Working out average DES winds

[Driver170 42]

Yeh TOW is minus taxi! Well it should be. And at takeoff i always make sure i have sufficient fuel to complete the flight.

[pcubine 143]

It does make a difference with what way you enter it.

What difference does a couple of hundred pounds make?

[Driver170 42]

Why? Well i asked a pilot that i speak too and he said -

 

There should be no difference between the ZFW from the loadsheet and the FMC as the loadsheed ZFW will be entered into the PERF INIT page. The GW should be close, preferably within a 100kgs and it usually is, only difference could be due to either fueling a bit more than planned or longer than planned APU runtime.

 

 

So when i have my PFPX OFP in front of me i expect my ZFW to match the NGX like it does in real life but like that pilot said the GW should be off 100kg, which it does in my NGX and i'm perfectly happy with that.

 

So what i do is enter my ZFW from PFPX and then set my fuel and it all matches up perfect now except the GW which is understandable because the FMS over reads

[scandinavian13 5,192]

 

 

like it does in real life

 

Not really. Your friend fed you poor information (not bad, just poor).

 

Look at a flight release. Note that there's a line next to all of those numbers. Why would there be an ACT line there if it was perfect every time? It's not.

 

Last minute non-rev. Better print out a new release!

Nope. Note the change on the paperwork, ensure it doesn't put you over limits, sign, send, done.

 

Aviation isn't cut and dry, and it's not perfect. Numbers are never "bang on."

[Spin737 102]

 

 

Last minute non-rev. Better print out a new release!

Nope. Note the change on the paperwork, ensure it doesn't put you over limits, sign, send, done.

 

[ed note: Dang it! I have a beautiful bullet point example with math and stuff. I killed it somehow with my new computer. Grrr.]

 

Actually, that is how my company does it. We do get a new release. Our ZFW should always match.

 

Other companies have a figure they can use for overweight or underweight to figure out the new fuel burn to make sure they won't be short on fuel or heavy on landing. Say, every 1000lbs of weight = 0.2lbs of change in fuel burn.

 

We have everything automated and it updates and fixes pretty easily. Good stuff.

 

I'll maybe re-type my example, but it's time to cook some dinner.

[scandinavian13 5,192]

[ed note: Dang it! I have a beautiful bullet point example with math and stuff. I killed it somehow with my new computer. Grrr.]

 

Actually, that is how my company does it. We do get a new release. Our ZFW should always match.

 

Other companies have a figure they can use for overweight or underweight to figure out the new fuel burn to make sure they won't be short on fuel or heavy on landing. Say, every 1000lbs of weight = 0.2lbs of change in fuel burn.

 

We have everything automated and it updates and fixes pretty easily. Good stuff.

 

I'll maybe re-type my example, but it's time to cook some dinner.

Really? Hmm. A bunch of my ramp/airline time was spent with an LCC, and that extra paper was a luxury. I guess it would make sense to print a new release as long as you're printing a new manifest.

 

What about bag count discreps?

[JoeDiamond 67]

 

 

I'm hoping someone can steer me in the right direction on how to work out average DES winds?

 

If you are referring to the descent forecast page there are as many different techniques for entering the information as there are Boeing pilots.  I enter the winds for FL340, FL240 and 14,000 feet.  I put in a rough estimate of the temperature deviation, no need to do the math as it's not going to matter that much.  Altimeter setting is self explanatory.  If I think I will need anti-ice for the descent I'll set the altitudes based on the destination weather.  I'm usually doing this just after reaching the top of climb so it's just an estimate at that point.

 

Some pilots only put in the descent winds if there is a tailwind.  Others never put anything in.  It's all technique.

[Spin737 102]

Really? Hmm. A bunch of my ramp/airline time was spent with an LCC, and that extra paper was a luxury. I guess it would make sense to print a new release as long as you're printing a new manifest.

 

What about bag count discreps?

We get a Load Closeout before we push via ACARS. This has our pax count and ZFW and a few other things.

 

If we are getting ready to push and we get a MASTER CAUTION - DOORS, the rampers have probably opened the FWD CARGO to add a bag. The LOAD CLOSEOUT revision will probably chime the ACARS in a few seconds. It's all automated and quick. Sometimes we'll get a revision or two without notice saying there was a change in bags. No biggie unless it causes us to go over a release weight and then we'll get an Amendment to our release at about the same time over ACARS.

 

When I was at the regionals, I did thousands of Load Manifests by hand and we did have a column for last minute bags.

[Driver170 42]

 

 

I thought they should be bang on! He said - The loadsheet (in full: load and trim sheet) contains only the weight and balance information and the ZFW should match.

If you are referring to the descent forecast page there are as many different techniques for entering the information as there are Boeing pilots.  I enter the winds for FL340, FL240 and 14,000 feet.  I put in a rough estimate of the temperature deviation, no need to do the math as it's not going to matter that much.  Altimeter setting is self explanatory.  If I think I will need anti-ice for the descent I'll set the altitudes based on the destination weather.  I'm usually doing this just after reaching the top of climb so it's just an estimate at that point.

 

Some pilots only put in the descent winds if there is a tailwind.  Others never put anything in.  It's all technique.

 

Hi joe, Thats not what i'm looking for! I'm looking to find out how to average out the descent winds so i can use it for my descent planning.

[scandinavian13 5,192]

 

 

Thats not what i'm looking for! I'm looking to find out how to average out the descent winds so i can use it for my descent planning.

 

Vernon,

 

There's no need to get an average if you're using the method Joe prescribed. Using the function on the DES forecast page will do it all for you.

 

If you're looking to average the wind, some basic maths will be just fine:

Sum all the wind at each altitude. Divide by number of altitudes.

Sum all of the degrees at each altitude. Divide by number of altitudes.

 

No idea why one wouldn't use the method my video, or Joe is referencing, though...

[Driver170 42]

I enter enter all data in the forecast page FL300 FL180 FL90 if significant. And for the average wind correction per 10 kts : +/- 2 nm tailwind/headwind. So knowing my average i can add or subtract NM

[scandinavian13 5,192]

 

 

I enter enter all data in the forecast page FL300 FL180 FL90 if significant.

 

This will adjust the T/D marker as appropriate, which means that this:

 

 

 

And for the average wind correction per 10 kts : +/- 2 nm tailwind/headwind. So knowing my average i can add or subtract NM

 

...is irrelevant

 

You're duplicating efforts by using old rules of thumb. Again, you have to look at the big picture with things like this. Each and every time you have a question, it seems like you're trying to gather so much detail that you're getting yourself lost.

 

ZFW should match, sure, but if it's a couple hundred off, it's not a huge deal.

DES Forecast takes care of adjusting the T/D for you, which means that all of the nifty rules of thumb don't really matter, other than to confirm what the T/D is telling you.

 

Step back. See the big picture.

[JRBarrett 3,076]

I enter enter all data in the forecast page FL300 FL180 FL90 if significant. And for the average wind correction per 10 kts : +/- 2 nm tailwind/headwind. So knowing my average i can add or subtract NM

No real need to average anything - the FMS does that for you in its calculation of winds entered on the descent page. I always fly with r/w weather injected by ASN. I use the Foreflight iPad app for getting current NOAA winds aloft for my destination. I'll typically enter predicted descent winds for 25,000, 16000, 10,000 and 6,000. The FMS will use the values you enter and apply an integration and smoothing function to (internally) predict the wind direction and velocity at any point on your programmed descent path.

 

If you wanted to take the average of the data points for your own interest you can, but predicting the actual wind direction and velocity between the specified altitudes cannot be done using a simple averaging formula - doing it accurately requires calculus.

[downscc 1,327]

When it comes to winds, averaging is always wrong.  For example, fly from A to B with headwinds and then fly from B to A with exact same winds.  The average wind is zero but you will spend more time flying in the headwind so your average exposure to wind is non-zero.  Use the three different wind levels on the descent page, and if you want a backup calculation there is always the old rule of thumb of 'drop thousands and multiply by 3.'

[Driver170 42]

My weather pack that i make up during pre flight has the favourable descent winds that i need for the forecast page and during descent i keep a close eye on the winds and see if they are within what was predicted by ASN. But 9/10 its always spot on!