Wierd - landing lights flashing on and off in flight

[Dave T-S]

Driving home last night minding my own business, time around 1905 so it was dark, there was a plane on finals about 6 miles out from EGSS runway 023 heading towards me, couldn't see what it was but from the noise/profile probably a LCO 737 or similar, and the landing lights were flashing on and off at about two second intervals for all of the 30 seconds or so I saw it in the air.

Very odd! Any suggestions?

Incidentally, does anyone know the lamp spec (voltage, type etc)for your average landing light - VERY bright - are they xenon gas discharge or something - could use a set for my Subaru:D

[knobbygb]

It's supposed to be a way to signal to an aerodrome that you are 'compelled to land' if, for example, you are unable to contact them to get clearance or have been refused permission, but have to land. In reality I wouldn't have thought it was used much, if at all by commercial traffic in the UK.

Perhaps the captains granny lives under the flightpath and he was showing off?

[Human Factor]

A number of corporates are fitted with this system and it's not uncommon in the US. Apparently a good way of scaring the birds ........

Same as suggesting marriage on a first date!:D

[saudipc-9]

Human is right on this account. It has everything to do with birds. If you were looking at the aircraft some are fitted so that the landing lights not only flash on and off but also on opposite sides to each other.

[Dave T-S]

Human factor/saudipc-9
Thanks for the replies. It's a bit odd that it was pitch black, either a problem with owls at EGSS, or the no2 pressed the wrong button I guess! :confused: :D

[Departures Beckham]

You mentioned that you thought it could have been a low-cost airline, perhaps it was a cost saving measure. By having the lights on for two seconds and then off for two seconds, they were only using half the power ;)

[PaperTiger]

Not a signal, not for scaring birds, not cost-saving.
Strobe or alternate-flash landing light systems are for greater visibility, of the be-seen type. Several manufacturers, search google if interested.

Available as retrofit on all 737 models, although I don't remember seeing them on DC-9s/MadDogs. New-build airliners all have built in strobes these days .

[canberra]

ive seen gulfstreams with these sort of lights on the nosewheel.

[woderick]

The common Landing Light sealed beam across most of the modern Boeing and Airbus fleet is a Quartz 28v 1000w thing.
I guess your car's electrical system would struggle with two of them !

[fruitloop]

Dave TS,
For the scooby-do get two 737 logo lamps.13.8 volts and 250 watt.(4 inch) !!:D :D
Cheers

[Dave T-S]

PaperTiger
Interesting - the first I have seen...may well have been a Ryanair 737-800 then as they are probably among the newest stuff at EGSS.

fruitloop
Sounds ideal....hmmm, I wonder where I can get a set?!:D

[Dave T-S]

Answer..... www.candlepowerinc.com !

[niknak]

It is predominantly a bird scaring device, and very effective it is to.

You'd be suprised at the amount of bird activity at night, which is not just restricted to the normal nocturnal variety, for a start, they're attracted by airport ground lighting, don't ask me why, perhaps it's 'cos it's something they don't have in their nests.:)

[PaperTiger]

It is predominantly a bird scaring device

No, it's predominantly a human visibility aid.

and very effective it is too.

Maybe. http://www.aphis.usda.gov/ws/nwrc/field/sandusky/pulsing_lights.html

[TR4A]

It increases the life of the bulbs too.

[Celtic Frog]

Yep..all 3 things...
It increases light bulb life (not sure why 'cos I remember getting physics lesson at school explaining how th einitial switching on of a lightbulb places the maximum surge through it)...but these bulbs are designed so that they get switched off before reaching their peak temperature. (I think) All too scientific for me.
Also easier for humans to see.

Hope it doesn't scare the frogs !!:D

[chiglet]

I ain't seen it.......YET
30+ years at Manch....and ALL lights are "Steady"
we aim to please, it keeps the cleaners happy

[vector4fun]

Odd, I've been seeing them for years here in the States. I'd say most of SWA's 737s have them now....
:cool:

[maninblack]

Lots of mythology out there, chaps.

1) Bird Scaring...this came about after a European manufacturer, working with a now defunct airline, came out with a forward pointing twin strobe light based on the high intensity strobes used on the North Sea and MOD aircraft technology but using a single flash tube. As the aircraft aceelerates down the runway, or lands, the system increases the flash rate in order to convince bird that the aircraft is approaching faster than it really is. The trials results were somewhat mixed as some trials supported the theory and others didn't.

2) The light units are 115V with a step down to 28V for the sealed beam units, the power varies from aircraft to aircraft and can run from 100 watts for a turn off light up through the standard sizes of General Electric sealed beam units.

3) There are very few gas discharge lights in service on aircraft as the manufacturers are wary of such "unproven" technology.

4) The original reason for flashing landing lights was for recognition purposes on approach, as requested by the tower for visual identification. Whether this is commonly used I don't know.

[Finishing the ATPL]

Any idea where I can get a set of 250W B737 logo light bulbs?

I like the idea that was suggested on pg. 1

[Dave T-S]

Finishing the ATPL

www.candlepowerinc.com

:D

[Mister Geezer]

Seen it on a Falcon before. Can't remember if it was a 900 or a 2000. The two wing root landing lights were flashing alternately. Looks odd initially but it is a good idea for collision avoidance!

[Mara]

The system is known as a "Pulse Light" system. There are a number of STC's available for various aircraft types. Generally this system is pitched by the STC holder, both as a visual aid and as a bird deterrent. My personal experience is that the system works extremely well at both.
On your second point concerning aircraft lamps for cars. Most aircraft landing light systems function on 28VDC. On larger aircraft this is done by placing power transformers between the lamp and whichever AC bus is supplying. At roughly $140 to 260 USD per lamp, I think you’d be better off heading to your local boat shop for a good 12 Volt 50,000 candle power, hand held lamp.

[Pom Pax]

Ground lights attract insects, birds eat insects.

[Dave T-S]

Mara
The first part of my question re the pulsing was serious, but the car lamps bit was a bit tongue in cheek (and i've got xenon gas discharge dip lamps on the car, 100w main beam plus xenon gas discharge drive lamps so plenty of light output):D

However, having looked on the lamps website out of curiosity, I note that you can get a 13v 250w 290,000 candle power 146mm dia landing lamp unit:D Only drawback is the 25 hour life:(