When such a vector line is part of the flight plan, where does Fuel on board get its numbers from. Does it assume a certain distance flown on that vector or does it go from start of the vector line to the first following fix on the approach
Fuel predictions using vector for missed approaches do not take into account the fuel after landing. FMC fuel is fuel on arrival.
When using the Alternates FMC function, you can control what fuel prediction method will be (e.g. DIRECT or after MISSED APPROACH) for calculation of Alternate Fuel on arrival. If Missed Approach is selected but the missed approach ends in a Vector, the fuel calculation assumes last coded point prior to Vector for calculation.