PMDG B77X & PFPX Fueling Figures

[BrianW 124]

In the T7 LRC is about the equivalent of using a CI of 180, so any CI below that in flight should give you a fuel savings over what you planned using LRC.

Are you making sure to do step climbs?

Brian

[Raphael_Chacon 42]

Hey,

 

i noticed that i actually flew more time than expected too, there is something to investigate around that.    I use Online reports to capture my flights and i noticed that i actually flew almost 12 hrs, and i was supposed to fly 10hrs something....  So,  weather?  Timing?  Headwind?     All of those?.....     :huh:

 

I ill check the weather configuration, and i will repeat the flight backwards from SBGR to KORD and see what happens...

 

Im sharing the results with you guys....   Thanks

 

;-)

[CaptCraig 226]

First things first, is your PFPX profile for the aircraft you intend to fly matching the weights of your aircraft in the sim?  I know it's a silly question because it should be the first thing you do in PFPX when you go to fly and aircraft.  

 

Next I'd go down to the weather thing at the bottom of your PFPX and before you even enter your departure airport, refresh it.  Just click Active Sky and then go to Active Sky again in the drop down.  

 

Next make sure your Active Sky program is running LIVE wind data.

 

What fuel rules are you using for your flight?  Did you modify anything?  Are you using one of the downloadable sets? 

 

Like everyone is saying, I've always noticed that my fuel is bang on, like we're talking less than half a tonne difference in most cases.  Other than what I've mentioned I can't think of anything else.  

 

Are you using auto cruise time accel?  

[Michar83 7]

Are you actually running out of fuel completely, or do you mean that the insufficient fuel message pops up every flight?

[PatrickM 2]

Hey,

 

i noticed that i actually flew more time than expected too, there is something to investigate around that. I use Online reports to capture my flights and i noticed that i actually flew almost 12 hrs, and i was supposed to fly 10hrs something.... So, weather? Timing? Headwind? All of those?..... :huh:

 

I ill check the weather configuration, and i will repeat the flight backwards from SBGR to KORD and see what happens...

 

Im sharing the results with you guys.... Thanks

 

;-)

That sounds exactly what happened to me! When you see that something goes wrong, check that you need 60sec for 60 real sec.!

[BelowMinimums 32]

Havent read anybody say this yet, so make sure you're also inputting the correct payloads in the FMC.

 

If PFPX gives you 40,000 lbs of cargo put 40,000 lbs of cargo in the FMC and make sure your FMC gross weight is the same as the PFPX planned gross weight.

 

I also end up +/- a ton or so of fuel which I'd say is pretty accurate

[downscc 1,327]

Okay, got PFPX and Topcat the other day, studied for a day then played with a long route. Today, I fired up PFPX and ASN, planned the AAL138 77W flight VHHH-KDFW (Hong Kong to Dallas), preflight the PMDG version of an AAL 77W and off we went. First thing I noticed was that PFPX allowed 34.4 klbs remaining at KDFW allowing for alternates, hold, taxi and US Flag contingency whereas FMS allowed 18.7 at KDFW. I lowered the reserves to remove the insufficient fuel message and started the 14hr flight. Enroute winds were very close to forecast thanks to ASN, initially light headwinds until abeam Japan then tailwinds kicked in as forecast. Three hours into flight my remaining fuel forecast for KDFW had decreased from 18.7 to 16.7 klbs then started increasing through nine hours where it was at 31.1 klbs and at landing 38 klbs. I was released with 291.4 klbs and the difference of +3.6 klbs was only a 1.2% variation.

 

The only problem I had with PFPX was application hang when payload value approach a couple thousand pounds of max or selecting MAX, which I have already posted in the PFPX forum. This only happens to the 77W, the 77L works as expected.

 

Needless to say I am please with PFPX fuel planning.

[Richard McDonald Woods 168]

Hi Dan,

Great to hear of your long flight experiences. They very much match mine.

Cheers, Richard

[scandinavian13 5,192]

 

 

whereas FMS allowed 18.7 at KDFW.

 

Not sure what you mean here.  If you used  the PERF INIT datalink, it's not necessarily "allowing" that value.  It's just offering that as an example value.  It doesn't know your destination alternate, contingency, and other values, so it's basically a guesstimate from PMDG of a reasonable value.  It's not at all guaranteed to meet regulatory requirements, which PFPX's will.  That's a field that you'll definitely have to edit (along with your CI if you change it flight to flight like I do).

 

PFPX is definitely a great tool, provided you're giving it the right numbers and right picture of things!  Good to see some numbers to back it up.  I don't usually do too much observation other than "I made it to my destination with fuel left - okay, kill the sim..."

[downscc 1,327]

 

 

Not sure what you mean here

 

Poor choice of words on my part... what I meant was the expected value of fuel remaining at destination displayed on PROG page. I don't use PERF INIT and haven't found a good reason to skip setting up those flight parameters myself yet.  I meant to illustrate how much the fuel remaining on PROG page varied throughout flight and ended up within about 1% of total released at end of flight. I found this interesting because before PFPX I used the PROG remaining value to plan my fuel load.

[Richard McDonald Woods 168]

Guys!

 

I have concentrated on keeping tabs on the waypoint times, and only occasionally recording FREM at each waypoint, although I do carefully check FREM at re-dispatch waypoint.

 

In future I shall check each waypoint FREM for accuracy and report back.

 

Cheers, Richard

[downscc 1,327]

Hi Dan,

Great to hear of your long flight experiences. They very much match mine.

Cheers, Richard

Richard:  Do you experience a PFPX app hang when calculating a 77W flight that has payload either MAX or with couple thousand pounds of maximum (777-300ER only)?? I do everytime, and only way to run a calculation is to reduce payload such that there is about 3000 lbs underload, regadless of limiting constraint. I've asked for help in the PFPX forum without response yet but I know you from years of posts here and hope you might be able to help. If you are not having app hangs (the status message in  lower left corner with the 1-2-3-1-2-3... dots annimation stops) how about posting your 77W weights and max pax numbers.  I am using numbers found in FCOM and FMS and assume they are okay, but am stumped unless others have same problem. Many thanks.

[Richard McDonald Woods 168]

Hi Dan,

 

Unlike you, I only ever specify number of passengers and freight load, and that always in kilos. I like to fly the B77W heavy, so usually specify 299 px and 35000 kgs of freight, giving a ramp weight of around 300 tonnes.

 

Using my BA aircraft, and therefore BA configured, and specifying payload as MAX, I get a usable FP. I guess, therefore, that your PFPX problem lies in the aircraft configuration that you are using.

 

My aircraftt configuration is:

- engines GE90-115BL

- OEW 167,829 kgs

- PX capacity 299

- all performance adjustments unaltered.

 

I suggest being a little more adventurous in your parameters to ascertain where the problem lies.

I hope this helps a little.

Regards, Richard

 

PS I subscribe to your feelings about Christian Grill's responses. His must be one of the greatest products, utterly spoilt by the almost total lack of fixing reported problems 

[downscc 1,327]

Thanks Richard, we are using the same DOW and I changed max Pax to match yours but still have app hang, I notice that now I can get a app hang consitently when re-planning a flight. For example, it will successfully calculate a flight with nbr pax and cargo values entered and then when I re-plan to adjust payload once or three times then it freezes. I'm going to try an uninstall then reinstall, which I never recommend, but I'm out of ideas. Thanks again for your feedback, at least I know it should be working.

[downscc 1,327]

 

 

and that always in kilos.

 

And that was the key that I overlooked.  Thanks to Stephen Cook in the PFPX forum who setup same VHHH-KDFW flight with weights same as mine and repeated the appHang, then found that if KGS were used instead of LBS PFPX would behave as expected, no appHang. I have confirmed this as well on same and different route/weights. Seems bug is in v1.15 for B77W using LBS, must use KGS... I have sent info to PFPX support regarding this find.