sqa380fan
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What Constitutes Severe Turbulence?

Wed May 29, 2013 4:37 am

I'm by no means a frequent flier, but I was on VX29 from JFK to SFO last night (5/27) and while overflying southern Iowa and Nebraska, we encountered what seemed to me like a prolonged stretch of moderate to severe turbulence. Drink service was suspended, and someone's glass of wine in the preceding row spilled everywhere. There were a few points at which it seemed the pilots (or autopilot I suppose?) were having trouble controlling the aircraft. I'm pretty sure we flew straight through a thunderstorm, because I could see lightning outside. As aware as I am about the extremes to which planes are tested and certified, it was quite an unnerving experience.

Anyway, this leads me to a few questions:
•What constitutes severe turbulence? In my mind, what I experienced seemed to qualify.
•Does severe turbulence cause structural damage, and if so, how often does this happen? How much can a plane take? (I realize this is somewhat hard to answer)
•Have there ever been any crashes (in the past 50 years or so) tied directly to turbulence? I'm talking about passenger A/C and not smaller planes, i.e. regional jet and larger.

Obviously, turbulence is part and parcel with flying, so I know it happens all the time to varying degrees, I guess I'm just asking about particularly bad instances and their effects on an airplane and its structural integrity.

Thanks!

PS Anyone fly across the country in the past couple days and have a similar experience?

[Edited 2013-05-28 21:40:15]
 
AR385
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What Constitutes Severe Turbulence?

Wed May 29, 2013 4:47 am

Quoting sqa380fan (Thread starter):
•What constitutes severe turbulence?

I believe there is no proper definition but I have heard that when the plane sis haking so much it becomes very difficult for the pilots to read the instruments, then that is considered severe turbulence.

Quoting sqa380fan (Thread starter):
•Does severe turbulence cause structural damage, and if so, how often does this happen? How much can a plane take? (I realize this is somewhat hard to answer)

Yes, it may cause structural damage. It does not happen often. The plane can take A LOT.

Quoting sqa380fan (Thread starter):
•Have there ever been any crashes (in the past 50 years or so) tied directly to turbulence? I'm talking about passenger A/C and not smaller planes, i.e. regional jet and larger.

I can only recall two jet airliners that have crashed and it can directly be attributed to turbulence: A BOAC 707 in Japan due to rotor waves around MT. Fuji (the plane did not have to be there) and a Braniff Bac-111 in the US mid-west. Both in the sixties I believe or maybe in the latter fifties. There may be more crashe out there, but I don´t remember other ones.
 
flymia
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What Constitutes Severe Turbulence?

Wed May 29, 2013 4:59 am

If the wine glass went up and hit the ceiling, passengers were screaming and objects were being thrown around the plane the it was sever turbulence. You probably were in the moderate range. There is some type of way of classifying it based on how much control of the airplane there was. You can probably find it on a forum search or google.

As for flying right into a thunderstorm I doubt it. Not many pilots will take an aircraft into a thunder storm that is as high as 35,000ft or so. Now they could have flown over one or fairly close to one. And of course a cruise altitude lighting would be visible from over 50-70 miles away.
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ssteve
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What Constitutes Severe Turbulence?

Wed May 29, 2013 5:07 am

Quoting sqa380fan (Thread starter):
Drink service was suspended, and someone's glass of wine in the preceding row spilled everywhere

That reaches the moderate threshold... honestly that would be unremarkable on a turboprop, so you should probably embellish some more!
 
AA737-823
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What Constitutes Severe Turbulence?

Wed May 29, 2013 5:22 am

Turbulence is something I just can't stand, and that's after literally HUNDREDS of airline flights in my relatively short lifetime. AND, it's also in spite of being employed as an airline mechanic!
What you experienced was most likely "moderate" turbulence.
Legitimate "severe" turbulence must go into the aircraft logbook, and a maintenance inspection must be performed on the airframe. Depending on how severe it is, the inspection can be very detailed.

As far as what the airplane can "take," I can tell you that wings are required to be tested to 1.5 times the anticipated maximum load factor. Thus, if the manufacturer expects that the airplane will experience a certain level of force on the wing, say ten pounds for example, it must be tested to withstand fifteen pounds before the aircraft wing design will be accepted by the FAA.

As far as flying straight into a thunderstorm, no, you didn't. The sky is large; either the pilots will choose to fly through the tamer portions of the cell (keep in mind, they're well informed; the received a weather brief before flight, and have a fantastic onboard weather radar in front of their faces), or will divert to a different airport.
 
bomber996
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What Constitutes Severe Turbulence?

Wed May 29, 2013 5:47 am

Light Turbulence:

Turbulence that momentarily causes slight erratic changes in ;altitude and/or attitude (pitch, roll, yaw). Report as Light Turbulence

or

Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude
or attitude. Report as Light Chop.

Occupants may feel a slight strain against seat belts or shoulder straps. Unsecured objects may be displaced slightly. Food service may
be conducted and little or no difficulty is encountered in walking.

Moderate Turbulence:

Turbulence that is similar to Light Turbulence but of greater intensity. Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations
in indicated airspeed. Report as Moderate Turbulence

or

Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude. Report as Moderate Chop.

Occupants feel definite strains against seat belts or shoulder straps. Unsecured
objects are dislodged. Food service and walking are difficult.

Severe Turbulence:

Turbulence that causes large, abrupt
changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be
momentarily out of control. Report as Severe Turbulence

Occupants are forced violently against seat belts or shoulder straps.
Unsecured objects are tossed about. Food Service and walking are impossible.

Extreme Turbulence:

Turbulence in which the aircraft is
violently tossed about and is practically impossible to control. It may cause structural damage. Report as Extreme Turbulence.

http://www.navyaircrew.com/blog/2009...re-turbulencehow-are-they-defined/

Peace   
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Dreadnought
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What Constitutes Severe Turbulence?

Wed May 29, 2013 5:58 am

Quoting flymia (Reply 2):

If the wine glass went up and hit the ceiling, passengers were screaming and objects were being thrown around the plane the it was sever turbulence.

I've experienced that twice. Once on an Eastern L-1011 in the 70s from Houston to JFK if I recall. We had to land someplace along the way to offload a few people who were injured. I distinctly remember seeing the drinks trolley leave the ground and crash onto some (luckily) empty seats.

The other time was on a Swissair A320 to Moscow in the late 90s. Not as bad as the Eastern flight, but one thing I found particularly unnerving was the fact that it sounded (and felt), like the plane was being rammed from outside by a truck every few seconds. I'd never heard effect that before.
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sqa380fan
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What Constitutes Severe Turbulence?

Wed May 29, 2013 6:19 am

Thanks for all the highly informative responses. I could see it being in the upper moderate range, based on what some of you have said. I have no doubt that there's been much worse though (duh), but it nonetheless goes on record as far and away the worst flight I've ever had the displeasure taking. There were definitely some sudden and powerful altitude changes, and it sounded to me like the thrust was reduced at certain points to slow the plane down a bit.

If you'd like to see the flightpath, check this out: http://flightaware.com/live/flight/V...9/history/20130527/2255Z/KJFK/KSFO
Seems we went pretty close to some of the severe weather areas. As for the thunderstorm, we must have been very close to it, because the lightning seemed no more than a couple miles from the airplane. At times, I could also see the strobe lights on the wingtips illuminating the (clouds?) through which we were passing.
 
comorin
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What Constitutes Severe Turbulence?

Wed May 29, 2013 6:43 am

Related question:

tdscanuck once explained here that turbulence is caused by wind gusts, correcting an impression of mine that it was caused by airflow with a turbulent (non-laminar flow) nature. What then causes rhythmic turbulence, where you feel that you are flying over a rough road? Are these sheets of vortices caused by shear between layers of air moving at different speeds?

Thanks in advance.
 
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What Constitutes Severe Turbulence?

Wed May 29, 2013 8:11 am

Quoting Dreadnought (Reply 6):
I'd never heard effect that before.

I was on a very bumpy UA flight IAH-ORD where the turbulence was a pretty strong moderate level but it sounded like somebody was hitting the wings with sledgehammers the entire time. This went on for about 70% of the flight. It was very noisy.
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peterjohns
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What Constitutes Severe Turbulence?

Wed May 29, 2013 9:02 am

Quoting comorin (Reply 8):

There are different kinds of turbulances. I´ll try and point out some.
First and most common, are all kind of turbulances caused by convection. Warm air, heated by the sun, rises, forms clouds, makes wind, makes turbulance. Think of big thunderstorms- it can be very severe. Can occur everywhere, at all times.

Second we have the turbulance that is produced by mountain waves. Occurs with wind, or rather larger air currents, moving over land and blowing over mountain ranges ( Andes, Rockies, Alps, Himalaya) or single mountains.
Imagine water flowing in a stream with rocks in it. The water churns, turns, even flows opposite to the Stream direction behind a large object.
The air does exactly the same around and over mountains. The so called rotors in the lee of a mountain can be very powerful, and dangerous to an aircraft flying through them. They can reach up to the cruise level of a jet.

Last we have the jetstream. Global winds meandering the world at high speeds, coming (not only) by the world turning.
Entering these wind systems with higher velocity then the surrounding air is also marked by turbulance.
 
csavel
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What Constitutes Severe Turbulence?

Wed May 29, 2013 10:15 am

This is severe turbulence. Even the F/As look shook up.

As others have said, highlyg doubtful you flew through a direct thunderstorm. There is some sort of optical issue where lightning from 50 - 100 miles away looks like it is only a mile or two away. Plus in cloud with the strobes blinking it is easy to see an optical illusion. But yeah, you probably had moderate and you were close to a CB. Perhaps 20 miles or so.

Although this always makes me wonder  .
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sqa380fan
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 12:15 pm

Quoting csavel (Reply 11):
This is severe turbulence. Even the F/As look shook up.

That's crazy, I definitely didn't experience anything that bad! Would I be right in assuming that the A/C was inspected to some degree post-flight, or is such a sudden drop in altitude/turbulence unremarkable from a structural standpoint?

Quoting csavel (Reply 11):
Plus in cloud with the strobes blinking it is easy to see an optical illusion.

The strobes were one thing, but as we reached what seemed like the edge of the storm, I could definitely see lighting and knew it was something other than the strobes. It was flashing all around us but I'm sure you're right in saying it was farther away than it seemed. Hard to tell from my vantage point!
 
sccutler
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 12:32 pm

"Severe" turbulence is, to be honest, much worse than you can imagine. When a commercial passenger aircraft (my Bonanza is, after all, also a "passenger" aircraft) encounters turbulence strong enough to be legitimately classified as "severe," you'll see overhead bins opened (as a result of airframe flexing), contents strewn about, any loose objects will have been flung far from their owners, and lap children will be bleeding and injured, because all those silly people who are too cheap to buy a seat for the baby cannot maintain a hold on them.

You will also likely see injured people, if they did not have seat belts on, or if the seat belt was too loose.
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roseflyer
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 4:53 pm

This is what severe turbulence looks like:

http://www.liveleak.com/view?i=152_1338163867

Current airplanes are certified for 16Gs. People usually pass out before ever getting near the structural limits of the airplane. On very rare occurrances it happens, but with the weather radar on modern airplanes, no pilot will go through it.

Severe turbulence usually results in injuries due to the rapid and significant changes in altitude as the airplane is difficult to control.

Most airlines will suspend service and instruct crews to remain seated for moderate turbulence.
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tockeyhockey
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 5:01 pm

to add on to the thread:

do any particular planes do better in heavy turbulence than others? is there any technology out there to mitigate the effects of turbulence on the passengers and flight crew?
 
ghifty
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 5:06 pm

Quoting tockeyhockey (Reply 15):
is there any technology out there to mitigate the effects of turbulence on the passengers and flight crew?

Doesn't the Dreamliner's computer systems have the capability of predicting wind gusts and deflecting ailerons in advance? I remember reading something to that accord..
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tistpaa727
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 5:18 pm

I have been wondering the same thing. I fly a lot for work and this past March on a flight between Atlanta and Boston (DL 757) I experienced the worst turbulence (for me) yet after 30+ years of flying. My drink went up about half way to the ceiling, people were quite freaked out and the wing flex was incredible. It looked like (probably an optical illusion) the engine was swaying on the pylon. Lasted a good 40 minutes.

The most amazing part was the noise. The wind (I am assuming it was the wind) sounded like freight trains hitting the side of the plan and jarring us side to side.

I had to reassure the passenger next to me after we both were covered in my Sprite the plane could take more abuse than either of us could imagine. Even knowing that though was little comfort when we were going through it.
Don't sweat the little things.
 
roseflyer
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 5:53 pm

Quoting tockeyhockey (Reply 15):

do any particular planes do better in heavy turbulence than others? is there any technology out there to mitigate the effects of turbulence on the passengers and flight crew?

There is a lot of anecdotal data on it, but the heavier the airplane, the less the turbulence affects the ride. It’s basic physics that more force is required to accelerate a heavier airplane which means less impact of turbulence.

The airplane’s inherent stability does have a role in going through turbulence, but it is rarely felt by a passenger. Airplanes design is moving towards less stable designs, which have less drag and are more efficient that use control logic to improve stability. Control logic won’t help an airplane return from an upset attitude as quickly as a stable airframe will. The effects are minor, but some times a yaw damper or gust suppression system can be felt in the cabin.

Also it is important to be close to the center of gravity. Airplanes do flex, so being near the wing will reduce turbulence. Being in the tail can often be worse since the tail surfaces are experiencing different forces than main wing, which can cause some bending. The 777-300 and A340-600 are known to have visible bending in the fuselage.

In general, no two flights are the same, so comparing how different airplanes handle turbulence as a passenger is not very good. However, pilots tend to notice the differences.
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vikkyvik
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 8:19 pm

Quoting Roseflyer (Reply 18):
There is a lot of anecdotal data on it, but the heavier the airplane, the less the turbulence affects the ride. It’s basic physics that more force is required to accelerate a heavier airplane which means less impact of turbulence.

True, though turbulence and other aerodynamic effects are applied through pressure (or shear stress, but anyway), so if an airplane that's twice as massive has twice as much surface area subjected to whatever pressure, the resultant acceleration will be the same.

Obviously, mass and surface area don't necessarily scale 1:1, though.

Quoting Roseflyer (Reply 18):
Control logic won’t help an airplane return from an upset attitude as quickly as a stable airframe will

Interesting. I would have thought that neutrally stable / unstable aircraft, due to greater maneuverability, would be able to return from an upset attitude quicker.
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rwessel
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 8:21 pm

Quoting Roseflyer (Reply 14):
Current airplanes are certified for 16Gs.

Certainly not. It's not a single number for transport aircraft, but it's somewhere between 2.5 and 3.8G positive and 1G negative. *Seats* are certified to 16G vertical, to help survive a crash.

Quoting Roseflyer (Reply 18):
There is a lot of anecdotal data on it, but the heavier the airplane, the less the turbulence affects the ride. It’s basic physics that more force is required to accelerate a heavier airplane which means less impact of turbulence.

The mass of the aircraft has little to do with it. After all, the thing that causes the bump to be transmitted to the aircraft is the wing, which is holding up the aircraft in any event, and all other things being equal is sized proportionately to the mass of the aircraft (thus it produces a proportionate "bump" to the size of the aircraft). What does matter is wing *loading*. An aircraft with a wing loading of 120lbs/sqft will ride through turbulence better than one with 30lbs/sqft wing loading - the smaller wing of the former will generate less total force (per square foot of wing) when hit by the gust, than the latter.
 
Type-Rated
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RE: What Constitutes Severe Turbulence?

Wed May 29, 2013 9:00 pm

And remember that when you are flying through a cloud that may contain a thunderstorm the areas of turbulence are usually somewhat limited to the "cells" embedded in the thunderstorm cloud. Unless you enter a cell or get too close to one you can actually have very smooth air. The cells show up on the weather radar so the pilot usually can see where they are.

Anyone who has flown Houston-Dallas much in the summertime have probably noticed their plane weaving back and forth as it flies. This is usually because the pilot is weaving between the cells to give his passengers the smoothest possible ride.

So you can fly through a thunderstorm and have a pretty decent ride because the pilot is avoiding the areas of turbulence.
But if the storm is strong enough a lot of pilots will divert around it, which usually is the best thing to do. Usually this is when they see a wall of cells along their flight path.
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comorin
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 1:54 am

Quoting peterjohns (Reply 10):
There are different kinds of turbulances. I´ll try and point out some.
First and most common, are all kind of turbulances caused by convection. Warm air, heated by the sun, rises, forms clouds, makes wind, makes turbulance. Think of big thunderstorms- it can be very severe. Can occur everywhere, at all times.

Second we have the turbulance that is produced by mountain waves. Occurs with wind, or rather larger air currents, moving over land and blowing over mountain ranges ( Andes, Rockies, Alps, Himalaya) or single mountains.
Imagine water flowing in a stream with rocks in it. The water churns, turns, even flows opposite to the Stream direction behind a large object.
The air does exactly the same around and over mountains. The so called rotors in the lee of a mountain can be very powerful, and dangerous to an aircraft flying through them. They can reach up to the cruise level of a jet.

Last we have the jetstream. Global winds meandering the world at high speeds, coming (not only) by the world turning.
Entering these wind systems with higher velocity then the surrounding air is also marked by turbulance.

Thank you for the descriptions and explanations of the various kinds of turbulence.

Quoting rwessel (Reply 20):
The mass of the aircraft has little to do with it. After all, the thing that causes the bump to be transmitted to the aircraft is the wing, which is holding up the aircraft in any event, and all other things being equal is sized proportionately to the mass of the aircraft (thus it produces a proportionate "bump" to the size of the aircraft). What does matter is wing *loading*. An aircraft with a wing loading of 120lbs/sqft will ride through turbulence better than one with 30lbs/sqft wing loading - the smaller wing of the former will generate less total force (per square foot of wing) when hit by the gust, than the latter.

True, but can you please help us folks who feel riding in a big car is smoother with a physical analogy?

Thanks
 
vikkyvik
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 4:29 am

Quoting comorin (Reply 22):
True, but can you please help us folks who feel riding in a big car is smoother with a physical analogy?

It's a bit of a different situation than flying, but I suppose the closest analogy is that the "spring loading" (suspension loading, but that doesn't sound as good) of the car is similar to the wing loading of the airplane. So a heavier car that still rests on 4 wheels will be more resistant to upset than a lighter car on 4 wheels.

That's more-or-less conjecture, though, and obviously cars have suspensions that are tuned for the specific car.
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spacecadet
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 5:20 am

Quoting csavel (Reply 11):
This is severe turbulence. Even the F/As look shook up.

I've always thought the distinction between "severe" and "extreme" was as muddy as the distinction between "moderate" and "severe". I have gone through turbulence the pilot himself has described as "severe" and it didn't look like the cabin had been ransacked like that afterwards.

Although, I do notice that in both your photo and the later video that was posted, it appears that trays were on the tables at the time of the turbulence, which would explain all the stuff in the aisles.

Turbulence also doesn't always have the same onset. Most of the incidents where objects like that end up in the aisles were sudden in onset, with passengers describing smooth flight and then a large jolt that sent everything flying. But with no meal service going on, passengers mostly strapped in for cruise, and a more gradual onset that lets people prepare (by holding on to objects, or whatever), I can see a severe turbulence encounter that wouldn't result in much obvious aftermath.

Quoting tistpaa727 (Reply 17):
It looked like (probably an optical illusion) the engine was swaying on the pylon.

In my aforementioned encounter above, I saw the same. I have never seen anything like this in any of my 35 years worth of flights before or since *or* in any YouTube videos I've ever found. The engines in the encounter I had looked like they were rotating about 45 degrees on the pylon.

Quoting Roseflyer (Reply 18):
The effects are minor, but some times a yaw damper or gust suppression system can be felt in the cabin.

In the back of a 747, you can feel the yaw damper snapping back and forth suddenly. The early models were so bad that people were reportedly throwing up in the cabin. Apparently Boeing made an early change to tame it, but it has still always seemed more violent than the yaw dampers in any other plane I've flown on during turbulence.
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comorin
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 5:25 am

Quoting vikkyvik (Reply 23):
Quoting comorin (Reply 22):
True, but can you please help us folks who feel riding in a big car is smoother with a physical analogy?

It's a bit of a different situation than flying, but I suppose the closest analogy is that the "spring loading" (suspension loading, but that doesn't sound as good) of the car is similar to the wing loading of the airplane. So a heavier car that still rests on 4 wheels will be more resistant to upset than a lighter car on 4 wheels.

That's more-or-less conjecture, though, and obviously cars have suspensions that are tuned for the specific car.

Thanks, Vikkyvik! One last thing: Does this mean a large plane and a small plane with the same wing loading will react similarly in turbulence?
 
rwessel
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 6:37 am

Quoting comorin (Reply 25):
Does this mean a large plane and a small plane with the same wing loading will react similarly in turbulence?

Approximately yes. The usual "all other things being equal" caveat applies. For example, a wing might be designed for high-speed or low speed flight, depending on the mission of the aircraft, and yet the two aircraft might end up with similar wing loading. The aircraft flying at the faster indicated airspeed (IOW, the normal cruise speed of the aircraft with the "fast" wing will be higher than the aircraft with the "slow" wing) will typically react more strongly to turbulence. Also things like wing flex impact the ride. Turbulence often includes a change in wind direction as well, and the aircraft's directional stability will impact the reaction to that (an aircraft with more directional stability, aka a more effective vertical stabilizer) will swing (weathercock) into the changed wind more sharply than one will lesser directional stability. An aircraft with more dihedral effect (more actual dihedral, more swept wings, lower CG), will accompany that wind shift with a more pronounced roll.
 
olddominion727
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 6:57 am

Quoting AR385 (Reply 1):

Lets not forget the AA A300 from JFK-SDQ (I think) Dec 2001 crashed on Long Island, I know it was going to some place in the DR. The final report I believe was "Wake Turbulence" from a JL flight.
 
FCAFLYBOY
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 7:07 am

Quoting sccutler (Reply 13):

Sorry to correct you there, however when the seatbelt sign is illuminated, infants under 2 years MUST be attached to their parent or guardian via an infant seat belt.

If the seatbelt sign is not illuminated, in my opinion, a responsible parent would never have a child under 2 in its own seat, even if money was no issue. As a father to an 8 week old boy I found this post to be both condescending and disrespectful. Sorry to go OT.
 
MD88Captain
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 1:02 pm

I'm often surprised to have a passenger complain about turbulence upon exiting the airplane and I can't remember any turbulence. Some people have no tolerance for bumps. I've got decades of flying under my belt (pushing 20k hrs) but I've seen very little severe turbulence. Maybe 2 or 3 times for very brief moments. (I'm excluding a wind shear event that was sporting but wasn't really the same thing.)

Most of what people get really upset by is moderate turbulence or moderate chop (different terms meaning slightly different things). Spilled drinks = moderate. An airplane will go through moderate turbulence all day long without damage.

If unbuckled people are hitting the overhead = severe or extreme.
 
comorin
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 1:59 pm

Quoting rwessel (Reply 26):
Quoting comorin (Reply 25):
Does this mean a large plane and a small plane with the same wing loading will react similarly in turbulence?

Approximately yes. The usual "all other things being equal" caveat applies. For example, a wing might be designed for high-speed or low speed flight, depending on the mission of the aircraft, and yet the two aircraft might end up with similar wing loading. The aircraft flying at the faster indicated airspeed (IOW, the normal cruise speed of the aircraft with the "fast" wing will be higher than the aircraft with the "slow" wing) will typically react more strongly to turbulence. Also things like wing flex impact the ride. Turbulence often includes a change in wind direction as well, and the aircraft's directional stability will impact the reaction to that (an aircraft with more directional stability, aka a more effective vertical stabilizer) will swing (weathercock) into the changed wind more sharply than one will lesser directional stability. An aircraft with more dihedral effect (more actual dihedral, more swept wings, lower CG), will accompany that wind shift with a more pronounced roll.

Thank you again, much obliged.

On many flights (esp TATL tracks) it seems like the aircraft settles into a light chop for much of the journey. Is this because it is in a stream of moving air (Jetstream?) that may itself be turbulent?
 
AngMoh
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 2:14 pm

Quoting FCAFLYBOY (Reply 28):
If the seatbelt sign is not illuminated, in my opinion, a responsible parent would never have a child under 2 in its own seat, even if money was no issue. As a father to an 8 week old boy I found this post to be both condescending and disrespectful. Sorry to go OT.

I had my 1.5 year old daughter in her own seat. But I used a car child seat to strap her in. I presume you approve of that...

Quoting Md88Captain (Reply 29):

I'm often surprised to have a passenger complain about turbulence upon exiting the airplane and I can't remember any turbulence. Some people have no tolerance for bumps. I've got decades of flying under my belt (pushing 20k hrs) but I've seen very little severe turbulence. Maybe 2 or 3 times for very brief moments.

I am one of those who is super sensitive to turbulence... The only severe turbulence I had was 20 years ago in australia. We went through a thunderstorm front as we could not go around or over it. At least we received a clear warning from the captain about what we were going to get and the crew cleaned out the cabin before we went through it. It was the only time ever I had to put seats upright and tray table stowed in the middle of a flight. The most amazing part is that we went from severe turbulence to silky smooth flight with clear blue skies near instantaneously.

Quoting comorin (Reply 30):
On many flights (esp TATL tracks) it seems like the aircraft settles into a light chop for much of the journey. Is this because it is in a stream of moving air (Jetstream?) that may itself be turbulent?

I remember one flight across the pacific where we took the jetstream to safe fuel and arrive earlier. It was like driving over a cobblestone road for 12 hours. No real turbulence but just continuous shaking and rattling. I had nausea for another 4 hours after the flight...
727 732 733 734 735 73G 738 739 739ER 742 743 744 752 753 762 772 77E 773 77W 788 A300 A310 A319 A320 A321 A332 A333 A343 A345 A346 A359 A35K A388 DC-9 DC-10 MD11 MD81 MD82 MD87 F70 ERJ145 E170 E175 E190 E195 ATR72 Q400 CRJ200 CRJ700 CRJ900 BAE146 RJ85
 
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Dreadnought
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 2:23 pm

I have to make sure this gets in...



[Edited 2013-05-30 07:24:30]
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flymia
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 3:32 pm

Quoting olddominion727 (Reply 27):
Lets not forget the AA A300 from JFK-SDQ (I think) Dec 2001 crashed on Long Island, I know it was going to some place in the DR. The final report I believe was "Wake Turbulence" from a JL flight.

The wake turbulence was not what brought the aircraft down. The wake turbulence caused the first officer to use excessive rudder input which caused a structural failure.
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loalq
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 3:59 pm

This...

"...this is your captain speaking. We have a small problem. All four engines have stopped."
 
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Acey559
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RE: What Constitutes Severe Turbulence?

Thu May 30, 2013 4:02 pm

Quoting Md88Captain (Reply 29):

I've had situations where the flight attendant will call up and ask us to turn the seat belt sign on because they're getting tossed around in the back, but up front there's not a single bump to speak of. I'd assume that's exacerbated even more on longer airplanes than my Embraer.
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sccutler
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 4:29 am

Quoting FCAFLYBOY (Reply 28):

Quoting sccutler (Reply 13):

Sorry to correct you there, however when the seatbelt sign is illuminated, infants under 2 years MUST be attached to their parent or guardian via an infant seat belt.

If the seatbelt sign is not illuminated, in my opinion, a responsible parent would never have a child under 2 in its own seat, even if money was no issue. As a father to an 8 week old boy I found this post to be both condescending and disrespectful. Sorry to go OT.

No apology called-for - I am glad to have been corrected on this point.
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flood
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 4:36 am

Quoting loalq (Reply 34):
This...

Same flight...



from:
http://abcnews.go.com/blogs/lifestyl...nce-creates-chaotic-mealtime-mess/



[Edited 2013-05-31 21:38:44]
 
737tanker
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 4:07 pm

Quoting FCAFLYBOY (Reply 28):
Sorry to correct you there, however when the seatbelt sign is illuminated, infants under 2 years MUST be attached to their parent or guardian via an infant seat belt.

Just wondering what is an infant seat belt? If you are talking about the baby carriers where the infant is strapped to the front of the parent then these can't be used for takeoff and landing. When my wife was flying with our daughter, when she was an infant, the F/As made her take our daughter out of the carrier and hold her for takeoff and landing. when I talked to F/As at work about this they told me that it is an FAR, which they agreed was stupid, where all infants had to be out of those chest carriers for takeoff and landing.
 
anstar
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 4:55 pm

Quoting 737tanker (Reply 38):

Just wondering what is an infant seat belt?

An infant seatbelt is one that loops into the adults seat belt and then fastens around the infant. It is provided by the airline and not something you can bring onboard yourself.
 
spacecadet
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 5:46 pm

Quoting olddominion727 (Reply 27):
Lets not forget the AA A300 from JFK-SDQ (I think) Dec 2001 crashed on Long Island, I know it was going to some place in the DR. The final report I believe was "Wake Turbulence" from a JL flight.

The wake turbulence did not cause that accident - in fact the wake turbulence was described as light to moderate. The first officer overreacted to it. He didn't really need to do anything at all because the A300 is a stable airplane that will correct itself, and the turbulence was not bad enough that it was causing large bank angles or anything. But instead, he put large and abrupt pedal inputs into the rudder, which snapped the tail off.

This is all in the report.

Wake turbulence *can* be startling, but the pilots of AA587 knew about it beforehand so that wouldn't explain the first officer's reaction. I'm sure we've all had many encounters with wake turbulence as passengers - any time you take off and immediately feel turbulence, there's a good chance that's wake turbulence - but I do recall one time flying along at cruise in smooth, clear air in a Delta 757 when suddenly it felt like we actually hit something. It didn't feel like turbulence, it was a sharp "bang" that would have dumped me out of my seat if I wasn't wearing my seat belt, and then a couple more quick shudders before the air just as suddenly smoothed out again. Luckily it was a night flight and everybody was seated, mostly sleeping. I sat wondering what had happened for a few seconds, and then the pilot came on the intercom and said "Good morning, sorry about that wakeup call just now, but we just passed through the jet wash of another airplane." He of course sounded completely calm but he obviously knew it must have been a strange feeling for the passengers.
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Dreadnought
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 6:41 pm

Link did not work last time...

Here is the truth behind turbulence.



[Edited 2013-06-01 11:42:14]
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AR385
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RE: What Constitutes Severe Turbulence?

Sat Jun 01, 2013 7:18 pm

Quoting olddominion727 (Reply 27):
Lets not forget the AA A300 from JFK-SDQ (I think) Dec 2001 crashed on Long Island, I know it was going to some place in the DR. The final report I believe was "Wake Turbulence" from a JL flight.
Quoting flymia (Reply 33):
The wake turbulence was not what brought the aircraft down. The wake turbulence caused the first officer to use excessive rudder input which caused a structural failure.
Quoting spacecadet (Reply 40):
The wake turbulence did not cause that accident - in fact the wake turbulence was described as light to moderate. The first officer overreacted to it.

Yes, it was wake turbulence, but I interpreted the OP´s question to only take into account weather related turbulence. If we list also the accidents caused or having wake turbulence as a factor, which I consider in this context to be "atificial" turbulence, then the list would be much, much bigger.
 
737tanker
Posts: 367
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 12:37 am

Quoting anstar (Reply 39):
An infant seatbelt is one that loops into the adults seat belt and then fastens around the infant. It is provided by the airline and not something you can bring onboard yourself.

I'm not saying that this doesn't exist but there is no such thing on WN aircraft all the WN F/As I've talked with haven't heard of them either. So it can't be a FAA requirement otherwise WN would have them.
 
shufflemoomin
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 1:16 am

What's the worst turbulence captured on video? Anyone have good links?
 
spacecadet
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 1:43 am

Quoting shufflemoomin (Reply 44):
What's the worst turbulence captured on video? Anyone have good links?

There aren't a lot of good videos, because people do tend to overreact and think turbulence is worse than it is, and even "good" turbulence videos can be marred by the perception that the camera-person is exaggerating it with camera movements (which may or may not be true - it's hard to hold a camera steady in turbulence!). Also, it does always feel worse when you're actually in it, so videos of it never look as impressive as being in it does.

This one is probably the best/worst I've personally found: http://www.youtube.com/watch?v=te1lwciuKnI

About mid-way through it gets pretty bad - just watch people's heads/bodies and listen to the sounds. It's not just the camera bobbing.

This one is pretty cool, although it's hard to tell how bad the turbulence really is, it doesn't seem that bad but it's just cool video: http://www.youtube.com/watch?v=9YDaycWlwnU

I actually search for turbulence vids every once in a while and I've never found one that approximates my experience that I mentioned earlier, where the pilot actually said over the intercom that it was severe turbulence and the engines were bobbing and rotating around so cartoonishly on their pylons. I've looked for that specifically in videos, because it was really unnerving to see it and I just want to know if others have seen the same thing. Some people do show the engines in their turbulence videos and I never see them move all that much. This leads me to believe that severe turbulence probably *is* pretty rare on commercial flights.
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chrisrad
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 3:03 am

Welcome aboard Malaysia Airlines! Winner of Best Cabin Staff 2001,2002,2003,2004,2007,2009,2012
 
United1
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 3:10 am

Here is a good one....look at the wing flex... http://www.youtube.com/watch?feature=endscreen&v=pll0P7pnrxI&NR=1

And of course and oldie but a good one....probably just heavy turbulence.

http://www.youtube.com/watch?v=i9IhQxmt08U

[Edited 2013-06-01 20:15:27]
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Slcpilot
Posts: 614
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 3:29 am

Quoting spacecadet (Reply 24):
In the back of a 747, you can feel the yaw damper snapping back and forth suddenly. The early models were so bad that people were reportedly throwing up in the cabin. Apparently Boeing made an early change to tame it, but it has still always seemed more violent than the yaw dampers in any other plane I've flown on during turbulence.

That is consistent with my first (remembered) aircraft flight! We crossed the Atlantic on anPan Am 747 in the very rear of the aircraft. It was a very uncomfortable experience in terms of yaw. I can only imagine the same was felt in the very front.

Cheers!

SLCPilot
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YXwatcherMKE
Posts: 384
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RE: What Constitutes Severe Turbulence?

Sun Jun 02, 2013 4:00 am

Back in late September 1999 possible 98. I was on an afternoon DL flight out of CVG to MCO that had been delayed by a ground stop due to a very strong thunderstorm as we sat in out seats in the MD80 the plane suddenly moved several yards. The only problem with that was it was sideways to the right. Mind you the a/c was connected to the tug and the L1 door was open because the the jetway was up to the a/c. At that point the captain said that we would need to exit the a/c so they could conduct an inspection of the a/c. After an hour they announced that we were to return to the a/c to claim our personal property because we would need to switch to an different a/c. Well about 30 minutes later we boarded another MD80 and departed with a new thunderstorm headed into the greater CVG area. By the time we got airborne (#4 in the Que) that t-storm was very close in fact as we climbed we could see a tornado forming to the west (right side of the a/c) A few moments later the pilot came on the intercom and said that the tornado was headed right at us and they were asking for a course change, Just as he said that, he said very loudly "brace for turbulence". And boy did we get it. Every over head bin opened and most of the stuff in them came out and the plane rocked side to side several times five people needed to go to the hospital afterward. We could hear alarms from the flight deck because the intercom was still on. Several people afterward said that the tornado had passed directly under us. The pilot a short time later came back on the intercom and inform us that we would be returning to CVG because there were several alarms that could not be cleared. There were several people complaining that we had to go back to CVG, they wanted to get away from the storms. Once back on the ground at CVG we were told that we would be re-booked to other flights. Which made me happy because I had enough of that weather and I had been booked on a 757. I love the take off on a 757. 5.75 hours after the first a/c sliding sideways I was finally on my way to MCO with clear weather the whole way.
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