AVSIG: Strobing Runway Lights wwswsigarch.jpg (7236 bytes)

✈ . . . . . . ✈ . . . . . ✈ . . . . ✈ . . . ✈ . . ✈ . ✈ . . ✈ . . . ✈ . . . . ✈ . . . . . ✈ . . . . . . Touch-and-Go to our Live Forum (This is a Read-only Archive of the 2004-2017 AVSIG Forum)


AVSIG Discussion Sections >> Training & Proficiency

Pages: 1 | 2 | 3 | 4 | >> (show all)
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Strobing Runway Lights
      #445860 - 12/15/17 09:25 PM

No, I'm not referring to the rabbit. Here's a report of how LED runway/centerline lights may cause some problems for arriving aircraft. (CALLBACK is great, and this month's issue had some especially interesting reports...including this one).
--------------------

Now You See it, Now You Don’t

A Bonanza Pilot became distracted and confused when he perceived the runway edge and centerline lights cycling on and off while ATC assured him that they were on steady.

■ I was transiting the final approach path of…Runway 16R and observed the runway edge and center line lights cycle on and off…at a rate of approximately 1 per second. It was very similar to the rate of a blinking traffic light at a 4-way vehicle stop. The [3-blade] propeller speed was 2,400 RPM. This was observed through the entire front windscreen and at least part of the pilot side window. I queried ATC about the reason for the runway lights blinking and was told that they were not blinking. It was not immediately obvious what was causing this, but I did later speculate that it may have been caused by looking through the propeller arc.

The next day [during] IFR training while on the VOR DME Rwy 16R approach, we observed the runway edge and center line lights cycle on and off…at a rate slightly faster than 1 per second. The propeller speed was 2,500 RPM. I then varied the propeller speed and found that at 2,700 RPM, the lights were observed strobing at a fairly high rate, and at 2,000 RPM the blinking rate slowed to less than once per second. This was observed through the entire approach that terminated at the Missed Approach Point (MAP). The flight instructor was also surprised and mentioned that he had not seen this before, but he also doesn’t spend much time behind a 3-blade propeller arc.

I would speculate that the Pulse Width Modulation (PWM) dimming system of the LED runway lights was phasing with my propeller, causing the observed effect. I would also speculate that the effect would…significantly differ at other LED dimming settings…and behind a 2-blade propeller.

I found the effect to be entirely confusing and distracting, and would not want to make a landing in such conditions.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ray Tackett
Top Gun


Reged: 04/30/04
Posts: 8892
Loc: Philadelphia, USA
Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445862 - 12/15/17 10:19 PM

The Law of Unintended Consequences strikes again. I'll bet all the test
flights were jets or multi-engine props.

--------------------
Ray,

Owner, Lake Wood Be Gone

Turning quality lumber into sawdust and noise since 2013.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445863 - 12/15/17 11:20 PM

Quote:

I would speculate that the Pulse Width Modulation (PWM) dimming system of the LED runway lights was phasing with my propeller, causing the observed effect.




Maybe. Doing the math, 3 blades x 2400 Rev/min x 1/60 min/sec = 120 cycles/sec. Exactly what you'd expect for a light powered by the 60Hz mains.

Yes, standard dimmers use a type of PWM for dimming, but I don't think that's the real issue. The problem is the LEDs "flicker" in time to the AC mains that the old incandescent (being a heat-based device) couldn't.

The problem here might be retrofitting dimable LED bulbs on a conventional circuit. I haven't looked to see how dimable 120V LED bulbs work, but I'd imagine they have to be responsive to the "PWM"/dimming of the conventional system to function properly. Simply rectifying and smoothing the incoming voltage is going to result in a bulb with really strange dimming characteristics. (Normal brightness until below 50% and then rapid dimming as the cycle drops.) As a result, a strong 120Hz strobe is quite likely.

An LED system designed from the ground up to be LED may run at a higher PWM speed and not cause that problem.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Hartmann CIC
Top Gun


Reged: 05/18/04
Posts: 7323
Loc: Chico,CA
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445864 - 12/15/17 11:23 PM

When Concord NC revamped their runway lights with LED side and centerline...touchdownzone, the works, initially they only ran on high beam.

When landing at night especially with low vis, the tendency was to flare a little high. But you can really see the runway!

--------------------
Jeff

nothing clever to say right now...


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ralph Jones
Top Gun


Reged: 08/31/01
Posts: 21214
Loc: 4CO2
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445865 - 12/15/17 11:25 PM

The wagon wheel effect strikes again...;-)

You should make a video and put it on reddit/aviation. (although the cellphone video scan might muddy the waters a bit).

--------------------
Ralph Jones
LS-4a N49LS 6R


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Ray Tackett]
      #445867 - 12/15/17 11:32 PM

Quote:

The Law of Unintended Consequences strikes again. I'll bet all the test
flights were jets or multi-engine props.




That Law also can take out EV systems from seeing those lights...they may need to have an IR emitter in each lamp.

(It's amazing to me how EV systems have penetrated the bizjet market)

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ray Tackett
Top Gun


Reged: 04/30/04
Posts: 8892
Loc: Philadelphia, USA
Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445869 - 12/16/17 01:13 AM

Indeed. My professional photographer friend who is also a retired electrical
engineer built a bunch of LED light fixtures for his studio. Shortly
thereafter, he found out that the camera he had modified for IR didn't see
much.

--------------------
Ray,

Owner, Lake Wood Be Gone

Turning quality lumber into sawdust and noise since 2013.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dunham (RDU)
Top Gun


Reged: 04/29/04
Posts: 6470
Loc: Chapel Hill, NC
Re: Strobing Runway Lights [Re: Jeff Hartmann CIC]
      #445873 - 12/16/17 01:27 AM

Wen Delta landed a 767 on the taxiway at Atlanta a few years back, turned out that the airport had edone the taxiway lights with LEDs but the runway lights were still incandescent. The LEDs were a lot more conspicuous, and the crew misidentified the taxiway as the runway. All downhill from there...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Randy Sohn
Gradn Exlated Ordre of teh Fyling Fingres


Reged: 08/31/01
Posts: 23187
Loc: Savage, MN - U.S.A.
Re: Strobing Runway Lights [Re: Scott Dunham (RDU)]
      #445874 - 12/16/17 01:57 AM

Quote:

All downhill from there...




Meb'be not "downhill" in a technical sense but - oohwhee - concur with your comment!

best, randy


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Scott Dunham (RDU)]
      #445877 - 12/16/17 03:15 AM

Scott -- I hear there have been issues calibrating the intensities of LED runway lighting, too.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445878 - 12/16/17 04:12 AM

Quote:

I hear there have been issues calibrating the intensities of LED runway lighting, too.




I'm not surprised. A colored LED will have a different spectrum than filtered incandescent. LEDs will tend to be on specific line of frequency rather than "broadband". Test instruments and the Mark1 eyeball show different intensities. IIRC, the eyeball tends not to respond to having all the power in a few lines of color (LED) rather than spread out (filtered incandescent).


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob Dubner
Super Imperial Member


Reged: 08/31/01
Posts: 4759
Loc: Extreme Upper West Side
Strobing Runway Lights [Re: Russell Holton]
      #445884 - 12/16/17 05:16 PM

This is deja vu all over again.

Once upon a time, when traffic lights were colored glass filters over white
incandescent bulbs, some blue was added to the green to make them more
visible to people with red-green color blindness.

Obviously, LEDs are they way to go, now; too many reasons for using them to
ignore -- lifetime, power consumption, and so on.

But it's going to take a few years to sort out. Clearly, the aliasing
wagon wheel effect of the LEDs seen through a propeller arc is unacceptable.
That's going to require DC drivers, or driving different LEDs in the clusters
at different phases and/or different frequencies, or something I haven't
thought of in the thirty seconds I've been considering the problem.

And the fact that LEDs radiate in narrow bands that some people might be
insentive to is also tricky. There aren't any white LEDs; they work by
having the LEDs, usually blue or ultraviolet, stimulate flourescent material
that radiate in the red, blue, and green, which combined produce a
pseudo-white. Now that a true safety need is being demonstrated, one can
only assume and hope that the folks developing those phosphors will continue
their efforts in making the radiation more broad-band.

Another thing that has to be kept under control is over-enthusiasm for cheap
bright light. A couple of streets in Brooklyn were outfitted with
experimental LED street lights. The street was lit up like an operating
theatre; pretty much everybody hated it. It seems to me that even the safety
argument for that much light is bogus; really bright light means really black
shadows that you can't see into because your eyes aren't dark adapted.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445919 - 12/18/17 02:27 PM

I see a flicker with the LED tail lights on some vehicles.

When they are moving across my field of vision, I get the flicker.

But I am also someone who used to have a heck of a time with a CRT with 60 Hertz refresh rate. I needed to set it to at least 72 Hz.

--------------------
Terry
Mostly 0W3


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Terry Carraway]
      #445932 - 12/18/17 05:54 PM

Quote:

I see a flicker with the LED tail lights on some vehicles.

When they are moving across my field of vision, I get the flicker.




That's probably the PWM - especially with lights that are both tail and brake lights. The PWM would be more noticeable in "tail" (brake off) mode.



Quote:

But I am also someone who used to have a heck of a time with a CRT with 60 Hertz refresh rate. I needed to set it to at least 72 Hz.



I can see it. I can put up with it if I'm helping someone, but if it's to be "my" machine, I up to to 72Hz.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gil Buettner [KAUW]
Top Gun


Reged: 05/17/04
Posts: 2847
Loc: Gateway to the Northwoods
Re: Strobing Runway Lights [Re: Bob Dubner]
      #445942 - 12/18/17 10:39 PM

Bob, here in snow country there is another problem with LED traffic lights. They don't generate the heat to melt snow off of the lenses.

--------------------
-Gil


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Bob Dubner]
      #445945 - 12/18/17 11:08 PM

Quote:

But it's going to take a few years to sort out. Clearly, the aliasing wagon wheel effect of the LEDs seen through a propeller arc is unacceptable.
That's going to require DC drivers, or driving different LEDs in the clusters at different phases and/or different frequencies, or something I haven't thought of in the thirty seconds I've been considering the problem.




I'm thinking about changing out the dimmer system to something that works on a different frequency. I'm not sure as there is any simple solution that preserves the dimming function.


Quote:

And the fact that LEDs radiate in narrow bands that some people might be insentive to is also tricky.



I'm sure this is review for you, but as far as I know, there's only two sources of light radiation: back body (thermal) and what I'd call "atomic".

The former is what happens when you heat something so hot it give off light. (Incandescent, halogen, etc.) That kind of light is smooth. (Looking at the spectrum.)

The other kind is the photons given off when an atom drops from a higher level of energy to a lower state. That photon wavelength is specific to the quantum states involved - so a given chemical always gives off the same line(s) of light. (Multiple lines many be involved for a single pure chemical as there may be multiple levels of energy involved.) This is true of florescent, mercury vapor, LEDs (both "direct" and phosphor-based, etc, etc. About the only difference is the method used to get the atoms into the higher energy state in the first place.

The only way to get "white" phosphor is to combine elements so the result looks white to the human eye, even though it's still made up of discrete lines.

This seems to be well established science for florescent lights. I'm not sure why it's a challenge for LEDs - at least the phosphor types.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Gil Buettner [KAUW]]
      #445996 - 12/19/17 06:54 PM

Quote:

Bob, here in snow country there is another problem with LED traffic lights. They don't generate the heat to melt snow off of the lenses.




Gil -- I'm seeing helicopter pilots using NVGs (Medevac) complaining that many obstruction lights are going LED...and goggles don't pick up more than half of those...and same with lights on hospital helipads. Hard to stop the train of "progress", I guess.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #445999 - 12/19/17 07:31 PM

Quote:

obstruction lights are going LED.



Given the level of effort it takes to get up there to change the bulb, I don't blame them.


Quote:

..and goggles don't pick up more than half of those...and same with lights on hospital helipads. Hard to stop the train of "progress", I guess.



Part of me wants to point out that's what happens when you rely on a convention that's not part of any standard. The goggles were sold with the idea that the lights would have IR radiation, but that's probably not in any current standard.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Russell Holton]
      #446007 - 12/20/17 01:04 AM

I'll blame the turkeys who designed and installed lights that are not fit for the intended use, especially on hospital heliports and with obstruction lights. A reasonable engineer would have foreseen the shortcomings, don't blame the nvg makers who designed the equipment when there were no LEDs.

I'd take the case of a medevac pilot who dies after hitting a stealth tower cloaked with nvg-invisible lights.

"Oh well" won't play well to the jury....


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446010 - 12/20/17 01:34 AM

Quote:

I'll blame the turkeys who designed and installed lights that are not fit for the intended use,



Please define "intended use". More to the point, can you find any specification that lists a requirement to have IR emitters? Because that's where an engineer is going to start.


Quote:

A reasonable engineer would have foreseen the shortcomings,



And how would an "reasonable engineer" know that? Again, where is the specs for nav lights that indicate that?


Quote:

don't blame the nvg makers who designed the equipment when there were no LEDs.



Which raises a question - did the nvg makers ever claim you could see nav lights? Or was that discovery made somewhere else (sales or user) and somehow turned into a practice that was unsupported by official documentation?


Quote:

"Oh well" won't play well to the jury....



Hmmmmm. A nvg that's completely blind to something that someone not wearing them could see. Seems like the "reasonable" test belongs somewhere else. Sure, you could make all the nav lights have IR, but what else (non-nav lighted objects) could be out there that wouldn't have a IR emitter yet are perfectly visible to the naked eye? And whose bright idea was it to fly with this blindfold that ignores visible light?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Russell Holton]
      #446012 - 12/20/17 02:48 AM

Quote:

Quote:

I'll blame the turkeys who designed and installed lights that are not fit for the intended use,



Please define "intended use". More to the point, can you find any specification that lists a requirement to have IR emitters? Because that's where an engineer is going to start.


Quote:

A reasonable engineer would have foreseen the shortcomings,



And how would an "reasonable engineer" know that? Again, where is the specs for nav lights that indicate that?


Quote:

don't blame the nvg makers who designed the equipment when there were no LEDs.



Which raises a question - did the nvg makers ever claim you could see nav lights? Or was that discovery made somewhere else (sales or user) and somehow turned into a practice that was unsupported by official documentation?


Quote:

"Oh well" won't play well to the jury....



Hmmmmm. A nvg that's completely blind to something that someone not wearing them could see. Seems like the "reasonable" test belongs somewhere else. Sure, you could make all the nav lights have IR, but what else (non-nav lighted objects) could be out there that wouldn't have a IR emitter yet are perfectly visible to the naked eye? And whose bright idea was it to fly with this blindfold that ignores visible light?




I think you've got your ivory tower engineer glasses on, Russell.

Engineers aren't limited to just blindly following specs, or at least companies that design equipment for an intended purpose shouldn't exclusively rely on such cramped engineering. Using a bit of brain power, and consultation with users (i.e., helicopter pilots who work down low a considerable amount of their flight hours, often in the dark and often with NVGs), should have rendered a better result. Fundamentally, that's an engineering problem as well as a management of engineers problem.

The intended use is warning pilots of low altitude aircraft of obstructions. If a significant percentage of the user community finds them invisible during nighttime hours, they don't pass muster and are inherently defective.

Yes, shame on FAA for not having a better informed approval process in place. But, after all, we don't need big government and industry can do just fine on its own....and when it doesn't it can pay the piper with liability awards.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Nancy Zeitlin [HPN]
AVSIG Member


Reged: 04/29/04
Posts: 2728
Loc: KHPN
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446028 - 12/20/17 04:47 PM

There may have been some Ivory Tower glasses on, but to me, it sure looks like the NVG designers were wearing them. NVGs that are insensitive to visible light? Useful in tactical situations, perhaps, but a general purpose night vision aid that ignores any part of the visible spectrum just doesn’t cut it in MY book.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Nancy Zeitlin [HPN]]
      #446034 - 12/20/17 09:07 PM

Quote:

There may have been some Ivory Tower glasses on, but to me, it sure looks like the NVG designers were wearing them. NVGs that are insensitive to visible light? Useful in tactical situations, perhaps, but a general purpose night vision aid that ignores any part of the visible spectrum just doesn’t cut it in MY book.




Hi Nancy - The idea was likely that being insensitive to light would prevent them from being overwhelmed with artificial light sources. And, hey, what came first, the NVGs or the LEDs? Seems like a reasonable lighting developer for aviation applications would have asked the question, "how do these play with NVGs that are routinely used by helicopter pilots?" But it seems that question might not have been asked. A shame, it is.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
John O'Shaughnessy [FCM]
Top Gun


Reged: 09/13/01
Posts: 5059
Loc: Minnesota
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446035 - 12/20/17 09:24 PM

Quote:

Seems like a reasonable lighting developer for aviation applications would have asked the question, "how do these play with NVGs that are routinely used by helicopter pilots?" But it seems that question might not have been asked. A shame, it is.




Technology marches on. I did a quick Google search to see if anyone had created or is selling Night Vision Goggles that can see LED lights, but My Google-Fu is weak. I did find this 2009 warning from the FAA: http://www.ledsmagazine.com/articles/200...s-says-faa.html


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446036 - 12/20/17 09:28 PM

Quote:

I think you've got your ivory tower engineer glasses on, Russell.



I don't think so. I think it's more procedural/legal than anything.

Again, I ask who made the decision for allowing the use of nvg in that environment without any assurance that the lights would always be visible to nvg? That sounds to me like the first link in a accident chain.

The whole point of specs is so it will work in away that people have come to rely on.


Quote:

Engineers aren't limited to just blindly following specs, or at least companies that design equipment for an intended purpose shouldn't exclusively rely on such cramped engineering.



There's that word "should". I think an opposing attorney would tear that apart. I find it hard to believe the courts would hold someone responsible for something that isn't written down in a contract or specifications. I'm not sure as this falls into the area of "reasonably foreseen".

Let me ask - what is the point of nvg and why are they being used in this situation? For the military, it's part of stealth. For for civilians?


Quote:

Using a bit of brain power, and consultation with users (i.e., helicopter pilots who work down low a considerable amount of their flight hours, often in the dark and often with NVGs),



I had a interesting conversation over a company dinner last night. This person had connection with aviation. (I forget the details other than they got to see the future.) When I brought up this subject, she indicate that for the wind turbines on the North Shore, the community didn't want them lit at night. The military said to add IR reflective tape the entire length and call it good. They didn't even want any IR lights as they said it would just blind them.

So, there you go. Another user who wanted it differently.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: John O'Shaughnessy [FCM]]
      #446037 - 12/20/17 09:37 PM

Quote:

I did find this 2009 warning from the FAA: http://www.ledsmagazine.com/articles/200...s-says-faa.html




Seems like the FAA is putting the onus on the users of nvg, not the lighting that follows their specifications.

At this point, I think I could turn things around and point fingers at the nvg makers. There may be a reason to exclude some visible lights, but to exclude the bulk of "aviation red" spectrum for a product intended to be used by pilots?? That sounds like a bigger "fitness of use" issue.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Russell Holton]
      #446038 - 12/20/17 10:29 PM

Russell - Ah, there's more to liability than just what's in the contract....it's the common law concept of negligence which is built entirely on "what should a reasonable person" have done. And, the fitness for a particular purpose is the touchstone of a warranty claim, separate and apart from whatever the alleged specs may be. While an engineer may think he understands both the aviation application and the law, having not much experience in either should drive him to consulting with the expert users and not relying on specs that were written for and applied to incandescence.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Russell Holton]
      #446040 - 12/20/17 10:33 PM

The fact that the problem was identified in 2008 by the Canadians, and subject to an FAA publication of warning in 2009, with the LEDs still being installed and not upgraded to ameliorate the problem....well, that's a problem. And, as before, what came first, the NVGs (which, according to the FAA approval of them, set the operational environment), or the LEDs (that weren't designed to provide visibility through equipment used widely by helicopter pilots)?

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446042 - 12/20/17 10:40 PM

Scott, along this line is programming product "undocumented features". Many
times customers would find some neat way to accomplish a task using something
not listed as a feature in the programming product. Then we would come out
with an update, featuring new functions and correcting bugs. Sometimes this
would kill some of the "undocumented features" some customers were using.

Out first reaction might be, Tough bananas! But they were paying customers,
so, with very few exceptions, we soon (!) came out with an update that
allowed those features to again be performed (and documented them).


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Scott Dyer [HPN/NY]]
      #446044 - 12/20/17 11:28 PM

Quote:

The fact that the problem was identified in 2008 by the Canadians, and subject to an FAA publication of warning in 2009, with the LEDs still being installed and not upgraded to ameliorate the problem....well, that's a problem.



But who's problem? From the language in the documents, it appears to be the pilot's.


Quote:

And, as before, what came first, the NVGs (which, according to the FAA approval of them, set the operational environment), or the LEDs (that weren't designed to provide visibility through equipment used widely by helicopter pilots)?



To use Ward's terminology, the nav lights came first and the NVG's made use of an undocumented feature. However, in this case, the Golden Rule (he who has the gold makes the rules) is likely to play out differently.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott Dyer [HPN/NY]
Top Gun


Reged: 01/11/03
Posts: 20065
Re: Strobing Runway Lights [Re: Ward Miller POU-NY]
      #446053 - 12/21/17 02:17 AM

Quote:

Scott, along this line is programming product "undocumented features". Many
times customers would find some neat way to accomplish a task using something
not listed as a feature in the programming product. Then we would come out
with an update, featuring new functions and correcting bugs. Sometimes this
would kill some of the "undocumented features" some customers were using.

Out first reaction might be, Tough bananas! But they were paying customers,
so, with very few exceptions, we soon (!) came out with an update that
allowed those features to again be performed (and documented them).




Ward -- Indeed, and I'm surprised that nearly 10 years after the problem was identified that those paying customers haven't been sufficient impetus to work a fix.

--------------------
www.scottdyercfi.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob Dubner
Super Imperial Member


Reged: 08/31/01
Posts: 4759
Loc: Extreme Upper West Side
Strobing Runway Lights [Re: Russell Holton]
      #446061 - 12/21/17 06:36 AM

Russell, Scott has the right of it.

LEDs are being used instead of incandescents because they are cheaper.

But they *are* being sold as *replacements* for incandescents. There is a
built in assumption that a replacement should function the same way as the
thing being replaced.

If they don't function the same way, then they aren't replacements.

In other words, if they are sold as replacements, the functional spec is that
they have a similar radiation profile to the bulbs being replaced.

It's not enough that they are cheaper. They have to work the same way.
<shrug> The need for radiation in the IR spectrum could easily have been
anticipated. I feel sure there are phosphors that re-radiate in that band.
It could have been done. It should have been done.

I suspect that when an accident results from the changed performance of
something marketed as an improved replacement bulb, the plaintiffs in the
resulting lawsuit will prevail.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Strobing Runway Lights [Re: Bob Dubner]
      #446161 - 12/24/17 03:27 AM

There are also IR emitting LEDs. Used as illuminators in many NVGs.

So adding one IR LED to the array would also solve the "problem."

--------------------
Terry
Mostly 0W3


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: Terry Carraway]
      #446183 - 12/24/17 11:54 PM

Quote:

There are also IR emitting LEDs. Used as illuminators in many NVGs.

So adding one IR LED to the array would also solve the "problem."



If that's the desired solution, yes, it wouldn't be that hard. IIRC, IR LEDs were one of the first and may have even been before red LEDs. So, it's not a technology problem.

But it remains to be seen what the motivation for change will be. Clearly two different regulatory agencies are aware of the problem, and even at their slow pace you would have thought something would have been done by now.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Strobing Runway Lights [Re: Russell Holton]
      #446197 - 12/25/17 12:20 PM

The first high profile mishap.

And everyone will be yelling and screaming, and finger pointing.

And then, with will start working on a solution.

--------------------
Terry
Mostly 0W3


Post Extras: Print Post   Remind Me!   Notify Moderator  
John O'Shaughnessy [FCM]
Top Gun


Reged: 09/13/01
Posts: 5059
Loc: Minnesota
Re: Strobing Runway Lights [Re: Russell Holton]
      #446207 - 12/25/17 03:02 PM

Quote:

But it remains to be seen what the motivation for change will be. Clearly two different regulatory agencies are aware of the problem, and even at their slow pace you would have thought something would have been done by now.




I expect it'll only be addressed when it looks to be a profitable venture.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tom Charlton
Top Gun


Reged: 04/29/04
Posts: 2221
Loc: The west coast of Florida
Re: Strobing Runway Lights [Re: John O'Shaughnessy [FCM]]
      #446211 - 12/25/17 05:35 PM

Quote:

Quote:

But it remains to be seen what the motivation for change will be. Clearly two different regulatory agencies are aware of the problem, and even at their slow pace you would have thought something would have been done by now.




I expect it'll only be addressed when it looks to be a profitable venture.


Hi John,

Hear tell rules are typically written in blood?<ng>

Regards,
Tom Charlton

--------------------
The airplane has unveiled for us the true face of the earth. Antoine de Saint-Exupéry, 1939.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights [Re: John O'Shaughnessy [FCM]]
      #446213 - 12/25/17 07:06 PM

Quote:

I expect it'll only be addressed when it looks to be a profitable venture.



Cost-wise, it's cheap enough. The question is one of marketing and demand.

I think the heliports might be interested, but the rest may not.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | >> (show all)



Extra information
0 registered and 39 anonymous users are browsing this forum.

Moderator:  Mike Overly 

Print Topic

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled

Rating:
Topic views: 6381

Rate this topic

Jump to

Contact Us AVSIG

Powered by UBB.threads™ 6.5.5

Logout   Main Index    AVSIG Aviation Forum