View Full Version : LED Runway Lights
Doors to Automatic
25th Mar 2014, 23:36
I landed at Gatwick late last night and noted that the runway lights are now very bright LEDs. Never seen them before but they really do look the business!
Is this a new innovation? Is LGW one of the first airports with LEDs? Does anyone know how long they have been there and are other airports following suit? And does anyone know what the cost and time of upgrading a runway like Gatwick's is?
Intruder
26th Mar 2014, 05:59
KCHS (Charleston, SC, USA) has them. The colors are a bit different than incandescent lights, but they are very distinctive.
Andy_P
26th Mar 2014, 07:05
KCHS (Charleston, SC, USA) has them. The colors are a bit different than incandescent lights, but they are very distinctive.
Thats interesting. I would say the LED colours are probably correct. Its usually easier to get the correct chromaticity from LED as opposed to incandescent lamps.
Intruder
26th Mar 2014, 10:56
It's not a matter of "correct", but simply DIFFERENT.
Dan Winterland
26th Mar 2014, 13:35
The LEDs are usually whiter and can affect the bet result of the filtered light. The red, amber and blue lights aren't affected, but green light tend to look bluer than usual. I've noticed many airfield lights and indeed traffic lights where the white light behind the lens has been changed. And I've noticed some aircraft have rather blue looking green lights as well.
It probably doesn't make much difference, but interestingly, the International Maritime Organisation (the maritime equivalent of ICAO) in the Collisions Regulations (COLREGS) does specify chromatic parameters for light colours and if you change the bulb in the starboard nav light, you must also change the lens. And where I sail (Hong Kong) the local Marine Department have stopped people for having the wrong colour green light!
http://www.collisionregs.com/MSN1781.pdf
Alicante and Treviso also have the new LED lights. Very bright!
Dan Dare
26th Mar 2014, 14:25
I have noticed a strobe effect from different sources of LEDs (others don't seem to notice this) including from newer cars and some street and home lighting. I assume that the LED react to 50 Hz RMS very quickly in a way that incandescent lights don't. Would this also apply to an array of runway lights?
Andy_P
26th Mar 2014, 21:52
The LEDs are usually whiter and can affect the bet result of the filtered light. The red, amber and blue lights aren't affected, but green light tend to look bluer than usual. I've noticed many airfield lights and indeed traffic lights where the white light behind the lens has been changed. And I've noticed some aircraft have rather blue looking green lights as well.
It probably doesn't make much difference, but interestingly, the International Maritime Organisation (the maritime equivalent of ICAO) in the Collisions Regulations (COLREGS) does specify chromatic parameters for light colours and if you change the bulb in the starboard nav light, you must also change the lens. And where I sail (Hong Kong) the local Marine Department have stopped people for having the wrong colour green light!
They should be using coloured LED rather than coloured lenses. May not be the case though. The colours are specified by ICAO (and I think the FAA).
WRT boats, mine has LED nav lights, and they use a clear lens.
I have noticed a strobe effect from different sources of LEDs (others don't seem to notice this) including from newer cars and some street and home lighting. I assume that the LED react to 50 Hz RMS very quickly in a way that incandescent lights don't. Would this also apply to an array of runway lights?
The problem with feeding AC to LED's is they switch on and off. It does not affect an incandescent bulb, because as the voltage passes through 0, the filament remains heated.
The LED should be fed DC, and I would assume that this would be the case with runway lights.
Fursty Ferret
31st Mar 2014, 12:19
DC but brightness controlled via PWM.
Once you've noticed the "strobe" effect it's hard not to see it, especially on 27L/9R at Heathrow when they're set to maximum dazzle most of the time.
750XL
31st Mar 2014, 13:29
Hasn't MAN had LED lights for quite a while now?
Burnie5204
31st Mar 2014, 15:32
Yarp, installed a few years ago when they relaid the runway.
Piltdown Man
31st Mar 2014, 18:52
But if you want weird, try Alesund. The LED lights there are so highly directional you'll only ever see about 10 or 12 lights. As you move forward, another comes into view. On approach, they look normal. it's only on the ground they appear to change behaviour. And on takeoff it's like being in lo-viz, but you are not. Weird!
PM