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"Annual Winds" Calculation In Range Circles  
User currently offlineGRUIAD From United States of America, joined Sep 2010, 63 posts, RR: 0
Posted (3 years 5 months 5 days 14 hours ago) and read 3568 times:

I have seen range charts / maps or range circles from a specific airport (e.g. ORD) for Boeing and Airbus for various aircraft types in their inventories. A notation at the bottom of the page has references to assumptions. One of the assumptions is:

Typical Mission rules:
85% annual winds

What does the term "85% annual winds" mean in this case? Anyone that can help would be much appreciated.

5 replies: All unread, jump to last
 
User currently offlinemercure1 From French Polynesia, joined Jul 2008, 1495 posts, RR: 2
Reply 1, posted (3 years 5 months 5 days 8 hours ago) and read 3526 times:

Annual equivalent winds are computed from the mean seasonal values of equivalent winds and their standard deviations.

The technique involves an iterative procedure by which wind speeds are determined for any specified probability between 50 and 99 percent.

85% percentile winds would indicate that only 15% of all flts, would experience a headwind greater than the 85% percentile wind, or tailwind component less than the 85% percentile wind.

85% percentile historical winds/temps have been used for ages by Manufacturers and Airlines, to judge the mission capability of a given aircraft.

Mercure


User currently offlineAlasizon From United States of America, joined Apr 2007, 289 posts, RR: 0
Reply 2, posted (3 years 5 months 5 days 8 hours ago) and read 3525 times:

Quoting mercure1 (Reply 1):
85% percentile historical winds/temps have been used for ages by Manufacturers and Airlines, to judge the mission capability of a given aircraft.

Now its worth noting that BBD (Bombardier) quotes all their ranges at zero wind.



Window seats may be over-rated, but I'll take a window seat on a DC9 anyday
User currently offlinevikkyvik From United States of America, joined Jul 2003, 10035 posts, RR: 26
Reply 3, posted (3 years 5 months 5 days 5 hours ago) and read 3489 times:
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Quoting Alasizon (Reply 2):

Now its worth noting that BBD (Bombardier) quotes all their ranges at zero wind.

Is that just a range, or the plot on a range chart, though?

If it's just range (irrespective of airport) then it makes sense to quote with zero wind, because the wind you factor in will differ depending on your origin and destination.

If it's range from a specific airport plotted on a map, or range between specific airport pairs, then you can account for typical winds.

At least that's what makes sense to me!



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineAlasizon From United States of America, joined Apr 2007, 289 posts, RR: 0
Reply 4, posted (3 years 5 months 4 days 20 hours ago) and read 3423 times:

Quoting vikkyvik (Reply 3):
Is that just a range, or the plot on a range chart, though?

If it's just range (irrespective of airport) then it makes sense to quote with zero wind, because the wind you factor in will differ depending on your origin and destination.

If it's range from a specific airport plotted on a map, or range between specific airport pairs, then you can account for typical winds.

At least that's what makes sense to me!

They quote their ranges from specific airports around the world with 0 wind, as well as on their payload/range chart, it is quote with no wind.

Though considering the abilities of the CRJ, most aren't flown anywhere near there range. The CSeries, once it gets here, might need to account for 85% Winds.



Window seats may be over-rated, but I'll take a window seat on a DC9 anyday
User currently offlinevikkyvik From United States of America, joined Jul 2003, 10035 posts, RR: 26
Reply 5, posted (3 years 5 months 4 days 17 hours ago) and read 3386 times:
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Quoting Alasizon (Reply 4):
They quote their ranges from specific airports around the world with 0 wind, as well as on their payload/range chart, it is quote with no wind.

Gotcha, thanks!



"Two and a Half Men" was filmed in front of a live ostrich.
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