Weather changes, and forecasts get less and less accurate as the time between now and the forecast increases.

 

 

Kyle

Very true. Last year I had a discussion in the OpusFSX Forum with the developer about forcasted winds and I came to the conclusion that due to a unique set of circumstances the forecasted winds entered into the FMC during preflight could be as old as 18 hours. Towards the end of a 14 hour flight this could result in FMC containing wind forecasts from 28 to 32 hours old. The forecast is certainly out of date. Are the winds significantly diffferent in the newer forecast? Maybe or maybe not. But the two forecasts need to be compared.

 

Michael Cubine

 

 

Are the winds significantly diffferent in the newer forecast?

 

Is it going to snow tomorrow, or will it be sunny and kinda nice?  How sure are you about that?  :wink:

 

Remember, aviation forecasting is forecasting the same weather you're seeing forecasted from your daily news sources.  Sure, it might be slightly different source to source, because each one has a different person forecasting, but weather is weather.

 

Air stability is the main issue.

 

Stable air?  Chances are that the forecast won't change too much.

Unstable air?  Good luck...

 

You're from Tampa.  You should know better... :wink:

Sure, you can set your watch by the summer afternoon storms, but where is that anvil going to pop up, exactly?  Unstable air means it could be anywhere.  A front on the other hand?  I can tell you caparatively precisely where that storm is going.  Similarly, what will the wind look like?  The forecast could be stable, or it could be unstable.

 

It just depends on the day.

Careful.

 

What one operator does, another operator will turn upside-down, repaint, re-word, and otherwise contradict the former practice.  Example: SWA didn't use A/T or VNAV until recently, while other operators did.  Some operators leave landing lights on until 10.  Some turn some of the lights off at gear retract, and the rest at 10.

 

Aren't wind up dates enroute a new thing that's relatively rare? I certainly saw something not too long ago detailing new technology for updating descent winds; however that might have been the accuracy of the data rather than aircraft being able to receive the information.

 

Remember that your wind pull in the sim is current wind only.  Airline systems generally tend to have forecast winds mixed in to those data pulls to be more accurate for when the aircraft is planned to be there.  So, even if they didn't do it in the real world, you'd probably want to do it occasionally in the sim.

 

I use PFPX which from what I understands uses the ETA for each waypoint and gets the forecast winds for that time, so this is taken into account.

 

 

Aren't wind up dates enroute a new thing that's relatively rare? I certainly saw something not too long ago detailing new technology for updating descent winds; however that might have been the accuracy of the data rather than aircraft being able to receive the information.

 

If you're watching a doc that wasn't put out by someone like Lockheed or another current contractor (so, a doc by a news firm, Discovery, and so on), I wouldn't trust its date accuracy.

 

CPDLC is newer but still not entirely "new," per se.  ACARS has been around since the late 70s, and wind/weather data has been able to be uplinked since the 90s.  There may be newer systems that I'm drawing a blank on.

 

 

 

I use PFPX which from what I understands uses the ETA for each waypoint and gets the forecast winds for that time, so this is taken into account.

 

I wasn't aware it pulled forecast wind, but I never checked.  Either way, I just said 'careful' and if you did the research to know that it pulls forecast wind, then I'd call that a careful approach.

 

Still, one airline may do one thing that another doesn't.  Further, a crew will do one thing that another will not.  I never heard the end of the complaints about one captain my friend flew with.

If you're watching a doc that wasn't put out by someone like Lockheed or another current contractor (so, a doc by a news firm, Discovery, and so on), I wouldn't trust its date accuracy.

 

CPDLC is newer but still not entirely "new," per se.  ACARS has been around since the late 70s, and wind/weather data has been able to be uplinked since the 90s.  There may be newer systems that I'm drawing a blank on.

 

Can't remember. One for 777simmer to chime in on if he sees this maybe.

 

 

I wasn't aware it pulled forecast wind, but I never checked.  Either way, I just said 'careful' and if you did the research to know that it pulls forecast wind, then I'd call that a careful approach.

 

I'm not 100% as it was a forum enquiry and I can't remember if it was PFPX dev who answered. It seems to work though; I've flown quite a few long hauls using it and accuracy has been pretty good.

 

 

Still, one airline may do one thing that another doesn't.  Further, a crew will do one thing that another will not.  I never heard the end of the complaints about one captain my friend flew with.

 

Ah yes, the rarely spoken of aviation grey area (that shouldn't really exist). Bitten me in the past that has.

 

 

Can't remember. One for 777simmer to chime in on if he sees this maybe.

 

Problem is, he could only speak for the operator he flies for.  And, to be honest, pilots aren't always most knowledgeable of the capabilities of the technology in the cockpit.  Not to take a shot at him, or anything, but it's a truth I had to deal with in my last job.  They know it's there, and they know how to use it to their company SOP, but a good number of them didn't know much beyond that, despite existant extra capability.

 

 

 

I'm not 100% as it was a forum enquiry and I can't remember if it was PFPX dev who answered. It seems to work though; I've flown quite a few long hauls using it and accuracy has been pretty good.

 

Cool.  Definitely post if you see anything definitive.

 

 

 

Ah yes, the rarely spoken of aviation grey area (that shouldn't really exist). Bitten me in the past that has.

 

Not to divert the topic too much, but I disagree.  Nobody knows how to perfectly fly an aircraft.  While people should stick to best practices and company SOPs, no company has a perfect SOP.  Some of the better things in life are in the grey area.  The fringe is where you get bitten for pushing boundaries.

 

CIs are grey area.  Company and personal minimums are grey area (or are, at least, not a worldwide standard).  Perhaps I'm misinterpreting what you're getting at.

PFPX has a "Departure time". It will use forecasts relevant to the departure time (usually updated every few hours.)

So if the Forecast is right (crystal ball not included) the error should be negligible.

 

Of course this only works if you arrive at the various waypoints 'on time'. If you selected (or more likely didn't select) a Departure time, then spent hours before you did depart, your weather forecast may be hours out... and then the winds won't match.

 

Select a correct departure time in PFPX before releasing flight & saving the data, and depart at that time like a departure slot. Make sure your weather software is configured correctly to inject weather correctly into FSX, FSX default or FSinn weather off etc... 

 

However like the real world, forecasts aren't always 100% accurate. It can be very accurate, but the longer your flight, the more likely the winds at the end of your route will change (and even the forecast will change as more trending data becomes available to the Meteorological services.)

 

 

PFPX has a "Departure time". It will use forecasts relevant to the departure time (usually updated every few hours.)

So if the Forecast is right (crystal ball not included) the error should be negligible.
 
Of course this only works if you arrive at the various waypoints 'on time'. If you selected (or more likely didn't select) a Departure time, then spent hours before you did depart, your weather forecast may be hours out... and then the winds won't match.
 
Select a correct departure time in PFPX before releasing flight & saving the data, and depart at that time like a departure slot. Make sure your weather software is configured correctly to inject weather correctly into FSX, FSX default or FSinn weather off etc... 
 
However like the real world, forecasts aren't always 100% accurate. It can be very accurate, but the longer your flight, the more likely the winds at the end of your route will change (and even the forecast will change as more trending data becomes available to the Meteorological services.)

 

Thank you Hopskip you have answered my question I did not realize the time factor,

During my flight planning I tried to depart as scheduled but then I would also change

the time I wanted, And maybe that's why I've always had the discrepancies, will test

tomorrow.

thanks to everyone for your inputs.

altb

Giancarlo 

Thank you Hopskip you have answered my question I did not realize the time factor,

During my flight planning I tried to depart as scheduled but then I would also change

the time I wanted, And maybe that's why I've always had the discrepancies, will test

tomorrow.

thanks to everyone for your inputs.

altb

Giancarlo

Also be aware that time acceleration will result in you arriving at waypoints earlier than estimated, which will throw off the forecast wind.

PFPX has a "Departure time". It will use forecasts relevant to the departure time (usually updated every few hours.)

 

Trent

 

If I have read the above sentence correctly the following would occur. If I set a flight up at 10:00am to depart at 2:00pm PFPX will calculate the winds based upon a forecast that is valid at 2:00pm. Is this correct?

 

Thank you

Michael Cubiner

Trent

 

If I have read the above sentence correctly the following would occur. If I set a flight up at 10:00am to depart at 2:00pm PFPX will calculate the winds based upon a forecast that is valid at 2:00pm. Is this correct?

 

Thank you

Michael Cubiner

 

I believe this is the case.

Trent

 

If I have read the above sentence correctly the following would occur. If I set a flight up at 10:00am to depart at 2:00pm PFPX will calculate the winds based upon a forecast that is valid at 2:00pm. Is this correct?

 

Thank you

Michael Cubiner

 

That is correct. Additionally it knows roughly how long it will take you to fly through each of the waypoints, so if you depart at 14:00 for a 7 hour flight, the departure forecast (and early part of the flight plan) will be based on the weather forecast at 14:00, but the arrival planning will be based on the forecast at, say, 21:00.