You know the fuel level in each tank, and have a good estimate or actual flow data on engine fuel usage. Simple math says "leak" or "no leak".
If that would work, it is surprising it isn't in the software.
In monitoring IT systems seeing metrics like this over time is super valuable.
Also, like most engineers, you don't necessarily add systems for every conceivable thing that could go wrong. If you think about how many times this has happened against the millions of plane-miles travelled, you can see why it wouldn't necessarily have been high on the list.
If the number does not reach within expected margins, then show an error.
This protects against leaks, but also miscalculation of fuel needed by the pilots, misfueling, or efficiency loss somehow.
Perhaps the big innovation needed is accurate fuel quantity measurement.
Any sensor has a failure rate. If the probability that a sensor has failed isn't dramatically lower than the probability of a leak, then the pilots will do just what they did in the incident and assume a bad fuel sensor reading rather than a leak.
Another failure mode of fuel tank sensors is short-circuiting and blowing up the plane: https://en.wikipedia.org/wiki/TWA_Flight_800
It's not as simple as "fuel per time" because fuel usage and speed change massively with altitude.
What was missing here was a big warning to the pilots (that has since been added). But it's also standard procedure at all airlines to monitor fuel and required fuel calculations, which could have helped this crew if they did it earlier.
> Meanwhile, Airbus and the French Directorate General of Civil Aviation worked together to produce a recommended service bulletin modifying the Flight Warning Computers on A330 and A340 aircraft, allowing them to warn of possible fuel leaks by continuously comparing the planned fuel with the actual fuel on board.
If a human can do it, I would imagine a computer could automate the process. Likely wouldn't remove the need for the pilots to do it anyway, though; redundancy and reliability and all that.
FTFY.
It's a common misconception in the general population that the Captain always flies the plane and the FO supports them.
There's always a pilot flying, and pilot monitoring. The roles are usually decided before the flight by the Captain and have nothing to do with who is Captain and who is First Officer.