Jump to content

Sign in to follow this  
aceridgey

PMDG 777-300ER underburning fuel?

Recommended Posts

Hi guys,

 

I connect PFPX with ASN and regularly update and cross check remaining fuel against the flight plan.

 

In the year or so since the 777 has been out, I have never seen the 300er close to predicted fuel left. It's always underburned over the course of a flight with a gradual scale in the cruise.

 

For example a flight I've just done took off with 200kg more fuel than predicted

 

3 hours in ; 1.5tonnes

 

6hours 2.5 tonnes.

 

 

Can anyone look into this for me and see if they're getting the same results in the 300er?

 

(Please use accurate weather such as ASN)

 

Alex


Alex Ridge

Join Fswakevortex here! YOUTUBE and FACEBOOK

Share this post


Link to post
Share on other sites

 

 


Can anyone look into this for me and see if they're getting the same results in the 300er?
I have the same issue in the 777F. I don't have the the 300ER. See this thread - http://forum.avsim.net/topic/460941-eta-and-fuel-remaining-increase/. I still have not determined why  the fuel remaining decreases with no weather and increases with weather. 

Michael Cubine
xVxT6x.jpg

Share this post


Link to post
Share on other sites

I have not run trials with the 777-300ER and PFPX for this purpose (I did with the 777-200LR); however, I have flown quite a few long hauls in her with the AA colors.  The VHHH-KDFW is one I've done several times, and I have not noticed a significant variance between planned and actual fuel burns.  There is a variance, to be sure, but I am not seeing any that raise an eyebrow.

 

A flight should be flown repeatedly, each time varying just one variable, to have a demonstrated problem.  As Michael pointed out, many many flights have not yet exposed a problem of any significance.

 

It's worth identifying what might be considered significant.  If my actual trip burn is within 5% over a long trip then I'd consider that an insignificant variance. If the variance is >5% then you need to look at the difference in planned trip time verses actual and in all cases I've seen the trip took longer which means more fuel burn.  For a 200,000 lb fuel load, that means I wouldn't consider a variance of 10,000 lbs or less significant.  If you're off a ton is that really significant?

 

As inferred earlier, I have run these fuel burn trials in the 777-200LR in the past year with PFPX and ASN on flights >8hrs and I never saw a pattern in the actual fuel burns.  Sometimes actual numbers were so close to planned that it was interesting.


Dan Downs KCRP

Share this post


Link to post
Share on other sites

Hi,

 

Also for your knowledge, in PFPX you can assess and modify the fuel consumption of the profile of your aircraft while airborne. If you feel that the fuel calculation in PFPX doesn't match what you experience, then check the values in the profile. I'm not home so I don't have access to my computer to give you the exact reference but you will surely find it.


Romain Roux

204800.pngACH1179.jpg

 

Avec l'avion, nous avons inventé la ligne droite.

St Exupéry, Terre des hommes.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    15%
    $3,985.00 of $25,000.00 Donate Now
×
×
  • Create New...