Is Clear Air Turbulence becoming more common?
flightradar24.com
flightradar24.com
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 terrain… could be a contributing factor to increasing incidents of dangerous turbulence affecting flights, even if the conditions themselves haven’t become more common.
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.
OK but you'll need a citation for your assertion and that is only about reported CAT via media sources and not what the article is on about - CAT events worldwide.
The article invokes evidence across the entire planet and cites Prosser et al with 1979 vs 2020 graphics, evidence and discussion. It also concludes that jet streams are where CAT events are intensifying.
It cites data from several years ago (before the recent spate of stories) that only talks about increases in CAT-conducive conditions, but says nothing about increases in actual incidents. The article leaves maybe the impression that any recent spike in high profile turbulence events might be a result of the changes in jet stream activity but doesn’t actually provide much justification for that. Other posts on this thread point out that there was no actual increase in reported CAT encounters that correlates with the proposed mechanism so… unclear if the article’s data says much if anything about recent media-reported CAT events.
Yes, but the article doesn't claim your narrowing of the scope, that it's mostly just between Europe and Asia.
> Most of the recent widely publicized CAT injuries have been on long distance flights between Europe and South Asia.
> Planes taking more circuitous routes ... could be a contributing factor to increasing incidents of dangerous turbulence affecting flights
(Also consider that the principal question the article tries to answer is not "are there more CAT incidents?" but simply "is there more CAT?")
I glanced at a few current (as of today) routes, e.g. CDG->SIN[0], which don't fly anywhere near the areas of heavy CAT noted by the heat maps. Hell, let's take a look at the flight mentioned, the LHR-SIN SQ321[1], where a passenger died in may (though, as the article notes, it was later determined not to be CAT): that one doesn't fly through any high-CAT areas (and in fact does fly through Russian airspace).
> giving them less options to avoid weather conditions
The entire characterization of CAT is that it is unavoidable because the cause often doesn't have all that much to do with weather conditions, and even when it does, you don't get (enough) advance warning.
[0] https://www.flightstats.com/v2/flight-tracker/SQ/335?year=20...
[1] https://www.flightstats.com/v2/flight-tracker/SQ/321?year=20...
The reason it is top-rated is because it sounds extremely reasonable. This is enough for most people.
I am not judging on whether the comment is correct or not, just answering why it is top-rated. I find nothing weird about it.
I've never heard of anything of this nature regarding comments though.
It causes stories to essentially die. I saw one get upvotes which turned into going lower down the list until it fell off.
Paste the post id after id=
I don't know if there are other factors which might be masking a rise in incidence of CAT from accident stats?
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.
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.
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?
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.
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).
> 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.
[1] There's a speed limit for turbulence penetration, chosen such that the wings will stall, rather than over-stress the airframe.
> 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.
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.
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.
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.
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.
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 supply.
> 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.
Everything on airplanes is expensive. Even cabin amenities. You have to prove it won't start a fire, was installed correctly, won't interfere with other equipment, won't interfere with the aircrafts structure, and again requires technician hours and aircraft downtime.
Apple and Google could fix this my streaming accelerometer data to the ground when people are connected to in-flight wifi. It is fairly easy to identify which phones out of a set are the stationary ones.
Sounds like you're upset at Boeing and figured you would tell us you're upset on an unrelated thread. Note that it doesn't really matter if you are right to be upset at Boeing or not. It's still unrelated.
At some point the cost of trying to lie and cut corners becomes worse than the cost of compliance and the airlines and airplane companies will just become good at doing a good job here.
> You should ask instead why it is so expensive.
That is literally my question. I’m highlighting that 100k seems really high to make a system that opportunistically transmits data we are already capturing locally. Rather than a flippant “airplanes should be expensive”, why not ask what is the cheapest retrofit we can do that doesn’t change the safety profile. As I said, this system should not be in the critical path and shouldn’t be a required other than the airplanes should generally be maintaining it to be functional (i.e. the SLA can be 75-90% and still provide tremendous value instead of the 100% SLA target for flight critical components which is what that 100k price tag sounds like).
That this is something highlighted by crash investigators as something that would help in corner cases like incidents over the ocean is just gravy.
Also there's likely 200 accelerometers on board already. Onboard wifi is becoming ubiquitous. Perhaps an app that trades in wifi time for accelerometer time would be good trade-off. And wouldn't require tons of certification.
Edit: Turns out this already includes turbulence data, and this is streamed real-time! https://community.wmo.int/en/activity-areas/aircraft-based-o...
> France is doing it every 4 minutes for their planes
What are they doing exactly? Are you referring to the article?
However that data belongs to each airline.
But anyway, where are you seeing a claim that it costs $100k to record and save turbulence sensor data? I don't see anyone upthread claiming that, and the article doesn't touch on it at all.
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.
Therefore both can be true at the same time: turbulence events are increasing, but we are also getting better at predicting, avoiding, and dealing with these events.
Flight plans are now algorithmically generated to shave fuel usage.
Because weather forecasts are more accurate, the algorithms write flight plans that take the aircraft closer to storms. This saves fuel while slightly increasing the risk of severe turbulence.
Couple that with the lightweight materials used in modern aircraft, and passengers are likely to experience more frequent moderate to severe turbulence.
I was under the impression that, as the poles are MORE affected by global warming, the jet stream is becoming weaker? is that incorrect?
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/202...
...but I fully agree with the rest of your comment.
(Edit: though apparently the additional moisture in the Tropics more than counteracts any reduction in temperature difference: see link in Retric's comment)
The projected warming at the North Pole is much stronger than the projected warming at the equator, decreasing the temperature gradient. However the moisture carrying capacity of air increases exponentially with temperature. Since the equator starts warmer, a given change in temperature has a bigger effect on moisture carrying capacity. It turns out that heating up the equator by one degree Celsius and the North Pole by 2 degrees Celsius increases the moisture capacity gradient, despite the temperature gradient dropping. And that increasing moisture capacity gradient strengthens the jet stream.
(at least that's the intuitive reason they were probably going for. In reality there are many factors and a good bit of "if we simulate it this keeps happening")
But I also thought that it was the jet stream getting weaker that caused it to meander more (which sounds like it could increase CAT events ??), which we seem to be observing ??
The poles warm FASTER than the equator. Thus, the global temperature gradients are getting smaller.
And as a result, not only does the Jetstream weaken: as a result, weather patterns become more stable which leads to greater continuous periods of draught or flooding.
“The new study, by University of Chicago Professor Tiffany Shaw and NSF NCAR scientist Osamu Miyawaki, uses climate models to show that climate change intensifies this density contrast because moisture levels for air above the tropics will increase more than above the poles.”
https://news.ucar.edu/132935/jet-stream-winds-will-accelerat....
That weakening means the jetstream meanders more, with more latitudinal movement in its form.
The strength overall of the jetstream wind is weaker when it's meandering, but can also be much more intense in places.
This says nothing about humidity or energy or pressure, just windspeed and direction.
“The new study, by University of Chicago Professor Tiffany Shaw and NSF NCAR scientist Osamu Miyawaki, uses climate models to show that climate change intensifies this density contrast because moisture levels for air above the tropics will increase more than above the poles.”
https://news.ucar.edu/132935/jet-stream-winds-will-accelerat....
The article cites the Prosser Report which contradicts this claim, but I find it hard to understand how this could be true for very long. Why wouldn't the atmosphere stabilize as gradients diminish?
The truth is there are many oscillations and teleconnections(themselves being impacted by global warming) which influences this temperature gradient on a local/seasonal basis. QBO, El Nino/La Nina and mountain torque events to name a few can move and shift heat at the tropopause in a short period of time and is why we see this wider variance at both ends of the spectrum.
Now I know that it's the perfect name for a space pirate ship.
What does authenticating have to do with it? Is there doubt about data providence?
This type of technology would be incredible in my opinion, and I’m also of the opinion that increased turbulence (assuming it is actually increasing) could be easily tied to climate change and the recent warming of the pacific and Atlantic oceans due to regulations on sulfur in cargo ship fuel (but that’s a tangent to this topic)
That said, experiencing light chop on a modern large airplane presents no danger to the airframe or properly secured passengers. You really should be strapped in, though, especially if you're on a small plane. Wake turbulence, for example, actually does present a significant risk to smaller aircraft.
Other people will correct me if I am wrong, but I believe the last time a large commercial airliner was lost to turbulence was 1966. https://en.wikipedia.org/wiki/BOAC_Flight_911
Wild how far we've come.
A 40 foot drop is pretty scary; by comparison, an NCAA dive platform is 33 feet.
Aircraft have to be built light for the sake of efficiency (or even, just, being able to get off the ground.
There are certainly factors of safety... but not 3x+. Probably closer to 1.5.
https://www.law.cornell.edu/cfr/text/14/25.337
"(b) The positive limit maneuvering load factor n for any speed up to Vn may not be less than 2.1 + 24,000/ (W + 10,000) except that n may not be less than 2.5 and need not be greater than 3.8—where W is the design maximum takeoff weight.
(c) The negative limit maneuvering load factor—
(1) May not be less than −1.0 at speeds up to VC; and "
The 2.5 number is important. That right there is the +2.5 to -1.0 requirments for transport (i.e. seating more than 19 passengers) category aircraft.
Here's a quote from Boeing: "Our airplanes are built to withstand 3.75 G load before there is any kind of damage — that's almost four times gravity,” said Doug Alder, a spokesman for Boeing. “Some of the worst turbulence gets in the range of 2 to 2.5 G's, well below the damage tolerance.”
3.75 is not nearly enough to cause a blackout. It's also exactly 1.5 (typical airplane factor of safety) times 2.5
He's not saying the drop was 40 feet instantaneously, he's saying the turbulence and the subsequent recovery only caused a 40 foot deviation from the assigned altitude.
Just for reference, a descent rate on a standard flight is pretty normal at 40 feet per second. Some descent profiles can double that. The NCAA diver will hit the water at 46 feet per second.
This isn't to say either of those things really happen just it sometimes sure seems like it.
Two top level. You suck
Whether it's responsible for more CAT - who knows?
In a word, yes. Recent studies have shown a significant increase in the frequency and intensity of CAT conditions over the past few decades. This increase is linked to several factors, most notably climate change."
We've had this invisible hand of the market to regulate ourselves. Now we have the invisible hand of the planet. It won't be a fun ride either.
Also worth noting that to a passenger, CAT is the worst feeling you’ll have on most flights — the “oh shit we’re not flying anymore” vibe is real bad, and usually when you hit proper air again, the sudden jerk feels bad as well.
As someone with like 8 flight hours to my name, I’ll say to a learning pilot, stalling feels much worse than CAT would, it’s a different sort of not flying, it’s like “oh shit the plane forgot how to fly, what now”.
Obviously the wings need to lock into place for landing, and many structural elements of the craft would need to be redesigned.
Oh, excellent the altitudes that 99% of aircraft fly at, unaffecting the ultra rich who fly private jets at 40,000k-50,000k+.
I didn't realize private jets fly so high. What's the reason for the difference in elevations?
Most private jets aren't someone flying a billionaire around in a $60M Gulfstream, they're $3M toys being flown around by the owner to go to their ski trip.
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 adjusted for that, it cruised at the same altitude both ways from what I remember. Both flights used the same exact plane type (A330neo).
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.
Basically, with aircraft mass and angle of attack unchanged, \rho v^2 must be constant, so smaller density \rho -> higher air speed.