EFOB Amber
 

Hi everyone,
For A320 family before departure if the taxi time is too long and we dont have any extra fuel beside enough taxi fuel why does the extra fuel on the fuel page becomes amber? For exmpl we received 600 kg for taxi and we entered it on the fuel page, min required fuel for T/O is 7000 in the flightplan and we have 7800 on board(taxi + contingency) but the EFOB becomes amber at 7600 kg. I already entered the taxi fuel in the init b page as 600 kg why does it turn to amber before we burn the taxi fuel ?

double check the FPL routing for any extra routing or segments that may be in there, beyond what your flight plan fuel load expects

No FPL is correct and during taxi when it shows you dont have any extra fuel immediately after departure it gives you back your taxi fuel and somehow you have the taxi fuel as extra.

Are your step Alts and winds all uploaded into the FMS correctly

Did you round up alternate and final reserve generously? What does the FMS calculate as trip compared to your OFP? Sometimes it makes some noticeable difference.

are you a Flight Simmer (hey, great) or flying the actual airplane.

According to the FCOM:

"The DEST EFOB field will turn to amber, if the EFOB at destination becomes less than the MIN DEST FOB value displayed on the FUEL PRED page. "

The way contingency fuel is handled by the FMGS on the ground and in the air is playing a role here but I'm not sure of the explanation. Maybe someone else can add something?

However, there is a kind of "update lag" when it comes to the EFOB colour. Once it goes amber, it needs a good reason to go back green. Example, let's say your EXTRA fuel goes to -0.2 because of an incorrect route or long SID/STAR. You realise your mistake and make the correction and now EXTRA fuel is showing 0 or +0.1. Well, it's not enough to turn it green again immediately. It needs a "major update" like +0.2 or +0.3 EXTRA fuel before it changes colour. I've also seen this happen on occasions where I've entered the route first and forgot about the wind information (winds aloft or average wind component). Remember that the FMGS is constantly computing predictions as you enter information. At some point, the EXTRA fuel briefly dips below zero because it didn't know about the wind earlier. We then later return to add the wind information giving us a positive EXTRA fuel figure. But we don't see it go back to green until a later stage of the flight.