Doesn't that explain it? HN39 - no.
total fuel seems to reduce by 100-200 kgs at the time the centre tank empties
- I had followed that line too but BM is quite clear - the 'usable' ctre tank fuel is ZERO at that moment - gauge shows ZERO. Yes, we know there IS fuel to be scavenged but it is not 'usable' as far as the gauging is concerned - at least until it arrives in Tank 1.