View Full Version : Planning for wind speed on fuel calculations

Andy Rylance
11th Dec 2009, 16:27
Afternoon all,

I know nothing of this, but what is put into fuel load pre-planning with wind predicitions? Can you get a full forecast for wind speeds and directions at your requested level right the way across a flight and does that go into your flight plan? I realise on North Atlantic Tracks they are planned to make use of the jetstream, but say on north to south in Europe/Africa is any use made of wind speed predictions - can you get them and do they factor into your calculations?



11th Dec 2009, 16:43
Hi Andy,
Yep, this sort of information is freely available from numerous sources with varying degrees of accuracy. In the UK, the met office produce a form called F214. Other companies produce other maps, here's a link to one by Jeppesen
JetPlan.com Graphic Weather: Winds and Temp (http://www.jetplan.com/jeppesen/weatherServlet?&action=show&graphicType=wxMapWT&img=euwt340)

Fuel planning can be quite critical, particularly in large aircraft where it can make the difference of many thousands of $ whether you've got a 100kt head wind or tail wind. Too much fuel and it needs extra fuel burn just to carry the extra weight. Too little fuel and you can't get there.

Companies operating large aircraft have flight planning departments. A large part of their job is fuel planning.

Hope that helps.

11th Dec 2009, 18:40
Yep, our planners have a computerised system that looks (amongst other things) at a three dimensional wind/temperature matrix and compares various routes and altitude profiles between the departure and destination airport. We eventually get presented with a flight plan planned along the most efficient route at the most efficient flight levels. There's also a printout of a simplified matrix in our flight deck paperwork and these enroute winds and temperatures are loaded into our onboard management computers so they are able to run the enroute fuel and time predictions .

As welliewanger has said, it's a big deal for the all airlines because of fuel costs.

11th Dec 2009, 20:46
and it's incredibly accurate. very often the actuel wind is the predicited one to the degree and knot, even in the middle of the atlantic or the sahara. very impressive stuff.

Andy Rylance
12th Dec 2009, 18:13
Thanks that is interesting, especially the bit about the accuracy of forecasts and upper winds. So there is never a time now where a pilot would think a headwind is stronger than expected and ask for a level change...

12th Dec 2009, 18:22
Requests because the winds aren't as expected or desired happen frequently.

13th Dec 2009, 02:55
Speaking of winds, I never hear people reporting the weather anymore at MET reporting points on airways. Does anybody know why? Am I the only one reporting these days?

13th Dec 2009, 09:43
The weather is included automatically with every down loaded position report when using data link which almost everyone has these days.

13th Dec 2009, 09:58
Just the SAT and Wind,

13th Dec 2009, 11:31
None of the BA744 or 767 have datalink Met, this gives rise to forecast wind and particularly temperature errors (affects Mach No.) on routes where we are the only type flying. N Arctic to the West coast is a problem unless the 777 is doing Calgary or Seattle.

13th Dec 2009, 12:17
hmm not sure what exactly youre asking but if it helps our jar-ops derived fuel policy requires 7% of the trip fuel as contingency against forecast wind errors, or something like that. then again im in africa :ok:

13th Dec 2009, 20:43
The weather is included automatically with every down loaded position report when using data link which almost everyone has these days.
Nope. Not all position reports are automated, and "almost everyone" doesn't use them.

If a flight is using CPDLC, then you wouldn't hear his HF position reports in any case. If you do hear the position reports, you should hear the Met (SAT/wind) portion on random-track reports and at designated points (NOPAC tracks) and/or "as requested" (Atlantic). If you don't, the pilots are either ignorant or unprofessional when they omit them.

Also, in partial answer to the OP's question, airline dispatchers and flight planning systems account for wind forecasts. IIRC, full forecast headwind components must be considered for fuel burn, but only 50% of tailwind is allowed for "credit."