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Is Clear Air Turbulence becoming more common?

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Re: Is Clear Air Turbulence becoming more common?

#111

Post by eggy »

FabHK wrote: post #52
eggy wrote: post #36

Earlier quoted context omitted.

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.

I relax when it's turbulent. The airframe can handle it [1], and at least the pilots are awake. [1] There's a speed limit for turbulence penetration, chosen such that the wings will stall, rather than over-stress the airframe.

Thank you! That's definitely a great way to look at it. Complacency and habit breed accidents. Although not the the Boeing/mechanical issues. Still worried about the ghost in the machine or gremlins!

Re: Is Clear Air Turbulence becoming more common?

#112

Post by mulmen »

londons_explore wrote: post #105
MadnessASAP wrote: post #57

Earlier quoted context omitted.

> Do we really not record turbulence sensor data off the airplanes and download it when they’re on the ground? No, accelerometer data is only recorded to the FDR. Which has a limited storage window (1-24 hours depending on the aircraft) and is slow to download requiring moderately specialized equipment and a technician to carry out the task. Aircraft downtime and technician hours are both expensive and in short suppl…

Meanwhile an accelerometer, microcontroller and a years worth of storage for the data probably all could be made with $5 worth of parts and a summer intern...

Comments like this make me glad the FAA requires certification for everything.

Re: Is Clear Air Turbulence becoming more common?

#113

Post by mulmen »

vlovich123 wrote: post #76
MadnessASAP wrote: post #57

Earlier quoted context omitted.

> Do we really not record turbulence sensor data off the airplanes and download it when they’re on the ground? No, accelerometer data is only recorded to the FDR. Which has a limited storage window (1-24 hours depending on the aircraft) and is slow to download requiring moderately specialized equipment and a technician to carry out the task. Aircraft downtime and technician hours are both expensive and in short suppl…

I find it hard to believe that the headsets they are using for software and hardware meet that level of criteria. They’re clearly using off-the-shelf parts. Some amount of care is called for sure, but 100k to apply a software patch or tweak the tech in FDRs which are swappable and upgradable? A flight recorder is 10k. You can’t tell me it costs 90k to install a new one capable of sending data over the satellite link…

You’re solving a human problem with technology. Pilots are resistant to data collection because of the proven track record of airlines using it against them. Unintended consequences are fatal in aviation. Saying “it ought to be easy” is an immediately disqualifying statement. You should ask instead why it is so expensive. Then decide if there’s a margin worth eroding.

Re: Is Clear Air Turbulence becoming more common?

#114

Post by joohwan »

sandywaffles wrote: post #23

> [Clear Air Turbulence] is particularly common around the tropopause, the boundary layer between the troposphere and the stratosphere, at altitudes between 7,000 and 12,000 meters (23,000 to 39,000 feet) . Oh, excellent the altitudes that 99% of aircraft fly at, unaffecting the ultra rich who fly private jets at 40,000k-50,000k+.

Why is this comment being downvoted? Is it not true?

Re: Is Clear Air Turbulence becoming more common?

#115

Post by lxgr »

nytesky wrote: post #9

I wonder if this is like an immune system response by mother nature, it’s attacking the thing that’s warming it up i.e. air travel? Self correcting systems

On the other hand, so far I haven't heard any reports of any steel mill or cement plant being destroyed by clear air turbulence.

Re: Is Clear Air Turbulence becoming more common?

#116

Post by ghodith »

lxgr wrote: post #107
animex wrote: post #103

Could this be internet-enabled flight bias? Now that we have more and more WiFi enabled flights, more people posting about it on socials...so public awareness grows but as indicated before only incident-related stats are being recorded. One can extrapolate if incidents including damage or injury are not increasing per capita of flights it's probably not a trend.

What would prevent people from just posting the same videos and tweets once they land?

You forget because it happened five hours ago and you are now busy getting on with your life?

Re: Is Clear Air Turbulence becoming more common?

#117

Post by pc86 »

nickjj wrote: post #42
pc86 wrote: post #27

Earlier quoted context omitted.

Private jets don't really fly at 50k that often but I'm sure there are some that can. 40-42k is pretty common though. There are a handful of reasons. In no particular order: 1) additional separation between recreational private flights and scheduled commercial flights 2) higher performance in small private jets with typically less than 1k lbs of people and cargo 3) winds are generally faster the higher you go so you'…

> 3) winds are generally faster the higher you go so you'll usually go about at high as you're able, at least in one direction. I recently flew from NYC to Lisbon, Portugal and it was 6.5 hours there (flying east) and 7.5 hours back (flying west) because you go with and against the jet stream. I wonder if there's a noticeable difference if you fly at a lower altitude against the wind. It didn't seem like the plane ad…

Airlines have dispatch folks that spend a lot of time deciding what altitude and route to file. Yes there are defaults so it's certainly possible they were busy and just filed the same but especially days apart it's likely that was the optimal altitude.

They're also looking at fuel economy so even if it takes longer if the air is thinner and they burn less fuel they may still save money. I imagine there's a certain distance where those two lines cross that is probably baked into the dispatch software for each plane model.

Re: Is Clear Air Turbulence becoming more common?

#119

Post by SiempreViernes »

cpncrunch wrote: post #33
w14 wrote: post #29

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.... ) I don't know if there are other factors which might be masking a rise in incidence of CAT from accident stats?

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

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.

Re: Is Clear Air Turbulence becoming more common?

#120

Post by therobots927 »

jameshart wrote: post #104

Most of the recent widely publicized CAT injuries have been on long distance flights between Europe and South Asia. One thing that’s happened in the past couple of years along that air corridor is the squeezing of flight paths out of Ukrainian, Russian, Israeli, and Afghan airspace. Planes taking more circuitous routes, giving them less options to avoid weather conditions, much of the flight over hot mountainous terr…

Edit: I just realized that the chart is increase of probability between 1979 and 2020, so to modify my comment I’ll just say that it wasn’t just that geographic region that saw an increase. It seemed to correlate with the jet streams

Well the study in the link has a chart of some sort of duration weighted probability of CAT (which somehow ranges from 0 to 2.5 instead of 0 to 1?), which would correct for the total volume of flights because it’s a ratio. It’s more likely that the jet streams are getting more turbulent due to climate change.

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