Is Clear Air Turbulence becoming more common? • Hacker News Board

Re: Is Clear Air Turbulence becoming more common?

#91

Post by robxorb » Fri, Jun 28, 2024, 6:57 PM UTC

throwup238 wrote: post #64

dclowd9901 wrote: post #50

Earlier quoted context omitted.

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.

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 servi…

So this could be a trend in pilot reporting rather than turbulence?

Re: Is Clear Air Turbulence becoming more common?

#92

Post by tracerbulletx » Fri, Jun 28, 2024, 7:17 PM UTC

User23 wrote: post #89

alfalfasprout wrote: post #74

Earlier quoted context omitted.

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.

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 getti…

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.

Re: Is Clear Air Turbulence becoming more common?

#93

Post by JoshGG » Fri, Jun 28, 2024, 7:21 PM UTC

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?

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.

Re: Is Clear Air Turbulence becoming more common?

#94

Post by dmux » Fri, Jun 28, 2024, 7:29 PM UTC

rootusrootus wrote: post #58

stouset wrote: post #48

Earlier quoted context omitted.

When was the last time a commercial airliner crashed due to turbulence?

Best I can tell, 1966. https://en.m.wikipedia.org/wiki/BOAC_Flight_911

>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).

Re: Is Clear Air Turbulence becoming more common?

#95

Post by vessenes » Fri, Jun 28, 2024, 7:31 PM UTC

osipov wrote: post #22

Commercial pilot here. Instead of climate change, we should be talking about continuous descent profiles (CDPs) that have become more common in the past years 5-10 years. These profiles with idle engines allow for a smoother, more fuel-efficient descent by reducing the need for level-off segments. However, CDPs can increase the perception of turbulence during descent. This is because aircraft remain at higher altitud…

Interesting! I didn’t know that descent profiles had changed this decade. Now that you mention it, I seem to recall far less leveling off than when I was younger, at the very least you’ve incepted the idea into my head now.

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”.

Re: Is Clear Air Turbulence becoming more common?

#96

Post by vessenes » Fri, Jun 28, 2024, 7:34 PM UTC

hiatus wrote: post #24

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+.

> 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?

You got some good answers below, but in addition to those, also thinner air = less felt turbulence, so it’s more comfortable (provided your cabin pressurization is good).

Re: Is Clear Air Turbulence becoming more common?

#97

Post by card_zero » Fri, Jun 28, 2024, 7:37 PM UTC

thisisauserid wrote: post #78

I had never heard of Clear Air Turbulence until last month when I finally read the first Culture novel by Ian M. Banks: Consider Phlebas. Now I know that it's the perfect name for a space pirate ship.

Chris Foss seemed to think along similar lines when he made Gillan's album cover.

https://en.wikipedia.org/wiki/Clear_Air_Turbulence_(album)

Re: Is Clear Air Turbulence becoming more common?

#98

Post by dmux » Fri, Jun 28, 2024, 7:38 PM UTC

MisterTea wrote: post #70

Octabrain wrote: post #31

I hate flying with passion and get extremely scared when flying through turbulences but, there was a journalist in my country, that also had experience as a pilot and said once on TV that during turbulences, is one of the safest moments in a plane. I don't remember the reasons but is there anybody in here with knowledge in the field that could confirm/deny this?

I feel the same way about flying but a boating enthusiast friend bought up an interesting analogy. He asked me if I enjoyed boating and I said yes. Then he asked me if it was fun when you run over waves bouncing around and I said yes. Then he said that is exactly what turbulence is - wakes and waves in the air the plane is bouncing on so relax and enjoy the ride. Kinda made me feel a little better since I could now v…

If you've ever sailed, a more apt analogy would be heeling over extensively (and potentially capsizing) due to a gale. You could be sailing along just fine and then all of a sudden you're overpowered. A sail, after all (at least when sailing towards the wind) acts just like a wing of a plane.

Re: Is Clear Air Turbulence becoming more common?

#99

Post by largbae » Fri, Jun 28, 2024, 7:40 PM UTC

User23 wrote: post #89

alfalfasprout wrote: post #74

Earlier quoted context omitted.

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.

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 getti…

Is it possible that the overall increase in flights, areas served, and data collection is simply giving us more coverage?

Re: Is Clear Air Turbulence becoming more common?

#100

Post by TylerE » Fri, Jun 28, 2024, 7:44 PM UTC

oceanplexian wrote: post #73

antoniojtorres wrote: post #66

Earlier quoted context omitted.

I agree. It’s funny to think of the gap between safety and scary when talking about turbulence. Large planes can take an absolute beating and be completely fine, but it could feel like the end of the world inside.

A modern airliner is rated to something like 3-4G's including the safety factor, probably much more if it's not at max takeoff weight. I'm sure you could do a Mythbusters-style test but I'd assume most passengers would pass out from the negative and positive G forces long before the aircraft structurally failed.

You'd lose that bet. The wings would fail long before people blacked out. They're only required to withstand 2.5g positive. Blacking out takes more like 6. We can see from various crashes that that sort of G load does in fact cause most wings to fail.

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.