Vernon,

 

I'm not trying to start anything with you or the others, but why do you care how much your fuel savings is?

Vernon

 

See page 25 of the PFPX manual about Professional Flight Planner X - Bias Evaluation and how to use it. Also there are threads in the PFPX Forum about using this by people who had various problems with it. These threads have some goods ideas on how to come up with a bias for your a/c.

Say you fly a route that is planned to burn 10.0 (unitless - lbs or kgs doesn't matter as we'll be using %s here).

You routinely land having only burned 9.8 of that planned 10.0 (say you've done this at least 5 times and you're burning 9.8 each time).

 

That's a 98% burn. You could then adjust your burn bias (in the aircraft profile in PFPX) to 98% to see if the resultant values match up better:

 

 

If it's only on flights over an hour, my thought would be that the cruise bias should be the only one dropped for now, but play around with it.

 

Well i adjusted my figures to 103% for cruise from 115%. Maybe 115 was way to high and thats why i was ending up on flights over an hour with 1000kg +

 

I will try 104 per your picture

 

Cheers.

Vernon

 

See page 25 of the PFPX manual about Professional Flight Planner X - Bias Evaluation and how to use it. Also there are threads in the PFPX Forum about using this by people who had various problems with it. These threads have some goods ideas on how to come up with a bias for your a/c.

 

I'll have a snoop about over that way thanks.

15% adjustment to the book fuel flow is too much. It's definitely more in the 4% area, even on new 737's.

 

My flight plan fuel predictions using pfpx are always within 200kg to the actual fuel predictions, short or long haul. I'm confident I can reduce that gap, but I'm happy with that variance because I don't have to pay for fuel.

Hi brian.

 

I just changed my figures to 3 and the FMC now predicts 200-300 kg extra at destination!

 

 

I will try 104 per your picture

 

For what it's worth, that's not my picture, and it's not necessarily my recommendation: go with the metrics you obtain based on how you're operating the aircraft.

 

(Also: note the picture is for a 777 )

Well i looked closer last night and realised. Think for the NGX 4 range is a good number

The main thing that helped me was making sure the TOPCAT and PFPX aircraft profile weights match the NGX. Ensuring these correlate is a good start.

 

Automatically that got me to within 200kg difference between predicted and actual.

 

Through filling out of the Nav Log section of my flight plans, I'm sure I/PFPX can extrapolate that data to refine PFPX computed fuel flows and get it more accurate.