A320 FMGS, Use of History Wind

[aca-98]

On return flight to base, if route is nearly identical to previous one, how many of you use the History Wind option?

Thanks

[kijangnim]

Good morning, if you select history wind then you would have to enter next phase wind, otherwise the TOC wind will be propagated donwstream.
wind during climb will not infuence the TOC in terms of time, it will only in terms of distance, this is the criteria for using or not the history wind.
Regards

[F4F]

True, the use of history winds leads to very precise fuel computation from the FMS. But as kijangnim points out, doing so will imprint those to the TOC, and therefore one has to enter several wind for the cruise and descent part of the flight.
To answer you question, I don't see it used very often. Mostly on longer flights (3:00+) though our SOPs suggest the use of the history winds, they don't mandate it.


live 2 fly 2 live

[aulglarse]

History wind can be useful when your previous sector winds weren't as forecast, ie, unforecast high winds/jetstream.

The company I work for does not supply climb wind data so inserting history winds provides a more accurate TOC (as kijangnim pointed out).

Some days it can take up to 200nm+ to reach TOC when entering a strong tailwind/jetstream. In this case of using history winds, the TOC gives the crew a more accurate cruise segment and in turn may change the optimum altitude hence probable time and/or fuel savings.

[aca-98]

Thanks very much.

[ppppilot]

I will post again once checked, cause I am not sure, but in the A340 history winds are very useful. The FMS records winds when you are in descent below FL250. Those are history winds. Winds during the descent at FL250/150/050 (levels is what I need to check). Then if your next TO it does not take too long from the arr you will have actual winds, not forecasted, until that level. So it is useful for the calculations until TOC. After that you must introduce the wind forecasted at your cruise FL. Once the plane reaches the first wpt at cruise if you have not introduced the wind at that level the fms will assume the actual wind at that wpt for the rest of the route, updating on every wpt.
We use the history winds and download the cruise/dsc winds from the acars.

[kijangnim]

greetings
it records the winds at 5 flight levels starting at fl350 then every 5000 ft, the standard recomandation is to use the history winds if your takeoff is within 1 hour (STD turn around time).:ok:

[hborderas]

"Once the plane reaches the first wpt at cruise if you have not introduced the wind at that level the fms will assume the actual wind at that wpt for the rest of the route, updating on every wpt"

Which wind is that, the TOC history wind or your actual wind as per your ND?

[kijangnim]

Greetings

Before you reach the TOC the FMS would have computed data in order to elaborate a type of atmosphere through which your flight is taking place, and this is done for the PREDICTIONS, 5D predictions in fact, lat, long. altitude, time, and finaly FUEL.
If you didnot enter any wind in the cruise segment of the flight, the FMS will assume that the wind is calm = 0 kts, so he will compute a blended wind using the actual, averaged with the entered wind in our case 0, he will then use a percentage of the above and mix it with the actual wind using a percentage for "dilution" this percentage is based on a distance between the aircraft position and the next waypoint where a wind is supposed to be enetered, in our case 0 again. SO to cut it short at 100 nm he will use 100% of the actual wind, at 90 nm, he will use 90% actual wind weighted with 10 of the blended wind at 80 nm he will use 80% and so on.. :ok:
If you have used history wind, then the fms will propagate it fom TOD to TOC and use it as decribed below (in stead of calm i.e., 0 the FMS will use the wind closest to you CRZ level in the history wind list) :}

[EMIT]

Just to set the record straight: close to the aircraft, FMGS will use measured wind, farther ahead of the aircraft, FMGS will mix measured wind and forecast wind, much farther ahead it will use only forecast wind.

[320p]

Hello,

while on this topic,what is preferable (or more correctly, when) to use: Trip wind (on Int Page B) or the history wind (Int page A) followed by winds for cruise and descent?

[kijangnim]

Greetings EMT
Indeed this is what it does, the assumption is that the forcast wind is correct.