back to article FAA now says 5G airports may interfere with Boeing 737s

The US Federal Aviation Administration warned on Wednesday that 5G C-band transmissions may interfere with landing operations at a limited set of airports for most Boeing 737 aircraft. It issued an advisory calling for affected planes to observe modified operating procedures where 5G interference might occur. The FAA in …

  1. Yet Another Anonymous coward Silver badge

    In conclusion

    It appears that air may interfere with Boeing 737s

    1. pavel.petrman Silver badge

      Re: In conclusion

      Last few years have indeed shown us that to ensure the award winning* safety and reliability of 737s, they should not be put in contact with air in any manner.

      * "Award winning" appears to be a compulsory grammatical particle in any sentence related to the award winning United States of Erica.

      1. vtcodger Silver badge

        Re: In conclusion

        * "Award winning" appears to be a compulsory grammatical particle in any sentence related to the award winning United States of Erica.

        Indeed. "Award Winning" is an example of the a ninth grammatical category on top of the traditional eight -- noun, pronoun, verb, adjective, adverb, preposition, conjunction, and interjection. The ninth category is called the hype and apparently entered the language in North America in the mid Twentieth Century. It is used in place of, or along with, adjectives or pronouns and has no known utility other than being occasionally useful to pad the length of a line of poetry or song.

        1. Alan Brown Silver badge

          Re: In conclusion

          "The ninth category is called the hype"

          It's part of the PR category - which is a literal 1950s rebranding of "propaganda" because the latter name had become toxic after WW2

      2. cd

        Re: In conclusion

        I translate "Award Winning" as "Participation Trophy".

        1. MachDiamond Silver badge

          Re: In conclusion

          Don't forget to include "Industry Leading".

    2. Chris G Silver badge

      Re: In conclusion

      "It appears that air may interfere with Boeing 737s"

      And while tin foil may limit 5G signals from penetrating your brain, they may be less effective protecting you from a 737 attempting a landing.

      It seems there is not much communication between federal agencies when it comes to managing mutual resources.

      1. R Soul

        Re: In conclusion

        FWIW a 737 has never landed on my head whenever I've had my tinfoil hat on.

    3. Korev Silver badge
      Joke

      Re: In conclusion

      > It appears that air may interfere with Boeing 737s

      Yeah, when there is air the seem to end up flying up into the air; whilst in a vacuum they remain safely on the ground...

  2. ComputerSays_noAbsolutelyNo Silver badge

    Boing it on the cheap.

    While it may be good for the profit-books to use and re-use a decades old platform,

    the technical debt keeps on accumulating, and at some point it bites you in the proverbial.

    1. pavel.petrman Silver badge
      Coat

      Re: Boing it on the cheap.

      Thank you, I am now expecting FAA to announce that a new type of fitness tracker interferes with Loran and is therefore forbidden...

      1. Korev Silver badge
        Coat

        Re: Boing it on the cheap.

        You mean not fitbit for the purpose?

      2. Pirate Dave Silver badge

        Re: Boing it on the cheap.

        "a new type of fitness tracker interferes with Loran"

        I admit, I initially read that as "a new type of fitness tracker interferes with Lohan"

        Ad Astra Tabernamque

    2. jtaylor Bronze badge

      Re: Boing it on the cheap.

      "a decades old platform, the technical debt keeps on accumulating, and at some point it bites you"

      What do you propose in place of radar altimeters? Airlines do have GPS (newer tech) and barometers (older tech) but those provide only the location of the aircraft, not of obstacles beneath.

      1. Martin an gof Silver badge

        Re: Boing it on the cheap.

        A similar question came to my mind.

        These kinds of aircraft systems are not unique to one specific model of aircraft as far as I am aware. Since every single commercial 'plane carries a radio altimeter these days and most of those will use its data as input for auto pilot systems, why is the 737 being singled out? Surely similar problems will hit other Boeing aircraft and, indeed, Airbus etc. too?

        Oh, and if it's particulalry a problem at airports, surely the use of that band can be restricted near airports? 5G operates on many different bands and a bit of careful frequency planning could go a long way to solving this problem.

        Oh, I forgot. Corporations know best and can't be regulated too heavily.

        M.

        1. MachDiamond Silver badge

          Re: Boing it on the cheap.

          "why is the 737 being singled out?"

          Perhaps it uses a particular make and model. Likely there are other aircraft that use the same hardware, but might not be recognizable names like the Boeing jet.

      2. MachDiamond Silver badge

        Re: Boing it on the cheap.

        "What do you propose in place of radar altimeters?"

        Another radar altimeter.

        The issue with aircraft electronics is they take forever to be certified and the cost is very high. A company can spend tens of thousands to get a certification on something that costs £50 to make. This means that the part has to sell for thousands each to make back the initial investment. The same applies to upgrades of existing devices. The airlines are not going to be happy to need to replace all of their radar altimeters in every 737 they own. The cost could be £100k or more each since it takes union mechanic that holds an Airframe and Powerplant (A&P) license to perform the work. Provided, of course, that it doesn't take any modifications to the aircraft to fit the new kit.

      3. Col_Panek

        Re: Boing it on the cheap.

        How about a decent bandpass filter tacked onto the antenna?

  3. AbnormalChunks

    Photo...

    ...is of a Boeing 787 not a 737. Get a stock image of a South West Airlines aircraft much more appropriate.

    1. Anonymous Coward
      Anonymous Coward

      Re: Photo...

      It’s fine, story was written by @RAF_Luton

    2. Alan Brown Silver badge

      Re: Photo...

      787s are also vulnerable

      Yes really

      No airbus aircraft is vulnerable at _any_ US domestic airport

  4. Richard 12 Silver badge
    FAIL

    So now you do the testing?

    Or did you just not bother at all, and waited for the near-misses to stack up?

    The FAA really are incompetent.

    1. jtaylor Bronze badge

      Re: So now you do the testing?

      The FAA warned about this 6 months ago. https://www.reuters.com/business/aerospace-defense/faa-has-deep-concern-about-5g-network-plan-aviation-safety-letter-2021-10-29/

      They didn't sell the spectrum, the FCC did. Please keep in mind that not every country has privatized its airwaves.

      1. Anonymous Coward
        Anonymous Coward

        Re: So now you do the testing?

        "They didn't sell the spectrum, the FCC did."

        But the FCC could have put a proviso on that particular block of frequencies that they are restricted near airports.

        1. MachDiamond Silver badge

          Re: So now you do the testing?

          "But the FCC could have put a proviso on that particular block of frequencies that they are restricted near airports."

          Why would they do that? Most government agents are pandering to industry so they will have a cushy job waiting for them when they stop feeding at the public trough. If you analyze decisions made with this in mind, you start to see the rationale behind the policies.

          I would also think that 5G in and around airports is going to be very important to customers.

    2. John Brown (no body) Silver badge

      Re: So now you do the testing?

      Testing? They gave the all clear based on theory and have now back-tracked based on practical experience. Testing is expensive, so rarely carried out these days, as we in the IT industry, especially on the software side, are well aware of.

      1. Yes Me Silver badge
        WTF?

        Re: So now you do the testing?

        Please point to a reference for that "practical experience".

        I am still in disbelief that the people who designed radio altimeters in the 1960s would have made them susceptible to sidebands from a 3.98 GHz channel but not from a 3.80 GHz channel, which appears to be the FAA assertion. So where is the evidence?

  5. tip pc Silver badge

    Just when they are trying to convince us it’s safe

    Yet another bad optics story for the 737.

    I really don’t want to fly on a 737 again and actively choose airlines that don’t fly that aircraft. Sadly that puts sleazy jet on that list, but they are still on my no fly list.

    We flew TUI to Menorca in 2018, they subbed the flight out to Norwegian and it was a 737, not sure if it was a new NG or Max. If was well appointed with large screens, free WiFi, it was a comfy cabin and comfy flight. Good enough it was memorable for being good. I hope it was an NG, I won’t now knowingly get in a Max though.

    1. Anonymous Coward
      Anonymous Coward

      Re: Just when they are trying to convince us it’s safe

      I definitely avoid flying with companies using the 737. Not that I'm really expecting to crash, it's just about not being worried during the whole flight. I'm nervous in planes, even normal ones.

    2. First Light Silver badge

      Re: Just when they are trying to convince us it’s safe

      I always check when booking, but to be sure also check the safety card when on board. I flew with Norwegian and the safety card said 737 Max/NG meaning the card could be used for both types. I was assured by the attendant that we were flying on an NG.

    3. Scene it all

      Re: Just when they are trying to convince us it’s safe

      I do not understand this report. The Boeing 737 is hardly unique in using radar altimiters for precision landings in bad visibility. Just about every modern airliner, from any manufacturer, relies on the same technology.

      1. iron Silver badge

        Re: Just when they are trying to convince us it’s safe

        Yes but Boeing didn't bother to include RFI in their design process so it's shit.

      2. jdiebdhidbsusbvwbsidnsoskebid Bronze badge

        Re: Just when they are trying to convince us it’s safe

        "Just about every modern airliner, from any manufacturer, relies on the same technology"

        Not exactly the same technology. They might transmit in the same band but that's because they have to use the band licensed for radar altimeters. Not all radalts are the same. Different devices use different waveforms, processing, power levels etc. And the plane manufacturers don't necessarily design the radalts themselves. They might specify them in terms of form,fit and function, but they'll come from a supplier, and not all aircraft manufactures will use the same supplier. Different radalts will have different levels of susceptibility to interference, whether by accident or by design.

        1. rnturn

          Re: Just when they are trying to convince us it’s safe

          "Not all radalts are the same."

          Indeed. I was involved in some work back in the '80s that discovered that FM radio station transmitters -- and the stew of intermodulation frequencies that resulted from multiple FM transmitters in a locale -- could interfere with ILS receiver front ends. Not all receivers were susceptible to the same degree but some of the more commonly used (especially in general aviation) were affected the most. I recall wanting to be a fly on the wall at the meeting where the report was to be presented to the FCC (who would represent radio station operators who could be denied either an antenna location or proposed transmitter power if either interfered with the landing system) and the FAA (whose interested was in maintaining the protected airspace around an airport)---the fireworks would have been fun to watch.

  6. spireite Silver badge
    Flame

    I liken the last few 737 versions to be like a rewarmed chicken noodle/rice dsh.

    Both get worse with age,, but with a subtle difference....

    One may cause you to lose limbs, and the Boeing your life.

    1. Anonymous Coward
      Anonymous Coward

      The 737-900ER "Frankie Howerd" model is never subtle, missus...

  7. spireite Silver badge

    The Downfall: Boeing doc on Netflix.

    Staying on the 737 Max topic, the documentary is worth a watch, and is frankly concerning. Being an ex-aviation industry worker, I didn't think there was much I didn't know about the debacle.

    I still learned something.

    1. Anonymous Coward
      Anonymous Coward

      Re: The Downfall: Boeing doc on Netflix.

      I didn't think much of the new Netflix Documentary, as someone that has been following this from the beginning since the first crash (and following Boeing long before that), there wasn't anything new. The hidden footage of workers, was all previous footage.

      All it seemed to show was the complete lack of ethics/morals at the top of the company, again that was known, from previous investigations. Just seemed to be a rehash, I've seen better YouTube content.

      The documentary also missed a very important point: One thing that wasn't clear, was that if the pilot (as they did in flight ET302) turned off the MCAS system, what were the effects of not trimming to neutral before hitting Cut-Off.

      Describing MCAS as achieved by adding a few lines of code, seemed a pretty dumbed down, crude description for the programmers that had worked on it.

      1. tip pc Silver badge

        Re: The Downfall: Boeing doc on Netflix.

        The documentary also missed a very important point: One thing that wasn't clear, was that if the pilot (as they did in flight ET302) turned off the MCAS system, what were the effects of not trimming to neutral before hitting Cut-Off.

        They couldn’t trim to neutral because MCAS would keep cutting in. My understanding is that MCAS stopped the trim action when it was activated. So you keep pressing trim and it dies what you want until MCAS cuts in and does the opposite for 10s before stopping for 5 & repeating.

        Do your stabbing trim, see the wheel move the right way, keep stabbing trim and then the wheel moves the wrong way for 10s. Dealing with an unknown crisis just after you’ve put the flaps away something like that would be super confusing especially when you either don’t know about MCAS of have just heard about it and this is the first time experiencing what it does.

        As the documentary explained, turning off the electric trim after MCAS has activated, just like the Ethiopian pilots did, is not good enough as if it’s deployed too far and speed high the aero forces are too much to manually adjust the trim.

        These are things older 737 pilots knew because I’d an issue wihh to older jets that was rightfully designed out but new pilots had no idea as even Boeing didn’t know it was a thing at that point.

        Don’t try and blame the pilots for Boeings deliberate attempts to hide MCAS and not take responsibility for its actions.

    2. Alan Brown Silver badge

      Re: The Downfall: Boeing doc on Netflix.

      It's not just the Max

      The NG had major issues too:

      https://www.huffpost.com/entry/boeing-whistleblowers-unc_n_797515

      The fact that the FAA was utterly owned by Boeing by 2005 is underscored by the fact the whistleblowers were shopped back to the company by FCC officials (a federal crime in itself) within days and no punishment or investigation ever ensued

  8. steamnut

    Why the 737?

    Doesn't is strike you as odd that Airbus planes are seemingly ok? They too use radio altimeters. Surely the FCC and others who dish out band allocations thought about the possibilities of interference or are Boeing a bit marginal on the EMC specs? Is this something else that Boeing slipped under the radar with the FCC?

    Going to watch the Netflix program tonight. I'm sure it will not be very complementary.

    1. emfiliane

      Re: Why the 737?

      Did you even read the article? It's right there at the end.

      1. Anonymous Coward
        Anonymous Coward

        Re: Why the 737?

        I carefully did a search of the article and the word "Airbus" is not found.

      2. Stoneshop Silver badge
        FAIL

        Re: Why the 737?

        Airbus, while being an European company, and Europe having different radio bands and power levels assigned to radio altimeters and 5G than the US does, has their planes not flying exclusively in Europe.

    2. Anonymous Coward
      Anonymous Coward

      Re: Why the 737?

      In the EU we have a guard band between 5G & altimeter frequencies & lower transmit power, it appears in the USA the FCC, which I believe allocates spectrum, works like the patents service and lets the courts sort out blame when the bodies pile up.

    3. jdiebdhidbsusbvwbsidnsoskebid Bronze badge

      Re: Why the 737?

      "Doesn't is strike you as odd that Airbus planes are seemingly ok? They too use radio altimeters."

      Don't know about Boeing, but I do know that airbus tend to use a particular design of radar altimeter, that might be standard across the whole fleet. I also know that that particular design is more robust against interference than other designs. Other design considerations could trade off that robustness for other things, so I'm speculating as to why airbus is not affected - yet.

  9. TeeCee Gold badge

    There may be more.

    I have seen it reported elsewhere that this is not a 5G problem or a 737 problem, but a US of A one. Hence the lack of panic elsewhere, despite other places having airports and having 737s land at them.

    In a nutshell, the USA has a 5G band bang against the aviation one and some bleed over is inevitable. Funny that when a small company tried to do this (Lightsquared) they got shut down, but when the big telcos wanted to do the same it went through. I wonder how much that cost in bribeslobbying and feasibility studies?

    While they have a similar allocation issue in Japan, there they have mandated beamforming antennae on cell towers close to airports which aim the signal along and down rather than up. For some reason (cost to the telcos bringing out the bribelobby cash must be favourite), the US hasn't done this.

    1. Alan Brown Silver badge

      Re: There may be more.

      If that was the case, then Airbus aircraft in the USA would suffer similar problems at the same airports that Boeing aircraft do

      They don't

  10. Chairman of the Bored

    Poor choice of words in the release

    "Impacted systems" in the context seems painfully ironic.

  11. Anonymous Coward
    Anonymous Coward

    Just when you thought it was finally safe(?!?) to get on a 737...

    1. Stoneshop Silver badge
      Headmaster

      A definition of 'safe' which I wasn't aware of until now.

      Planes have a particular mode of locomotion that makes them susceptible to encountering zero altitude at unhealthy speeds. Given their record over the past decade or so I'd rate them as 'fairly safe', at best.

      1. John Brown (no body) Silver badge

        Re: A definition of 'safe' which I wasn't aware of until now.

        "encountering zero altitude at unhealthy speeds."

        That's not necessarily an issue. You also need to take into account the rate of decent.

        1. Stoneshop Silver badge
          Headmaster

          Re: A definition of 'safe' which I wasn't aware of until now.

          Even with a decent rate of descent you can get into trouble if the point at which you forcibly get stopped from descending any further isn't really suited for such a situation.

  12. Electronics'R'Us Silver badge
    Holmes

    Out of band power

    5G uses QAM as the modulation method (16, 64 and 256 equating to 4, 6 and 8 bits per symbol).

    The power spectral density (PSD) mathematically extends to infinity.

    The key question is just how much power extends beyond the allocated band and in what direction.

    Radar and radio altimeters have very sensitive receivers [1] so if there is sufficient out of band power from a 5G transmitter it can interfere with the receiver most likely both directly and by intermodulation products.

    The fact that Japan (which uses the same bands) has mandated beamforming [2] and requiring the signal to point downwards mitigates the problem significantly.

    There are 2 fundamental types of radio altimeter; pulsed (which is more properly referred to as a radar altimeter) and frequency modulated continuous wave (FMCW). The first uses time of flight to calculate the altitude and the second compares the received frequency to the currently transmitted frequency. (That's the simple description - entire books have been written on the subject).

    Both types can be susceptible but FMCW (very common for approach and landing radio altimeters) is particularly susceptible to intermodulation issues which is highly likely to be the problem here.

    1. Below -100dBm (that's 0.1 picowatt or 100 femtowatt)

    2. This has its own issues but outside of the main lobe the signal can be suppressed significantly.

    1. DaemonProcess

      Re: Out of band power

      Thanks for that info, I'm generally ignorant of this tech - it is a bit like doppler but with EMR instead of sound?

      Another ignorant teenager's question along the lines of tin foil hats, couldn't they just fit upside-down metal umbrellas on top of the 5G transmitter towers near to airports..

      The Japanese method seems more power efficient to me anyway.

      Verizon / Comcast / whoever's board is penny pinching a couple of million in spend when their accounts report in billions.

      1. jdiebdhidbsusbvwbsidnsoskebid Bronze badge

        Re: Out of band power

        "Thanks for that info, I'm generally ignorant of this tech - it is a bit like doppler but with EMR instead of sound?"

        Kind of like Doppler, in the sense that the FMCW radalt measures a frequency shift, and translates that into a time.

        The FMCW radalt transmits a chirp waveform (the frequency increases linearly over the duration of the pulse). While that is propagating to the ground and back, there is the same replica waveform running inside the device. Because of the time taken for the transmitted waveform to return back from the ground, it arrives with a frequency shift compared to the replica waveform which has been increasing in frequency during the transmission. The replica and received waveforms are mixed together to produce a signal with a frequency equal to the difference in frequencies of the replica and transmitted waveforms. Because you know the chirp rate, you can easily convert that frequency difference to a time, and thence a distance.

        By using a chirp waveform, you can have a longer pulse, which means more energy (not power) in the pulse, which makes it more robust against interference (or, you can trade off transmitted power instead). A fixed frequency pulse has to be a lot shorter to avoid interfering with itself when the ground return comes back (you must stop transmitting before the ground return comes back). The chirp waveform can still be transmitting while the ground return comes back, the changing frequency giving you the discrimination to still see the return signal.

  13. Anonymous Coward
    Anonymous Coward

    Can't Boeing just follow their SOP and try it out on a few hundred non-white people?

    1. Anonymous Coward
      Anonymous Coward

      Some people think it was intentionally done... black ops.

  14. Anonymous Coward
    Anonymous Coward

    Drone angle

    Are they sure there isn't any way to blame this on drones ?

  15. Marty McFly Silver badge
    Facepalm

    The blame

    Everyone likes to jump all over Boeing at the slightest excuse. It seems to me the FCC & FAA are not doing their jobs. These frequencies should not have been allocated to 5G if they cause interference with aircraft, regardless of the manufacturer & model.

    Oh, and let's not forget... This is the same industry that has told us to shut off all electronic devices to keep them from interfering with aircraft systems. I have yet to hear about a plane crashing because someone in seat 23C forgot to switch off their cell phone.

    1. Stoneshop Silver badge
      Holmes

      Re: The blame

      Everyone likes to jump all over Boeing at the slightest excuse. It seems to me the FCC & FAA are not doing their jobs.

      Porque no los dos tres?

  16. Anonymous Coward
    Anonymous Coward

    Everyone likes to jump all over Boeing at the slightest excuse.

    It depends if you consider the risk in context of the other very much not slight problems that Boeing has had of late "slight".

    I wouldn't.

  17. HammerOn1024

    Learn to Love...

    The band pass filter. There are several aviation rated and have been for decades, a couple have FAA cert's already. The US army has done quite a job of testing their systems witch some the same as those in the Boeing's.

    1. John Brown (no body) Silver badge

      Re: Learn to Love...

      AIUI, the problem isn't radio altimeters being aviation rated and bandpass filters being aviation rated. Even though both devices are rated, putting them together means you have a "new" device, that needs to be rated as a unit.

  18. sanmigueelbeer Silver badge

    In other Boeing-related news: Each Boeing 787 Dreamliner Produced Will Have to Be Individually Certified By FAA

    Not really a Boeing-related fault but still looks bad for the company.

  19. W4YBO

    "Concerns about the effect 5G signals may have on aviation systems have been discussed for years..."

    FAA and FCC have both been aware of the problem since the late 1990s. If you listen to top-of-the-hour radio newscasts and have noticed occasional gaps in the audio, sometimes accompanied by a squeak, then you have too. It's often caused by a C band radar altimeter flying directly over the C band satellite antenna. Operating a licensed (supposedly interference protected) ground station digital audio receiver, the broadcaster I worked for filed several interference complaints. I'm retired now, but I still notice the holes and squeaks in the news audio. It'll probably take great loss of life before they actually do something about it.

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