7 ms·

This does not seem to be borne out by the accident statistics, which apparently show no trend in turbulence related accidents. (https://www.ntsb.gov/safety/safe

by w14 2y ago

This does not seem to be borne out by the accident statistics, which apparently show no trend in turbulence related accidents. (https://www.ntsb.gov/safety/safety-studies/Documents/SS2101.pdf https://www.ntsb.gov/safety/safety-studies/Documents/SS2101....) I don't know if there are other factors which might be masking a rise in incidence of CAT from accident stats?

cassepipe 2y ago
The article seems to say that other than direct passenger injury, the issue is premature airframe fatigue, which I guess that if remarked on inspections, does not end up in the incident category.
cpncrunch 2y ago
Also, they just looked at 2 years, so there could be cherry picking. Jet stream is affected by el nino. 1979 was weak el nino, 2020 was moderate la nina. https://ggweather.com/enso/oni.htm https://ggweather.com/enso/oni.htm
- dclowd9901 2y ago
  Right, and those two years are generationally distant. Another question I have is if pilots have a stable mechanism (that is, an unchanged objective sensor or something) that records the CAT or if it’s recorded by pilots, whose sensitivity to CAT might differ over time. Didn’t mention in the article how it’s measured.
  - throwup238 2y ago
    CATs are recorded in pilot reports using terms like "light", "moderate", "severe", and "extreme" which each have a definition. I.e. severe is "Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food service and walking are impossible." I think only severe and extreme turbulence need mandatory reports and the lower two levels are a bit more subjective ("Food service and walking are difficult") Newer planes have sensors to measure eddy dissipation rates which are an objective measure of turbulence but I don't know how widespread those systems are and whether they get reported anywhere. They're mostly used for long distance transoceanic flights.
    - oceanplexian 2y ago
      Unsecured objects being tossed around has no real meaning, it’s about controllability of the aircraft. I’m a pilot and it’s been a while since I went over PIREPS but generally severe is rarely used, severe means the turbulence is so bad you can no longer control the aircraft. What most passengers imagine as severe is probably light turbulence. Most of the time it’s not even reported. As a side note if you’re ever on an aircraft and not secured at all times, you’re making a huge mistake.
      - withinboredom 2y ago
        I watched Cast Away. I always wear my seat belt.
      - makestuff 2y ago
        Have there been any reports of true severe clear air turbulence (where the pilot cannot control the plane) or are all of these cases not technically severe because the pilots were in control the entire time and it was just a bumpy ride? Another question I have is what do you do in that scenario if you can't control it? Just ride it out and hope for the best?
      - orhmeh09 2y ago
        Is using the bathroom or stretching your legs advisable?
        throwup238 2y ago
        You don't have to live in fear of turbulence when flying, just keep your seatbelt on when you're seated. Turbulence is fairly rare but it's still a numbers game. The probability that you experience it the 99% of the time you're seated is much higher than the probability of experiencing turbulence while standing, especially since pilots proactively turn on the seatbelt sign when turbulence is expected.
    - robxorb 2y ago
      So this could be a trend in pilot reporting rather than turbulence?
- SiempreViernes 2y ago
  Why do you say that? Just looking at the plots in Prosser et al (2023) it is obvious they had a lot more years than just two. If you actually read the short paper you'll find they actually used reanalysis data sampled at a rate of every three hours across 42 years to compute their statistics: > Global ERA5 reanalysis data (Hersbach et al., 2020) [...] were extracted on the 197 hPa pressure level with 0.25° horizontal resolution at three hourly intervals from 1 January 1979 to 31 December 2020. To allow the computation of CAT diagnostics that require vertical derivatives, fields on the 188 and 206 hPa levels were also extracted. The 21 turbulence diagnostics were then calculated from the extracted reanalysis fields every three hours. How you go from that to "they just looked at 2 years" is beyond me.
eggy 2y ago
Yeah, you should have more concern over human error and Boeing than this. But, boy, the more I have flown and the older I am, the more I get anxious during turbulence when I fly.
- stouset 2y ago
  When was the last time a commercial airliner crashed due to turbulence?
  - rootusrootus 2y ago
    Best I can tell, 1966. https://en.m.wikipedia.org/wiki/BOAC_Flight_911 https://en.m.wikipedia.org/wiki/BOAC_Flight_911
    - stouset 2y ago
      Then I think we can safely worry about other things than turbulence :)
      - septic-liqueur 2y ago
        But you never know... You might be the first one :-)
    - dmux 2y ago
      >The Boeing 707 jetliner involved disintegrated mid-air I'm guessing their use of "disintegrated" there is supposed to be taken literally as dis-integrated, but upon first read, I took it for its more colloquial meaning (which to me is closer to pulverized, turn to dust, dissolve etc).
    - kelnos 2y ago
      Oh man: > Several booked passengers cancelled their tickets at the last moment to see a ninja demonstration. These passengers, Albert R. Broccoli, Harry Saltzman, Ken Adam, Lewis Gilbert, and Freddie Young, were in Japan scouting locations for the fifth James Bond film, You Only Live Twice (1967). The James Bond franchise would likely have been quite a bit different had Broccoli died in 1966. Crazy to think he and his colleagues cheated death because they wanted to play tourist a little bit longer than originally scheduled.
vanderZwan 2y ago
Well, assuming that there is indeed more turbulence, that could also mean more vigilance against accidents, so that could even itself out as safety regulations get stricter than in the past. Also, this is mentioned in the conclusions: > The report includes an important discussion of the risk to unrestrained occupants onboard aircraft, including flight attendants – who account for nearly 80% of those seriously injured in turbulence-related accidents. Key recommendations in the report are intended to help ensure better protections for flight attendants ... which makes me think of two more possibilities: 1 - I suspect any careless flight attendant involved in a turbulence-related accident would learn their lesson after the first time, and take better safety precautions. Perhaps that is a stabilizing factor on the number of accidents, since the number of flight attendants who need to learn that lesson the hard way is probably more a function of how many new flight attendants enter the field than it is a product of how much turbulence there is. 2 - Flight attendants under-report minor accidents so they don't get into trouble for not respecting safety rules Of course, this is pure speculation (and assuming that the premise of there being more CAT incidents holds up), I'm sure the actual document goes into this kind of thing in more detail but I don't have the time to dig through 115 papers.
- FabHK 2y ago
  > I suspect any careless flight attendant involved in a turbulence-related accident would learn their lesson after the first time, and take better safety precautions. They are briefed, no need to learn their lessons after the first time. However, it's part of their job to walk around the plane (eg to serve food), and so they're less likely to be seated than pax. That is the (rather obvious) explanation for the fact that they constitute a very high proportion of victims, not "careless"ness.
ImaCake 2y ago
Certainly no detectable trend in that data. But the accident frequency is so low that the random variation dominates and makes it impossible to distinguish any trend. What is demonstrably increasing is CAT, due to climate change. But considering how infrequent these incidents are we might not see a clear increase for several decades.
- vlovich123 2y ago
  Do we really not record turbulence sensor data off the airplanes and download it when they’re on the ground? I’m also surprised that these airplanes have on demand satellite TV streaming to these airplanes but airlines claim that it costs 100k to add that to existing planes. There’s just no way it’s 100k per plane - there must be a cheap way to retrofit the data without having it be reliable since it’s opportunistic. And heck, France is doing it every 4 minutes for their planes so why can’t Americans figure out how to do it.
  - TylerE 2y ago
    If satelite TV is down, some passengers are mildly annoyed. If a regulatory required part of the aircraft is non-functional, you're not going flying today.
    - vlovich123 2y ago
      You’re saying it’s impossible to have an optionally required feature? If the satellite TV is down some sensor data isn’t sent. Why would that be cause for grounding the plane? You could easily make the regulation an SLA like all routes flown must be sending data for 90% of the flights on that route for the month and failures to meet the SLA are investigated. Also I’ve flown a bunch and I’ve rarely seen the Internet link go out except where there’s technical limitations like crossing the ocean where they can’t maintain an internet and have to rely on preprogrammed content. Given how much money they make from cabin internet, the airlines are clearly incentivized to apply pressure to keep those things running. I doubt I’ve seen anyone be really annoyed when there’s technical difficulties. Most people who fall into that category would have made other arrangements for entertainment anyway.
_moof 2y ago
An increase in the frequency of clear air turbulence doesn't necessarily entail an increase in reportable accidents and incidents. The NTSB is only notified when a specific set of criteria are met. See 49 CFR Part 830 for details. If the increase in turbulence is all light to moderate turbulence with no serious injuries, there's nothing to report to the NTSB.
- deleted 2y ago
  [deleted]
- alfalfasprout 2y ago
  This deserves to be the top comment. Turbulence accident statistics are only going to ever reflect clear air turbulence if the aircraft sustained detectable damage or passenger(s) sustain serious enough injuries.
  - User23 2y ago
    In that case what’s the explanation for clear air turbulence events having an exactly proportionally lower rate of causing damage and injury such that the rate has remained flat despite the increase in events? What’s making turbulence safer? Edit: this isn’t a rhetorical question. I’m very interested in any proposed actual mechanism. As someone who is very alarmed by turbulence I’d love a reason to believe it’s getting safer.
    - tracerbulletx 2y ago
      There's no reason there couldn't be a statistical increase in turbulence without a statistical increase in accidents if the intensity hasn't crossed a threshold for the amount of turbulence todays planes can safely sustain.
    - largbae 2y ago
      Is it possible that the overall increase in flights, areas served, and data collection is simply giving us more coverage?
    - 2y ago
rdtsc 2y ago
Could be an inverse relationship, too - the more frequently they occur the more experience, training and guidance the pilot, and the other crew members get to manage it: how to control the the airplane, urge passengers to wear seatbelts more, etc.
JoshGG 2y ago
There is a big factor out there that is 'masking a rise in incidence of CAT from accident stats'. It's Aerospace Engineers and the aviation engineering and safety community. -- Most CAT events (seen so far) are survivable by current aircraft designs, so you can have an increase in CAT without a spike in crashes and other accidents.

by w14 2y ago

cassepipe 2y ago

The article seems to say that other than direct passenger injury, the issue is premature airframe fatigue, which I guess that if remarked on inspections, does not end up in the incident category.

cpncrunch 2y ago

Also, they just looked at 2 years, so there could be cherry picking. Jet stream is affected by el nino. 1979 was weak el nino, 2020 was moderate la nina. https://ggweather.com/enso/oni.htm https://ggweather.com/enso/oni.htm

dclowd9901 2y ago
Right, and those two years are generationally distant. Another question I have is if pilots have a stable mechanism (that is, an unchanged objective sensor or something) that records the CAT or if it’s recorded by pilots, whose sensitivity to CAT might differ over time. Didn’t mention in the article how it’s measured.
- throwup238 2y ago
  CATs are recorded in pilot reports using terms like "light", "moderate", "severe", and "extreme" which each have a definition. I.e. severe is "Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food service and walking are impossible." I think only severe and extreme turbulence need mandatory reports and the lower two levels are a bit more subjective ("Food service and walking are difficult") Newer planes have sensors to measure eddy dissipation rates which are an objective measure of turbulence but I don't know how widespread those systems are and whether they get reported anywhere. They're mostly used for long distance transoceanic flights.
  - oceanplexian 2y ago
    Unsecured objects being tossed around has no real meaning, it’s about controllability of the aircraft. I’m a pilot and it’s been a while since I went over PIREPS but generally severe is rarely used, severe means the turbulence is so bad you can no longer control the aircraft. What most passengers imagine as severe is probably light turbulence. Most of the time it’s not even reported. As a side note if you’re ever on an aircraft and not secured at all times, you’re making a huge mistake.
    - withinboredom 2y ago
      I watched Cast Away. I always wear my seat belt.
    - makestuff 2y ago
      Have there been any reports of true severe clear air turbulence (where the pilot cannot control the plane) or are all of these cases not technically severe because the pilots were in control the entire time and it was just a bumpy ride? Another question I have is what do you do in that scenario if you can't control it? Just ride it out and hope for the best?
    - orhmeh09 2y ago
      Is using the bathroom or stretching your legs advisable?
      - throwup238 2y ago
        You don't have to live in fear of turbulence when flying, just keep your seatbelt on when you're seated. Turbulence is fairly rare but it's still a numbers game. The probability that you experience it the 99% of the time you're seated is much higher than the probability of experiencing turbulence while standing, especially since pilots proactively turn on the seatbelt sign when turbulence is expected.
  - robxorb 2y ago
    So this could be a trend in pilot reporting rather than turbulence?
SiempreViernes 2y ago
Why do you say that? Just looking at the plots in Prosser et al (2023) it is obvious they had a lot more years than just two. If you actually read the short paper you'll find they actually used reanalysis data sampled at a rate of every three hours across 42 years to compute their statistics: > Global ERA5 reanalysis data (Hersbach et al., 2020) [...] were extracted on the 197 hPa pressure level with 0.25° horizontal resolution at three hourly intervals from 1 January 1979 to 31 December 2020. To allow the computation of CAT diagnostics that require vertical derivatives, fields on the 188 and 206 hPa levels were also extracted. The 21 turbulence diagnostics were then calculated from the extracted reanalysis fields every three hours. How you go from that to "they just looked at 2 years" is beyond me.

eggy 2y ago

Yeah, you should have more concern over human error and Boeing than this. But, boy, the more I have flown and the older I am, the more I get anxious during turbulence when I fly.

stouset 2y ago
When was the last time a commercial airliner crashed due to turbulence?
- rootusrootus 2y ago
  Best I can tell, 1966. https://en.m.wikipedia.org/wiki/BOAC_Flight_911 https://en.m.wikipedia.org/wiki/BOAC_Flight_911
  - stouset 2y ago
    Then I think we can safely worry about other things than turbulence :)
    - septic-liqueur 2y ago
      But you never know... You might be the first one :-)
  - dmux 2y ago
    >The Boeing 707 jetliner involved disintegrated mid-air I'm guessing their use of "disintegrated" there is supposed to be taken literally as dis-integrated, but upon first read, I took it for its more colloquial meaning (which to me is closer to pulverized, turn to dust, dissolve etc).
  - kelnos 2y ago
    Oh man: > Several booked passengers cancelled their tickets at the last moment to see a ninja demonstration. These passengers, Albert R. Broccoli, Harry Saltzman, Ken Adam, Lewis Gilbert, and Freddie Young, were in Japan scouting locations for the fifth James Bond film, You Only Live Twice (1967). The James Bond franchise would likely have been quite a bit different had Broccoli died in 1966. Crazy to think he and his colleagues cheated death because they wanted to play tourist a little bit longer than originally scheduled.

vanderZwan 2y ago

Well, assuming that there is indeed more turbulence, that could also mean more vigilance against accidents, so that could even itself out as safety regulations get stricter than in the past. Also, this is mentioned in the conclusions: > The report includes an important discussion of the risk to unrestrained occupants onboard aircraft, including flight attendants – who account for nearly 80% of those seriously injured in turbulence-related accidents. Key recommendations in the report are intended to help ensure better protections for flight attendants ... which makes me think of two more possibilities: 1 - I suspect any careless flight attendant involved in a turbulence-related accident would learn their lesson after the first time, and take better safety precautions. Perhaps that is a stabilizing factor on the number of accidents, since the number of flight attendants who need to learn that lesson the hard way is probably more a function of how many new flight attendants enter the field than it is a product of how much turbulence there is. 2 - Flight attendants under-report minor accidents so they don't get into trouble for not respecting safety rules Of course, this is pure speculation (and assuming that the premise of there being more CAT incidents holds up), I'm sure the actual document goes into this kind of thing in more detail but I don't have the time to dig through 115 papers.

FabHK 2y ago
> I suspect any careless flight attendant involved in a turbulence-related accident would learn their lesson after the first time, and take better safety precautions. They are briefed, no need to learn their lessons after the first time. However, it's part of their job to walk around the plane (eg to serve food), and so they're less likely to be seated than pax. That is the (rather obvious) explanation for the fact that they constitute a very high proportion of victims, not "careless"ness.

ImaCake 2y ago

Certainly no detectable trend in that data. But the accident frequency is so low that the random variation dominates and makes it impossible to distinguish any trend. What is demonstrably increasing is CAT, due to climate change. But considering how infrequent these incidents are we might not see a clear increase for several decades.

vlovich123 2y ago
Do we really not record turbulence sensor data off the airplanes and download it when they’re on the ground? I’m also surprised that these airplanes have on demand satellite TV streaming to these airplanes but airlines claim that it costs 100k to add that to existing planes. There’s just no way it’s 100k per plane - there must be a cheap way to retrofit the data without having it be reliable since it’s opportunistic. And heck, France is doing it every 4 minutes for their planes so why can’t Americans figure out how to do it.
- TylerE 2y ago
  If satelite TV is down, some passengers are mildly annoyed. If a regulatory required part of the aircraft is non-functional, you're not going flying today.
  - vlovich123 2y ago
    You’re saying it’s impossible to have an optionally required feature? If the satellite TV is down some sensor data isn’t sent. Why would that be cause for grounding the plane? You could easily make the regulation an SLA like all routes flown must be sending data for 90% of the flights on that route for the month and failures to meet the SLA are investigated. Also I’ve flown a bunch and I’ve rarely seen the Internet link go out except where there’s technical limitations like crossing the ocean where they can’t maintain an internet and have to rely on preprogrammed content. Given how much money they make from cabin internet, the airlines are clearly incentivized to apply pressure to keep those things running. I doubt I’ve seen anyone be really annoyed when there’s technical difficulties. Most people who fall into that category would have made other arrangements for entertainment anyway.

_moof 2y ago

An increase in the frequency of clear air turbulence doesn't necessarily entail an increase in reportable accidents and incidents. The NTSB is only notified when a specific set of criteria are met. See 49 CFR Part 830 for details. If the increase in turbulence is all light to moderate turbulence with no serious injuries, there's nothing to report to the NTSB.

deleted 2y ago
[deleted]
alfalfasprout 2y ago
This deserves to be the top comment. Turbulence accident statistics are only going to ever reflect clear air turbulence if the aircraft sustained detectable damage or passenger(s) sustain serious enough injuries.
- User23 2y ago
  In that case what’s the explanation for clear air turbulence events having an exactly proportionally lower rate of causing damage and injury such that the rate has remained flat despite the increase in events? What’s making turbulence safer? Edit: this isn’t a rhetorical question. I’m very interested in any proposed actual mechanism. As someone who is very alarmed by turbulence I’d love a reason to believe it’s getting safer.
  - tracerbulletx 2y ago
    There's no reason there couldn't be a statistical increase in turbulence without a statistical increase in accidents if the intensity hasn't crossed a threshold for the amount of turbulence todays planes can safely sustain.
  - largbae 2y ago
    Is it possible that the overall increase in flights, areas served, and data collection is simply giving us more coverage?
  - 2y ago

rdtsc 2y ago

Could be an inverse relationship, too - the more frequently they occur the more experience, training and guidance the pilot, and the other crew members get to manage it: how to control the the airplane, urge passengers to wear seatbelts more, etc.

JoshGG 2y ago

There is a big factor out there that is 'masking a rise in incidence of CAT from accident stats'. It's Aerospace Engineers and the aviation engineering and safety community. -- Most CAT events (seen so far) are survivable by current aircraft designs, so you can have an increase in CAT without a spike in crashes and other accidents.