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Wig/wag Alternating Landing Lights On A WN 737?  
User currently offlinePflueeb From United States of America, joined Jun 2005, 14 posts, RR: 0
Posted (9 years 4 months 4 days 1 hour ago) and read 6791 times:

Hello! I've been lurking on this excellent website for years now and FINALLY joined after what I saw last night.

Here in Las Vegas I saw a Southwest (WN right?) 737 coming in to land and its under-the-wing landing lights as well as the 2 lights on the nosegear were wig-wagging back and forth. Alternating slowly in a harmonized fashion.

I've never seen this in all of my years of plane watching. You see this effect on locomotives but not airplanes. Their landing lights are always in a steady burn.

What does this mean? Anybody know? Thank you and I look forward to being a member here!

18 replies: All unread, jump to last
 
User currently offlinePHLBOS From United States of America, joined Mar 2004, 7533 posts, RR: 24
Reply 1, posted (9 years 4 months 4 days 1 hour ago) and read 6761 times:

I believe only WN's 733s and maybe 735s are equipped with this strobe-light feature; it's was either on Boeing's option list or WN added it (aftermarket?) for a special effect. Their 73Gs (that I've seen land at PHL) are the standard steady burn.

Welcome aboard, BTW.  Smile



"TransEastern! You'll feel like you've never left the ground because we treat you like dirt!" SNL Parady ad circa 1981
User currently offlineFlyingTexan From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 4 months 4 days 1 hour ago) and read 6761 times:

First, welcome to a.net.

Second, no alarm. Those are standard equipment on SWA jets as far as I can tell. I assume new deliveries come equipped with blinking landing lights.

As you probably know from reading this board, there are several active SWA employees and hoards of planes watchers. Perhaps some can add more detail.


User currently offlineFI642 From Monaco, joined Mar 2005, 1079 posts, RR: 2
Reply 3, posted (9 years 4 months 4 days 1 hour ago) and read 6735 times:

My friends at WN say it's to "scare birds"- as there are normally a lot of birds around airports. Whether or not that's true is another thing . .


737MAX, Cool Planes for the Worlds Coolest Airline.
User currently offlineDfwRevolution From United States of America, joined Jan 2010, 984 posts, RR: 51
Reply 4, posted (9 years 4 months 4 days 1 hour ago) and read 6719 times:

>> (WN right?)

Correct... Southwest IATA code is WN and their NSYE stock ticker is LUV.

>> I've never seen this in all of my years of plane watching. You see this effect on locomotives but not airplanes. Their landing lights are always in a steady burn.

I was under the impression it is a conservation method. Alternating the lights extend their lives compared to burning them steady.


User currently offlinePflueeb From United States of America, joined Jun 2005, 14 posts, RR: 0
Reply 5, posted (9 years 4 months 4 days ago) and read 6676 times:

DFW Revolution--what you say about conservation makes sense, however why was that occurence the first time in decades of plane watching that I've seen that?

The obvious intended use of landing lights is to shine on the runway on approach. Granted, he may have switched them to steady burn at the outer marker--I don't know.

It was just really freakish to see a 737 coming in with slow alternating lights---looked kind of cool actually!

Lastly, I was thinking that perhaps it was a way of signaling the tower and/or identifying himself to another plane or helicopter (which are prominent here over the Strip doing tours).


User currently offlineUsAirways16bwi From United States of America, joined May 2004, 1004 posts, RR: 4
Reply 6, posted (9 years 4 months 3 days 23 hours ago) and read 6634 times:

A while back, I started a thread on the same topic.

http://www.airliners.net/discussions/general_aviation/read.main/87108

http://www.airliners.net/discussions...general_aviation/read.main/1601925

and I wasn't the only one who had the same question. Hope you find your answers.


User currently offlineGQfluffy From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 4 months 3 days 22 hours ago) and read 6586 times:

Quoting DfwRevolution (Reply 4):
I was under the impression it is a conservation method. Alternating the lights extend their lives compared to burning them steady.

Huh. I thought turning lights (fluorescent, halogen, zeon, incandescent) on and off were harder on the bulbs then just leaving them on...

fluffy  confused 


User currently offlinePHLBOS From United States of America, joined Mar 2004, 7533 posts, RR: 24
Reply 8, posted (9 years 4 months 3 days 22 hours ago) and read 6551 times:

Quoting GQfluffy (Reply 7):
Huh. I thought turning lights (fluorescent, halogen, zeon, incandescent) on and off were harder on the bulbs then just leaving them on...

I believe that's true for all bulb types except incandescents.



"TransEastern! You'll feel like you've never left the ground because we treat you like dirt!" SNL Parady ad circa 1981
User currently offlineZOTAN From United States of America, joined Jan 2005, 611 posts, RR: 0
Reply 9, posted (9 years 4 months 3 days 22 hours ago) and read 6533 times:

I always thought it had something to do with visibility. Its eaiser to see the blinking lights from a distance then the steady ones from what I heard.

User currently offlinePflueeb From United States of America, joined Jun 2005, 14 posts, RR: 0
Reply 10, posted (9 years 4 months 3 days 16 hours ago) and read 6442 times:

Thanks USAirwaysbwi for the links---apparently my question has been answered! Funny though, cause you'd think that if it's good for Southwest it would be good for everyone. Increased visibility.

Later,


User currently offlineNASCARAirforce From United States of America, joined Feb 2005, 3184 posts, RR: 4
Reply 11, posted (9 years 4 months 3 days 15 hours ago) and read 6408 times:

Actually since most people are new, this is an often discussed topic. Surprised it has been a while since it been brought up.

I believe it is for better visibility at night.

A lot of corporate jets have this option. I have seen it a lot on Falcon 900s and 2000s, as well as some of the newer Lear jets


User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 12, posted (9 years 4 months 3 days 15 hours ago) and read 6386 times:

The alternating blinking lights are for bird strike protection. Nothing more, nothing less.

User currently offlineAsstChiefMark From , joined Dec 1969, posts, RR:
Reply 13, posted (9 years 4 months 3 days 13 hours ago) and read 6321 times:

I believe only WN's 733s and maybe 735s are equipped with this strobe-light feature

They're not STROBE lights! Strobes are filled with xenon gas and are fired using a high-voltage power supply. Landing lights are usually incandescent because they have filaments that burn in a vacuum.

Mark


User currently offline1MillionFlyer From , joined Dec 1969, posts, RR:
Reply 14, posted (9 years 4 months 3 days 13 hours ago) and read 6313 times:

DL had pulsing nav lights om their ex-Western 727's I beleive. the Green, Red and White lights all pulsed with the flip of a switch.

User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 15, posted (9 years 4 months 3 days 13 hours ago) and read 6293 times:

Most of the answers posted so far aren't accurate.

The purpose of the alternating light is to make the plane more obvious to other traffic during day (and night). It is easier to pick up flashing lights using your peripheral vision than to pick up steady lights during the day. Also, the lights burn steadily at a predetermined altitude AGL (from what I've seen, just before overflying the runway threshold, 200ft?). Aircraft with these installed usually have an option for either steady burn or pulse. These lights have been available for GA planes for quite some time.

http://www.avtek2.bizland.com/pulsar_info.htm

 twocents 


User currently offlineTornado82 From , joined Dec 1969, posts, RR:
Reply 16, posted (9 years 4 months 3 days 13 hours ago) and read 6283 times:

Quoting FLY2HMO (Reply 15):
It is easier to pick up flashing lights using your peripheral vision than to pick up steady lights during the day



Quoting Pflueeb (Thread starter):
You see this effect on locomotives but not airplanes

Same reason for blinking "Ditch lights" on a train. They're to be visible to the motorist at the crossings, since the train will most always be in the peripheral vision of a vehicle (or pedestrian) crossing a rail crossing. At night time though I would think the pilot wants his landing lights on solid for the visibility even before just getting to 200ft AGL. In terms of a landing plane, 200 AGL isn't much.


User currently offlineMD11dude From Canada, joined May 2004, 135 posts, RR: 0
Reply 17, posted (9 years 4 months 3 days 12 hours ago) and read 6258 times:

The sceamers(200s) of WestJet Also do that. Definatly different looking on approach.


CP979
User currently offlineStealthZ From Australia, joined Feb 2005, 5714 posts, RR: 44
Reply 18, posted (9 years 4 months 3 days 12 hours ago) and read 6236 times:
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Quote:
I was under the impression it is a conservation method. Alternating the lights extend their lives compared to burning them steady.

Not so...

Quote:
Quoting GQfluffy (Reply 7):
Huh. I thought turning lights (fluorescent, halogen, zeon, incandescent) on and off were harder on the bulbs then just leaving them on...

I believe that's true for all bulb types except incandescents.

Not so either... It is especcially true of incandescents, the constant flashing causes the filament to vibrate(constant expansion/contraction).

Pulsing the lamp does not extend it's life over a steady state, it minimises the reduction in life that would be caused by flashing it on and off.
The rise & fall in intensity is also more eyecatching than on/off, that is why the rotating beacons on emergency vehicles etc were more noticable than simple flashing lights

Visibility is greatly enhanced, from personal experience at SYD watching hundreds of QF Dash-8 approaches, those with pulselite systems stand out from the haze much earlier.
Birds eyes have a much higher "flicker rate" than humans, hence the spirals and patterns on Prop spinners and fan hubs so I would think that benefit is a minimal but welcome bonus.

Regards

Chris



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