Funny 777 ZFW?

[captainsazzman 83]

when i manually enter fuel my ZFW changes and flips about. For example the correct one will be 209.1 kgs which then changes to 180kgs or something like that. I get around this by entering another random fuel level so the corrcect ZFW comes back then I re enter the desired fuel from my flight plan. Has anyone noticed this behaviour? (P3D 3.1). If it helps I use a 777 startup panel state of '777 short' but with zero payload and 17% fuel saved

[Paul_Smith 92]

180Kg's of fuel? Not 180,000Kgs? Are you trying to use the FSX (or P3D) default Fuel screen? It doesn't work with advanced PMDG models.

[captainsazzman 83]

180Kg's of fuel? Not 180,000Kgs? Are you trying to use the FSX (or P3D) default Fuel screen? It doesn't work with advanced PMDG models.

180  in thousands i mean. I was writing it the FMC way. No, I use the FMC

[downscc 1,327]

It is normal for the PMDG77X fuel input field to result in slightly lower fuel quantity. My habit is to round up my input to accommodate this quark; however, I've never seen a modified ZFW entry.  I think it's backwards to enter a ZFW then fuel since you're never going to fuel the aircraft with pax on board, I always enter the fuel, then call for catering service and when they are done I'll board pax and enter the ZFW.

[Paul_Smith 92]

It is normal for the PMDG77X fuel input field to result in slightly lower fuel quantity. My habit is to round up my input to accommodate this quark; however, I've never seen a modified ZFW entry.  I think it's backwards to enter a ZFW then fuel since you're never going to fuel the aircraft with pax on board, I always enter the fuel, then call for catering service and when they are done I'll board pax and enter the ZFW.

Why wouldn't you fuel what pax on board? Apart from quick turnarounds, many long flights from short runways needs a refuelling stop and you really do not want to be unloading your premium passengers in places like Djibouti just so you can top up on gas. 

[downscc 1,327]

Regulations vary among different jurisdictions, I think where fueling with pax on board is allowed there are specific measures that must be taken such as crew on board and emergency exits cleared, emergency slide areas available, coordinated communications between crew and ground personnel include others such as catering. Sure it can be done but as a rule I think operators prefer not to if given a choice.

[skelsey 765]

Refuelling with pax on board is possible but does have an impact on both flight and cabin crew.

 

Basically -- seatbelt signs OFF, no smoking signs ON, brief the pax not to smoke and ensure that they have their seatbelts unfastened. 1L needs to be open with the jetbridge/steps in position (and preferably steps at the back as well wherever possible).

 

Generally at least one pilot is required on the flight deck and needs to have visual contact with the refueller or somebody supervising the refuelling (i.e. the dispatcher).

 

The main issue I would think is that the cabin crew generally have to be on station at the doors in case of an evacuation, which I imagine probably hinders their ability to prepare the cabin for departure.

[captainsazzman 83]

It is normal for the PMDG77X fuel input field to result in slightly lower fuel quantity. My habit is to round up my input to accommodate this quark; however, I've never seen a modified ZFW entry.  I think it's backwards to enter a ZFW then fuel since you're never going to fuel the aircraft with pax on board, I always enter the fuel, then call for catering service and when they are done I'll board pax and enter the ZFW.

I know right?? Its very weird only seen this recently with 3.1 and Yes I did a clean reinstall of the sim AND windows, even re ran the 777 installer to repair but no dice. What I do is randmozie the payload using the  payload button then tweak the passenger numbers a bit to my liking. Then I go to fuel and enter a specific number in the top left. Most times, that causes my ZFW to change which is an error. There is a work around where I click between the preset fuel values on the fuel page until ZFW becomes what it was then I try re entering manual fuel. After a try or two Iam able to have the correct ZFW with the desired fuel. Strange behaviour nonetheless. Any clues?

[downscc 1,327]

I've not noticed a change in behavior with fuel entry since beta testing.

 

I suggest you change your work flow to entering fuel first then enter payload or ZFW.  Maybe what you are seeing is an adjustment to payload to accommodate the amount of fuel you're loading to keep things below max ramp weight... just guessing since I always enter fuel first.

[captainsazzman 83]

I've not noticed a change in behavior with fuel entry since beta testing.

 

I suggest you change your work flow to entering fuel first then enter payload or ZFW.  Maybe what you are seeing is an adjustment to payload to accommodate the amount of fuel you're loading to keep things below max ramp weight... just guessing since I always enter fuel first.

Interesting observation. If it helps my default 777 panel state is essentially the SHORT state with 1% payloed and 1/3 Fuel (from the presets in the FUEL page). The reason why I set payload first is because I first decide how much Im gonna carry then use the ZFW in Simbrief to get the amount of fuel I need which is then entered in the 777 fmc. Further testing reveals that grounds ops is not affected by changing ZFWs. 

I've not noticed a change in behavior with fuel entry since beta testing.

 

I suggest you change your work flow to entering fuel first then enter payload or ZFW.  Maybe what you are seeing is an adjustment to payload to accommodate the amount of fuel you're loading to keep things below max ramp weight... just guessing since I always enter fuel first.

Also when the ZFW is wrong (has changed erroneously), clicking on ZFW in the PERF page to  retrieve zero fuel weight gives a double decimal number like 198.234.232 which is mathematically impossible. Goes back to a proper number after the "workaround"

[captainsazzman 83]

Yep I cracked it this happens on low payloads and the reason why it has gone unnoticed so long is that most people fly their 777s HEAVY, i fly light medium hauls. Try creating a panel state on the 200LR based off the SHORT state but with empty payload. Save that and restart the sim using it as a default 777 state. Change payload to any level below 50% (try the low 40s) and then try entering manual fuel amount in the FUEL page. If ZFW doesnt change, try switching between the preset fuel levels and using manual entry again. I guarantee yiou will see hyour ZFW change. Tested mostly on a 300ER, also seen at least once in the LR