5 ms·

I think there is some context missing from this; The 5G band that was auctioned off is only one step next to the band used by radar altimeters - essentially a

by _s 4y ago

I think there is some context missing from this; The 5G band that was auctioned off is only one step next to the band used by radar altimeters - essentially a piece of equipment on aircraft that gives it its precise height above the ground. Aircraft can and do have barometric (pressure corrected) and GPS altimeters as well (which are usually giving you your height above sea level - and knowing the height of the terrain you can work out your height above ground), all of which feed into the various systems allowing them to have an accurate height at any given point during the flight. This is most needed when flying “precision 3D approaches”, usually in bad weather when visual contact with the ground may not be possible until the wheels actually touch the ground. Autopilot systems that land the aircraft fly these “approaches”, and thus rely greatly on their height, speed and distance. These radar altimeters were mostly designed and certified back in the 80’s (or even earlier!) - and it’s a lot of work to have any equipment certified - especially today. Hardware + software back then was nowhere near as good as it is today, yet many of these altimeters still being produced today would be to the original spec from a few decades ago - which had a much wider tolerance or sensitivity to the frequencies, so when you have a frequency only a few steps away - a slightly older / worn equipment with perhaps not the best shielding will definitely pick up some surges from frequencies next to it. Blame the FAA for their archaic and slow, near impossible process to get equipment certified. Blame the Aircraft / Equipment manufacturers for not updating their equipment with the times, but that’s on the FAA for making this process difficult- see 737 certification as an example, leading to the max accidents. See https://en.m.wikipedia.org/wiki/5G#Aviation https://en.m.wikipedia.org/wiki/5G#Aviation

Someone1234 4y ago
> FAA for making this process difficult- see 737 certification as an example, leading to the max accidents. The certification process being "difficult" isn't why the 737 Max was unsafe. The FAA allowed Boeing to self-certify its safety, and voices inside the company were ignored or silence. They literally created a system to save a buck for their clients then outsourced development of that system to save another buck, then rubber-stamped it themselves. Blaming this on too much or too difficult regulation is farcical. PS - I also find the entire thrust of this argument contradictory: "Equipment built in the 80s wasn't high enough quality for the new 5G operating environment, so we need to weaken 'difficult' regulation today to make producing lower quality equipment cheaper, tomorrow be damned."
- eru 4y ago
  Regulation has more than one dimension. We are not limited to talking about 'weakening' or 'strengthening' regulations. We can talk about making saner rules, too.
- _s 4y ago
  Going through the process to type certify the Max as anything other than a 737 would’ve been far more expensive, slow and painful for Boeing and all its customers because of how slow and difficult the FAA is. They added the MCAS because they didn’t want the Max to be a different type, which meant starting the certification process from scratch. They were able to self certify precisely because it was a 737 type. Yes - there were many issues that lead to the accidents and you can’t really point to just the one thing; but ultimately it did boil down to a culture at the company created by the environment it operates under. I’m not defending Boeing here - if anything, I’m more upset at them as they had the engineering will and talent, the political and financial backing to make meaningful changes to the regulatory environment and make aviation safer as a manufacturer - but they chose greed. Lastly, that’s nowhere near what I said but I can see how you can get to that conclusion. I’m an aviation enthusiast and a Pilot (feel free to go through my post history) - and it’s not a question of weakening regulation; it’s a matter of streamlining ways to get new technology certified faster - it only took 3 decades for the FAA to give the STC for unleaded gasoline etc etc.
  - broeng 4y ago
    Just to add a bit to this, as far as I understand, they didn't want the Max to be certified as something other than a normal 737, not because of certifying the aircraft, but because it would also mean all pilots would need additional training or even new type ratings to fly it. Though, adding the MCAS, which in certain circumstances overrides the pilots instructions, should most certainly have triggered new training for the pilots for those situations, at the very least.
  - photochemsyn 4y ago
    I'm pretty sure the reason that Boeing didn't want to certify the Max as anything other than a 737 is that this would have required expensive pilot-retraining for all airlines purchasing that aircraft, and this would have put Boeing in a bad position relative to Airbus, with the main factor being 'fuel burn per seat' where the Airbus A320neo had an initial advantage. The plane designs are nicely compared here (2014), esp. Fig 2: https://seekingalpha.com/article/2765285-the-battle-on-the-narrow-body-market-boeing-737-next-generation-or-airbus-a320 https://seekingalpha.com/article/2765285-the-battle-on-the-n... The shoddy software primarily responsible for the Boeing 737MAX disasters was introduced so that Boeing could market the planes to airlines as a standard 737 that required no expensive pilot training programs, as far as I can tell. The nature of the FAA's regulatory process seems mostly irrelevant here, unless rushing poorly designed products with huge risk profiles to market to help Boeing improve sales is something the FAA should promote... note also that Boeing lost around $30 billion in market value over the MAX debacle, which could have been avoided by FAA being more strict, even if that mean fewer plane orders.
darksaints 4y ago
This is just as much the FCCs fault as the FAA. They were the ones that certified the frequency usage of these altimeters, and they should have noticed that these altimeters could experience interference from satcom frequencies over 400MHz (!!!) away. They could have stopped this decades ago, but they let it go on long enough to become a massive problem. A lot of people don't seem to grasp the magnitude of the spectrum lost to this snafu. At today's realizable spectral efficiencies, that is 2.5 TB/s of usable data throughput lost to the 400MHz guard band alone. It's also ~$130B worth of revenue that the FCC could have had if they could actually sell it.
- toast0 4y ago
  Sure, the receivers could experience interference from satcom frequencies in theory, but in practice satcom broadcasts are very low strength, so there was not much risk of harmful interference until the frequency was repurposed for terrestrial, high power broadcasts. You don't put hurricane windows on buildings that have no hurricane risk, and you don't put tight bandpass filters on receivers in the satellite bands. When hurricane patterns or satellite bands change, you get problems though.
  - darksaints 4y ago
    Satcom downlinks might be low power, but uplinks, especially from dedicated base stations (as opposed to satellite phones) can easily run into the hundreds of watts.
- shadowgovt 4y ago
  The problem here was sort of ideal for falling through the cracks. The FAA is an executive administration ultimately organized under Dept. of Transportation. The FCC is an independent executive agency overseen, ultimately, by Congress. As a result, neither org has unilateral authority to tell the other to go pound sand, nor do their up-org leadership (ultimately, the President v. Congress). Their inability to find a resolution that didn't leave American pilots floundering is reflective of the inability of the Legislative and Executive branches to work together in modern federal governance, in general. Expect more issues like this in the future.
ominous_prime 4y ago
It doesn't matter how easy the new certification process is, or how the technical specification said it _should_ have worked; this was existing technology that was otherwise working. You can't come in and step on existing infrastructure, then declare ex post facto that it should have gotten out of the way before you got there.
deeblering4 4y ago
We enjoy accessible and safe air travel in no small part due to the strict regulations by FAA and EASA. Aviation is an industry where new products absolutely should not be fast tracked into deployment. The rules and regulations that are in place today were written in blood. If anything it's the weakening of these regulations (i.e. manufacturer self-certification) that enabled the MAX disasters.
kmeisthax 4y ago
No, blame the FCC for not properly clearing frequencies used by safety-critical equipment before reassigning them to 5G. They wanted to stick cellphones right next to altimeters, it should be their burden to make sure all the altimeters currently deployed won't get hit with sideband noise. The FAA's approach is reasonable because safety-critical equipment is, well, critical to safety. The FCC got rolled by the 5G hype train and failed to do its job - i.e. allocate frequencies to avoid unintended interference.
- naikrovek 4y ago
  there is a 220MHz buffer between the two bands. that's eleven (11) terrestrial commercial FM radio bands worth of gap. 220MHz is sufficient if your altimeter radar has the proper selectivity. ground radars are so selective that you can have two radar devices operating at the same frequency aimed at each other without interference.
  - TristanBall 4y ago
    Sorry? Would you mind explaining that for a layman? How do two devices on the same frequency, pointing at each other, not interfere?
    - naikrovek 4y ago
      because they look for reflected signals, which changes how the waveform is shaped, and there is circuitry which ignores unreflected inputs. additionally, the radars sweep through their bands rather than broadcast on all of it at once, so the chance of them looking for the frequency that the other radar is sending at the exact moment it is being sent is very small, and when it does happen it is easily ignored. the sweeping is what provides the ability to easily detect movement and change in distance from radar to target. this is all based on a book I read years ago, so I apologize if any of it is not exactly on the dot accurate.
      - TristanBall 4y ago
susanasj 4y ago
The FAA being archaic was absolutely not the cause of the MAX incidents. Boeing released a plane with a single point of failure that failed, and they also neglected to tell pilots and FAA about this single point of failure because pilots unions would have insisted on training in a simulator (which costs Boeing money) and the FAA may have insisted on a redesign or also simulator training. Your comment is a complete mischaracterization of the MAX incidents beyond what even Boeing public relations was willing to do.
- Dylan16807 4y ago
  It's relevant, at least. The single point of failure was a bad implementation detail of a bad feature, and that feature mostly existed because of how all-or-nothing the "aircraft type" training is.
- deleted 4y ago
  [deleted]
shostack 4y ago
Cat IIIc landings are no joke. https://www.aopa.org/news-and-media/all-news/2019/september/pilot/on-instruments-how-low-can-you-go https://www.aopa.org/news-and-media/all-news/2019/september/...

by _s 4y ago

Someone1234 4y ago

> FAA for making this process difficult- see 737 certification as an example, leading to the max accidents. The certification process being "difficult" isn't why the 737 Max was unsafe. The FAA allowed Boeing to self-certify its safety, and voices inside the company were ignored or silence. They literally created a system to save a buck for their clients then outsourced development of that system to save another buck, then rubber-stamped it themselves. Blaming this on too much or too difficult regulation is farcical. PS - I also find the entire thrust of this argument contradictory: "Equipment built in the 80s wasn't high enough quality for the new 5G operating environment, so we need to weaken 'difficult' regulation today to make producing lower quality equipment cheaper, tomorrow be damned."

eru 4y ago
Regulation has more than one dimension. We are not limited to talking about 'weakening' or 'strengthening' regulations. We can talk about making saner rules, too.
_s 4y ago
Going through the process to type certify the Max as anything other than a 737 would’ve been far more expensive, slow and painful for Boeing and all its customers because of how slow and difficult the FAA is. They added the MCAS because they didn’t want the Max to be a different type, which meant starting the certification process from scratch. They were able to self certify precisely because it was a 737 type. Yes - there were many issues that lead to the accidents and you can’t really point to just the one thing; but ultimately it did boil down to a culture at the company created by the environment it operates under. I’m not defending Boeing here - if anything, I’m more upset at them as they had the engineering will and talent, the political and financial backing to make meaningful changes to the regulatory environment and make aviation safer as a manufacturer - but they chose greed. Lastly, that’s nowhere near what I said but I can see how you can get to that conclusion. I’m an aviation enthusiast and a Pilot (feel free to go through my post history) - and it’s not a question of weakening regulation; it’s a matter of streamlining ways to get new technology certified faster - it only took 3 decades for the FAA to give the STC for unleaded gasoline etc etc.
- broeng 4y ago
  Just to add a bit to this, as far as I understand, they didn't want the Max to be certified as something other than a normal 737, not because of certifying the aircraft, but because it would also mean all pilots would need additional training or even new type ratings to fly it. Though, adding the MCAS, which in certain circumstances overrides the pilots instructions, should most certainly have triggered new training for the pilots for those situations, at the very least.
- photochemsyn 4y ago
  I'm pretty sure the reason that Boeing didn't want to certify the Max as anything other than a 737 is that this would have required expensive pilot-retraining for all airlines purchasing that aircraft, and this would have put Boeing in a bad position relative to Airbus, with the main factor being 'fuel burn per seat' where the Airbus A320neo had an initial advantage. The plane designs are nicely compared here (2014), esp. Fig 2: https://seekingalpha.com/article/2765285-the-battle-on-the-narrow-body-market-boeing-737-next-generation-or-airbus-a320 https://seekingalpha.com/article/2765285-the-battle-on-the-n... The shoddy software primarily responsible for the Boeing 737MAX disasters was introduced so that Boeing could market the planes to airlines as a standard 737 that required no expensive pilot training programs, as far as I can tell. The nature of the FAA's regulatory process seems mostly irrelevant here, unless rushing poorly designed products with huge risk profiles to market to help Boeing improve sales is something the FAA should promote... note also that Boeing lost around $30 billion in market value over the MAX debacle, which could have been avoided by FAA being more strict, even if that mean fewer plane orders.

darksaints 4y ago

This is just as much the FCCs fault as the FAA. They were the ones that certified the frequency usage of these altimeters, and they should have noticed that these altimeters could experience interference from satcom frequencies over 400MHz (!!!) away. They could have stopped this decades ago, but they let it go on long enough to become a massive problem. A lot of people don't seem to grasp the magnitude of the spectrum lost to this snafu. At today's realizable spectral efficiencies, that is 2.5 TB/s of usable data throughput lost to the 400MHz guard band alone. It's also ~$130B worth of revenue that the FCC could have had if they could actually sell it.

toast0 4y ago
Sure, the receivers could experience interference from satcom frequencies in theory, but in practice satcom broadcasts are very low strength, so there was not much risk of harmful interference until the frequency was repurposed for terrestrial, high power broadcasts. You don't put hurricane windows on buildings that have no hurricane risk, and you don't put tight bandpass filters on receivers in the satellite bands. When hurricane patterns or satellite bands change, you get problems though.
- darksaints 4y ago
  Satcom downlinks might be low power, but uplinks, especially from dedicated base stations (as opposed to satellite phones) can easily run into the hundreds of watts.
shadowgovt 4y ago
The problem here was sort of ideal for falling through the cracks. The FAA is an executive administration ultimately organized under Dept. of Transportation. The FCC is an independent executive agency overseen, ultimately, by Congress. As a result, neither org has unilateral authority to tell the other to go pound sand, nor do their up-org leadership (ultimately, the President v. Congress). Their inability to find a resolution that didn't leave American pilots floundering is reflective of the inability of the Legislative and Executive branches to work together in modern federal governance, in general. Expect more issues like this in the future.

ominous_prime 4y ago

It doesn't matter how easy the new certification process is, or how the technical specification said it _should_ have worked; this was existing technology that was otherwise working. You can't come in and step on existing infrastructure, then declare ex post facto that it should have gotten out of the way before you got there.

deeblering4 4y ago

We enjoy accessible and safe air travel in no small part due to the strict regulations by FAA and EASA. Aviation is an industry where new products absolutely should not be fast tracked into deployment. The rules and regulations that are in place today were written in blood. If anything it's the weakening of these regulations (i.e. manufacturer self-certification) that enabled the MAX disasters.

kmeisthax 4y ago

No, blame the FCC for not properly clearing frequencies used by safety-critical equipment before reassigning them to 5G. They wanted to stick cellphones right next to altimeters, it should be their burden to make sure all the altimeters currently deployed won't get hit with sideband noise. The FAA's approach is reasonable because safety-critical equipment is, well, critical to safety. The FCC got rolled by the 5G hype train and failed to do its job - i.e. allocate frequencies to avoid unintended interference.

naikrovek 4y ago
there is a 220MHz buffer between the two bands. that's eleven (11) terrestrial commercial FM radio bands worth of gap. 220MHz is sufficient if your altimeter radar has the proper selectivity. ground radars are so selective that you can have two radar devices operating at the same frequency aimed at each other without interference.
- TristanBall 4y ago
  Sorry? Would you mind explaining that for a layman? How do two devices on the same frequency, pointing at each other, not interfere?
  - naikrovek 4y ago
    because they look for reflected signals, which changes how the waveform is shaped, and there is circuitry which ignores unreflected inputs. additionally, the radars sweep through their bands rather than broadcast on all of it at once, so the chance of them looking for the frequency that the other radar is sending at the exact moment it is being sent is very small, and when it does happen it is easily ignored. the sweeping is what provides the ability to easily detect movement and change in distance from radar to target. this is all based on a book I read years ago, so I apologize if any of it is not exactly on the dot accurate.
    - TristanBall 4y ago

susanasj 4y ago

The FAA being archaic was absolutely not the cause of the MAX incidents. Boeing released a plane with a single point of failure that failed, and they also neglected to tell pilots and FAA about this single point of failure because pilots unions would have insisted on training in a simulator (which costs Boeing money) and the FAA may have insisted on a redesign or also simulator training. Your comment is a complete mischaracterization of the MAX incidents beyond what even Boeing public relations was willing to do.

Dylan16807 4y ago
It's relevant, at least. The single point of failure was a bad implementation detail of a bad feature, and that feature mostly existed because of how all-or-nothing the "aircraft type" training is.
deleted 4y ago
[deleted]

shostack 4y ago

Cat IIIc landings are no joke. https://www.aopa.org/news-and-media/all-news/2019/september/pilot/on-instruments-how-low-can-you-go https://www.aopa.org/news-and-media/all-news/2019/september/...