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Thread: Polarized sunglasses and pilots

  1. #1
    What's up? drk's Avatar
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    Polarized sunglasses and pilots

    Here's a little visual for you:
    Click image for larger version. 

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    Read this, please (kind of an Optiboard for pilots):

    https://aviation.stackexchange.com/q...ith-sunglasses

    Questions:
    1. Does anyone know if most avionics are LCD now?

    2. Anyone know anything about the "reflection-off-other-planes-as-beneficial" theory?

    3. I'm aware of, but don't understand circular polarization. Anyone? Bueller?

    4. "But you can convert the linear polarized light coming from the display into circular polarized light, which is not affected by polarizing sunglasses. As said, a simple foil on top of the display is enough." This is pretty interesting.

    5. "My opinion: The blue of the sky is also partially polarized and so shaded by glasses. Clouds and other objects stay bright and are better visible, which is a clear pro for polarized glasses". ​ I've noticed this, too. From the ground, of course.

  2. #2
    What's up? drk's Avatar
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    https://groups.google.com/forum/#!to...ng/1N5fA9byI7E


    Is there any lense/film I can put over top of the LCD screen to allow my

    polarized prescription lenses to still work ??

    Yes there is: You need a 1/4 lambda (quarter wave) retarder film. you

    can get it from Edmund Scientific (609)-573-6295. two pieces of 2"X2"
    for 560nm wavelength 10 mil thick cost $15. You will have to play
    with the orientation of the sheet to get maximum brightness - you will
    lose about a factor of 2. There should be almost no change for
    unpolarized sunglasses.


    Also check this out:
    http://www.apioptics.com/precut-filters.html

  3. #3
    Eyes eastward... Uilleann's Avatar
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    1. Newer A/C and jets, yes. Older GA craft, not so much.

    2. Meh. It never helped me specifically to spot or track traffic at any distance, or in any lighting condition. I always found the radar used and separation given by ATC to be far more reliable and beneficial. Particularly flying over the city. 99 times out of 100, when you spot traffic (during the day, when sunlight *might* cause a glint), it only looks like a small dark spot. So the entire "Polar suns will make this magical glint completely invisible!" argument is completely bunk IMHO.

    3. Circular polarizers are used in 3D movies, and for modern DSLR cameras in order to avoid causing issues with auto focus and exposure metering sensors. Not as effective as simpler linear polarizers for the Mk I Eyeball in sunlight though I believe.

    4. I'm failing to see the utility here?

    5. I *always* flew with polar lenses during my training, and never had any issues whatsoever, either with equipment, or seeing traffic. I did find cloud definition and light to be easier to read (important both when staying VFR or transitioning to IFR.), as well as takeoff and landings more comfortable with surface glare slightly reduced on runway and taxiway surfaces. KSLC is a sea of bright concrete in the high desert.

    But I'm sure you'll always have the vociferous guys screaming that polar lenses are "illegal" according to the FAA (completely false), and I even had to correct a non-pilot ABO "master" in one of my CE classes about that error. It really comes down to the pilot, their A/C type, flight conditions, and company rules & regulations if they are flying for someone.

  4. #4
    Master OptiBoarder rbaker's Avatar
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    FAA Application Process for Medical Certification

    Exam Techniques and Criteria for Qualification
    Items 31-34. Eye - Sunglasses

    Sunglasses are not acceptable as the only means of correction to meet visual standards, but may be used for backup purposes if they provide the necessary correction. Airmen should be encouraged to use sunglasses in bright daylight but must be cautioned that, under conditions of low illumination, they may compromise vision. Mention should be made that sunglasses do not protect the eyes from the effects of ultra violet radiation without special glass or coatings and that photosensitive lenses are unsuitable for aviation purposes because they respond to changes in light intensity too slowly.

    The so-called "blue blockers" may not be suitable since they block the blue light used in many current panel displays. Polarized sunglasses are unacceptable if the windscreen is also polarized.

    And this, straight from the horses mouth: https://www.faa.gov/pilots/safety/pi...sunglasses.pdf

  5. #5
    Eyes eastward... Uilleann's Avatar
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    From the FAA *brochure* - mind you, not from any reg book ever written:
    "POLARIZATION. Polarized lenses are not recommended for use in the aviation environment. While useful for blocking reflected light from horizontal surfaces such as water or snow, polarization can reduce or eliminate the
    visibility of instruments that incorporate anti-glare filters. Polarized lenses may also interfere with visibility through an aircraft windscreen by enhancing striations in laminated materials and mask the sparkle of light that reflects off shiny surfaces such as another aircraft’s wing or windscreen, which can reduce the time a pilot has to react in a “see-and-avoid” traffic situation."
    Sadly, perpetuating the traffic glint myth (it's about as pervasive as opticians thinking poly is created right from the devil's dandruff itself!) If you are so close that reaction times are *that* critical to avoid a potential collision, (and you're hoping wing glint will save you somehow) you're doing something very very wrong as PIC.

    It's interesting to note that there is no shortage of wild misunderstanding of even a basic understanding of what polarized light is on that board. This little gem from your first link had me in stitches!
    "Planes are made of metal, but usually are painted, too. The paint generates polarized glare." Wait...WOT?! LOL LOL

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    Master OptiBoarder OptiBoard Gold Supporter
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    Reflections are polarized perpendicularly to the plane of incidence that the reflection occurs from, this has about ZERO to do with a polarizing filter though. I mean I guess they are both polarized, technically an off axis polarized lens is still polarizing light, just not into your eye.

  7. #7
    What's up? drk's Avatar
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    Glad to have this level of conversation.

    I'm going to try to research whether you can slap a piece of circular polarizing film over an LCT display and still be able to see it with polarized sunglasses. That would be cool.

  8. #8
    Eyes eastward... Uilleann's Avatar
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    I can say anecdotally, that in the planes I have flown with glass in the cockpit (LCD screens among other e-display types), that the polar suns I was wearing (Maui's at the time) actually enhanced the screens. Removed all surface reflectivity and made the images more vibrant. It's as if avionics companies are smart enough to align their screens vertically to match linear polar sun lenses perhaps? Although, newer LCD displays appear to be much less susceptible to the old cross polarizing effect (OLED and many QLED displays seem to be more or less immune.) Though a smart pilot knows that the windscreens on some jets exhibit a nasty interference pattern, as can the canopy of some gliders and small GA craft.

    In short, fly smart (as ALWAYS), and if there's any question, err on the side of caution. But also don't be so scared to try something like polar lenses that you miss out on their potential benefits as well. Obviously, they aren't ideal of all pilots, in every A/C type. But they work, and work very well for many.

  9. #9
    Master OptiBoarder AngeHamm's Avatar
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    This is a really interesting conversation. I had one patient at a previous practice who was a commercial pilot who insisted that he was legally unable to have polarized lenses in the cockpit. I used to match the same crazy old red-brown tint for him year after year in the same deteriorating aviator frame.

    I wonder if this is like motorcyclists: half of them swear by polarized lenses, half of them swear they're incredibly dangerous.
    I'm Andrew Hamm and I approve this message.

  10. #10
    Eyes eastward... Uilleann's Avatar
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    To be 100% perfectly clear - there is absolutely, categorically, NO law or FAA regulation stating it is illegal/forbidden/restricted for any pilot to wear a polarized sunglass if they wish. NEVER has been, and unlikely there ever will be. Now, particular companies or groups may have a rule against polar for the pilots they employ, but that is a company rule, and absolutely not a law that applies to everyone.

  11. #11
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    Quote Originally Posted by Uilleann View Post
    To be 100% perfectly clear - there is absolutely, categorically, NO law or FAA regulation stating it is illegal/forbidden/restricted for any pilot to wear a polarized sunglass if they wish. NEVER has been, and unlikely there ever will be. Now, particular companies or groups may have a rule against polar for the pilots they employ, but that is a company rule, and absolutely not a law that applies to everyone.
    This is fascinating to me. Like AngeHammer, I too had a few commercial pilots who insisted that they couldn't wear polarized lenses in the cockpit. They were much more flexible than the fellow in her example-- they were happy to purchase new frames and have grey or G-15 tints-- but still made sure to go out of their way to make sure I didn't give them polarized.

  12. #12
    Eyes eastward... Uilleann's Avatar
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    The policy varies by airline/carrier. They may well have been restricted by their employer for any number of reasons against wearing polar lenses when they were 'on the clock' with them. But it had absolutely nothing to do with any law or FAA reg. It is always on a company by company basis, and can also be a type specific requirement as well.

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