Gusts
it is 240, but wind in a gust normally veers, so you might expect, say 250-260
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I would suggest that it depends on the hemisphere.
In the Northern Hemisphere the gusts tend to veer, ie increase in value, eg 270/10G20 will likely see the gust to be from greater than 270 (maybe 300).
In the Southern Hemisphere the gusts tend to back, ie increase in value, eg 270/10G20 will likely see the gust to be from less than 270 (maybe 240).
In the Northern Hemisphere the gusts tend to veer, ie increase in value, eg 270/10G20 will likely see the gust to be from greater than 270 (maybe 300).
In the Southern Hemisphere the gusts tend to back, ie increase in value, eg 270/10G20 will likely see the gust to be from less than 270 (maybe 240).
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....i'd suggest a spot of trolling is occurring here !!
Maybe page 24 of this report
http://www.bfu-web.de/cln_005/nn_223...indlanding.pdf
...Variations from the mean wind speed (gusts) are preceded by „G“ and are reported as under 1.1.1.2.
Gusts will be reported if during the average time interval the maximum wind speed (peak gust) exceeds
the mean wind speed by at least 10 kt. To determine the peak gust, the 3-second average of the wind
speed is used. For gusts no direction is given. [ …]...
will make you think....
Only half a speed-brake
hetfield: If I read your post correctly, your question is "how does a pilot tell whether or not is gust direction significantly different from the prevailing wind?"
The answer could be hidden somwhere deep in my MET notes or Annex3, both of which are outside reach now. I suppose it would be coded as 27015kt 190V330G28 then. If it is plain simple 24015G27 the criteria to include the variating direction code had not been met, i.e. the measured gusts are "reasonably" close to the prevailing direction. What do you think?
Sincerely,
FD (the un-real)
PS: One station on our network regularly reports something like V5G18mps; funny how this causes havoc during preflight to stay legal for dispatch, especially on contaminated runways.
The answer could be hidden somwhere deep in my MET notes or Annex3, both of which are outside reach now. I suppose it would be coded as 27015kt 190V330G28 then. If it is plain simple 24015G27 the criteria to include the variating direction code had not been met, i.e. the measured gusts are "reasonably" close to the prevailing direction. What do you think?
Sincerely,
FD (the un-real)
PS: One station on our network regularly reports something like V5G18mps; funny how this causes havoc during preflight to stay legal for dispatch, especially on contaminated runways.
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@FD
Well, according to mentioned report, gusts are not close to the prevailing direction.
So, x-wind and tailwind limits can be easily exceeded!
Well, according to mentioned report, gusts are not close to the prevailing direction.
So, x-wind and tailwind limits can be easily exceeded!
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Hetfield - for one who has been 'flying so long' I am amazed!
Firstly your page ref is wrong - it is 20 not 24. A quick look at the paragraph above your quote shows EXACTLY what I said in my first post:
"Given a generally smooth land surface area, when the wind blows strong and the weather is stormy, the most powerful gusts blow in the same direction as the wind above the boundary layer. In the northern hemisphere the wind veers clockwise about 10° to 20° with respect to the mean wind direction."
What is the problem? Oh, and how do you get a tailwind out of 270/10-20 on Runway 27?. This is why 'trolls' were mentioned by OCAS and explains my reply
Firstly your page ref is wrong - it is 20 not 24. A quick look at the paragraph above your quote shows EXACTLY what I said in my first post:
"Given a generally smooth land surface area, when the wind blows strong and the weather is stormy, the most powerful gusts blow in the same direction as the wind above the boundary layer. In the northern hemisphere the wind veers clockwise about 10° to 20° with respect to the mean wind direction."
What is the problem? Oh, and how do you get a tailwind out of 270/10-20 on Runway 27?. This is why 'trolls' were mentioned by OCAS and explains my reply
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Ladies, Please: back to aviation.
A/C type irrelevant; limtations. Rwy 26.
1. X wind = all X-wind + 1/2 gust; max 15 for autoland. W/V = 000/12G22. Can you land; do you ask the wind when at 200'agl (CAT 1 DA), does the gust veer to reduce the x-wind gust? Same argument for man' landing with greater numbers.
2. Tailwind. limit is 10kts. W/V 090/8G15. Can you land; ask the wind at 200agl?
Performance planners use 1/2 headwinds and 1.5 tailwinds for landing performance. I am asking about a/c limitations. There is nothing written down; Flt Ops have no idea and give no guidance. It is a grey area in an area of limitations. Do you divert with commercial consequences? Do you be a hero and land? Do you land, slide off the end, lose you licence and get fired? Staggeringly it is impossible to find a definitive answer from the powers that be. It is a safety and commercial issue, yet taken so 'unseriously' by managements.
Advices and opinions? Even better, any hard facts, especially EU ops?
A/C type irrelevant; limtations. Rwy 26.
1. X wind = all X-wind + 1/2 gust; max 15 for autoland. W/V = 000/12G22. Can you land; do you ask the wind when at 200'agl (CAT 1 DA), does the gust veer to reduce the x-wind gust? Same argument for man' landing with greater numbers.
2. Tailwind. limit is 10kts. W/V 090/8G15. Can you land; ask the wind at 200agl?
Performance planners use 1/2 headwinds and 1.5 tailwinds for landing performance. I am asking about a/c limitations. There is nothing written down; Flt Ops have no idea and give no guidance. It is a grey area in an area of limitations. Do you divert with commercial consequences? Do you be a hero and land? Do you land, slide off the end, lose you licence and get fired? Staggeringly it is impossible to find a definitive answer from the powers that be. It is a safety and commercial issue, yet taken so 'unseriously' by managements.
Advices and opinions? Even better, any hard facts, especially EU ops?
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Oh goody! Back to aviation.
X wind = all X-wind + 1/2 gust; - in my books, gusts have to be 'considered', no '50%'
Can you land - yes
do you ask the wind when at 200'agl - probably not if it is on my nav display
does the gust veer to reduce the x-wind gust? - in your example, yes (probably), and increase the tailwind
Same argument for man' landing with greater numbers.
2. Tailwind. limit is 10kts. W/V 090/8G15 - again yes (will have had a shufti at the runway performance, mind you)
ask the wind at 200agl? - again probably not
X wind = all X-wind + 1/2 gust; - in my books, gusts have to be 'considered', no '50%'
Can you land - yes
do you ask the wind when at 200'agl - probably not if it is on my nav display
does the gust veer to reduce the x-wind gust? - in your example, yes (probably), and increase the tailwind
Same argument for man' landing with greater numbers.
2. Tailwind. limit is 10kts. W/V 090/8G15 - again yes (will have had a shufti at the runway performance, mind you)
ask the wind at 200agl? - again probably not
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Ah, a debate at last
The best I could get from our flight safety department was that the tower reported wind takes precedence over other sources, including the little green arrow in the corner of your ND.
The rationale for this is that the info you have on IRS drift is not definitive enough to override any authorised reports, which the tower wind is (or should be). Plus it's the wind at the threshold that counts, not DH, MDA or anything else. (In the middle of nowhere, in the middle of the night, I suggest we all go very carefully in this age of instant expert analysis and litigation.)
The best I could get from our flight safety department was that the tower reported wind takes precedence over other sources, including the little green arrow in the corner of your ND.
The rationale for this is that the info you have on IRS drift is not definitive enough to override any authorised reports, which the tower wind is (or should be). Plus it's the wind at the threshold that counts, not DH, MDA or anything else. (In the middle of nowhere, in the middle of the night, I suggest we all go very carefully in this age of instant expert analysis and litigation.)
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I dont mind turbulence on my plane but gusts are the worst possible thing to have
I was landing my A321 plane the other day, perfectly lined up on a clear day and then suddenly a strong gust of wind blew the aircraft straight of course which takes an awfull lot and I spent another 15 minutes attempting it again [this time succesful]
I was landing my A321 plane the other day, perfectly lined up on a clear day and then suddenly a strong gust of wind blew the aircraft straight of course which takes an awfull lot and I spent another 15 minutes attempting it again [this time succesful]
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@Boac
If I open the pdf, it's 24/85.
However I don't want't to put the discussion to that low level....
Further on the report (24/85): For gusts no direction is given. [ …]
Regards
Firstly your page ref is wrong - it is 20 not 24. A quick look at the paragraph above your quote shows EXACTLY what I said in my first post:
"Given a generally smooth land surface area, when the wind blows strong and the weather is stormy, the most powerful gusts blow in the same direction as the wind above the boundary layer. In the northern hemisphere the wind veers clockwise about 10° to 20° with respect to the mean wind direction."
"Given a generally smooth land surface area, when the wind blows strong and the weather is stormy, the most powerful gusts blow in the same direction as the wind above the boundary layer. In the northern hemisphere the wind veers clockwise about 10° to 20° with respect to the mean wind direction."
However I don't want't to put the discussion to that low level....
Further on the report (24/85): For gusts no direction is given. [ …]
Regards
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Tailwind. limit is 10kts. W/V 090/8G15. Can you land; ask the wind at 200agl?
