When I access the POS REPORT page on the Lower CDU it gives a figure. This figure is a mystery as it appears to bear no relation to fuel required to destination, fuel remainng in tanks or any fuel to alternate calculation.

As example I am currently over the North Atlantic just west of 20 degs West where fuel to destination is 36.6 tonnes, fuel loaded pre-flight was 53.9 tonnes, and fuel on board was 41.9 tonnes.

Answers on a postcard to ...........

 

You don’t mention what figure was on the CDU , was it near the 41.9T figure?

It’ll be the calculated fuel figure passing the waypoint.

The totaliser figure shown on the upper DU is the sensed figure using the fuel quantity system, the calculated figure shown as on the CDU POS REPORT page is a figure calculated by using engine fuel flow figures and the engine run time .

The two figures are compared to help detect a fuel tank leak.

Er, the fuel figure on the Upper DU was 41.9 tonnes as stated (fuel on board). Hence my question.  😉

So what was the number reported? That would be helpful to know.

My guess is it was slightly higher than the FOB at the time.

That number should be reporting the fuel on board determined at the last waypoint you crossed.

No - the number reported was way lower - around 23 tonnes, about 1/3rd of the fuel on board. By comparison the PMDG B777 records the correct fuel figure over any waypoint.

I will record allfigures on my next B787 flight  🙂

Edited October 27, 20214 yr by roadrabbit149

Yes, let us know what you observe.

I'll keep a close eye on this as I am currently flying the B787.