Winds Aloft Question

[rogerr...@gmail.com]

Wondering which/how winds are used once a FP is created. For instance I created a fp from PDX to SEA, both locations specifically listed in the official wx forecasts for aviation. In Avare after insuring current wx was downloaded/updated I pressed on the green button for PDX and then SEA...the winds aloft forecast, in the case at 090, that popped up agreed exactly with the official wx. Then i go to Menu and hit simulate, then go to Plan and inactive/activate and winds are brought up for that FP, PDX to SEA, however the winds are different...as there is no start time, fp not activated the winds are some 'canned' winds from the past?? If wx has been updated can not those winds aloft be brought over to the FP? What are the ETE and fuel calculations displayed on the FP produced from? the real winds aloft or the displayed winds aloft which seem to be just arbitrary?. It is probably me just not understanding something. If I was planning on flying the next few days I could check the winds aloft as displaed when airborne with active fp and see if they reflect the real forecast and the data already in Avare under each location's wx data. But sitting on the ground and not flying for a few days I would like to understand how winds are aloft are used in the planning stage and how the ETE and Fuel usage is calculated and by which winds? Thanks

[Zubair Khan]

Thanks. Will take a look. I think winds are only for planning. So it will only work when in simulation mode, and plan is active. To not use winds, delete weather from download.

Thanks for reporting.

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[rogerr...@gmail.com]

Thanks, however for planning you would want the valid winds otherwise the resultant fuel and ETE data shown make no sense, and provide misleading or even dangerous info (I am assuming you have inputted your acft's speed in the pilot and aircraft section). Perhaps better to not even provide that data then. 

As I have not flown using this feature yet I would like some feedback from others who have used the FP screen, in nav mode, active---that is actually flying....does the FP screen then pull up the current winds along the route (using the avbl point by point data for winds aloft as if you were to long press on the route locations) and then figure the resultant ETE and fuel usage?

Thanks. Roger

[Peter A. Gustafson]

No, it doesn't. Avare uses GPS ground speed. As you asked for feedback... I will go further and say why I believe it shouldn't do anything but this.  I offer my opinion respectfully, as I'm sure there are others who disagree.

For light GA aircraft, the best estimator of ETA is current ground speed, as measured by GPS.  "Current winds aloft data", that is to say current forecast winds... this is big data but can be misleading if perceived to have precision and it should not replace your current best estimator (groundspeed) in small planes.

Forecast winds need to be interpolated from altitudes above and below (only reported every 3kft) and from positions up to hundreds of miles away (ie, only 3 predictions reported throughout the whole of Michigan's lower peninsula). So these "current winds data" are of little value in comparison to the current measured groundspeed.  Yes, look at current forecasts when considering alternate altitudes, this may be useful. But if the predicted winds at alternate altitudes are close such that a mental estimate doesn't yield an obvious choice, then the forecast won't be precise enough to overcome other factors (altitude=insurance, clouds/vis, precip, potential for traffic, etc).  Just my opinion.

[rogerr...@gmail.com]

''No, it doesn't'' (I haven't figured out how to bring down quotes yet).....ok, this is the info I was looking for. Again, I was trying to understand how Avare uses the data for planning as I noticed a discrepancy/diff btwn actual winds aloft  forecast avbl in other screens/modes of Avare and the winds plugged into a FP in sim mode. That was the essence of the question. Of course flying is different than planning and much must be taken into account before deciding to depart. Once airborne on a route then of course ETE/ETA derived from gps ground speed is the determining factor. That ETE/ETA is also a function of the winds aloft....in my case sited from PDX to SEA there are winds aloft forecast for 090, my altitude (actually either 085 or 095) at both those locations as well as AST, to the west. The winds aloft from the N at 20kts or from the S at 20kts has a sig influence on ETE and fuel calcs though neither represents a go/no go situation at that relatively short distance. 

So I was wondering then why any winds are used in the FP planning/sim stage as they are seem to be (at my level of understanding on how Avare works) completely arbitrary and not a function of valid forecast data...thus the ETE and fuel calcs are bogus too for planning purposes.. So why even input those winds into the FP planning mode? I will take Z's suggestion earlier and not download the wx so that the result is a no wind plan then mentally figure in the forecast winds. 

A more pertinent example might be a route I used to take, from MMV (about 30 miles SW of PDX) to RBL (N CA). In my aircraft with generally N winds (summer flying) it is doable with little concern though monitoring planned ETE/point to point is required. However if no tailwind or even worse a slight headwind a whole diff situation is present. Plugging in winds from the night before, valid for the actual dep time aid in planning and decision making. Same with updating that morning. As there are numerous winds aloft report forecast locations along the route---PDX, OTH, SIY, FOT, RBL---and the reporting alt of 090 matches my enroute alts---085 or 095---I find the planning data using the forecast winds quite useful in evaluating the go/no go situation for that single leg (of course you can and should always stop enroute if any question but the planning data makes that decision more or less likely too). And if my actual flight times after launch vary negatively from the plan using appropriate winds aloft forecast I can easily see this comparing it to the plan and make an appropriate decision. Once airborne what is is what is; though the ability to compare it to best avbl forecast winds and resultant ETE and fuel calcs (planning) I have found quite useful. As I am strictly day (no lights) vfr (absolutely no nav instruments, and I only go in the summer if the enroute conditions are forecast to be essentially clr (no to at worst infrequent sct clds and no precip!), and traffic (neg transponder not using any ATC procedures) it is the winds aloft situation in this instance, and other longer x-country flights I do that make a big diff to me, which is why I was concerned about the discrepancy I noticed and wanted to understand more on how Avare uses the forecast winds inputted (and the resultant ETE/fuel calcs)....

So anyway,, not to beat a dead horse nor venture into actual flight decision making, remember, I was just asking about planning and how to interpret the data I was seeing in the planning stage  I will not use the wx data in planning, thus getting a no wind ETE/ETA and fuel usage calc.

Thanks, Roger 

[Chip Davis]

Doesn't that depend on how far in advance you are flight-planning?  I wouldn't want Avare to consider winds aloft in any flight plan calculations more than a day or so ahead.

-Chip-

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[rogerr...@gmail.com]

Yes, of course. Winds aloft are only valid for a day or less ahead. Anything else is not valid. And we can not enter a dep time in the FP anyway so again who knows where the winds are coming from and w/o a dep time, you might be looking ahead just out of curiosity, a week ahead. Yet winds, not the only valid winds avbl or presented.

That is part of my 'confusion'...why are they even in there then? and if winds are presented should they not at least be the winds avbl from current info. Again I was trying to wrap my mind around the diff btwn the winds presented in the FP sim page vs the forecast winds aloft presented in the wx info when long pressing on a location and then resultant ETE and fuel calcs. Strictly trying to understand how Avare works....for actual flying of course it is the latest winds, say night before and just prior to dep that i want and still not sure if those are presented in the FP page the night before or morning when they would be valid for your planned dep. 

Actually just now I created a new FP on Avare, didn't use a saved on, to see how the winds may diff and be presented.  FP at 090 btwn PDX and SEA, both winds aloft reporting points...in FP and sim and inactive mode winds are presented as PDX 140@016, SEA 100@006, with time enroute 50:13, fuel 5.9 gal....switching to active it presents

------------------------------------------------------------------------------------------as PDX  140@016, SEA 180@011, with time enroute 46:50, fuel 5.5 gal

long pressing shows winds aloft forecast for now------------------------PDX  240@019, SEA  190@016 and the winds aloft forecast valid for this time periods shows

----------------------------------------------------------------------------------------------PDX  240@019,  SEA  !90@016.......

so we can see that the long press for PDX and SEA--dep point and dest point and reporting winds aloft locations are both the same so Avare is downloading, at least to the current wx page/long press the valid winds aloft. However on the FP mode the winds aloft are diff depending on whether using active or inactive on same FP (and so are ETE and fuel)  AND both winds aloft on FP active or inactive are different than the actual winds aloft forecast.  So that is what I was getting at. I wanted an understanding of this, why is this so? is there a way to get the proper winds? It is more in the area of understanding Avare and for planning purposes, not how to conduct a flight. At the risk of quoting myself---not beat a dead horse---I think the solution, for me at least,is to turn off wx/let it expire, and get a no wind FP if that works and plug in the winds aloft mentally. Or use the Menu page and switch to navigate and then it presents in FP with no winds aloft. I'll  have to wait till my wx expires to test wx this is the same as no wx downloaded.

Thanks, Roger

[John W SBA]

> I was trying to wrap my mind around the diff btwn the winds

I'm glad Roger asked, and that Peter clarified. Seems to me others
might have the same or related questions, so this topic in the Forum
will be helpful going forward.

My own strategy is to plan for winds by looking at ADDS and other online
sources via Firefox just before heading to the airport. That works best
for me, since at takeoff I typically have at least two hours' extra fuel
to destination with plenty of potential fuel stops along the way and no
set arrival time (or even destination or exact route, on many flights).
I tend to only use Avare's helpful Plan function for sketching a general
route to pass near scenic attractions and stay near roads & airports.
So my opinions don't matter much on this topic.

That said, I like Peter's reasoning about GPS speed and what I take to
be Roger's assertion that it could be helpful to have a clearly labeled
and documented option for winds aloft in Plan. At the same time, I'd
like to express my strong support for the Avare dev team to continue
doing only "what they want, when they want." That is, since Avare is
totally free and open source, anyone is welcome to modify the code and
offer it back to the project for everyone's use. So far, it seems
nobody has offered a winds aloft flight planning option. Since there
are plenty of great free options online, for me this works. :)

So again, thanks to all for the discussion.

Happy Flying -j

[Zubair Khan]

Avare will not allow planning with winds in future. It only plans with winds that were downloaded that were current at the time of weather download.

In flight (out of simulation mode) winds not used.

On ground (in simulation mode) winds used.

Aircraft speed is used from preferences.

-Z

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[Zubair Khan]

I tried it and it worked as described in Help.

Download weather

Go to simulation mode

Make a plan

Make the plan active

All winds at all altitudes in Plan are correctly displayed

All winds at all altitudes received with long press agree with winds in Plan

--

When Plan is not active, winds will not be updated (a bug I think but winds are not supposed to be used when Plan is not active).

When out of simulation mode, winds are not used and ground speed is used.

I think this should clarify everything.

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[patrice patrice]

Hi,

I have been looking at this last month during my biannual , and I faced some discrepancies in the winds from what I would have extrapolated (wind direction/speed).  I was wondering also if it would not be good to have a more details planning panel, where the users will be able to follow more easily how the calculation is done, and possibly input their own number in some of the fields.

This is something I could dive into, even if I haven't look at the code lately.


Pat.