danwoodman00
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NoobQ: Alternating Wing Lights On Landing?

Thu Dec 15, 2011 5:02 am

i was taking my son to the museum of flight in seattle this afternoon, and we were watching the SEA traffic on final for 13L-C-R.

we saw an AS 739 coming in, with what looked like alternating-flashing lights mounted on the outermost tips of the flaps. there were several other 73x, A32x, and Dash8 planes coming in, a few of which had similar lights working, but some did not.

conditions were low-ish clouds (i'm guessing 2000ft?), only slight winds from the south, and no precip falling.

could someone tell me what the lights are, and why they'd be mounted on the flaps on a 73x? seemed like an odd place for illumination...

thanks!

- d
 
tdscanuck
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 15, 2011 5:58 am

Quoting danwoodman00 (Thread starter):
could someone tell me what the lights are

Landing lights.

Quoting danwoodman00 (Thread starter):
why they'd be mounted on the flaps on a 73x? seemed like an odd place for illumination...

It think it's just on the 737-300/400/500, but there's a landing light on a hinge in the flap fairing. It drops down into the airstream when it's turned on. Shown in the retracted position:
http://www.b737.org.uk/images/flap_farings.jpg

On the 737NG those lights were moved to the belly. You can see them sticking out below where the leading edge meets the fuselage:


Tom.
 
flybaurlax
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 15, 2011 8:38 am

It's called pulse lighting. It makes it easier for the aircraft to be identified by other aircraft because the flashing catches your eye. I was also told it has a psychological effect on birds, and that they try to fly away from it. I'm not sure if the latter is correct.

http://www.youtube.com/watch?v=Yfv4W0rmNus

Alaska started putting them in a little over a year ago. It's a customer option, and the pilot can select between steady and pulse.
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Starlionblue
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 15, 2011 12:33 pm

Quoting tdscanuck (Reply 1):
Quoting danwoodman00 (Thread starter):
why they'd be mounted on the flaps on a 73x? seemed like an odd place for illumination...

It think it's just on the 737-300/400/500, but there's a landing light on a hinge in the flap fairing. It drops down into the airstream when it's turned on. Shown in the retracted position:

The DC-9, and I think also the MD-8x, has the landing lights in a flap track fairing. They also drop down when turned on.

There's a noticeable change in vibration when they come out.

[Edited 2011-12-15 04:33:54]
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danwoodman00
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 15, 2011 4:47 pm

thanks for the info and explanation -- the photos and youtube clip are exactly what we saw. much appreciated.

@flybaurlax -- so you're saying they're like "deer horns" for planes!?   
 
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ssteve
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RE: NoobQ: Alternating Wing Lights On Landing?

Fri Dec 16, 2011 4:57 am

You see them a lot with the seaplane traffic on Lake Union as well. Very eye-catching way to warn boaters they're on the runway.
 
Longhornmaniac
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RE: NoobQ: Alternating Wing Lights On Landing?

Fri Dec 16, 2011 5:58 am

Quoting Starlionblue (Reply 3):
I think also the MD-8x

The MD-80 landing lights are at the wingtips, but it's a similar drop down mechanism.

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rendezvous
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RE: NoobQ: Alternating Wing Lights On Landing?

Wed Dec 21, 2011 7:41 am

They certainly make the planes easier to spot when you're trying to find them.
Is the alternating light distracting during landing at night?
 
shamrock137
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RE: NoobQ: Alternating Wing Lights On Landing?

Wed Dec 21, 2011 9:18 pm

Quoting rendezvous (Reply 7):
Is the alternating light distracting during landing at night?

For most operators, procedure is to turn the lights from flash to steady at some point before landing. Some do it when passing through a set altitude, or when the gear is extended. During the day however, the lights can be left in flash right through the landing.
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Western727
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 22, 2011 2:17 am

Quoting Longhornmaniac (Reply 6):

They're fun to watch being extended (on final or just before takeoff) if they're illuminated before they're extended when it's dark out with sufficient humidity...the more humidity the better, of course. Quite dramatic to watch the beam shift from downward-illuminating (stowed position) to forward-illuminating.

The DC-9 family all has them, though I'm not sure about the 717.
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N243NW
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 22, 2011 3:31 am

Quoting Longhornmaniac (Reply 6):
The MD-80 landing lights are at the wingtips, but it's a similar drop down mechanism.

Yep. They do cause noticeable vibration, which is why many pilots turn them off and retract them just after the gear comes up. I loved watching the late evening departures from DFW from my bedroom window and seeing the lights go out as the aircraft passed overhead.
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wn700driver
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 22, 2011 3:41 am

Quoting tdscanuck (Reply 1):

It think it's just on the 737-300/400/500, but there's a landing light on a hinge in the flap fairing. It drops down into the airstream when it's turned on. Shown in the retracted position:

Quite true. Back when I was still working on 73s, there was a persistant rumor that the NGs were eventually going back to that configuration on the basis that the inboard (and lower positioned) landing lights were more subject to rock and runway debris damage. Did you ever hear anything about that?

Quoting Western727 (Reply 9):
They're fun to watch being extended (on final or just before takeoff) if they're illuminated before they're extended when it's dark out with sufficient humidity...the more humidity the better, of course. Quite dramatic to watch the beam shift from downward-illuminating (stowed position) to forward-illuminating.

When I was in mx, we'd do nightly light checks (among many other things) on those. When you turn the lights on, yes they do light up, then position.

I remember one night a few years back when I set the lights and from outside I heard whistling from near the lights. I knew that the whistling was the tune from some movie familiar to me but I couldn't quite place it until I heard the guy shout out "Tanis! I knew it!" when the lights stopped moving.

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tdscanuck
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 22, 2011 7:07 pm

Quoting wn700driver (Reply 11):
there was a persistant rumor that the NGs were eventually going back to that configuration on the basis that the inboard (and lower positioned) landing lights were more subject to rock and runway debris damage. Did you ever hear anything about that?

I heard the same rumours but I think it never got past the concept stage...it's been rumour for so long that, by now, I assume it's just not going to happen. They might have done something to the lenses to improve FOD resistance (similar changes were made to the APU drain mast).

Tom.
 
yeelep
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RE: NoobQ: Alternating Wing Lights On Landing?

Thu Dec 22, 2011 8:39 pm

Never heard that rumour, but have seen allot of cracked lenses. Honeywell does have a improved lens as of October 2009. Its identified by a mark approximately ½ inch in diameter, located in the center of the inside surface of the lens.
 
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HAWK21M
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RE: NoobQ: Alternating Wing Lights On Landing?

Wed Jan 04, 2012 8:09 am

Any study is Pulse lighting increases the life of the Landing light as the use is 50% of normal due to the flashing.....
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