Hi guys, I'm flying the NGX now since two months and it's every time an excitement to fly it. I'm currently on enroute from Phoenix to Minneapolis and I've noticed something I found every time flying the NGX: the fuel gauges disagree. I've loaded 21000lb via the FMC for that route and it's correctly shown on the fuel gauge on the engines display. But the FMC tells me on the PERF and PROG page that I have 21200lb fuel on board. It's allways these 200lb difference. Is that normal or am I doing something wrong?!

I just started to use Topcat for fuel planning and so have been paying more attention to fuel weights. I also found this (from memory I though the difference was around 400lbs). I would be interested in an answer to this too.

I just read in Chris Brady's Technical Guide that the fuel summation unit (FQIS on NGs) likes to over-read by 1-200kgs (=2-400lbs). Didn't know this was modeled on the NGX, but it sounds like a valid explanation.

A while ago, either on the forum or in a ticket, Ryan confirmed that it's a modelled idiosyncrancy of the 737NG.

I just read in Chris Brady's Technical Guide that the fuel summation unit (FQIS on NGs) likes to over-read by 1-200kgs (=2-400lbs). Didn't know this was modeled on the NGX, but it sounds like a valid explanation.

It is ! 150 to 250 lbs difference to be precise.

It is ! 150 to 250 lbs difference to be precise.

And we've found another obscure simulation of the real life 'NG. Freaking awesome. Thanks.

The 150-200lbs difference is how the actual NG does it, fuel quanity (Upper DU) is the one you use as "actual fuel remaining" as far as I know.

OK, thanks guys! So I´m not doing anything wrong, it´s just another strange NG anomality. Thanks PMDG for interating that. :(

Is it really that strange?What if I told you that your speedometer in your car disagrees with your actual speed.Furthermore, if you're really bored, jump into the FARs. You'll be surprised with what you'll find related to when the FAA requires gauges to be accurate.

What if I told you that your speedometer in your car disagrees with your actual speed

If that is hard try to explain why a car GPS can't measure elevation correct when everybody see a elevation value in the display, or the measuring fault of the GPS in the speed box!

Edited February 21, 201214 yr by flygarn1

Is it really that strange?What if I told you that your speedometer in your car disagrees with your actual speed.Furthermore, if you're really bored, jump into the FARs. You'll be surprised with what you'll find related to when the FAA requires gauges to be accurate.

Well, I thought that in commercial aviation everything has to be as exact as possible and thus such an inacurracy wouldn't be allowed at all.

Well, I thought that in commercial aviation everything has to be as exact as possible and thus such an inacurracy wouldn't be allowed at all.

:( :(

we only talking about 200 lbs here not to going to make that much of a difference in flying time

Is it really that strange?What if I told you that your speedometer in your car disagrees with your actual speed.Furthermore, if you're really bored, jump into the FARs. You'll be surprised with what you'll find related to when the FAA requires gauges to be accurate.

Yes, as far as ga is concerned I believe the fuel gauges in the Tampico I fly are only required to accurately indicate when the tanks are empty. I don't know if it's any different in airliners.

It is ! 150 to 250 lbs difference to be precise.

Indeed the finest simulation of an aircraft to date.

:( :(

:(