Wi-Fi proven to interfere with airline display units

Do you roll your eyes when asked to turn off your laptop during takeoff and landing on an airplane? Maybe you shouldn’t. Flightglobal is reporting that Honeywell Phase 3 Display Units are prone to interference from Wi-Fi signals. Interference is said to make the screens go blank on display units, although affected hardware hasn’t made its way into any airline fleets. It looks like the problem is tied more to in-flight Wi-Fi services than wireless signals generated by notebooks and smartphones.

Boeing, meanwhile, says: "Current testing by Boeing and Honeywell has determined that blanking may occur when a DU is subjected to testing procedures specified by the FAA requirements (AC-20-164) during installations of Wi-Fi systems on the airplane. Based on testing that has been conducted, Boeing and Honeywell have concluded that actual EMI levels experienced during normal operation of typical passenger Wi-Fi systems would not cause any blanking of the Phase 3 DU. This issue does not exist with the Phase 1 or 2 DU’s."

According to the article, Phase 4 DUs are unaffected, as well. What’s more, the screens apparently only go blank for a brief moment and return "within Boeing’s specified recovery timeframe." Sounds like much ado about very little to me.

Obviously, airlines should exercise an abundance of caution when transporting hundreds of people tens of thousands of feet in the air. There’s a good case to be made for making passengers turn off devices that can send and receive wireless signals, too. At the same time, however, I don’t really buy that my tiny Sansa Clip MP3 player has any shot at messing with a modern plane’s avionics systems. The last time I flew, the stewardess told me I wasn’t even allowed to hang my headphones around my neck during takeoff and landing because they could cause injury in the event of a crash. In the event of a crash, headphones are going to be the least of my problems. Thanks to Slashdot for the tip.

Comments closed
    • lilbuddhaman
    • 9 years ago

    i dunno if this was posted yet, but:

    Its not the signal that the electronic devices give out when they are operating properly (they are on different bands than anything remotely concerning flight equipment), its when they aren’t operating properly.

    When / If one of those devices goes bad, it has the potential to be a very small transmitter of a disruptive signal. The device itself could seem to be operating perfectly fine, but the transmitter could have something wrong with it, and while sending out your signal, it could also be spitting out multiple random frequencies of “trash” that you would be none the wiser about it.

    Given at minimum 1 device per person, on 200+ passenger planes, the chances increase that someone has a defective device that could be outputting be signal….or that while using that device IN FLIGHT, that the device could START outputting bad signals.

    So basically, the reason you turn off all that stuff is for a precautionary measure.

      • Corrado
      • 9 years ago

      But they only require you turn them off during take off and landing. Once you’re in the air, you’re free to turn on whatever you want.

        • lilbuddhaman
        • 9 years ago

        /shrug Don’t ask me, i’m just the mechanic. (literally, Electronics/Avionics mechanic turned medical instrument mechanic)

        • UberGerbil
        • 9 years ago

        Because at cruise on the victor airways or FL-whatever there’s a lot more margin for error. On approach and departure you’re in much more congested airspace and, on approach in particular, you’re using precision instruments (ILS, etc) that you don’t use the rest of the time and that may be particularly sensitive to interference. If you ask the pilots and the aviation safety folks, they’d rather have the passengers not using anything electronic at any stage of the flight, but they know that’s not realistic. So there’s a tension, and the compromise is to ask everyone to shut it down during the most sensitive parts of the flight. There’s another reason, of course: they want everything stowed during takeoff and landing anyway (laptops and even cell phones make fantastic projectiles during a runway excursion, and get in the way during an emergency evacuation), and ideally they’d like the pax to not be distracted in case they have to make any emergency announcements.

    • jpostel
    • 9 years ago

    Other than what I learned in college (engineering classes) I don’t know a whole lot about wireless.

    That said, I have an older pair of Jabra noise canceling headphones I use on flights. They work well, but every once in a while, I pick up rhythmic clicks and pops like when someone puts a BlackBerry too close to a speaker phone. They are wired and not BT, so I am not sure where it is picking it up, unless the noise canceling parts are picking up interference from other devices. The FCC might have tests for all this stuff and the FAA might have them too, but that does not change the fact that all our electronics do not operate the way we want all the time. Ever have to RMA something? Get a DOA motherboard or something? Turning off devices during takeoff and landing is just a precaution and not a violation of our human rights.

    I travel quite a bit, and I am really surprised when people argue over this. While I would like to have the option to use my phone while in flight, I can barely stand it when other people slow down the pre-flight process because they refuse to get off the freaking phone. I was once on a commuter flight of maybe 20 people where multiple people were heckling and shouting at a guy who would not get off his phone. I thought he was going to get kicked off the plane.

    • PRIME1
    • 9 years ago

    Whatever, they said the same thing about rabid badgers in the cockpit. I suppose we will have to stop using those now as well.

    • DF bobo
    • 9 years ago

    A plane’s flight control computer (the one that operates fly by wire, etc.) is hardened against EMI. A cell phone will not bring an airliner to the ground by itself or anything like that.

    The problem is that they do affect navigation and comms equipment. If those were hardened from electromagnetic waves, they wouldnt be able to pick up the signals they are designed to.

    Thats the gist of it but if you want to really read into it, check this out [url<]http://www.airliners.net/aviation-forums/tech_ops/read.main/291947/[/url<] that thread discusses (in great detail) things like airplane mode, etc. Best part of that is this post here, quoted from that thread. [quote<]...On my last 4 day trip we actually made a PA going into Houston when a pax had their phone on while we were shooting an ILS... We could tell it was going to be a problem when 40 miles out for IAH we heard the phone start "searching" for towers doing the dit da dit da's like others had said... so, PA one was made to turn them off... they didn't... we continued to listen to it for the next few miles, asked our FA over the inter-phone to find the person and get it off.. besides the dit da's... we also started watching our LOC start deflecting from side to side by half dots... NORMALLY we wouldn't really care because we're visual anyway and people are generally "stupid" and won't comply thinking we're being fake... in this case.. it was actually very important to get it off... so no one owned up to it... by 15 miles out... same issues and about to get into the clouds (low overcast layer with bkn around 300').. so we made one last PA and told the flat out truth... we were having radio interference, our navigation aids were oscillating and unless everyone made sure the phones were off/if we continued to have the interference we were not going to shoot the approach for their safety and would divert to somewhere it was clear...... go figure.. a few seconds after the PA.. it all stopped... our LOC centered up... and the audio went back to normal....[/quote<] bottom line, turn your cell phones off, they do cause interference.

      • sschaem
      • 9 years ago

      The post you quoted is fake…

        • jpostel
        • 9 years ago

        care to share how it is fake?

    • ludi
    • 9 years ago

    What amazes me is the number of people who are totally blasé about the requirements to shut off electronic devices during take-off and landing, and to shut off radio transmitters unless the flight expressly provides services. Have those people never in their life experienced a technical problem due to signal interference? Why risk it when traveling 600mph through air in a metal tube?

    The problem is not that any one device might be putting out enough energy to corrupt the avionics or communications equipment; the problem is all of them together. One ordinary modern commuter, particularly a techie or business-class patron, could easily be carrying the following into the cockpit:

    Laptop, with WiFi, Bluetooth, 3G data card, wireless mouse
    Smartphone with Bluetooth earpiece
    Kindle, Nook, or other tablet device

    In a typical case, that simple combination contains three cellular transceivers, three WiFi transceivers, and four Bluetooth transceivers, all capable of being active concurrently if the passenger is using some and forgets to disable the others…and in the case of an aircraft traveling 600mph across the countryside, the cellular transceivers will be operating in their higher-power search mode most of the time.

    Now multiply that times a majority portion of 120-odd passengers sitting in close quarters and then tell the fifteen-year-old aircraft electronics, born and tested before a practical smartphone even existed, to deal with it gracefully. And 99% of the time, they probably will anyway. It’s that other 1%, where everybody dies a fiery death because some selfish jackwagon couldn’t disconnect from the network for an hour and a screen blinks at a very bad time, that rightfully worries people.

      • Peldor
      • 9 years ago

      [quote<] One ordinary modern commuter, particularly a techie or business-class patron, could easily be carrying the following into the cockpit:[/quote<] Stay out of the cockpit, commuters! I don't care how good you are at that iPhone game landing the planes. I'm pretty blase about it (also accents) because I know every commercial flight for the past several years has had one or more 'jackwagons' such as you describe. It's not a 1% chance of fiery death. You're short a decimal point and a fistful of zeros.

        • ludi
        • 9 years ago

        Sorry, meant “cabin”. That gaff aside, you’re missing the broader point. In the vast majority of cases nothing happens. However that one combination of cases where a disturbance occurs cannot necessarily be predicted. Each fresh combination of passengers and devices is basically applying a Monte Carlo test to the aircraft based on their exact position in the cabin and operating conditions. NEARLY ALL of these combinations do not cause problems. However, there’s still a combination that might — and then you get a CrossAir Flight 498, where an autopilot disruption cause by coincident phone activity may have been contributory to an already bad situation.

        Besides, you know what happens when people disregard the instructions and something really bad finally does happen and a radio intereference cause is traced? TSA starts banning all personal electronics in the aircraft cabin, meaning that what you do take has to be in checked baggage (hope your batteries don’t freeze), and the phone that you accidentally carried into security goes into the disposal bin next to all the little toenail scissors and 1″ pocket knives.

        I’d like to avoid that outcome, myself.

      • sschaem
      • 9 years ago

      Do you also believe that ringing a few cell phone around a corn kernel cause it to pop ?

      Look, why do you think you can use your DECT6 and cell phone at the same time 1 inch from each other ?

      The amount of wifi or Bluetooth is not the problem.
      The problem is ‘defective’ avionics equipment that airline are to cheap to replace.
      So we endup with stories like LCD that blank out with wifi interference.. thats totally insane.

      Airline need to fix defective equipment. Telling kids to turn off their Nintendo DS is beyond silly in 2011.

      People thinking that this situation is A.OK puzzle me…

        • ludi
        • 9 years ago

        Some aircraft are kept in service for decades with proper maintenance. Avionics are upgraded periodically, but it requires a lot of time, money, and fresh testing to do so. Hence, upgrades are not performed more frequently than necessary.

        Why is it necessary OR EVEN REASONABLE for you, one passenger who will be in the air for 1-3 hours in a typical commuter flight, to expect to have all the electronic conveniences you would have on the ground?

      • Spurenleser
      • 9 years ago

      You make some very good points! The very few times I have flown there were always numerous people who waited until the very last moment with switching their devices off and sometimes the flight attendants even had to tell them several times. Why oh yes, of course you are so god damn important that you absolutely positively had to stay on the phone for these last 2 minutes …

    • sschaem
    • 9 years ago

    To be clear… DU = LCD Display Unit…. You know, the type found on ipods.

    Funny how all the system with a DU with integrated wifi (cant have a DU closer to a wifi beacon) never blank out
    even so they are subjected to the most powerfull wifi power source.

    How crappy can honeywell LCD display be to be so flaky…?!

    • blastdoor
    • 9 years ago

    I’ve noticed recently that the flight attendants are saying that devices must be completely turned off, not just put in “airplane mode”. At least on an iPhone, airplane mode seems like it ought to be perfectly safe — no wifi, no cellular.

    So why this new requirement to completely turn devices off? Are there Android phones out there that claim to be in airplane mode but then start sending out dangerous radioactive emissions?

      • ludi
      • 9 years ago

      A simple computer processor emits radiation at its operating frequencies and harmonics thereof; it can’t not. Those emissions are relatively small for one device, and limited to an absolute cap by FCC/CSA/etc. regulatory hurdles and the design features that go into building a certifiable device housing. But then figure that one simple electronic device might contain two or three discrete clocks, and one passenger might be carrying a half dozen electronic devices, and the aircraft might be carrying 50 or 150 pasengers, and it’s hard to predict what kind of interference patterns might emerge.

      Also, “off” is pretty easy to confirm, and thus failsafe against user error. Just because you know how to correctly put your iPhone into airplane mode, doesn’t mean the 16yo text-a-holic two rows over, does.

        • blastdoor
        • 9 years ago

        I wonder how the radiation from 50 cellphones compares to the radiation from the sun, cosmic rays, etc at 30,000 feet…

        Maybe we should only allow airplanes to travel through underground, lead-lined tunnels. We could take the wings off and put the fuselage on rails.

          • UberGerbil
          • 9 years ago

          Airplanes are tested at 30,000 feet. They can’t be tested with every permutation and combination of RF-emitting device in the cabin.

          And comparing to external sources is silly anyway: the fuselage acts as both an effective Faraday cage and radiation barrier that protects the avionics from whatever is going on outside. What it can’t do is protect the avionics from what’s going on within it.

            • blastdoor
            • 9 years ago

            Then why are pilots at elevated cancer risk?

            • ludi
            • 9 years ago

            Research is ongoing, but theories include:

            1. Higher exposure to cosmic radiation due to frequent time spent in upper atmosphere
            2. Disruption of melatonin cycle leading to poorer sleep habits
            3. Lifecycle choices unique to either pilot personalities, activities enabled by pilot schedules, or both

            Not all electromagnetic radiation is created equal, by the way, nor does it respond the same way when encountering different materials. Metals like aluminum, copper, and steel happen to be pretty good at capturing the sort of radio frequencies and power levels used by common communications equipment. That doesn’t mean a thin shell of aluminum skin and superstructure will stop, say, x-rays.

          • Wirko
          • 9 years ago

          You have just described a bus on rails.

            • demani
            • 9 years ago

            I’ve got an idea…what if we were to have one rail bus tow another rail bus? Or maybe a few rail buses all towed at once?

            Rail bus FTW!

          • blastdoor
          • 9 years ago

          How odd… my snarky cheap shot at Android gets no thumbs down, but my fuselage on rails comment gets two thumbs down? What goofy niche of friendless virgins did I offend with this comment?

            • rxc6
            • 9 years ago

            I don’t know if you offended any virgins… I just know that it was a very DUMB comment. And on top of that you are paying attention to the rating system :roll eyes:

      • PixelArmy
      • 9 years ago

      What an odd way to snipe at Android…

        • Corrado
        • 9 years ago

        To be fair, they still haven’t seemed to be able to reliably send SMS messages to the proper people 100% of the time.

          • rxc6
          • 9 years ago

          And Apple has problem with time and alarms… see what I did there?

      • ShadowTiger
      • 9 years ago

      Usually these decisions are not made by engineers but rather by executives or insurance agencies. Maybe the plane can’t get insurance if they don’t force people to turn off their devices… who knows.

      BTW i’m assuming that there is such an insurance

      • NeelyCam
      • 9 years ago

      Last time I flew, they said “turn off or switch to airplane mode or similar” (Alaska Airlines)

      • xii
      • 9 years ago

      It’s probably because most people are idiots and it’s easier to see the device is really off than if they somehow managed to find and set the flight mode correctly. You can’t really expect flight attendants to learn to operate and check each and every existing device. Off is off, it’s usually pretty obvious the device isn’t transmitting anything then.

      • BenBasson
      • 9 years ago

      Who knows what any given device does or does not do in “aeroplane mode”. It’s not like there’s a mandatory set of standards for mobile devices to adhere to. Better to be safe and turn devices off, it’s only during take-off and landing, I’m sure everyone can occupy their brains in other ways during that time.

    • rhettigan
    • 9 years ago

    If consumer electronic devices of any sort posed any real threat to airline safety, they’d not be allowed even into the terminal.

    • cobalt
    • 9 years ago

    I read a quote that said they were testing at elevated signal levels, and that the blanking was momentary, so probably nothing to be too concerned about.

    Man, you must have had the same flight attendant I had on a recent flight. She was making people take their iPod shuffles out of the set-back pocket because they “weren’t reading material”. She let me keep my 5-pound book in there, though, despite it being heavier than many laptops…..

    • Flying Fox
    • 9 years ago

    “Bring back the word ‘stewardesses'”!
    [url<]http://www.ebaumsworld.com/jokes/read/397599/[/url<]

    • Vasilyfav
    • 9 years ago

    I’m sure people can take a break from the internet for 3-4 hours on domestic flights. After all, people somehow survived until the wireless age, right?

      • Majiir Paktu
      • 9 years ago

      Humanity survived before toilets, too.

        • Vasilyfav
        • 9 years ago

        And if the requirement for transoceanic flight would be to piss in a bottle, people would gladly do it rather than take a ship.

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