LED potential on the airfield

The growing acceptance of LED technology for use in different airports globally is testament to the technology’s potential in this area.

Wherever you are in the world, regardless of the size or type of the airfield, the airfield lights provide guidance for pilots and those engaged in airside operations. But although a simplistic approach may achieve this function, the vital role that the lights play in the operation of an airport may hold potential for management. That potential could yield greater operational efficiency, effect cost savings, improve safety and help meet future demands on capacity.

New Technology

The key to these savings in many people’s eyes is new technology. Companies such as Siemens ADB, Thorn, Alstom and Carmanagh are offering ranges of taxiway lights suitable for airport usage. Light Emitting Diodes (LEDs) offer some basic improvements over traditional tungsten halogen lamps.

According to Bruno Urbaing of Siemens ADB, traditional lamps provide on average between 1000 – 1500 hours of operation in normal conditions. Contrast this with the estimated 56,000 hours of use Bruno claims his LED lights are capable of, and it is apparent that real reductions in maintenance intervals can be achieved. “In normal conditions a lamp has to be replaced on average once a year. Light fittings may also need minor maintenance for things such as broken filters,” Bruno says. “However, if you replace the light source with something which lives as long as the fixture itself, you are making a large cost saving.”

The lamps also offer increased power efficiency over traditional lamps, although according to Urbaing the main advantage lies within elongating the operational lifespan of the light source to one congruent with its neighbouring components. The value benefit has been driving the interest in LEDs for airfield applications, and Urbaing claims that the uptake of LEDs in the airport sector is now increasing expotentially. “The sales of LED lights are increasing. Siemens has sold between 20 – 30 000, and currently each year we make as much as the previous cumulative years put together.”

The value of these sales are evenly split between Europe and the U.S. at the moment, despite the relative size of the American market for lighting products. The reason for this, Urbaing says, is that the majority of sales into North America are for elevated taxiway edge lights, whereas Europe, because of its high density of Cat III airports, has a greater need for the more expensive inset lights.

General Aviation

Indeed, small general aviation airports in the US, such as Truckee Tahoe in California, have been amongst the first to adopt LED technology. Here in the mountains the pioneering spirit of the airport has helped to embrace LED technology. Dave Gotschall, Airport Manager of Truckee Tahoe purchased 480 solar powered LED taxiway lights from Carmanagh in January 2004 for their taxiways. His purchasing decision was affected by the USD 1.2 million cost of a hard-wired system (10 per cent of which would have to be met by the airport itself) and a phased installation over a 3 year period. The solar powered LEDs in comparison offered a lower initial investment, lower running costs and easier installation than the LEDs.

“Basically for the same 10 per cent we could acquire and install them all ourselves in a month,” says Gotschall. “The annual cost of electricity to power a hard wired system was also about USD 18 000 a year in 2003. The lights are supposed to have a life time of 5 – 8 years, meaning we could get a 100% payback during their lifecycle.

Considering the reduced disruption, that they are more environmentally friendly, and the cost, we gave it a shot,” says Gotschall. 18 months later and following a winter which saw the airfield buried in up to eight foot of snow, only six of the 480 have needed replacing under warranty. This was because of failed valves allowing the ingress of moisture into the battery compartments.

For Truckee and other similarly remote airports with limited power capabilities, solar powered LEDs offer benefits hard to disagree with. “I think they have a lot of applications. If you are in a commercial facility where you can spend the money on a hard-wired system, then all power to you. But for the vast majority of smaller airports, this is the way to go,” says Gotschall.

Further up the scale

With over 5,000 general aviation airports similar to Truckee and over 9,000 private airports in the US alone, this market is considerable. However, the product is also suitable for larger airports in temporary and permanent barricades, construction, taxiway and low lying obstruction lighting applications. Furthermore, Allister Wilmott of Carmanagh states that the company is currently seeking additional FAA and ICAO approvals for obstruction lighting, taxiway lighting and runway edge lighting.

He also regards his lights as more reliable than hard-wired lights. “Each individual light has its own power source which guards against power outages and LEDs which are rated for up to 100,000 hours of use,” he says. Concerns about the solar power source are managed by power management technology, which adjusts the LEDs output when voltage levels drop, during times of poor solar insulation, extreme environmental conditions or improper installation.

Commercial airports

Whether solar or not, many larger airports will find themselves retrofitting the LED lights on programme, and in the UK this has lead to close collaboration between industry and government to ensure safety is not diminished. The AOA’s (Airport Operators Association) technology working group ran a serviceability trial at London Heathrow. The Chairman of the working group, Peter Patrickson, who is Airside Manager at Birmingham International Airport, now believes that the only obstacle to widespread LED use on airfields is the regulatory one. “The trials at Heathrow were successful,” he says. “The lights are very suitable, with even protection against lightning strikes provided for. The installation itself is slightly different, but perfectly compatible with existing systems. We would seriously look at them for any major change.”

The Heathrow trials resulted in a set of standards and procedures which have now been adopted by the UK CAA. According to Paul Fenton-Jones, the policy officer responsible for the CAA’s section on aerodrome ground lighting, the standards will be updated by the Autumn this year. “There were some technicalities that we wanted to see mature, but we can now consider all the possibilities from a safety point of view,” he says. “Since these will be retrofitted into existing control circuitry we wanted to be sure that there are no subtle interferences caused by that in a light’s failure mode. Our own tests and the manufacturer’s have shown that this will not be the case.”

Approval for the lights is still being phased in though, since the authority’s view naturally errs on the side of caution. Approval will start with comparatively low risk areas such as taxiways and apron areas before use on higher safety critical areas is permitted. “Taxiway lights can be dealt with a lot easier than runway lights,” Fenton-Jones comments. “High intensity approach and runway services, guard lights on runway stop bars, and runway position stop bars will probably be given permission in 12 months.”

Drawbacks

However, it is not just the safety aspect which is delaying the complete introduction of LEDs onto the entire airfield. Actual LED technology requires further development before it can provide the luminsence required for approach lighting on runways. High intensity coloured lights are possible, but white lights require a combination of coloured LEDs and are some way off. Research by LED manufacturer’s continues unabated on this though, and the general consensus is that the technology will provide solutions within three to five years. “For the moment we are limited to the taxiways.” says Bruno Urbaing. “It will probably be within five years when will be able to have the products suitable for runways and approaches.”

In the meantime traditional lights will continue to be necessary.