WZZ fuel distribution

SimBrief Dispatch
1

In the default/LIDO layout, there is a concept of minimum takeoff fuel, which includes:

  • trip fuel
  • contingency fuel
  • alternate fuel
  • final reserve fuel
  • MEL fuel
  • ACF90/ACF99 fuel

Then everything else goes outside of the minimum takeoff fuel:

  • ATC fuel
  • WXX fuel
  • APU fuel
  • tankering fuel
  • regular/generic additional fuel (EXTRA)
  • additional fuel for minimum arrival fuel (FOD ADD)
  • additional fuel for actual/minimum/pre-existing block fuel (FOB ADD)

The WZZ format has a different concept, minimum block fuel vs. planned block fuel. Currently, it seems only tankering fuel specifically goes “in between” those (as TANKER/EXTRA).

I was wondering if perhaps FOB ADD and maybe even regular/generic additional fuel should go there as well? Especially FOB ADD, which seems like it could be described as “involuntary/automatic tankering fuel” due to the fact that said fuel happens to already be in the tanks?

In addition, it seems:

  • FOD ADD has its own line (ARRDLY)
  • everything else is summed up as ADD fuel, even ACF90/ACF99 (albeit the presence of the latter modifies the label on that line)

I would think it might make sense to have APU and MEL fuel (as well as, possibly, ACF90/ACF99) on dedicated lines?

Looking at the layout, it seems like a possible reason reason this is not already the case is that there is typically not enough room for additional lines without breaking the layout or requiring an additional page for the remainder of the fuel breakdown / pilot signatures?

Although I can sort of see/find space for two additional lines at the bottom of the first page, provided no more than 4 to 6 lines of dispatch remarks are present? And it also seems the layout is actually allowed to spill over to a second page when 7 or more lines of dispatch remarks are present, so maybe not?

There may still be other reasons why this is not the case, I am just wondering and/or thinking out loud, in a way :slight_smile:

Another this I’ve seen (more generically, rather than specific to the WZZ layout) is that FOB ADD and FOD ADD seem to be mutually exclusive; I wonder if this is always the case IRL?

Otherwise, it seems to be that they could technically easily be split? For example, currently:

FUEL           ARPT   FUEL   TIME
---------------------------------
TRIP            CPH   2453   0055
CONT 15 MIN     SKS    666   0015
ALTN            AAR   1261   0032
FINRES                 984   0030
---------------------------------
MINIMUM T/OFF FUEL    5364   0212
---------------------------------
FOD ADD               1589   0036
---------------------------------
T/OFF FUEL            6953   0249
TAXI            AMS    200   0020
---------------------------------
BLOCK FUEL      AMS   7153

If I already have 8 tons of fuel on board, then I get:

FUEL           ARPT   FUEL   TIME
---------------------------------
TRIP            CPH   2444   0055
CONT 15 MIN     SKS    663   0015
ALTN            AAR   1261   0032
FINRES                 984   0030
---------------------------------
MINIMUM T/OFF FUEL    5352   0212
---------------------------------
FOB ADD               2448   0056
---------------------------------
T/OFF FUEL            7800   0309
TAXI            AMS    200   0020
---------------------------------
BLOCK FUEL      AMS   8000

Whereas one could get instead:

FUEL           ARPT   FUEL   TIME
---------------------------------
TRIP            CPH   2444   0055
CONT 15 MIN     SKS    663   0015
ALTN            AAR   1261   0032
FINRES                 984   0030
---------------------------------
MINIMUM T/OFF FUEL    5352   0212
---------------------------------
FOD ADD               1589   0036
FOB ADD                859   0020
---------------------------------
T/OFF FUEL            7800   0309
TAXI            AMS    200   0020
---------------------------------
BLOCK FUEL      AMS   8000

Note that this would probably make more sense and/or be easier to implement if FOD ADD was actually part of the minimum takeoff fuel. I wonder if there are any IRL operators that would consider FOD ADD as such?

Also, when used for ETOPS purposes, APU fuel should probably/definitely be considered part of minimum takeoff fuel (and possibly be added to the ETOPS fuel instead of extra fuel or its own line on those formats that do support it)?

Since there is currently no way (on Simbrief) to distinguish between APU fuel used for ground/taxi or similar purposes vs. air/ETOPS requirements, this is more of an idea for the future when/if the distinction gets implemented.

Regards,

Tim

2

Hi Tim,

I have updated the WZZ layout to include FOB ADD and EXTRA fuel types in the TANKER/EXTRA line now.

Most airlines plan extra fuel for the same set of reasons (MEL, ATC, WXX, etc). The fact that WZZ does not separate them onto their own lines seems to be intentional (maybe they use dispatch remarks to tell the pilots what the ADD fuel is for). But in any case, I feel like it’s more accurate to merge the remaining fuel types into the ADD line for this layout.

I suspect this is highly operator specific. But I’ve made some changes to SimBrief that makes it possible to have both FOD ADD and FOB ADD in the fuel ladder now. Basically it should work the same way as you showed in your example.

Let me know if you find any weird behavior though, the math was a bit more complicated than I originally thought and it’s possible I could have overlooked something.

Cheers,

3

Thanks! It seems to work at first glance, but I will be on the lookout for unexpected discrepancies or whatever we should call them.

Cheers,

Tim

4

There seems to be a rounding error here:

6711 + 664 + 1107 + 1550 + 1993 + 2336 + 1408 adds up to 15,769 only. Not sure it’s a big deal since it’s only off by one.

Regards,

Tim

5

Technically

If we are saying WXX and ATC needs to be aboard at brake release, and those are fuels for specific valid reasons, where it needs to be a part of Min Brake Release, then it should be added to the Min T/OFF value, and listed above the line.

We will tanker at work only if fuel is unobtainable at the destination - tankering for economy yes we do, but if we cant carry that gas its not the end of the world - that’s below the line.

The rest of the values below the line are fine.

1 Like
6

I might have fixed this now, but wasn’t able to test extensively. Let me know if you still have the issue.

Cheers,

7

Seems OK so far, will keep an eye out.

Thanks,

Tim