[HN Gopher] FAA says 5G could impact radio altimeters on most Bo...
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FAA says 5G could impact radio altimeters on most Boeing 737s
Author : pseudolus
Score : 183 points
Date : 2022-02-23 18:12 UTC (4 hours ago)
(HTM) web link (www.reuters.com)
(TXT) w3m dump (www.reuters.com)
| fshbbdssbbgdd wrote:
| I don't know much about aviation or electrical engineering, and
| I'm wondering if anyone could help me understand something.
|
| It seems like the telecom and aviation industries (along with the
| FCC and FAA) disagree on a question of fact: does 5G equipment
| interfere with radio altimeters?
|
| There's a way that the FAA could convince me, and probably all
| the politicians. Shoot a video with a radio altimeter and some 5G
| equipment where the radio altimeter malfunctions. Put it on
| YouTube. Do a press release.
|
| This seems like an obvious step if the underlying issue exists.
| Any reason they haven't done this?
| gdavisson wrote:
| You're using the wrong burden of proof here. You're assuming
| it's safe until proven dangerous, while the FAA is (properly)
| treating it as dangerous until proven safe.
|
| Take the recent 737 MAX debacle as an example. Its MCAS hadn't
| been proven to be dangerous when it went into production, but
| it turned out that it was. Result: two airplanes fell out of
| the sky and 346 people died. It's the FAA's job to prevent this
| sort of thing from happening, and in this case (unlike the 737
| case) they're doing that job.
| ethbr0 wrote:
| My guess is that RF interference is not binary. So the question
| is not "Does 5G equipment interfere with radio altimeters?" but
| rather "Could 5G equipment _ever_ interfere with radio
| altimeters, under any set of feasible conditions? "
|
| Which is a harder question to answer, but how seriously we
| should (and usually do) take air safety.
| moonchrome wrote:
| If you can't reproduce those conditions in an artificial
| scenario setup to exaggerate the effect - how are they
| feasible ?
| bluGill wrote:
| The question isn't can you reproduce it in an artificial
| setup, the question is can you do it in the real world? I
| can think of a lot of ways to cheat in the lab (turn the
| power to 11...) that create situations that in the real
| world wouldn't happen and so I wouldn't worry about it.
| However that doesn't change the fact that if you can
| recreate it in the real world I'm really worried.
| addaon wrote:
| The question isn't really whether the radalt fails in any
| particular test (spoiler: it probably won't). It's whether
| there's an edge case where the safety case for the aircraft
| depends on correct operation of the radalt AND there's a
| failure. I haven't seen the fault tree for the 737, of course,
| so I don't know what reliability is required from the radalt to
| be safe; but with the radalts I've worked with it's not
| unreasonable to have an undetected failure rate requirement of
| 10^-8/hour or better. (Detected failure rates can be much
| higher.) Testing enough to show that you're not violating that
| is /hard/.
|
| Speaking a bit from my own experience, I suspect the guard
| bands on most radalts out there are wide enough that 5G
| interference isn't a practical issue. I've seen radalts with 30
| MHz guard bands around the 4.1 GHz / 4.3 GHz limit frequencies
| of interest... and that's friggin' huge. (I'm also sure there
| are radalts with much smaller guard bands that use more of the
| available bandwidth for better performance.) But this is hard
| to analyze fully. Taking the example of the unit I'm thinking
| of, the center frequency is from a non-temperature-compensated
| oscillator -- so your worst case is an extreme temperature
| going to assymetric guard bands, a unit with a weak bandpass to
| begin with, and a 5G system pouring a lot of energy at (or
| even, in violation of spec, a bit beyond) the edge frequency.
| Probably fine. 10^8 fine?
| tjohns wrote:
| > The question isn't really whether the radalt fails in any
| particular test (spoiler: it probably won't)
|
| Annecdata, but... I know two commercial pilots who have both
| recently run into interference with their radar altimeters
| during landing/takeoff. It certainly doesn't affect all
| aircraft (depends on the particular avionics installed), but
| from what I've heard it is a real issue.
| kayson wrote:
| It's not so black and white. From what I've read, radio
| altimeters operate in the 4.2-4.4 GHz range, and the 5G
| spectrum in question is 3.7-3.98 GHz. RF systems generally work
| by choosing a center frequency (say 4.3 GHz for altimeters),
| and trying to filter off anything outside the band of interest
| (4.2-4.4 GHz). The junk that remains is noise as far as the
| system is concerned, and has to be budgeted for very carefully.
|
| The problem is that radio altimeters are pretty old, and their
| filtering technology is not great. So even though they are
| filtering the 3.7-3.98 GHz 5G band, it's not as effective as a
| modern RF system/filter would be. Previously, this wasn't the
| issue because nothing was broadcasting in that band at
| particularly high power.
|
| That's the second component of the problem: power. The radio
| altimeter system is capable of handling some amount of noise
| power caused by unwanted broadcasts, among other things.
| Previously, satellites were using this band, and they were so
| far away that between the distance-based attenuation of the
| signal and the limited filtering, radio altimeters could
| operate unaffected.
|
| 5G is a different story, though. The towers are much closer to
| the runway, so the leakage power is much higher. Whether this
| actually causes a problem for the altimeters is then dependent
| on a number of factors, including the distance to the 5G tower,
| the transmit power level, the direction of the 5G antennas,
| etc.
|
| Could it cause a problem? Sure. I bet if you pointed a
| directional 5G antenna straight at a particularly crappy radio
| altimeter, you could materially affect its operation. But there
| are many mitigation strategies that could be used, like
| requiring lower transmit power, further antenna distances,
| appropriate directional transmissions, etc. These strategies
| have been used successfully in other countries.
|
| The real concern should be the total lack of collaboration
| between the FAA and FCC. It's turning into a jurisdictional
| pissing contest.
| zachberger wrote:
| > The problem is that radio altimeters are pretty old
|
| Interestingly the 737-200 is excluded from this airworthiness
| directive. 737-200s are the oldest, still-operating members
| of the 737 family.
| bastardoperator wrote:
| Total noob question, why isn't Boeing building/buying new
| radio altimeters that can filter better? Is it a money
| thing, a technology thing, maybe both?
| altairprime wrote:
| While not a direct answer, see also: "Boeing engineers
| lost controls of the company" (2019)
| https://news.ycombinator.com/item?id=21304277
| cyberpunk wrote:
| Certification I guess. It probably takes 2 years (at
| least) and an insane amount of money to change any
| component on an already certified plane.
| bastardoperator wrote:
| Sounds like they better get to work.
| lamontcg wrote:
| Looks like they need to get started on it.
| thrashh wrote:
| AFAIK it's not so much a lack of collaboration. It's more
| nuanced than that.
|
| The lower frequencies used by Europe for 5G are already
| allocated for amateur and other uses here in the US. I
| believe Europe has been more willing to take away amateur
| bands.
|
| However here in the US, the FCC was trying to maintain those
| existing allocations and thus they chose to reuse 3.7-3.98
| GHz instead, which is currently allocated for fixed satellite
| and other links.
|
| Therefore what FCC did is potentially better for everyone, if
| we can find out that radio altimeters--which should be
| filtering out frequencies that never belonged to them--are
| still able to work correctly.
|
| The issue is that, as you may know, if you engineer for
| something but don't actually regularly test for it, you never
| actually engineered for that case. Up until this point, this
| case was never tested in production... because it has never
| existed in production.
|
| At the end of the day, we are between a rock and a hard
| place.
| jamesdwilson wrote:
| Add it to the list of reasons to not get on a 737
| _moof wrote:
| There is no good reason not to get on a 737.
| ummonk wrote:
| I find Airbuses have more passenger comfort. Is that not a
| good reason to you?
| kube-system wrote:
| That's mostly up to configuration, no?
| alkonaut wrote:
| Most 737s are among the safest planes ever built (because they
| aren't MAX). Whether or not the MAX will live up to the safety
| record of the previous gen going forward is yet to be seen.
| jacquesm wrote:
| Going forward? You don't get to wipe off a chunk of the graph
| that you don't like, the crashes that happened and the
| flights that happened without crashes are all part of the MAX
| safety record (oh, and that goes for the 'rebranded' version
| as well).
| kube-system wrote:
| The 737NG ranks among the top few safest models of plane. Do
| you only fly on Embraer ERJs?
| TameAntelope wrote:
| Do Embraer altimeters work properly?
| kube-system wrote:
| That's still to be determined. They're approved for low-
| visibility landings at fewer airports than any other
| passenger jet (including the 737), according to this:
| https://www.faa.gov/5g
|
| But, let's not compare apples and oranges. _Concerns_ about
| safety doesn 't kill people, it protects them. The 737NG
| has a very low accident rate, and if you're looking for a
| plane with a statically lower incident rate, the ERJ is
| your only other clear choice. This is regardless of the
| fact that the FAA only allows ERJs to land in low-
| visibility at 3/4 of US airports.
| eric__cartman wrote:
| The Boeing 737 design was introduced 50+ years ago and is still
| used (albeit not in 50 year old planes) today in a multitude of
| airlines for passenger travel.
|
| That said the 737 MAX fuckup is something that neither Boeing,
| or the many worldwide air travel regulatory institutions should
| be forgiven for. But that doesn't make the 737 design itself
| bad. That particular iteration, due to Boeing's attempt
| undertake Airbus and falsely sell the planes to airlines as a
| drop in replacement with zero extra training needed
| unfortunately resulted in deadly crashes. The people that
| decided on that should be charged on the deaths that occured
| because of their greediness.
| adolph wrote:
| > The people that decided on that should be charged on the
| deaths that occured because of their greediness
|
| For whom should the buck stop? Boeing, who designed the
| upgrade with lower carrier costs in mind? The carriers who
| bought and flew a compromised flight program in order to
| offer lower ticket costs? The passengers who choose a carrier
| based on cost instead of quality?
| eric__cartman wrote:
| Ok, I got a little carried away there. From what I
| understood from reading the reports on the various crashes,
| (I don't have a background in aviation so take this with a
| gigantic pair of tweezers) the crashes could have been
| prevented by simply informing, and briefly training the
| pilots with the newly introduced systems that corrected the
| pitch of the nose to compensate for the change in engines
| while maintaining the same body. But instead of doing that
| from the start, Boeing marketed the plane to airlines as a
| drop in replacement for their old 737 fleet where the
| pilots would need no extra training as it should behave
| "exactly the same" as the old one.
|
| Whoever decided on that should be mainly responsable for
| this. Of course the passengers don't have the fault and the
| airline would be at fault only if they continued using the
| decommissioned planes that were known to be unsafe. I'm not
| mistaken issues have been mitigates and those planes are in
| use in many areas of the world now.
|
| There's nothing wrong with designing an upgrade with lower
| carrier costs in mind, but any potencial differences on how
| the plane behaves should always be informed, even if a
| computer is supposed to correct for it.
| fpoling wrote:
| It is not a matter of simple pilot training. It turned
| out pilots had only 10 seconds to disable the system
| after that it would be too late. This is exactly what
| happened at the second crash. The disable switch was
| pushed but it was not possible to recover.
| ummonk wrote:
| I believe they would have been able to recover had they
| cut the throttle and let the airspeed reduce to the point
| that they could manually trim the aircraft.
|
| Hard to blame them though - while it was definitely pilot
| error when they got stuck focusing on trying to fix the
| elevator trim issue and neglected to heed the overspend
| warning and take the aircraft out of military power, this
| issue was no doubt precipitated by the lack of proper
| information that Boeing had provided to pilots regarding
| the functioning of the MCAS system.
| peheje wrote:
| A few extracts from the wiki site. Source
| https://en.wikipedia.org/wiki/Boeing_737_MAX_groundings
|
| ..The 737 MAX's larger CFM LEAP-1B engines are fitted
| farther forward and higher up than in previous models.
| The aerodynamic effect of its nacelles contributes to the
| aircraft's tendency to pitch up at high angles of attack
| (AOA). The MCAS is intended to compensate in such cases..
|
| ..MCAS was supposed to compensate for an excessive nose
| up angle by adjusting horizontal stabilizer before the
| aircraft would potentially stall..
|
| ..MCAS played a role in both accidents, when it acted on
| false data from a single angle of attack (AoA) sensor..
|
| ..elected to not describe it in the flight manual or in
| training materials, based on the fundamental design
| philosophy of retaining commonality with the 737NG..
|
| ..thus minimizing the need for significant pilot
| retraining..
|
| ..Thus, airlines can save money by employing and training
| one pool of pilots to fly both variants of the Boeing 737
| interchangeably..
|
| ..As an automated corrective measure, the MCAS was given
| full authority to bring the aircraft nose down, and could
| not be overridden by pilot resistance against the control
| wheel as on previous versions of the 737..
|
| - Fixing a problem (engine size/placement not analysed)
| with a more complex solution (MCAS). - Acting on only 1
| sensor. - Not described in manuals. - Not able to
| override.
|
| Text-book red flags. Definitely greedy managers that
| pushed towards this. However the engineers involved must
| have a bad taste (at Boeing and FAA). Engineers should
| take an oath like doctors do "Hippocratic Oath". The
| relationsship between business and engineering must be
| strictly defined. Compromises has to be taken, even in
| safety critical systems, but when taken it can't be the
| same business that can assess it OK. Engineers must be
| able to say categorically no and have it recorded outside
| business, without fear of losing jobs.
| Ftuuky wrote:
| Almost don't want to fly on Boeings ever again...
| mcguire wrote:
| " _" 5G interference could adversely affect the ability of
| aircraft to safely operate," said the bosses of Boeing and
| Airbus Americas, Dave Calhoun and Jeffrey Knittel, in a joint
| letter to US Transportation Secretary Pete Buttigieg._
|
| " _" Airbus and Boeing have been working with other aviation
| industry stakeholders in the US to understand potential 5G
| interference with radio altimeters," Airbus said in a
| statement._"
|
| https://www.bbc.com/news/business-59737194
| haggy wrote:
| The article body and headline are (of course) at odds IMO. The
| headline is very much "doomscroll" material while the article
| points out that interference could basically manifest as having
| to rely on secondary systems and protocols to land. If I'm
| missing something then happy to be corrected :D
| jandrese wrote:
| Airline accidents almost never have a single cause. It
| requires multiple failures to align before you have disaster.
| Malfunctioning radio altimeters could be one of those
| factors.
|
| That said, this is Boeing's fault. They need to clean up
| their act ASAP, and it seems like they've been banking on the
| FCC covering up their mess and are now running around with
| their hair on fire.
|
| A reasonable stopgap may be to simply not allow 5G towers to
| use the frequencies ranges in question within some radius of
| an airport (20 miles?) for a few years until Boeing fixes the
| problem.
| jreese wrote:
| A 20 mile radius of any airport likely covers a significant
| portion (60-70%) of all urban/suburban population. They
| might as well just give up on that spectrum at that point.
| eftychis wrote:
| Maybe, dare I say, Boeing should go back to following the
| spectrum guidance. Is it going to move to the THz channel next
| and start complaining about visible light?
|
| The information is all over the place
| (https://ecfsapi.fcc.gov/file/101041916430138/GN%20Docket%20N...)
|
| I would flip their argument on its head and state that as
| altimeters are that critical, make sure they follow the spec to
| the letter.
|
| It's, like other commenters said, as if your neighbour sends you
| an eviction notice for your own house because you are next to
| him.
|
| 5G has taken a tremendous amount of effort and multiple years of
| work -- people have spent a decade on this. Boeing decided to not
| follow the spec. I think I will switch to Airbus. ;)
|
| tl;dr: if Boeing can not keep inside a spectrum for the altimeter
| what else have they "cheated on?"
| p_l wrote:
| Airbus has the same issue. So does Bombardier. So does
| Dassault.
|
| Using the eviction notice metaphor , this is a developer
| building a stadium with sound system rocking your walls every
| night, because someone sold them a parcel too close for noise
| abatement.
| intrasight wrote:
| As is often the case, this will be an issue for the lawyers to
| battle over.
|
| The airlines have basically claimed squatters rights to those
| frequencies owned by 5G carriers.
| f3rnando wrote:
| Dont blame it on the waves
| ChicagoBoy11 wrote:
| Anyone know what that interference would look like in a cockpit?
| Would it be immediately recognizable as something wholly
| inaccurate in the radio altimeter (or even no reading whatsoever)
| or is there the chance that it produces an ever so slightly
| different reading? The opposite, of course, being the far worse
| scenario.
| kube-system wrote:
| As I understand (not a pilot but just interested in aviation),
| these altimeters are critical for use during low visibility
| landings, to determine when it may be safe to continue landing,
| or when they must abort landing (e.g. if they can't see the
| ground yet because of fog)
|
| Being wholly inaccurate or no reading may be equally dangerous
| if it happens at the wrong time.
| nati0n wrote:
| Am a pilot, but just PPL, from my understanding the greatest
| threat is forcing the autopilot to perform certain maneuvers
| thinking terrain is closer than it actually is.
| tempnow987 wrote:
| The idea they can have this type of interference low to the
| ground in a landing situation (when the reflected power is
| high) is a total failure on behalf of boeing. I can't even
| fully get my head around the physics that would get you an
| issue with even normal filtering, much less what once should
| be able to do on an airplane with high fixed costs and safety
| of life factors.
|
| Amazing they can't do GPS as a cross check on indicated
| altitude over a terrain model.
| vel0city wrote:
| > Amazing they can't do GPS as a cross check on indicated
| altitude over a terrain model.
|
| I mean they could, but they skimped out on just getting a
| halfway decent filter for frequencies 200MHz away from
| their signals what are the odds they'd pay for that.
| p_l wrote:
| GPS is incapable of getting even close to the resolution
| required from radar altimeter, and altitude ranging in GPS
| was always worse than its circular error probable in 2d -
| and the best accepted dynamic, unaided GPS deviation is big
| enough to show the same result between correct landing,
| missed landing, and a fiery crash.
|
| The problem is that radar altimeter is very precise device
| that for best precision needs to use _all_ of its 200MHz
| bandwidth _on transmit_. And there are no methods to
| recognize that as part of the return in its own 200MHz band
| (or in the guard band) a random CDMA-encoded signal
| radiated outside of allocated spectrum (happens) reflected
| of random crap around the airport and gets interpreted as
| valid data. This is an analog system where the analog
| characteristics are core to how it works, so the methods
| that allow tight channel spacing in communications tech _do
| not work for radar altimeters_
| kube-system wrote:
| 1. This isn't just a Boeing problem. Not only does the FAA
| have these concerns for other jets, they've also prohibited
| some other jets from landing at some airports in some
| conditions because of it.
|
| 2. Boeing doesn't get to decide to just cross check against
| GPS. The FAA has rules about the equipment that can be used
| for various types of landings.
| _moof wrote:
| These altimeters are required for decreased ILS minimums and
| autoland. You can perform a Cat I ILS down to 200' AGL in
| 1/2-mile visibility just fine without any radar altimeters.
| mLuby wrote:
| Right, and I think the FAA requires airliners to be capable
| of landing in IFR ("low visibility") conditions, which makes
| sense--you don't want trans-oceanic flights to crash because
| the weather abruptly got worse at their destination and they
| can only land when it's clear skies.
|
| So "this altimeter may be inaccurate near 5G" means "this
| airliner may not be airworthy near 5G" which means airlines
| must ground those planes. It sounds like there are enough of
| them that it'd seriously affect air travel.
|
| Recommend https://youtu.be/I9QHvd2bOvU which even managed to
| work some 5G-related jokes in there.
| _moof wrote:
| The incidents I've seen have been outright failures, not
| incorrect indications (of any amount).
| mulmen wrote:
| The altimeters are used by the auto pilot, especially in bad
| weather. In the cockpit the altimeter would probably give
| obviously false readings, but in that case the plane can't land
| and has to divert. It is possible the interference could cause
| the radar to give a plausible but incorrect reading, but this
| is a worst case and to my (limited!) understanding, remote
| possibility.
| clement12 wrote:
| luibelgo wrote:
| Original press release https://www.faa.gov/newsroom/faa-
| statements-5g
| oplav wrote:
| Very anecdotal, but a flight my wife was on 3 weeks ago returned
| to the terminal before takeoff and had to switch planes because
| of an altimeter malfunction. The pilot cited it was because
| people didn't turn off airplane mode.
| nwallin wrote:
| If I understand this correctly, the FCC has allocated the
| 4.2GHz-4.4GHz band for radar altimeters. The FCC has also
| allocated the 3.7GHz-3.98GHz band to 5G. It turns out that the
| radar altimeters, as manufactured, use spectrum outside their
| allocated band, down to and including part of the 3.7GHz-3.98GHz
| 5G band.
|
| Am I missing something?
|
| If a rancher buys a plot of land from 34.42degN to 34.44degN to
| graze his cattle on, but in actual fact grazes his cattle all the
| way from 34.37degN to 34.47degN. Then a farmer buys a plot of
| land from 34.37degN to 34.398degN to grow wheat on. Does the
| rancher still get to herd his cattle down to 34.39degN to feed
| his cattle? The cattle have to eat, after all, and cutting down
| the grazing land by 30% could cause some cattle to starve to
| death. And the rancher has a vested financial interest in
| ensuring his cattle are well fed, and that wheat is good eating.
| And the rancher has always been grazing his cattle there, what
| right does the farmer have to till the soil on the racher's
| grazing land? And we, the American public, have the right to buy
| beef. Why should the farmer purchasing 34.37degN to 34.398degN
| interfere with my ability to buy a steak?
|
| Does any of this make any sense to anyone?
|
| Unless there's additional information I'm unaware of, it seems as
| if the design and/or manufacture of the radar altimeter is not
| fit for purpose. Using 3.7GHz to 3.98GHz for 5G doesn't break the
| radar altimeters; the radar altimeters are _already broken_ and
| must be fixed or grounded, because the equipment is broken and
| unsafe.
|
| If 5G equipment is emitting _outside_ of its allocated
| 3.7-3.98GHz spectrum then the FCC needs to drop a brick on that
| of course.
| mcguire wrote:
| There is no way to build a perfect filter. 5G equipment _will_
| emit outside of its assigned spectrum and radar altimeters
| _will_ receive signals from outside their spectrum. The next
| important variables are the power of the transmitters and the
| effectiveness of the receiver 's filters (and the sensitivity
| of the receiver). Radar altimeters have been doing their thing
| for decades because the previous uses of that band had much
| lower power.
|
| Your analogy is a great demonstration why reasoning-by-analogy
| fails, by the way.
| darksaints wrote:
| High power radio bandpass filters allow for guard bands on
| the scale of a single mhz. Maybe a couple mhz if trying to
| protect low power usage from high power interference. The
| radar altimeters have 200mhz of fallow spectrum to use for a
| guard band. That is two orders of magnitude larger than what
| is needed by even outdated signal processing capabilities.
|
| Your retort is a great demonstration why reasoning by
| bullshitting fails.
| upofadown wrote:
| >High power radio bandpass filters allow for guard bands on
| the scale of a single mhz.
|
| Not at 4GHz. This stuff works in terms of percentages of
| the frequency in use. The higher the frequency the larger
| the guard bands required for any sort of practical
| filtering.
| mcguire wrote:
| https://www.rtca.org/wp-
| content/uploads/2020/10/SC-239-5G-In...
| LatteLazy wrote:
| Don't The FCC set maximum levels of noise a device can emit
| and minimum levels of noise other devices must tolerate.
| Unless the antennas are way above their limits this shouldn't
| be an excuse...
| lxe wrote:
| I don't think this is true. There's plenty of ways to build a
| filter that won't meaningfully interfere across such large
| swaths of rf bands.
| ricw wrote:
| presumably that's why the two spectrums have a 0.2GHz gap
| between them, which btw is massive. based on 2020 mid-
| spectrum prices, this is worth a staggering $66B.
| anfilt wrote:
| We are talking radar here though. Radar in general is more
| sensitive to noise. It's not a digitally encoded signal
| like communications. It's looking at the reflections of
| radio waves and their strength among other things. This is
| an analog process the sensor is using. Before digitally
| encoded broadcasting was the norm the gaps between
| frequencies tended be wider to limit noise. For
| communication even with analog encodings like AM, FM ect...
| The noise floor is quite a bit higher before it becomes
| unusable for communications compared to radar. Radar needs
| to look at a wider band of spectrum as things will get
| shifted more from reflection and such. Further it needs to
| read the much weaker reflected signals. The signal is
| weaker because lots of energy will be lost by the time it's
| reflected. So it's quite possible some higher order
| harmonics operating on the edge of the 5G spectrum could
| bleed into the frequency area the radar is using above the
| expected noise floor.
|
| Keep in mind these sensors were designed and approved long
| before the FCC allocated this spectrum above this range to
| 5G. 200 Mhz may be massive for communications, but not that
| is not entirely true for radar.
| [deleted]
| teawrecks wrote:
| > Your analogy is a great demonstration why reasoning-by-
| analogy fails, by the way.
|
| Douglas Hofstadter would like a word with you.
| upofadown wrote:
| The distance between the transmitter and receiver is quite
| important. Signal strength is inversely proportional to the
| square of the distance. At some distance you are going to
| have problems no matter how good the filters are. The problem
| here is that the receiver is mobile.
|
| Aircraft flying over C band satellite dishes (what used to
| use the current 5G band) used to cause interference to those
| dishes. In that case the problem was that the transmitter was
| mobile. Now the C band satellite people will have to fight
| interference from 5G transmitters in what remains of their
| band.
| labcomputer wrote:
| With radar, it's actually worse! Received signal strength
| is proportional to the fourth power of distance (1/r^2 on
| the way to the target, then 1/r^2 on the way back to the
| radar).
|
| That's part of the reason 5G is such an issue, despite the
| ostensibly-large guard band. You need _really_ good filters
| on the cellular 5G equipment to make sure it doesn 't leak
| into the radar band.
| pinephoneguy wrote:
| It's probably not good to nitpick but with the land analogy you
| have zoning (the lack of zoning that led to the West Texas
| disaster comes to mind) and animals (bees etc) tend to cross
| land boundaries so it's not quite that clear cut.
|
| It all does sound a bit silly though. I will say I wish the FCC
| was as happy handing spectrum/power to unlicensed users as it
| is to what are nearly exclusively Qualcomm customers.
| Ansil849 wrote:
| > The cattle have to eat, after all, and cutting down the
| grazing land by 30% could cause some cattle to starve to death.
|
| You lost me here at this point in the comparison. How is this
| analogous to the situation with altimeters?
| profile53 wrote:
| The planes have to fly and preventing them from doing so
| could cause financial harm/bankruptcy/transportation delays.
| notatoad wrote:
| I think what you're missing is that assigning blame isn't
| especially helpful. those altimeters are already in the
| airplanes. those planes are serving an important purpose, and
| grounding them until they can be fitted with altimeters that
| only operate in their allowed spectrum would be more harmful
| than disallowing 5G equipment from operating in that spectrum.
|
| a rancher allowing his cattle to graze outside of his allowed
| land doesn't result in a fiery crash that kills hundreds of
| people.
|
| you're right, the planes are in the wrong and they should be
| fixed. but that's kind of not the point.
| gentryb wrote:
| I'm curious as to why you think the planes should be fixed,
| but "that's kind of not the point"? It seems to me that it's
| pretty far out of the frequency boundaries.
| Swenrekcah wrote:
| If this is the case the solution is simple.
|
| Postpone the 5G allocation, make the altimeter
| manufacturers/users pay market price for the spectrum to
| those that would have gotten it allocated until they can
| return the spectrum, and also pay a fine to the government
| for using spectrum not allocated to them (in the past,
| current and future breach covered with the rent mentioned
| before).
|
| And give some timeframe by which spectrum must be returned.
| tjohns wrote:
| The radar altimeters aren't "using" (in the FCC sense) any
| of the 5G spectrum. This is an issue on the receive side.
| The FCC primarily regulates transmission, and the
| transmitters themselves are compliant. The FAA's TSO-C87
| doesn't have any requirements for rx filtering either. So
| there's no legal grounds to fine anyone.
| joshmlewis wrote:
| > It turns out that the radar altimeters, as manufactured, use
| spectrum outside their allocated band, down to and including
| part of the 3.7GHz-3.98GHz 5G band.
|
| Did the FAA say this is what's happening for sure? If so that
| answers a lot of questions I've had because like you said they
| are on different parts of the spectrum so it should not be an
| issue unless something is operating out of spec.
| tjohns wrote:
| So, here's what's actually happening in a nutshell...
|
| The FCC allocated a specific band for radar altimeters to
| transmit in. The FCC only specified rules on transmission,
| and the radar altimeters are 100% compliant with the FCC
| rules and only transmit within their assigned band.
|
| The FAA published TSO-87C, which is the technical spec for
| the radar altimeters. But this also just covers transmission
| and performance. There's nothing in this spec about rejecting
| external interference. The radar altimeters are compliant
| with this spec as well.
|
| The problem is on the unregulated receive side. All radio
| signals have some amount of bleed-over into adjacent bands
| due to harmonic interference. Historically, the adjacent
| frequencies were used for low-power satellite communication,
| and the manufacturers added enough filtering to protect
| against the harmonic interference from these low-power
| stations. They did not anticipate a high-power (5G) signal in
| those adjacent bands, and nothing in the FAA/FCC
| specifications protected against it either.
|
| So it's not that the radio altimeters are "using" the
| adjacent bands, but the receive filtering is (in some cases)
| insufficient to account for the new (louder) users of the
| adjacent bands.
| Spooky23 wrote:
| The difference is that cows don't fall from the sky and kill
| hundreds of humans in the process.
|
| "Fix the thing" is the correct answer, but managing risk in the
| meantime in this regulatory environment is a shade of grey.
| Doing nothing puts people at risk. Grounding aircraft cripples
| a critical industry. Delaying 5G costs two network operators a
| lot of cash.
| hasmanean wrote:
| It's more like, you can fence off your cattle but you can't
| fence off the birds and the bees.
|
| So even if the cattle stay within their limits, the grass
| relies on bees coming in from neighbouring farmland to stay
| healthy.
|
| If you pave the area outside a cattle ranch the grass inside
| will die on the borders.
|
| So you have to zone the land outside the fences to make sure it
| some other ranch or else left wild.
|
| The same with spectrum. Adjacent frequency bands have to
| allocated to uses which do not produce a lot of interference
| that travels very far or is used very much.
| awb wrote:
| > If a rancher buys a plot of land from 34.42degN to 34.44degN
| to graze his cattle on, but in actual fact grazes his cattle
| all the way from 34.37degN to 34.47degN. Then a farmer buys a
| plot of land from 34.37degN to 34.398degN to grow wheat on.
| Does the rancher still get to herd his cattle down to 34.39degN
| to feed his cattle?
|
| If you're actually curious about this specific scenario, in the
| US it's typically referred to as "adverse possession":
| https://en.wikipedia.org/wiki/Adverse_possession
|
| > in the English common law tradition, courts have long ruled
| that when someone occupies a piece of property without
| permission and the property's owner does not exercise their
| right to recover their property for a significant period of
| time, not only is the original owner prevented from exercising
| their right to exclude, but an entirely new title to the
| property "springs up" in the adverse possessor. In effect, the
| adverse possessor becomes the property's new owner.[2][b] Over
| time, legislatures have created statutes of limitations that
| specify the length of time that owners have to recover
| possession of their property from adverse possessors. In the
| United States, for example, these time limits vary widely
| between individual states, ranging from as low as three years
| to as long as 40 years.
|
| Also, in some states like California you have to pay taxes on
| the land for a certain period of time before you can claim
| ownership.
|
| But yes, in your specific case it is possible to raise cattle
| on someone else's land for long enough to be able to legally
| claim that land as your own.
| LeifCarrotson wrote:
| Your analogy is slightly oversimplified because it assumes a
| fully functional fence (probably two, with a road between them)
| between the wheat fields and the cattle. The cows might gaze
| longingly across the road at the wheat fields and the wheat
| farmer might smell some manure while harvesting, but the fence
| is fully functional. In real life, a 2200 lbs steer might not
| think much of a mere barbed wire fence or high-voltage tickle
| separating it from the wheat field...but that's stretching the
| analogy a bit too far into the weeds.
|
| A better analogy needs to understand that the filter on both
| sides of the equipment is imperfect.
|
| Replace the altimeter with, say, Mount Rushmore National
| Monument, and replace the wheat farmer with, say, a putrid
| landfill, sewage processing operation, or CAFO chicken farm.
| Neither the monument nor the viewing areas extend beyond the
| surveyed boundaries of the monument. But part of the appeal is
| that it's a pleasant, quiet, natural place in the middle of a
| national forest: abutting it with something smelly, noisy, or
| ugly might be legal but would harm it even though it doesn't
| extend past the property markers.
|
| Personally, I do think they need to upgrade and phase out the
| altimeters to be more tolerant against interference. But
| they're not necessarily broken, just too slow to adapt past the
| scope and capabilities of the tech available in 1967.
| peteradio wrote:
| More like the rancher keeps his beefs within the usual limit
| but one or two can escape from time to time.
| ddod wrote:
| I can't say if it's right or wrong, but in relation to your
| specific example, there are "adverse possession" laws that
| grant legal rights to the occupier of land in the US.[1]
|
| [1] https://www.nolo.com/legal-encyclopedia/neighbor-built-
| fence...
| buescher wrote:
| It's the receiver, so it's more like, you're asserting your
| right to leave your door wide open on a street that is
| suddenly much more busy.
|
| De facto possession of spectrum was heavily litigated in the
| early days of radio. There basically is none (not legal
| advice!), essentially no one has a claim on spectrum in the
| USA that is not assigned or regulated by the FCC. You have to
| sign away any claim to spectrum from before the establishment
| of the FCC to get a ham license or similar radiotelephone
| licenses. Nobody is around anymore that was operating then
| anyway. The language is blandly bureaucratic but in context
| that is what it means: "The Applicant/Licensee waives any
| claim to the use of any particular frequency or of the
| electromagnetic spectrum as against the regulatory power of
| the United States because of the previous use of the same,
| whether by license or otherwise, and requests an
| authorization in accordance with this application."
|
| There is probably some similar language in the applications
| for other licensed bands.
| thamer wrote:
| If the page says that "you have reached your article limit":
| http://archive.today/a4pso
| Damogran6 wrote:
| Is this last month's news or something new?
| mcguire wrote:
| Do they mean radar altimeters? " _That would result in "increased
| lightcrew workload while on approach..._"
|
| Who wrote this?
| fancyfredbot wrote:
| In Europe there are Boeing 737s and 5G C band radio masts. I'm
| guessing the laws of physics are the same in Europe. So I'm
| confused. What are they doing differently there? Why don't the US
| do the same thing?
| Jon_Lowtek wrote:
| EU 5G uses 3.4 to 3.8 GHz
|
| US 5G uses 3.7 to 3.98 GHz
| fancyfredbot wrote:
| Thank you! I'm now wondering why the US didn't stop at 3.7GHz
| and limit power levels too?
| eftychis wrote:
| See page 3 second half.
| https://ecfsapi.fcc.gov/file/101041916430138/GN%20Docket%20N...
| dcdc123 wrote:
| EU C-band rollouts are 200Mhz lower than in the US, making for
| almost twice as much gap between them. That said, EU is still
| starting to get worried [0] after some tests showed
| malfunctioning equipment can cause interference.
|
| [0] https://strandconsult.dk/blog/5g-is-suddenly-a-flight-
| safety...
| DocTomoe wrote:
| We (Europeans) use other frequency bands for 5G: 700 MHz, 1.8,
| 2.1 and 2.7 GHz. That's comfortably far away from the 4.2 GHz
| band radio altimeters use.
|
| Why the US decided to use 3.8 GHz for their 5G, only God knows.
| stingrae wrote:
| It is a poor design on the part of the altimeter designers.
| 200MHz should be plenty far away.
| mcguire wrote:
| Or poor design on the part of 5G transmitter designers?
| tyingq wrote:
| Somewhat amusing that the radio altimeters in 737-200 models
| aren't affected, while all others are. The 200 models entered
| service in the late 1960s.
| flerchin wrote:
| I figured that meant that the 200s don't have radio altimeters.
| tyingq wrote:
| No, they do have them.
|
| Here's the actual text, so it's only some of the 200's that
| are unaffected:
|
| _" Based on Boeing's data, the FAA identified an additional
| hazard presented by 5G C-Band interference on The Boeing
| Company Model 737-100, -200, -200C, -300, -400, -500, -600,
| -700, -700C, -800, -900, and -900ER series airplanes, except
| for Model 737-200 and -200C series airplanes equipped with an
| SP-77 flight control system"_
|
| And the SP-77 does include a radio altimeter...apparently a
| nicely selective one.
|
| https://public-inspection.federalregister.gov/2022-03967.pdf
| anfilt wrote:
| I see a lot people blaming boeing here? These sensors radar
| sensors were made before even the FCC allocated the 5G spectrum.
|
| Let's also not forget 5G equipment will emit outside of its
| assigned spectrum even with a buffer zone between frequencies.
| Especially when you consider the harmonics. Now each order of
| harmonic gets weaker from primary frequency.
|
| As for these altimeter sensors anyone have a datasheet for them?
| Quite curious what the recommended noise floor for these are?
| manquer wrote:
| All equipment can emit outside the allocated frequencies, which
| is why you have band pass filters .
|
| FAA is really the problem not Boeing, like any company they
| only did the bare minimum required to get certification .
|
| Had FAA they mandated stronger specs initially or at-least
| forced Boeing to upgrade in the last 10 years this was being
| discussed and allocated, this won't be a problem. That will be
| expensive for Airlines(grounding loss of revenue) and Boeing
| (recall,certification and upgrade) nobody wants to foot the
| bill so FAA kept delaying .
|
| Time and again we have seen FAA favor the industry even at the
| cost of lives (like with 737-MAX grounding) so this is not all
| that surprising from them
| anfilt wrote:
| We are talking about radar here the receiver will be
| receiving weak signals that are reflected. They may also have
| slight shifting in frequency due to reflection. The noise
| floor is much lower for radar than communications. A radar
| receiver also will generally read a wider frequency band than
| communications. 200Mhz between frequency bands may seem like
| a lot for communication purposes, but that is not necessarily
| true for radar.
|
| Also you can't make a perfect band pass filter, also for
| radar the band your going to be filtering is gonna be wider
| to begin with. Also all transmitters will emit higher order
| harmonics of the primary frequency, if the broadcast power is
| high enough those harmonics could very well be above the
| noise floor of other frequencies.
| ameminator wrote:
| Wow, this along with potential interference problems in weather
| radar [0], it's obvious the FCC bungled allocating the 5G
| spectrum. What a shame that they gave into industry pressure over
| other practical considerations.
|
| However, it doesn't surprise me that the FAA, which allowed the
| Boeing 737Max fiasco, is back here coming to Boeing's defense.
| What happens when 2 captured regulators collide?
|
| Edit: added spacing and changed "radio" to "radar" for clarity
|
| [0] https://www.npr.org/2019/07/02/737919100/forecasters-
| caution...
| LeoPanthera wrote:
| For clarity, "weather radio" is usually used as the name for
| the broadcast service operated by the NOAA on 162MHz. This
| remains unaffected.
|
| You are describing the 23.8GHz radar used by satellites.
| ameminator wrote:
| Sorry about that. I was thinking of radar as a subset of
| weather-related radio. I'll fix that for clarity. Thanks for
| pointing it out.
| w0mbat wrote:
| This is not true. 5G uses spectrum way outside the band that
| RADAR altimeters are supposed to be using. Boeing had years to
| fix their shoddy RADAR equipment, and the fix now can be as
| simple as fitting a high-pass filter.
| ameminator wrote:
| If 5G was using spectrum way outside the band that these
| altimeters are supposed to be using... then we wouldn't have
| this issue. Those 737s aren't new, they certainly had
| permission to use that spectrum for years and while they may
| have had years to fix their equipment, it's certainly not as
| trivial as "add a high pass filter".
|
| Now, I do agree that this should have been caught 5-10 years
| ago, when the standard was being developed. Boeing's
| incompetence wouldn't surprise me, which is probably why we
| see "FAA says problems for Boeing in 5G" as the headline,
| instead of "Aircraft companies warn of interference in
| safety, navigation equipment, ask FCC to reconsider" as the
| headline, _5 years ago_. Although, as noted in the article,
| it seems that the FAA _has_ been warning about the conflict -
| I 'm just surprised that the FCC would go ahead with 5G if
| they had been flagged early enough.
|
| So here we are, the FCC, in its negligence, assigned
| conflicting portions of the spectrum, Boeing, in its
| incompetence, didn't catch it - and now it's a big mess.
| initplus wrote:
| Well the whole point is they didn't have permission to use
| that spectrum. The interference the FAA is complaining
| about is explicitly outside of the radalt allocated
| spectrum.
|
| FCC has allocated radalt's 200Mhz, with another 200Mhz
| guard on either side. If these devices are not properly
| filtering out frequencies outside of this massive 600Mhz
| range, those devices are faulty and should never have been
| certified by the FAA in the first place.
|
| It's reasonable for the FCC to assume that spectrum users
| will not be affected by interference from so far outside
| their allocation.
| peeters wrote:
| > Those 737s aren't new, they certainly had permission to
| use that spectrum for years
|
| This statement seems to be at odds with what many others in
| this thread are saying: that they were never approved to
| operate in this band. I don't know enough about this issue
| to know who is correct--do you happen to have a source for
| that since you are certain of it?
| jaywalk wrote:
| They never had permission to use the 5G spectrum, and in
| fact never did. The issue is that the filtering is so
| shoddy that signals more than 200MHz away from the band
| they are using can cause issues. The fault for that lies
| squarely on Boeing.
| maxsilver wrote:
| >they should have caught this 5-10 years ago
|
| They mostly did. They've been warning about this for 3+
| years now (see this report from the FCC back in September
| and October 2019) https://ecfsapi.fcc.gov/file/102214765103
| /AVSI%20RA%20Interi...
|
| They couldn't have warned folks about more than a year or
| so sooner than that, because the spectrum bands for 5G
| hadn't even been fully decided prior to it. (The public
| notice of band reconfiguration only got announced back in
| May 2019)
| ummonk wrote:
| Yup, they should suspend the rollout due to noncompliance
| by airplane manufacturers and fine said manufacturers for
| the delay.
| avianlyric wrote:
| > Those 737s aren't new, they certainly had permission to
| use that spectrum
|
| No they don't, and never have. Hence the current shit show
| today.
|
| Boeing got away with it because old users of the 5G
| spectrum where lower power satellite comms. Hilariously the
| oldest 737 model is unaffected by this issue, probably
| because Boeing actually let their engineers do good work
| back then, rather than forcing them to produce the sloppy
| crap they build today in the name of profit.
| amirhirsch wrote:
| The fix can be as simple as doing nothing. All the antennae
| in question are directional and there is no evidence of
| interference.
| Czarcasm wrote:
| That's not true. I work in aviation and we've had a number
| of reports of radar altimeter interference during takeoff
| and landing near airports with the new 5G towers. Older
| aircraft are particularly effected.
| amirhirsch wrote:
| Can you share these reports? How does interference
| exhibit itself?
|
| It seems there a disagreement on factual truth which as
| another commenter pointed out could be resolved by say a
| YouTube video showing "here's a radar altimeter
| malfunctioning near a 5G antennae"
|
| Also your comment seems inconsistent with the fact that
| the telcos delayed deployment of 5G towers near airports
| due to concerns about interference during takeoff and
| landing. So how can there be reports of interference from
| 5G tower if they haven't even been deployed there (edit:
| are these international reports)?
|
| (I work on radar, this all feels like lawyers lawyering
| and techies blogging, but not engineers engineering)
| joefigura wrote:
| Agree, the societal benefits of 5G are far higher than the
| cost of retrofitting aircraft with radar altimeters that are
| compatible with 5G.
| stingrae wrote:
| Note weather radar impacts some channels of 5GHz WiFi resulting
| in some FCC/ETSI requirements that that WiFi be able to detect
| it and back off.
| https://en.wikipedia.org/wiki/Dynamic_frequency_selection
| tempnow987 wrote:
| It's not obvious at all. Boeing shouldn't be using these
| frequencies and this has been 10 years in the making. Boeing
| should fix their equipment to operate within its assigned range
| (+ the huge guard bands they gave them for no real reason).
|
| This is like your neighbor driving onto your lawn, and then
| demanding you move out of your house. They should drive right
| back onto their lawn.
| mardifoufs wrote:
| What about older planes? I'm not sure if boeing should be
| responsible for retrofitting all of their older planes just
| because of change that happened years later.
| throwaway894345 wrote:
| If Boeing sold planes with altimeters that rely on
| frequencies that weren't allotted to aviation, then Boeing
| sold defective planes and should absolutely be responsible
| for retrofitting them. The fact that those frequencies are
| recently coming into use is immaterial.
|
| It would be different if Boeing designed their altimeters
| to only depend on spectrum that was allocated for aviation,
| but then the FCC came along and carved the 5G spectrum out
| of the aviation spectrum after Boeing built its planes.
| bluGill wrote:
| Airplanes have a lifespan, older ones are mostly retired,
| and the rest need their radios updated to modern standards
| anyway. Airplanes from the 1950s normally will last
| essentially forever, but modern airplanes are built with
| lighter materials that have the downside of metal fatigue
| from normal flexing and so they have to be retired after so
| many uses. (beware of this when flying backward country
| airlines, it isn't unheard of for a "retired" airplane to
| be put back into service in a backward country - Boeing
| thinks they should be retired, but their standards are
| conservative and so there is potentially a lot of life left
| in the air frame before it suddenly falls apart killing
| everyone on board)
|
| Note, their are airplanes built today that don't have the
| metal fatigue issues - material selection is a complex
| process that each design needs to consider. I'm not sure
| what the 737 is made of.
| nimih wrote:
| What do you mean by "backward country" in this context?
| cogman10 wrote:
| In any other broadcasting circumstance "It'll be hard to
| come up to the spec we should have been following for
| years" would not be an acceptable excuse. They have a huge
| chunk of spectrum with a very wide guard band.
|
| If a TV station started leaking over another channel, you
| can bet that'd be shut down almost immediately, regardless
| of the cost to the station for putting up faulty
| broadcasting equipment.
|
| Boeing should be required to fix their broken electronics.
| Sucks to suck.
| upofadown wrote:
| >If a TV station started leaking over another channel,
| you can bet that'd be shut down almost immediately,
| regardless of the cost to the station for putting up
| faulty broadcasting equipment.
|
| Any leaking that happens is caused by the 5G transmitters
| in the case under consideration. You are confusing two
| issues. The issue here is that strong and close
| transmitters can not be properly blocked by some of the
| radar altimeters in use under the separation rules
| established by the FCC.
|
| An important job of the FCC is separating TV transmitters
| that are close in frequency so that they do not cause
| problems. If you live next door to a TV transmitter you
| will have no hope of receiving signals on adjacent
| channels. That is because of the physical limitation of
| your receiver and has nothing to do with the transmitter
| leaking anything.
| hasmanean wrote:
| Tv stations do leak into adjacent bands. They contribute
| to the noise floor. It's just that your real tv station
| broadcasts at 10,000W or whatever so it drowns out the
| other noise.
|
| When it comes to radar, they cannot increase the TX power
| and have to detect a lower RX power. Also since they are
| analog any interference manifests itself as a direct
| error.
|
| It's like saying you should never be able to hear a
| whisper from your neighbours house. Obviously you can
| limit the amount of loud noises coming from your
| neighbours. You can't silence them completely.
| tssva wrote:
| Boeing's altimeters should have always operated within the
| frequency bands allocated to them and been resistant to
| interference from other bands. These altimeters are
| operating outside the specification they should have met
| when deployed. This is an utter failure on the part of
| aircraft manufacturers, airlines and the FAA. They are all
| screaming loudly to try to shift the public perception to
| this being an issue created by the FCC and telecom
| companies.
| NovemberWhiskey wrote:
| > _Boeing 's altimeters should have always operated
| within the frequency bands allocated to them and been
| resistant to interference from other bands. These
| altimeters are operating outside the specification they
| should have met when deployed._
|
| What is your basis for this extraordinary claim?
| jaywalk wrote:
| What's extraordinary about the claim? The guard band
| between 5G and radio altimeters is ~200MHz, which is
| massive. If your filtering can't handle signals over
| 200MHz away from what you're looking at, then it's
| garbage filtering.
| anfilt wrote:
| 200 Mhz may be massive for communications (especially
| digital encoded signals), not necessarily for radar when
| you sensor is receiving weak reflected signals that very
| likely can have a frequency shift on reflection. So radar
| receivers need to receive on a wider frequency band than
| a receiver for communications.
|
| Depending on the strength of 5G transmitters the higher
| order harmonics could be above the noise floor.
| NovemberWhiskey wrote:
| Especially for FMCW applications using homodyne
| transceiver architectures; like you see in most civilian
| radar altimeters.
| avianlyric wrote:
| This is not an extraordinary claim, it's how all basic
| radio spectrum allocation works.
|
| How else are you supposed to make sure that equipment
| made today won't interfere with equipment made tomorrow
| if people don't stick within their frequency allocations?
|
| The claim above is basically the equivalent of "car
| should have always operated on the roads that are
| allocated for them, and should never have been driving
| through empty fields". If you're driving your car through
| a field you don't own, you don't get to complain when
| someone builds a house there.
| NovemberWhiskey wrote:
| Do you know how a typical radar altimeter works? Do you
| know what the source of the specifications for radar
| altimeters for airborne applications is?
| MobiusHorizons wrote:
| How is it extraordinary? Equipment is typically required
| by law to operate only within its specified frequency
| bands. 5G spectrum was never allocated to aircraft radar
| altimeters.
|
| I agree that quoted suggestion lacks nuance in the
| history that brought us to this state, but from a
| technical perspective it does not seem extraordinary.
| More that it simply advocates a very expensive and
| uncooperative way to solve a problem of the commons.
| NovemberWhiskey wrote:
| Equipment is required to _emit_ only within its allocated
| frequency bands. No-one is suggesting that the radar
| altimeters are emitting outside of their allocation; but
| there 's no law that says that devices have to be immune
| to interference from other transmissions outside their
| allocate bands.
| heyflyguy wrote:
| What are you talking about "guard bands" ?
|
| Is there spectrum assigned alongside the radalt to ensure no
| crosstalk?
| leoqa wrote:
| "Guard" is a common frequency for all pilots to
| listen/communicate. It's very rarely used as intended and
| is mostly cat meows and fart noises.
| mlindner wrote:
| That is completely unrelated.
| https://en.wikipedia.org/wiki/Guard_band
| addaon wrote:
| Guard frequency (121.5) is different than "guard bands"
| in this context. Guard bands are, as was guessed, a
| frequency range at the edge of an allocation where no
| energy is /intentionally/ transmitted, and where received
| signal /should be/ disregarded. Basically it allows the
| reality of some frequency spillage to be accommodated
| between what would otherwise be adjacent frequency
| allocations.
| avianlyric wrote:
| Yes exactly that.
|
| The FCC allocated spectrum for radalts to use, then set
| aside an equivalent amount of spectrum (which is an insane
| amount of spectrum for a guard band, easily double what
| most uses get) above and below the radalts spectrum as
| guard bands that no one is allowed to use.
|
| The guard bands ensure that if there is a little spill over
| from 5G (which there won't be because modern radios are
| better than that), or if the radalts have crappy filtering
| on their front ends (which it seems they do). Then nothing
| bad will happen, because the guard bands give everyone lots
| of space for sloppy engineering (which Boeing seems to be
| abusing)
| mcguire wrote:
| I realize it's fun to hate on Boeing, but you do realize
| Airbus, the Airline Pilots Assns.
| (https://www.alpa.org/resources/aircraft-operations-radar-
| alt...), and the ICAO(https://www.icao.int/safety/FSMP/Meetin
| gDocs/FSMP%20WG11/IP/...) are also concerned?
| hammock wrote:
| > What happens when 2 captured regulators collide?
|
| The FCC is more political than the FAA, but the FAA more
| critical to US economy. As of right now it seems the FAA is
| winning.
| bb88 wrote:
| I don't believe that anymore after the 737-Max incident
| (Downfall on Netflix is good btw).
|
| The FAA serves Boeing -- and no one else right now.
| sokoloff wrote:
| I watched Downfall and I have to say that while they
| _technically avoided lying_ about the actions of the EA302
| crew, the storyline they presented doesn't match the flight
| data recorder data.
|
| Downfall says "the crew knew about the MCAS risk, figured
| out they had an MCAS fault, applied Boeing's checklist
| response, and still the airplane crashed". All four of
| those things are independent and true facts.
|
| What is omitted (and readily available to the filmmakers)
| is that EA302's thrust setting remained inappropriately
| high (94% N1, takeoff thrust), causing an excessive
| airspeed, causing the crew to be unable to return the
| stabilizer to a normal trim setting by hand after using the
| electric cutout, which led them to the (correct) conclusion
| that they should turn the electric stab trim back on and
| command aircraft-nose-up via the electric system, which
| they did. That means that they _undid_ the checklist
| response. Then, after doing that successfully for a short
| period of time, they stopped commanding nose-up trim and
| _left the stab trim powered up_ (contravening the
| checklist), allowing MCAS to continue to command the fatal
| nose down trim.
|
| So they got dealt an emergency situation and the airplane
| crashed. Boeing has some blame here, but Downfall's
| presentation of the events as the crew responding correctly
| with Boeing's checklist would make most politicians blush
| and worry they'd be caught lying.
| Retric wrote:
| FCC is vastly more important for the US economy than the FAA.
| FCC covers Cellphones, Radar (Aircraft+Weather), WiFi,
| Bluetooth, Satellites (GPS+Weather+Communication, etc),
| Radio, CB, Emergency Services, TV etc all the way out to
| astronomy. Their mandate further covers interference from
| both electronic devices like vacuum cleaners and physical
| structures. Add it up and we are talking a huge chunk of the
| US economy directly or indirectly involved.
|
| Further the FAA is extremely dependent on the FCC, being
| unable to detect or communicate with aircraft would make air
| traffic control nearly impossible. They would still be
| responsible for crash investigations, pilots, aircraft
| manufacturing etc, but in the worst cast the only way to fly
| safely would be under clear skies.
| technofiend wrote:
| >They would still be responsible for crash investigations
|
| I think that's the NTSB? Otherwise you're not wrong about
| air traffic control, equipment and pilot certification.
| Retric wrote:
| NTSB is primary on aircraft accidents, but they FAA plays
| a major role both in investigation and enforcement.
|
| https://pilot-protection-
| services.aopa.org/news/2020/july/01...
|
| The dual role is more clear when you consider
| investigations may uncover issues that are irrelevant for
| this crash but could cause other crashes.
| hammock wrote:
| You are right. Perhaps I should have said more influential
| over larger chunks of the economy. Less political and more
| powerful than the FCC.
| radicaldreamer wrote:
| Well FAA is a cabinet level agency while the FCC is not
| Retric wrote:
| Cabinet level agency isn't a thing. At the high level org
| chart you see the FCC but not the FAA. https://www.usgove
| rnmentmanual.gov/ReadLibraryItem.ashx?SFN=...
|
| This is because the FAA is under the United States
| Department of Transportation, while the FCC is an
| independent agency. https://en.wikipedia.org/wiki/United_
| States_Department_of_Tr...
|
| To see the difference goto: https://www.usa.gov/branches-
| of-government
|
| Executive Department Sub-Agencies and Bureaus has FAA.
| Independent Agencies has FCC. What is and isn't an
| independent agency is complicated but the EPA, NASA,
| FDIC, Federal Reserve System are independent as are less
| critical agencies like Institute of Museum and Library
| Services, Peace Corps, Railroad Retirement Board.
| mlindner wrote:
| This isn't on the FCC but instead the FAA dragging their feet.
| radicaldreamer wrote:
| How is the FCC "captured"? They're out there making a killing
| on auctioning out these frequencies with massive guard bands
| and are extremely patient with legacy users of those
| frequencies.
| tedunangst wrote:
| If I use 11/8 for private network addresses because it's easier
| than trying to keep everything in 10/8, and then DoD starts
| advertising those routes on the public internet, did the DoD
| bungle their rollout?
| vmception wrote:
| > What happens when 2 captured regulators collide?
|
| When moneyed interests compete it becomes the same as their
| being no moneyed interests
|
| An average case outcome
|
| Not obvious what would happen here though, just a general
| reality that mostly undermines the "rich shadow organization
| controlling everything" idea
| dogleash wrote:
| >When moneyed interests compete it becomes the same as their
| being no moneyed interests
|
| No. That's very incorrect.
|
| For example: Moneyed Interest #1 wants A & B, Moneyed
| Interest #2 wants A & Not-B. It's entirely possible that
| Not-A is a bad business model, but is also in the interest of
| the citizenry at large to have Not-A be law.
| vmception wrote:
| Ok, you're right they can have niches and get their model
| regulations
| FrameworkFred wrote:
| I'm no expert, but why can't we just add some regulation that
| says the insurance carriers will be responsible for any liability
| beyond 2024 (or whatever) and that they're free to charge
| whatever they want based on the make and model of the altimeter
| in use on the plane?
| kube-system wrote:
| Insurance is generally a reverse-looking science and does a
| really bad job at proactively measuring risk.
|
| You save more lives by having an engineer analyze potential
| problems with the plane before it crashes, than you do by
| waiting for one to crash so an actuary can count it.
| rtkwe wrote:
| Why not make something safe instead of trying to end run an
| economic incentive to safety? Airplanes are one of the safest
| per mile form of transportation in the US because we regulate
| the actual safe flight instead of playing economic games to get
| companies to act safely.
| United857 wrote:
| Maybe I'm missing something obvious but why just Boeing? Does
| Airbus use a different band and if so, why doesn't Boeing switch
| to solve the problem?
| reincarnate0x14 wrote:
| From my understanding, Boeing's radars will receive a much
| wider band than Airbus', combined with most other countries
| allocating 5G spectrum further away from the expected radar
| frequencies. They could switch but it would involve massive
| effort and possible recertification of the airframes.
| p_l wrote:
| Bad reporting, simply.
|
| This issue hits _ALL PLANES_ that use standard frequency radar
| altimeters. Including Airbus, Bombardier, Cessna, Learjet,
| Dassault, etc.
|
| What happened is that aside from trying to put limits on
| transmission characteristics for C-band _near airports_ , there
| is a concerted action to verify how the many different models
| of radar altimeters interact with 5G interference. This is a
| report on configurations sold by Boeing, from Boeing, as they
| went over all configurations they've sold of specific types.
| ummonk wrote:
| Boeing's receivers are picking up radio signals well outside
| the band allocated to radio altimeters - they got away with
| this until now because the nearby bands were unused.
| amelius wrote:
| Probably another case of Boeing execs choosing the cheapest
| solution instead of the most robust one. And now society has to
| pay for it, again.
| protomyth wrote:
| AINdebrief recently had a podcast episode (#46 for January 31,
| 2022) on this subject.
| https://www.ainonline.com/podcast/aindebrief/aindebrief-epis...
|
| _In this episode, AIN contributing editor Mark Huber explains
| the 5G C-band interference issue that can affect aircraft radar
| altimeters. He explains how we even got into this situation, why
| there is the potential for the 5G wireless networks at Verizon
| and AT &T to interfere with radar altimeters, what the FAA is
| currently doing to temporarily ease the problem, and what can be
| done long term to solve this issue._
| purplezooey wrote:
| Clubber wrote:
| We should starve the beast but keep taxes so we can pay for the
| overspending over the last 40 years.
|
| Why feed the beast when it just does whatever the donors tell
| it. It's no longer our beast.
| ugjka wrote:
| Is 3.7-3.98 GHz range somehow particularly useful for mobile
| operators?
| mdasen wrote:
| It's not that it's particularly useful so much as it's
| available. The FCC has been clearing spectrum because more
| spectrum means that carriers can offer faster 5G services. Mid-
| band spectrum (in the 2.5-6GHz range) is particularly useful
| because it offers a good combination of range (measured in
| miles) while still having a decent amount of spectrum available
| and the possibility of things light higher-order MIMO to offer
| capacity gains.
|
| Millimeter-wave spectrum (in the 20-50GHz range) has lots of
| spectrum available, but its range is often in the 50-300 foot
| range. It's also important to realize that because we're
| talking about a radius, when we turn that into a circle the
| difference gets magnified. A 1 mile range means covering 88M
| square feet. A 100 foot range means covering 31,000 square
| feet. 53x more range turns into 2,800x more area covered.
|
| Initial 5G networks in the US often used 5-20MHz of low-band
| spectrum (below 1GHz). This does have some utility as 5G NR is
| marginally more efficient, even in low-band spectrum. However,
| deploying with 100-200MHz of mid-band spectrum offers the kind
| of huge gains that offer 10x (or even more) data speeds.
|
| https://assets.weforum.org/editor/SPPQ747R8Fd63ilAo4xvfjMNFU...
|
| There isn't really a lot of spectrum that hasn't been allocated
| so it's often a game of figuring out who you can move for the
| least cost and most benefit. They chose to move C-Band
| satellite operators (at a cost of billions). Previously, the
| FCC freed up spectrum in the 600MHz range by having TV
| broadcasters relocate from UHF channels above 37 to lower
| channels.
| LatteLazy wrote:
| Sorry to rant, but... I drives me nuts when people use "could" in
| this context.
|
| 5G has been in development for over a decade I think. It's been
| deployed in the real world since 2019. So what the fuck have the
| FAA and FCC been doing in that time? You would have thought
| someone would have actually determined whether 5G can interfere
| with one of the most popular commercial aircraft?
|
| Really? No one checked? No one asked?
|
| This has been a mainstream news story for 4 weeks.
|
| And no one at the FAA or FCC has put a 5G antenna next to an 737
| and even tried check? No one has put together pilots logs or
| looked at aircraft systems logs? And in that time presumably 100s
| of 737s have taken off and landed and flown over these?
|
| At this point, we know 2 things: It's very unlikely this an issue
| or we'd have seen a lot of serious incidents probably including
| an actual crash AND we need a federal organisation that manages
| aircraft safety and another for communications including EM
| spectrum to avoid inference and we don't actually seem to have
| either.
|
| I work with trading tech. Nothing complex or amazing. Just money,
| nothing safety critical. Sometimes things break or we have bugs.
| I can say a lot of things to my boss when something goes wrong, I
| can't say "It could be a massive problem, but I haven't bothered
| checking despite having 4 weeks to at least start" so I don't
| really know.
| sgc wrote:
| I see their statements as indicating that they do know in fact
| there are failure modes that will occur some of the time. When
| you use could in this context, it's to indicate that it won't
| happen in all circumstances, not that you don't know if it can
| happen at all.
| LatteLazy wrote:
| That's what gets me: they don't seem to know. Or at least
| they don't want to say?
|
| If they know there is an (intermittent, occasional) issue
| then ground the planes. Don't announce it, but cryptically
| and then do nothing and wait for a few 100 deaths.
|
| If they know there isn't a problem then shut up.
|
| And if they don't know, why the fuck don't they know after
| (at least) 4 weeks of testing. Can't they at least say all
| tests fine or 99% of tests fine or we crashed 4 planes but
| maybe the test pilots were just bad?
| mcguire wrote:
| See https://news.ycombinator.com/item?id=30445969
|
| "They mostly did. They've been warning about this for 3+ years
| now (see this report from the FCC back in September and October
| 2019)
| https://ecfsapi.fcc.gov/file/102214765103/AVSI%20RA%20Interi...
|
| "They couldn't have warned folks about more than a year or so
| sooner than that, because the spectrum bands for 5G hadn't even
| been fully decided prior to it. (The public notice of band
| reconfiguration only got announced back in May 2019)"
| metacritic12 wrote:
| There seems to be evidence that there's just a turf war going on:
|
| https://www.wsj.com/articles/pete-buttigiegs-5g-crash-landin...
|
| Overall it seems like the FCC was trying to be innovative, while
| the FAA's precaution in fact is the malaise that's been infecting
| all of US government: overapplication of the precautionary
| principle, that any risk, even if small an theoretical, is worth
| stopping change for (but not asymmetrically for motivating
| change).
| luxuryballs wrote:
| Why do we even need 5G it seems like there's always something,
| whether real or tinfoil, risks and unknown risks, so at one point
| do we decide that what we have is good enough?
|
| Is there not any room in the regulatory world for "better safe
| than sorry"? At some point we could maybe just stop adding new
| energy waves to the sky.
|
| It's like the Wi-Fi router thing, it's to the point where I'm
| going to need to buy a big piece of land to live on just so I
| don't have 50 different Wi-Fi networks bombarding my house 24/7.
| I mean they say it's safe to have a Wi-Fi router but did they
| study having 50 at once?
| [deleted]
| doikor wrote:
| > Why do we even need 5G
|
| Ever tried to use 4G in a crowded place? Network congestion is
| the main reason.
| teeray wrote:
| > Why do we even need 5G
|
| Because smartphone sales have leveled off and consumers are
| content holding onto their devices longer.
|
| Manufacturers and telcos have become addicted to the 1-2 year
| device renewal cycle and want it back. Thus the marketing
| department instills "5G" as a need in the mind of the consumer.
|
| Also, for people on metered plans, it behooves the telco to
| develop means for you to exhaust your quota as quickly as
| possible to get you into overages (and subsequently onto a
| pricey unlimited plan).
| vkou wrote:
| > Why do we even need 5G it seems like there's always
| something, whether real or tinfoil, risks and unknown risks, so
| at one point do we decide that what we have is good enough?
|
| Because it consists of non-ionizing EM waves, the risks of
| which are very well understood.
|
| https://www.youtube.com/watch?v=i4pxw4tYeCU
|
| And if you're concerned about the amount of non-ionizing EM
| waves in your environment from these 50 wi-fi networks, you
| should never go outside, since the sun is constantly blasting
| you with ~1,000,0000 GHZ-frequency electromagnetic waves, at an
| energy flux of ~1300 watts/square meter. It's half a dozen
| orders of magnitude more[1] energy than those fifty wi-fi
| networks are putting out. They aren't even a rounding error.
|
| The only thing the 5G 'controversy' reveals is that the public
| is happy to listen to people who don't know anything, as long
| as they are being told what they want to hear.
|
| [1] Not just more energy, more dangerous energy. Solar
| radiation, unlike 5G, is actually ionizing. Those radiation
| waves carry enough energy to break molecular bonds in your
| body.
| ummonk wrote:
| While I don't think the paranoia around 5G is justified, this
| isn't an appropriate comparison.
|
| Humans have a barrier, known as the "skin", that's designed
| to block the electromagnetic radiation from the sun and
| repair the damage it causes. Many of us even have an extra
| protective compound in us known as "melanin". Nevertheless,
| damage to this barrier from the sun is responsible for
| causing many cases of cancer and people often wear protective
| compounds, known as "sunscreen", to reduce cancer risks by
| blocking out the most dangerous ionizing radiation.
| egl2021 wrote:
| And in extreme conditions, many of us use something known
| as "clothing".
| fpoling wrote:
| It is more subtle than that. There are various protein
| molecules that vibrate inside the cells as a part of their
| normal functions including those responsible for immune
| system functions. As such there are absorption spectra due to
| resonance with vibration frequencies. This was mostly ignored
| in past, but there are speculations that 5-5O GHz radiation
| can be absorbed affecting molecular functions with unknown
| consequences.
| selimthegrim wrote:
| And where is this published?
| fpoling wrote:
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5406447/
| amirhirsch wrote:
| You read the abstract and still shared this here?
|
| "A case series of 64 patient-reported outcomes subsequent
| to use of a silver-threaded cap designed to protect the
| brain and brain stem from microwave Electrosmog resulted
| in 90 % reporting "definite" or "strong" changes in their
| disease symptoms."
|
| (edit: in case it isn't clear, this is not how you
| science)
| fpoling wrote:
| Well, you have asked for it and I wrote initially
| "speculations" without citing this. The idea that complex
| protein molecules may absorb 5-50 GHz radiation via
| proposed mechanism in the paper is at least plausible and
| the calculations from the paper does not look like
| totally unsound. So this should be investigated.
| Johnny555 wrote:
| I don't understand how they could conclude that their
| sleeping caps had any effect when they apparently went
| into the study with the belief that they work and decided
| not to have a placebo control group because it would be
| unethical.
|
| _As these patients were all ill, many undergoing
| olmesartan treatment with therapeutic intent, we decided
| that ethical considerations precluded the distribution of
| "placebo caps" without the silver threads._
|
| And they were apparently distributed to those that
| requested them, likely those that already thought they
| would work:
|
| _Sleeping caps" were sewn and, upon informed request,
| distributed free of charge to members of our follow-up
| olmesartan cohort._
| Johnny555 wrote:
| _did they study having 50 at once_
|
| Wifi signal drops off with the square of your distance from the
| radio. So if you feel safe sitting 5 feet from your own router,
| you're only getting 1/25th as much signal from your neighbor's
| router 25 feet away (well, almost certainly less since it's
| going through walls, windows, etc). (some factors can change
| this, like if he has a high gain directional antenna pointed
| directly at you, you could see more power from his router than
| from your own)
|
| So unless you're sitting in a Wifi router store surrounded by
| wifi routers, you're not getting irradiated by 50X more power
| even if your computer can see 50 wifi networks around you.
| sschueller wrote:
| Is this a failure of the FCC to properly hand out frequencies?
| mulmen wrote:
| Yes. They knew the dangers but the telcos wanted frequency. So
| the FCC attempted to undermine the aviation industry group that
| actually knows how radar altimeters work.
|
| Blancolirio covers this in several videos, although his take is
| more nuanced than mine.
|
| https://www.youtube.com/watch?v=942KXXmMJdY
| tempnow987 wrote:
| Absolutely garbage reporting. The FAA / Boeing have no right
| to the frequencies in question. Even worse, they were given
| guard bands the size of their entire allocation which is
| ridiculous, and it still wasn't enough.
| atkailash wrote:
| jjtheblunt wrote:
| is this a failure of the lobbying system, with Qualcomm funding
| something in their interest which is contrary to aviation
| interests?
|
| (I mean that i do not know the answer)
| Sanzig wrote:
| While this should have been better studied before the spectrum
| was allocated, it's not really the fault of the FCC.
|
| These radar altimeters have very wide front-ends, as as a
| result are highly susceptible to out-of-band emissions. The
| radars are allocated from 4.2 to 4.4 GHz, so the bottom edge of
| the radar altimeter band is 200 MHz _above_ the top end of the
| 5G band in question (3.98 GHz).
|
| The fact that these radar altimeters are susceptible to out-of-
| band interference that is literally further away in the
| spectrum than the width of their entire allocation is IMO an
| engineering failure. Yes, spectrum management (rightfully)
| tends to err on the side of not forcing the incumbents to make
| modifications to existing systems. However, better filtering
| would resolve this issue and it is shocking that the engineers
| who designed them didn't foresee that other services would
| eventually be allocated in adjacent bands. Avionics is often
| NRE dominated, they couldn't have sprung for a cavity filter?
| Or if that was too expensive, designed more headroom in the LNA
| before saturation and filtered the out of band signal with a
| crystal or SAW filter at IF? Rejecting out of band that far
| away is not rocket science.
|
| I don't think it's unreasonable in this case to temporarily
| suspend the rollout and give the aviation industry a deadline
| to fix its radars, but it should only be temporary. Any other
| radio service would be told to take a hike if it keeled over
| due to out of band interference that far away.
| mianos wrote:
| From an engineering perspective, I would guess, as an
| avionics tech, back in the age of dinosaurs, these radio
| altimeters are probably of a very old simplistic design as to
| have dead simple and reliable electronics built with an
| absolute minimal number of parts. The carrier generation is
| probably just a crystal and an analogue multiplier with lots
| of phase noise and wide band so a similarly simplistic
| receiver can pick it up.
| jandrese wrote:
| This seems like Boeing trying to get the government to cover
| their butt because they did shoddy work on the altimeters.
| They were allocated spectrum for the equipment and then built
| a system that monopolized frequencies well outside of the
| allocated spectrum.
|
| I completely agree that Boeing needs to issue a recall order
| on all affected hardware and provide a fix. This should be
| painful, it is basically punishment for trying to cut corners
| on safety equipment.
| adolph wrote:
| Given Boeing's reliability vector, the fix might be more
| painful to others than itself.
| mulmen wrote:
| First, these altimeters are not made by Boeing.
|
| Second, the FCC was already involved in their development
| and certification.
|
| Third, these radars have been in operation for _decades_.
|
| You are talking about thousands of planes that have to be
| modified to accommodate telcos. If anyone should pick up
| the tab for this it is Verizon and AT&T.
| krisoft wrote:
| > First, these altimeters are not made by Boeing.
|
| Who cares? The comment you are responding to says "they
| did shoddy work on the altimeters." That doesn't mean
| that Boeing built the altimeters.
|
| They specced them, procured, inspected, installed and
| sold it with the whole airplane. If the pilots' chair
| collapses, that's shoddy work on part of Boeing, and
| nobody would talk about how they are just buying the
| chairs from someone. Same with the radio altimeters.
|
| > Third, these radars have been in operation for decades.
|
| Ok? Sometimes corners cut bite you in the backside only
| after decades.
|
| There is one question which matters: Are the 5G towers
| transmitting on frequencies assigned to the use of radio
| altimeters or not? If they are they must stop. If the
| radio altimeters degrade or might degrade because of
| transmission outside of their assigned range and guard
| then they are faulty.
| mulmen wrote:
| > Are the 5G towers transmitting on frequencies assigned
| to the use of radio altimeters or not?
|
| Yes, they are.
|
| > If they are they must stop.
|
| Agree.
| Dylan16807 wrote:
| > Third, these radars have been in operation for decades.
|
| That makes their domination of spectrum far outside their
| range _worse_.
|
| If anything, threaten to retroactively charge them for
| all that bandwidth.
| kube-system wrote:
| This isn't commercially allocated spectrum. It's in
| reserved radio navigation spectrum which is used all
| around the world by multiple different users.
| Dylan16807 wrote:
| It should have similar value either way.
| kube-system wrote:
| Yes, but it's collectively used. We don't charge anyone
| for it because it's a public resource.
| worker767424 wrote:
| > Third, these radars have been in operation for decades.
| You are talking about thousands of planes that have to be
| modified to accommodate telcos.
|
| Perhaps Boeing should have bid of the spectrum that their
| products depend on being unused.
|
| This is essentially the government leasing out previously
| unused federal land for mineral extraction and a nearby
| rancher saying "it ruins my view," only with safety
| concerns added in.
| dmitrygr wrote:
| Boeing does not usually make avionics. Companies like
| Garmin, Collins, and Honeywell do.
| TheJoeMan wrote:
| To add: if you ever read an FCC label on a device it says
| "must be able to accept harmful interference" or similar.
| So I'd argue the Boeing devices are the ones out of spec,
| should be immediately revoked as out of compliance by the
| FCC, and be done with it so the masses can enjoy 5G in
| peace.
|
| I believe no agency should consider downstream effects of
| applying the law, to ensure fairness. Why should Boeing get
| a pass but say an out of compliance robotic lawnmower gets
| enforced?
| [deleted]
| willidiots wrote:
| That's a Part 15 label (see https://www.ecfr.gov/current/
| title-47/chapter-I/subchapter-A...) and it doesn't apply
| to avionics / radio navigation systems.
|
| (I do agree this is Boeing's issue to fix, 200MHz guard
| band is huge, Boeing needs filters)
| kube-system wrote:
| Does Boeing even make the radio altimeters?
| jandrese wrote:
| They certainly certified them on the aircraft. If it
| means putting pressure on the subcontractor that actually
| built them or finding a suitable replacement then so be
| it.
| gbear605 wrote:
| Unless the airlines are installing the altimeters
| themselves, it seems like Boeing is still the relevant
| company. If your car's airbag has a malfunction, the car
| manufacturer does the recall even if the fault lies with
| the airbag manufacturer. Presumably Boeing would then go
| on to sue the altimeter manufacturer though.
| kube-system wrote:
| Yes, I am simply suggesting the accusations in the first
| two sentences are misplaced.
| theYipster wrote:
| Aviation doesn't work that way. Airlines have direct
| aftermarket relationships with all of the OEMs making the
| components on their airplanes. From a certification and
| warranty standpoint, Boeing is the design authority, and
| if there is an FAA mandated fix for 737 RAs, Boeing will
| have a role to play. Whether Boeing is responsible
| financially or logistically for the fix depends on the
| nature of the failure (is it limited to the component or
| is it a systems engineering issue) as well as the
| contracts Boeing has with their supply chain and their
| airline customers.
| manquer wrote:
| That doesn't seem to be practical. Maybe for some big
| parts like engine airlines have direct relationships but
| all parts including radar altimeters ?
|
| An modern commercial plane has tens of thousands of
| suppliers supplying millions of parts. No airline [1]
| could even imagine to have the staff to manage OEM
| relationships with that many indirect suppliers. That is
| what you pay Boeing for.
|
| If that was the case no airline could afford to buy more
| than 1 type of plane or certainly not more than one
| manufacturer, you would need to handle all the suppliers
| in the industry?! it would be incredibly inefficient to
| do this for them individually .
|
| ---
|
| [1] Maybe United , American or Delta could have that kind
| of staff, but given the airlines operating margins in the
| last 2-3 decades even that seems unlikely
| [deleted]
| vkou wrote:
| It's Boeing's job to make sure that the altimeters they
| put into planes are fit for use. It doesn't matter if
| those altimeters are sourced from Boeing, General
| Electric, Uzbekistan, or the Moon - Boeing is the one who
| has to make sure they work. It's why they make the big
| bucks.
|
| Boeing can argue with and sue their suppliers, but that's
| not a problem for anyone but them and their supplier.
| mdasen wrote:
| Yes and no. Many other countries are using C-Band, but often
| under slightly different conditions. Some countries licensed
| frequencies that stop significantly farther away from the
| spectrum used by radio altimeters. Some countries have mandated
| lower power levels for C-Band. Some countries have created
| larger exclusion areas around all airports (rather than the
| smaller, temporary exclusion areas around some airports in the
| US). Some countries have mandated a downward tilt for C-Band
| antenna panels (nationwide or in areas around airports) so that
| the transmissions aren't going go up as much (but a downward
| tilt also limits the transmission range which is bad for
| wireless carriers).
|
| I think one of the big things in the US is that anything that
| makes C-Band harder to work with makes it hard for 2 of the 3
| wireless carriers to compete. T-Mobile has a lot of 2.5GHz
| spectrum that it has been using to launch high-speed 5G
| services. Verizon and AT&T had been waiting for their C-Band
| spectrum to be usable to launch their high-speed 5G services.
| In Europe, if all carriers are facing the same restrictions,
| it's a level playing field. In the US, if Verizon and AT&T face
| restrictions that T-Mobile doesn't face (for most of its
| spectrum since it's 2.5GHz and not C-Band), that doesn't offer
| a level playing field.
|
| I think it's also more contentious in the US because we have a
| much more suburban and rural population. Transmission distance
| is really important in the US because people expect to get
| modern services even in low-density areas. Verizon built its
| business on the idea that you should expect excellent wireless
| coverage even in places that have virtually no people.
|
| I think another part of it is that the FAA is often very
| cautious and it seems like they didn't coordinate well with the
| FCC in voicing their concerns early on enough.
|
| The FAA does have a web page on C-Band (https://www.faa.gov/5g)
| which is their official stance on the subject. They cite "Lower
| power levels, antennas adjusted to reduce potential
| interference to flights, different placement of antennas
| relative to airfields , and frequencies with a different
| proximity to frequencies used by aviation equipment" as reasons
| why the C-Band situation in the US is different from that in
| other countries. Is the FAA being too cautious? Maybe.
|
| Ultimately, no one wants their business plans disrupted.
| Airlines don't want to see issues that delay landings. Verizon
| and AT&T don't want to see things that delay their ability to
| provide fast 5G service.
| enos_feedler wrote:
| So what kind of settlement do we anticipate as compensation to
| Verizon and AT&T for allowing them to bid and purchase spectrum
| and then not allowing them to capture value from that spectrum,
| post-purchase? Seems like a slam dunk for a hefty payout of some
| kind.
| InitialLastName wrote:
| You could pull it directly out of the pockets of the aircraft
| manufacturers who had years of opportunities to flag and fix
| these issues, too.
| enos_feedler wrote:
| Yes. C-band and it's usage for 5G didn't just turn up
| yesterday. Even if they do get payouts they will just it to
| give every customer free Apple/Samsung stuff.
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