Ever since Ryan created the advanced tutorial #2 for the NGX, I have been computing my fuel load for the NG with the most accurate fuel planner out there, the FMC itself.   The idea here is that the real life dispatchers use a desktop version of the FMC software when they compute fuel loads and routes.   I also remember PMDG's resident aeronautical engineer guru who worked behind the scenes on the mathematics behind the NGX flight model claiming the FMC is the go to tool.   Now, with the release of PFPX, how confident is PMDG in using PFPX as the sole source of fuel computations?   I understand there may be some slight differences between the FMC and PFPX figures, but I would hate to not use PFPX as intended, and it seems more realistic to use a professional dispatch program versus in the aircraft FMC.

 

Should we trust PFPX when it comes to the NGX and soon to be released 777 for computing fuel? 

 

Should we trust PFPX when it comes to the NGX and soon to be released 777 for computing fuel?

 

You can trust PFPX with your life. The parameters for the 772LR was given to the developers directly from PMDG which again got them from Boeing. Just make sure you have updated the nav-database to 1309 and you should be all set!

 

I'm really looking forward to planning the DXB-SFO route and see how good it really is

For the NGX I had 0.6 difference less fuelburn then what pfpx calculated.

For the 747X I had a 1.6 difference more fuel burn then calculated on a 4500nm flight.

 

So, it's pretty spot on

For the NGX I had 0.6 difference less fuelburn then what pfpx calculated.

For the 747X I had a 1.6 difference more fuel burn then calculated on a 4500nm flight.

 

So, it's pretty spot on

0.6what? 600 KGs?

 

Verstuurd van mijn GT-I9300 met Tapatalk

 

 

I did a 550NM flight with the -700 today using PFPX. It's time prediction was spot on. It predicted an EET of 1:22 and when I touched down at destination, the chronometer was displaying 1 hour and 22 minutes. No more, no less. Fuel prediction was off by 200KG because I climbed straight to FL390, whereas PFPX planned a initial cruise level of FL370 with a step climb to FL390.

I noticed that with the PMDG 737-800 aircraft profile in PFPX I was getting very different fuel numbers between PFPX and Topcat.  Both Topcat and PFPX aircraft profiles had the same weights set.  I must be doing something wrong.  You'd think topcat and PFPX would both compute the same fuel.  Maybe because PFPX is taking into consideration weather and route?

I too am finding it spot on.  My EET's have been +/- 1 minute over 45-60 minute flights and within 200 lbs of estimated burn off.  It should be noted that I primarily fly in the USA where most STARs and many SIDs have a interval "vector" segment that adds some variability over the direct waypoint-to-waypoint-to-runway that a lot of the European SIDs and STARs set you up with.  This unpredictable vector component easily accounts for a 1 minute difference and 1-200 lbs of fuel.

Can somebody tell me if you are changing your weight profile for the B737 or the PMDG 738 data set inside of PFPX or TOPCAT?  Or are you just using what the default values are?  

 

Thanks,

I noticed that with the PMDG 737-800 aircraft profile in PFPX I was getting very different fuel numbers between PFPX and Topcat.  Both Topcat and PFPX aircraft profiles had the same weights set.  I must be doing something wrong.  You'd think topcat and PFPX would both compute the same fuel.  Maybe because PFPX is taking into consideration weather and route?

 

Topcat is a Performance Calculator and only gives very, very rough fuel estimates. That is why there are two products....

Topcat is a Performance Calculator and only gives very, very rough fuel estimates. That is why there are two products....

 

That's what I assumed. I guess I just thought that topcat and pfpx fuel values would be close.  I was wrong.  

I recommend everyone check out Scandinavian's concise explanation of the difference between TOPCAT and PFPX, and how they both are used for entirely different tasks:

http://www.youtube.com/watch?v=IhZuuUNwx7k

 

His video will go a long way in helping to eliminate all the confusion that has ensued since the PFPX release.  

 

Basically, TOPCAT's fuel estimate is just that, an estimate using great circle routing between two points.  It does not take into account variables like temperature, altitudes, winds.  That is PFPX's job.   TOPCAT is only used to compute takeoff and landing speeds.  I have used TOPCAT for ages, but have always used a separate fuel planner, spreadsheet, or FSBuild to compute fuel loads.

 

 

Basically, TOPCAT's fuel estimate is just that, an estimate using great circle routing between two points.  It does not take into account variables like temperature, altitudes, winds.  That is PFPX's job.   TOPCAT is only used to compute takeoff and landing speeds.  I have used TOPCAT for ages, but have always used a separate fuel planner, spreadsheet, or FSBuild to compute fuel loads.

 

Yep.  I didn't watch the video, I just figured that out for myself.  Also I've figured out that the default weights in PFPX are good for the PMDG model.  I just crossed APNEL expecting 12.1KG remaining and the NGX said 12.3.  Not bad at all.  I'll keep an eye on it for further down my route and see if the fuel prediction vs actual grows or stays relatively close.  

 

I really like this program.  It almost makes VatSpy obsolete too.  

I really like this program.  It almost makes VatSpy obsolete too.  

 

How is that? Isn't VatSpy to show what ATC is online for Vatsim?

Is PFPX showing online controllers on Vatsim and/or IVAO now too?

 

That said, I will certainly getting PFPX as soon as I can. Looks like a great program and will make planning so much more accurate. Loving the look of the winds aloft feature. Might even be able to start flex routing myself on the longer flights that don't include NATS, AUSOTS etc.

 

However a flightplanning tool isn't a "Who's controlling what areas on Vatsim tonight" tool.

How is that? Isn't VatSpy to show what ATC is online for Vatsim?

 

Is PFPX showing online controllers on Vatsim and/or IVAO now too?

 

Yes.  It does include traffic and ATC on Vatsim and IVAO.

What weights are used for PAX in the NGX?