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Severe turbulence/mountain wave 10th March 2007

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Severe turbulence/mountain wave 10th March 2007

Old 12th Mar 2007, 04:43
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Snoop

If it was severe in a 737 or A-320 etc, imagine what it was like in the back of a 757-200 or 300?

There is nothing wimpy about what happens to passengers or flight attendants who are thrown sideways on top of beverage drink carts or are thrown into the ceiling....feet first, one presumes? What we call light-moderate 'code 3' up front in the c0ckpit is worse in the back of many aircraft, near the aft galleys.

Read the article in (US) "Airways" magazine about two or three months ago about what a pilot learned regarding certain cavalier ATC attitudes (among some, but not all) towards many pilot requests which he was expected to learn and apply, when he then became a controller.
His article is titled "Circle of Jerks" : his words, not mine. Y'all remember who we carry around.
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Old 12th Mar 2007, 07:00
  #42 (permalink)  
 
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Wimp comment: I agree, not being a native English speaker I thought the meaning of wimp is less inflamatory than it turned out to be. My post is edited for this. The rest of my post remains valid however.
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Old 12th Mar 2007, 07:52
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Ignition Override: U.S. controllers and European controllers are two entirely different breeds, believe me.
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Old 12th Mar 2007, 09:22
  #44 (permalink)  
 
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I asked for, and got, my requested descent from FL370 to FL330: not that the turbulence particularly mitigated but it did give me a tad more space between the yellow bars on the PFD - 1.3 g buffet limit. When the speed is varying so fast that you are going from full thrust to idle to try to stop it hitting the red, and the you can't maintain altitude and the aircraft is rolling violently, you don't want to hang around in it.

That type of motion isn't a problem for the guys at the front, strapped in and with very few loose articles on the flightdeck, but for pax and cabin crew it can be terrifying and dangerous respectively.

The sig wx chart indicated nothing: Bordeaux were warning of "turbulence" over the Pyrennees at all levels but no indication of the severity. Last night with the same northerly wind, albeit a tad stronger at FL370 the ride was occasionally choppy, no more.

The easyJet wasn't a Wimp: he was simply trying to get his aircraft out of the turbulence for safety. If the ride he was suddenly subjected to at FL390 was anything like ours at FL370 he would have had even less of a margin than us.

Following requests from half a dozen aircraft for immediate descents from 370 and 390 other aircraft following were requesting early descents before the wave hit them: if the controllers already knew that 370 and 390 were bad why did they not warn the crews and offer descents?
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Old 12th Mar 2007, 09:27
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Turbulence conditions can change rapidly. Suddenly, the lower levels are affected and not the upper ones. Would you offer a different altitude if you were an ATC? I wouldn't - I would let them know that previous a/c were encountering these problems at said levels, but the decision is up to the PIC.

If you offer actively your name might show up in the accident report...
 
Old 12th Mar 2007, 10:07
  #46 (permalink)  
 
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Perhaps some of the ATC-ers dont quite understand the conditions that we can experience in severe turbulence.


Send them up for a fam flight in Scotland during a stormy night in a small turboprop, and they'll soon realise.

I have had the pleasure( ) of experiencing some sporting weather conditions this winter, and it wasn't much fun. Add some icing to the equation just to make it a little more interesting.

All vomit bags full !

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Old 12th Mar 2007, 10:09
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ATC.

If ATC knew of the turbulence - esp the severity experienced by previous a/c - then I would expect at least they passed the info on & at which levels they had reports from.
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Old 12th Mar 2007, 10:14
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ATC are our allies, not our foes. Keep that for management..

WWW
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Old 12th Mar 2007, 10:27
  #49 (permalink)  
 
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slowing down helped us a lot - didnt hear anyone else calling to slow down though. Doesn't that help you chaps in the airliners?
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Old 12th Mar 2007, 10:54
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Wind & ATC

Sorry, I wan't attacking ATC, merely wondering if they provided warning? Was that what the original poster meant? If not, why?

"Just out of curiosity,what was the wind doing around that region of the Pyronees on that day?" Dwaine Pipe

It was very strong gusting to 140Kph at the surface apparently.
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Old 12th Mar 2007, 11:55
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At 370 it was around 040/41 just north of MLA
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Old 12th Mar 2007, 12:03
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South of the Pyrenees (north of Zaragoza) it was 000/65 at FL360
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Old 12th Mar 2007, 12:28
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Were there any lenticular clouds around?
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Old 12th Mar 2007, 12:37
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There were not any lenticular clouds in the west Pyrenees at least.
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Old 12th Mar 2007, 13:08
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PIREPs

This is a PIREP situ, were any passed to ATC? Were you ACRAS equiped so Ops/Dispatch could log?
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Old 12th Mar 2007, 14:18
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I wasn’t there and didn’t experience this event, but I have in the past.

I would suggest that this was a manifestation of rotors. The strength of the wind is not the issue here, but the presence of a deep, stable layer with little vertical shear throughout the troposphere.

In such circumstances, when the wind is incident on a barrier such as a mountain range, longitudinal harmonic vortices called rotors can form just like from the reed in an organ pipe. The question of lenticular cloud is germane because the presence of such clouds is a sign of the possibility of rotors.

Stacked lenticularis, particularly when in regularly spaced groups is a harbinger of the presence of rotors and the possibility of severe turbulence. Also the clouds produce severe icing as a result of forced uplifting of saturated air. They should be avoided if possible. The rotors will be between and below the lenticularis as they generally form in the 'troughs' of the lee wave. Conversely, the clouds mark the peaks of the wave.

Such phenomena may not be forecast on significant weather charts, since no winds below 80 kts are shown, and their incidence may be temporary and sporadic. The art of the professional airman is to recognise the warning signs, and be prepared:

- A deep stable layer with little shear up to the trop. Check the wind charts.
- An incidence over a lateral barrier of less than about 30˚
- A warm moist airmass

If you’re not fortunate enough to avoid it, keep the attitude as constant as you can, ditch the autothrust and make smooth adjustments with power, remember you may be close to the surge boundary, tolerate the variations in speed and altitude within reason.

Make a ‘securité’ broadcast on the frequency in use and 121.5 giving your position, level and heading.

You won’t be able to maintain RVSM, and the call to ATC is MAYDAY if you can’t achieve a sympathetic reclearance.
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Old 12th Mar 2007, 16:22
  #57 (permalink)  
 
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@ Real slim Shady, your milder tone makes much more sense to me now.
"When the speed is varying so fast that you are going from full thrust to idle to try to stop it hitting the red, and the you can't maintain altitude and the aircraft is rolling violently, you don't want to hang around in it."
I guess my reply makes as much sense to you
"Whenever possible he will get descend, if he has to wait and cannot he should declare that he's unable to maintain level and emergency separation can be applied."
Your quote: "The easyJet wasn't a Wimp"
I went over that already, took that word back.
Your quot: "Following requests from half a dozen aircraft for immediate descents from 370 and 390 other aircraft following were requesting early descents before the wave hit them: if the controllers already knew that 370 and 390 were bad why did they not warn the crews and offer descents?"
My quote: "Rest assured that any pilot asking for a level change due turbulence will get it but not at any price. As a final note you can also rest assured that we will try our very best to warn you about turbulence and try to plan you at different levels."
There's a big difference between your initial post and this subsequent post, I'll buy the second real slim shady a beer :-)

@ WWW "ATC are our allies, not our foes. Keep that for management..

WWW"
I'll buy you a beer anytime.
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Old 13th Mar 2007, 04:04
  #58 (permalink)  
 
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I have been following this thread with interest. I have had a fair amount of experience with wave and rotor, both as a passenger flying up and down the Rocky Mountains and as a tow pilot up to 10,000' and in gliders up to FL240.

I have always found (and read) that the worst turbulence is associated with the rotors which usually occur at or below the tops of the mountains and that above the mountain tops, the flow is laminar and often uncannily smooth.

Was the high altitude turbulence encountered over the Pyrenees due to wind shear or high speed penetration of short period waves? I imagine waves that appear smooth to me at 50 kts, might seem quite different at 500 kts.

Classic "rotor" seems unlikely at the altitudes reported. Are there any meteorologists who can comment?
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Old 13th Mar 2007, 07:34
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The question popped up, why ATC doesn't inform pilots in time offering other levels... Well, I'd say that as it was written before our workload can get really high even with a few aircraft in turbulence, but if there's medium or heavy traffic and/or military traffic then especially.

For example... The top of the lower sector is FL345. You're flying at FL370, wanting to know about the turbulence. If you wanna go down below we need to coordinate with the lower sector if they can take you.

If the sectors are collapsed into one, one problem less, but still if everyone wants to fly on the same levels it's not that easy to manage sometimes for 15-20 planes in the sector, especially that you can't base your separation even on the 'more or less same speed for same type a/c'...

Other thing is that we might be busy with arranging something for someone else and/or trying to figure out how's it going to work with all of you going up/down... It takes time as well.

If there's MIL traffic in the area talking to MIL controllers only, they might also wanna change level. The we only got a phone call saying he's going to that level due turbulence and the rest is up to us.

We're trying to help as much as we can, but sometimes we simply don't have the time to tell you about the turbulence 10 minutes ahead just when you're 2-3-4 minutes ahead. Sorry, but I think you might be able to pick up some clues if you're listening carefully to the frequency which is not always the case for certain (not all) people. It's really annoying in a busy enviroment if you need to give the instruction 3-4 times because someone's just not listening. And the others are waiting in the meanwhile, because we're taught to follow the routine 'first things first'. You might be shaking up there for a minute more but first of all two others shouldn't hit...

It also takes a time from our thinking time (you might notice, this is the thing what we lack of at most) if someone's talking about his turbulence for a minute on the frequency - "eeer, radar we're picking up some turbulence here at FL390 overhead xxx, do you have any reports on eeeer lower levels because we're not able for higher today since we're too heavy or do you know if it'll smooth out in a few minutes or for how long will it last?"
Avoid it as much as you can pls. We can see where you are, what is your level - just give us the info and what you want so we can think of something. Thanks

We do our best guys to help you out, but with your help in small issues we can help you maybe even better.


Make a ‘securité’ broadcast on the frequency in use and 121.5 giving your position, level and heading.
I'm not quite sure it's a good idea, since 121.5 should be used only for emergency purposes... I'd rather prefer you to inform others on the 'chat' frq or to tell the ATC - as briefly as you can pls.
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Old 13th Mar 2007, 14:07
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french/spanish airspace are special!

i love it when in french and often spanish airspace, you can hear the controller and other aircraft speaking quite energetically in french/spanish and having a recognizable term "turbulence."!!!! etc

not much help for non english speakers, and we have to tie up the frequency even more with questions in english about the same information!!

and like it or not the native language aircraft get priority for sure. only human nature i suppose, especially when the controller is under a load. the native language must be a lot easier!!

cheers;
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