That’s what it already does though. We get a total fuel figure in the flight deck (FOB) and a figure for how much the engines have used (FU - measures flow in t

That’s what it already does though. We get a total fuel figure in the flight deck (FOB) and a figure for how much the engines have used (FU - measures flow in the pylons). Add the two together and if the resulting number isn’t what the flight started with then there’s a leak. The challenge is knowing where the leak is.