Interesting. To me it does not really make sense to think in terms of fuel left because, no matter the reserves, there can always be a situation so unlikely, so outside the ordinary, that it will drain all fuel reserves before you make it to the planned destination.
I have no clue how else to think about it though.
So maybe the thing we can improve is an understanding of likelihood?
I.e. prevent the journey from occurring if weather conditions are likely to be adverse above a certain threshold?