy-management system ensures the lights have enough power to operate effectively – up to 200 hours on a single charge.
While popular for off-grid, emergency or humanitarian aid operations, this versatile technology is also helping to complement permanent primary lighting systems at some of the world's busiest commercial airports. The international airports with a green approach to lighting include Dubai International, Gatwick, Singapore Changi and Toronto Pearson.
"With a quick set-up, no scheduled maintenance and complete freedom from the costs and logistical restrictions associated with installing and operating a grid or generator-powered system, solar LED lights offer a versatile and cost-effective alternative for a variety of applications," says Zegger-Murphy.
Installing solar-powered LEDs can also be beneficial for meeting energy targets. "For organisations that are responsible for large assets, the move to green technology is important. For example, the UK Government and military bodies have high power-saving targets to meet and have certainly taken an interest in it," says Farmer.
Little by little
LEDs, both solar and circuit-powered, are becoming more and more widespread but there are many airports that still haven't taken up the use of either. For many, however, they do form part of a longer-term strategy. For example, Halifax Stanfield International is receptive to new and energy-efficient light sources and its combined services complex, which is under construction, will incorporate LED lighting technology. However, its actual airfield has undergone a number of lighting updates over the past few years there still isn't an airfield project that allows for a complete LED installation. However, the airport facilities manager confirms this will be addressed in future upgrades.
San Diego International Airport (SAN), with the busiest single runway in the US, has not as yet incorporated portable, stand-alone or solar-powered LEDs into its lighting systems. According to Steve Duboce, SAN's airport operations specialist, SAN's lighting systems are not compatible with this new technology. "Stand-alone LEDs and solar-powered technology is not in use
because the airfield lighting and signage system requires incandescent bulbs," says Duboce.
In the short term Duboce says that SAN will continue to operate according to FAA specifications, but in the future a lighting project incorporating LEDs will take place.
"A taxiway and airfield signage replacement project with FAA approval is scheduled to proceed in the summer of 2009," he says. "The project will include the replacement of all taxiway lighting with standalone LEDs as well as existing taxiway and runway signage to fluorescent energy-saving signs."
Existing infrastructure has cost a lot of time and money to create and this, combined with necessary FAA approvals, means that the implementation of new lighting systems is going to take time. "By making small system changes that correspond to the LEDs' linear dimming characteristics we can greatly reduce or eliminate the electronics required in the light fitting, thereby further reducing energy consumption and retaining the proven architecture of the series circuit," says Rainey.