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

Re: Is Clear Air Turbulence becoming more common?

#51

Post by vlovich123 » Fri, Jun 28, 2024, 3:32 PM UTC

ImaCake wrote: post #46

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?

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.

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.

Re: Is Clear Air Turbulence becoming more common?

#52

Post by FabHK » Fri, Jun 28, 2024, 3:34 PM UTC

eggy wrote: post #36

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?

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.

Re: Is Clear Air Turbulence becoming more common?

#53

Post by FabHK » Fri, Jun 28, 2024, 3:37 PM UTC

vanderZwan wrote: post #39

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?

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…

> 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.

Re: Is Clear Air Turbulence becoming more common?

#54

Post by aidenn0 » Fri, Jun 28, 2024, 3:42 PM UTC

ThinkingGuy wrote: post #49

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?

Airline pilot/author Patrick Smith has a pretty informative article about turbulence on his website: https://askthepilot.com/questionanswers/turbulence/

"Fewer than forty feet of altitude change"

A 40 foot drop is pretty scary; by comparison, an NCAA dive platform is 33 feet.

Re: Is Clear Air Turbulence becoming more common?

#55

Post by FabHK » Fri, Jun 28, 2024, 3:48 PM UTC

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+.

The A320 has a ceiling of 39,100–41,000 ft, the 737 of 37,000 or 41,000 ft, the 747-8 and A350-900 and A380 of 43,100 ft.

Re: Is Clear Air Turbulence becoming more common?

#56

Post by TylerE » Fri, Jun 28, 2024, 3:48 PM UTC

vlovich123 wrote: post #51

ImaCake wrote: post #46

Earlier quoted context omitted.

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.

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.…

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.

Re: Is Clear Air Turbulence becoming more common?

#57

Post by MadnessASAP » Fri, Jun 28, 2024, 3:50 PM UTC

vlovich123 wrote: post #51

ImaCake wrote: post #46

Earlier quoted context omitted.

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.

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.…

> 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 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.

Re: Is Clear Air Turbulence becoming more common?

#58

Post by rootusrootus » Fri, Jun 28, 2024, 3:53 PM UTC

stouset wrote: post #48

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.

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

Re: Is Clear Air Turbulence becoming more common?

#59

Post by FabHK » Fri, Jun 28, 2024, 3:58 PM UTC

pc86 wrote: post #27

hiatus wrote: post #24

Earlier quoted context omitted.

> 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?

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'…

Note also that at higher altitudes the air is less dense, but the plane should fly at the same indicated/calibrated airspeed to generate the same lift, which means that it flies faster (at higher true airspeed).

Basically, with aircraft mass and angle of attack unchanged, \rho v^2 must be constant, so smaller density \rho -> higher air speed.

Re: Is Clear Air Turbulence becoming more common?

#60

Post by FabHK » Fri, Jun 28, 2024, 4:02 PM UTC

sandworm101 wrote: post #34

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?

It is safe because you are flying. Airplanes almost never have issues at altitude. Problems occur when closer to the ground. Landing/takeoff are the most dangerous times, the transitions between flying and not flying.

The aviation industry has a perfect record, they've never left anyone up there.