Shear Rate ?
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Shear Rate ?
the column of the CFP with the WIND ... W/C ... SR
can anyone shed some light on the SR bit ...
shear rate I've been told and it indicates the probability of encountering
turbulence, I can't find any written reference though ...
thank you.
can anyone shed some light on the SR bit ...
shear rate I've been told and it indicates the probability of encountering
turbulence, I can't find any written reference though ...
thank you.
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The following refers to the Windshear/Turbulence bit:-
...these figures are approximate/(more accurately..'emperical')
CAT may be expected in regions where :
(a) Vertical wind shear is greater than 4 knots per 300 m.
(b) Horizontal temperature shear is of the order of 5 deg Centigrade per 150 km.
(c) Horizontal windshear is greater than 25 knots per 150 km (moderate) and 50 kt per 150 km (severe).
JG
...these figures are approximate/(more accurately..'emperical')
CAT may be expected in regions where :
(a) Vertical wind shear is greater than 4 knots per 300 m.
(b) Horizontal temperature shear is of the order of 5 deg Centigrade per 150 km.
(c) Horizontal windshear is greater than 25 knots per 150 km (moderate) and 50 kt per 150 km (severe).
JG
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thanks Jim, but what about the SR column in the computer flight plan, it
will contain numbers ranging from 1 to 15 (I think so) ...
where can I find written reference for what the numbers mean ?
will contain numbers ranging from 1 to 15 (I think so) ...
where can I find written reference for what the numbers mean ?
Suggest you look in your company's documentation.
AFAIK SR is not mandated by any regulatory body and is provided as a "nice to know" thing by whatever company produces your flightplans. In my experience it is really no better than the information that can be gleaned from a SigWx chart.
AFAIK SR is not mandated by any regulatory body and is provided as a "nice to know" thing by whatever company produces your flightplans. In my experience it is really no better than the information that can be gleaned from a SigWx chart.
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As suggested above, check your company doc and is info only, but this might be of some help:
Shear rate: rate of change of wind velocity in knots per 1000 ft.
The higher the figure, the greater the degree of turbulence to be expected.
Windshear Severity:
There is no Windshear limit to output, and the shear rate tolerance level is up to each individual carrier standard or company policy.
No Min. nor Max. value
01 to 04 = Light Turbulence
05 to 09 = Moderate turbulence
10 and Above = Severe Turbulence
Enjoy the ride
MP
Shear rate: rate of change of wind velocity in knots per 1000 ft.
The higher the figure, the greater the degree of turbulence to be expected.
Windshear Severity:
There is no Windshear limit to output, and the shear rate tolerance level is up to each individual carrier standard or company policy.
No Min. nor Max. value
01 to 04 = Light Turbulence
05 to 09 = Moderate turbulence
10 and Above = Severe Turbulence
Enjoy the ride
MP
As esreverlluf says, you can get a better idea by examining the Sig Wx chart. I've seen shear rates over 16 on CFPs and the trip was as smooth as a baby's bum while at other times a shear rate of 1 or 2 and as rough as guts. There are other factors which come into it not just the shear rate.
Regards,
BH.
Regards,
BH.
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Meto,
you said it is wind velocity change per 1000FT.can you describe it in detail?
say our cruise level is 350, SR=10,is that mean from ground to FL350, wind velocity is 10kt increase per 1000ft, or between fl350 and fl340 or fl 360 , the different is 10 kt?
you said it is wind velocity change per 1000FT.can you describe it in detail?
say our cruise level is 350, SR=10,is that mean from ground to FL350, wind velocity is 10kt increase per 1000ft, or between fl350 and fl340 or fl 360 , the different is 10 kt?
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As said above this shear factor is the change of windspeed in knots, per 1000 feet. In other words most flightplanning systems use the windspeed a 1000 below your planned level and 1000 feet above, and divide by 2 to get the average. Or to calculate them in a few "blocks" of altitude levels.
There is no limit of how high it can be of course, as it is simply the change in windspeed and it can be a indication of a possible turbulence, but by NO means does it indicate that there IS turbulence no. You can have a 14 in smooth ride and 2 with moderate CAT so it does not indicate neccessarily that there is turbulence. But it can be a hint of possible turbulence, among with other factors.
There is no limit of how high it can be of course, as it is simply the change in windspeed and it can be a indication of a possible turbulence, but by NO means does it indicate that there IS turbulence no. You can have a 14 in smooth ride and 2 with moderate CAT so it does not indicate neccessarily that there is turbulence. But it can be a hint of possible turbulence, among with other factors.
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SR is absolutely right.
Shear rate is an indication ONLY (sometimes not so correct (at least at the time you fly through the concerned area)), and refers to level(s) above/below within a certain predicted location and time frame that may both change (so is mother nature).
Fly safe
MP
Shear rate is an indication ONLY (sometimes not so correct (at least at the time you fly through the concerned area)), and refers to level(s) above/below within a certain predicted location and time frame that may both change (so is mother nature).
Fly safe
MP
Last edited by MetoPower; 29th May 2012 at 13:45.
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From my experience the shear figure quoted on a CFP is merely a figure the supplier of the CFP calculates and it is notoriously difficult to obtain a definitive description of what it actually does mean or what it is based on. It is just a number and one assumes that the bigger the number the worse the turbulence is likely to be. However, in practice the ones I currently get given seldom bear any resemblance to actual conditions experienced and are thus nigh on useless and largely a waste of ink.
Previous suppliers of CFPs have done better, so quality of info seems to vary with supplier. Helpful, eh?
Previous suppliers of CFPs have done better, so quality of info seems to vary with supplier. Helpful, eh?
