Aaa OK, I misunderstood. I import this data from the plane or simbrief.
There’s an on-screen keyboard for the tablet. You have to enable it in the tablet options.
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Anyone else noticed GSX always fuels like 200kg more than the block fuel given on simbrief?
GSX rounds up the Simbrief fuel load to the nearest 100 pounds and then adds 100. It is intentional. I read somewhere why it does that, but I can’t recall where I saw it.
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That’s also what we do in real life when we load the flight plan fuel and have no reason to request extra fuel. If our FPL Block is 7648Kg we’ll tell 7.8 to the dispatcher.
Prolonged use of APU for air conditioning on the ground? Ask for another 200Kg.
Bit of turbulence on the route or runway change? Add another 10min (400Kg).
Bad weather on arrival? Add 30 minutes for a second approach attempt before committing. 1200Kg.
Everyone else diverting, expected delays, the whole continent has bad weather? Add a full extra hour of fuel (2400Kg) or even more. Just mind your landing weight and and the temperature at the destination (to prevent CSFF).
The fuel is for the pilots to decide, not the flight planning software used by dispatch. Always think of fuel as time. On the 737 a good figure is 1h = 2400Kg (5300lbs)
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Yeah, but I would prefer I had the choice of adding extra fuel not a computer program. If I want extra fuel I will add it in Simbrief. I just don’t understand why GSX comes up with a value that is not what it is told. On all other aircraft it adds the amount in the plan.
Maybe it is just the way it works with the integration with the PMDG.
Yeah exactly, at the moment GSX is deciding, not me.
Btw, of course agree with everything you’ve said about why to take extra!
That’s not extra. That’s just what rounding of safety numbers is like in aviation. You can’t add individual Kgs to the fuel tanks in the 737. It’s an old airplane. The fuelling valves are opened and closed manually unlike in other airplanes where the fuelling operator can dial in an exact number where the valves will close. The fuel capacity indicators are not that precise. We round to the next 100Kg and then add 100 Kg more. We call that “standard fuel”.
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I typically add 2,000lbs to the simbrief fuel numbers, and see roughly the same fuel qty over destination that I consider acceptable in reality. I’d see the simbrief dispatcher fired. 
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Why the 100kgs extra?
If my plan said 80357 and I wanted plan fuel I’d order 80400, not 80500. It would be the same if the required fuel was 80398 and it was always the same when I flew the 737. Just intrigued why you’d add an extra hundred?
An extra 100kgs on every sector soon adds up to lots of extra fuel cost for the airline does it not? Probably tens of thousands (if not hundreds of thousands depending on the size of the airline) of tonnes of extra fuel over a 12 month period for no obvious reason.
FWIW I’ve given up trying to use the GSX fuel truck with the 737. No matter what I do it shows up, I tell it what fuel I want and it immediately disconnects. I just set it via the FMC now and forget about the truck itself.
Have you disabled ‘show msfs fuel/cargo…’ (or something like that, sorry memory) in the gsx aircraft settings?
Can I ask how one would change the departure configuration when taking off on a short runway? I always take-off with standard 5 flaps and don’t touch the engine settings and wonder what actions are usually taken in real life?
It works fine for me. Check the GSX options, this is what I have set: Always refuel progressively = ON / Detect custom aircraft system refueling = OFF / Assistance service Auto Mode = OFF
I’ll check. Do those same settings work with the Fenix Airbus?
Yes, they do.
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Nice one, thanks
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The FMC calculates fuel in tons with only one decimal and it rounds conservatively.
Your FPL says you need 8176Kg and you request 8200Kg. It’s a hot day and you used the APU during the whole turnaround. Your taxi is delayed after pushback due to ramp congestion. Then you’re n.5 on departure. You reach the holding position after using more TAXI fuel than expected and you see the message “Using reserve fuel”. Now you have to return to stand to get more fuel because your fuel indicators decimal number changed by 0.1T due to the way it rounds conservatively… Embarrassing.
A return to stand is far more expensive (delays, more fuel burnt, risk of CTOT, stand fees, fuel bowser fee) than adding 100Kg more on those rare flights that we depart with just standard OFP fuel. Keep in mind that most of the times we load more fuel than the OFP says whenever there’s a good reason and there usually is.
In my case it’s also defined in our operations manual. On first departures in the morning the airplane will be pre-fueled before the pilots arrive. This is to avoid delays. Our ground ops staff will always pre-fuel the airplane with at least OFP Block Fuel rounded up to the nearest 100 kgs + 100 kgs as a minimum.
So Block rounded to the nearest 100 kgs + 100 kgs is considered a standard fuel load that we’ll be happy with whenever there’s no sound operational reason to load extra fuel. Anything on top of that is considered PIC Discretionary Fuel and on our EFB a dropdown menu will activate for us to type in the reason for the extra fuel requested (eg. WXR, RWY CHG, DEICING, CTOT, PushAndHold…)
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A higher flap setting would allow you to spend less time on the ground but will affect your initial climb performance. A take off can be limited in different ways. One is, like you said, the length of the runway. But it can also be limited by initial climb performance (obstacle affecting second segment climb gradient). Depending on what’s limiting the departure we will make a decision on how to depart (different flaps settings, full thrust, improved climb and second segment extension or even departing with bleeds off).
On 99.9% of the runways I operate from the airplane can depart safely with the standard F5 and various degrees or thrust reduction. In 6 years of 737 opearation I’ve only used flaps other than F5 maybe 10 times. There are some departures that are climb gradient limited in which a F1 departure will be necessary. F1 departures increase the risk of tail strike due to reduced tail clearance.
I do remember some cases where we always used F25 for take off but not for performance reasons. On some Ukrainian runways the surface was so incredibly bumpy that we used the highest flap setting to unstick the airplane from that runway as early as possible. These were incredibly long and wide runways but very poorly maintained. Seeing the kind of airplanes they had it makes sense.
When performance limited we explore options in this exact order:
-Activating IC/EXT speeds: Increased Vr for improved climb + Extension of 2nd segment (Higher MFRA or Engine Out Acceleration Height).
-Lower flaps when climb limited or higher flap settings when runway limited.
-No engine bleeds take off (this one is last because it involves supplementary procedures and reconfiguration of the A/C panel shortly after take off).
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Most interesting thanks! Is full thrust achieved by taking off in manual rather than TO GA or do I need to change thrust settings in the MFC?
Forgive me, but the way you’ve described that makes literally zero sense.
Obviously I know how the FMC calculates fuel. I’d hope we can agree that whilst the FMC is a guide, what you’ve uplifted and the fuel on your gauges vs your plan is what matters at the end of the day.
That aside, the scenario you’ve described is exactly what contingency fuel is for. In the exceptionally infinitesimal chance you were to burn all your contingency fuel over and above your taxi fuel during taxi (and I’ve never got close even once in 11 years flying the 737 and 9 years of flying the 787) then that is why, assuming you meet the criteria to do so, you’re able to commit to your destination and dispense with your alternate, making sure you always have enough fuel to land with Final Reserves intact. If the weather wasn’t good enough to do that then you wouldn’t likely have taken flight plan fuel anyway. IIRC correctly Contingency Fuel on the 737 was 5% of trip or 200kgs as an absolute minimum. That’s more than enough to account for any unforeseen taxi delays on a 737.
100kgs is a rounding error and there’s absolutely no chance I’d return to stand from the holding point for the sake of that amount. Or are you saying the figure you enter as reserves in to your FMC is Final Reserves + Alternate + Contingency? Obviously that would be incorrect, because that isn’t your reserve fuel. I know airlines have variances on the way they do things but assuming you operate in Europe we’re all operating under the same regulations, so the bigger picture stuff is the same.
No, full thrust is achieved at 26K without assumed temperature. Some airlines have the option to bump to 27K.