Originally Posted by FCOM DSC.22_20.50.10
[3R] FOBThis field displays the fuel on board, which is computed:
- With information from the fuel flow and fuel quantity sensor (FF + FQ), or
- From FF only (enter/FF to deselect FQ), or
- From FQ only (enter/FQ to deselect FF).
The pilot can modify this number.
So you can enter FF, and then a manual number which may not represent the actual fuel flow.