How does Bingo Fuel work?

[ETF]

Will my staff provide a pop-up when air units are at bingo fuel? I thought they use too back in the early 90's
Can't seem to get that option or am I missing something?

[MarkShot]

Works for me. It pops up with I think 8% left. Then, if you ignore it, it pops up again at bingo. Also, the groups icon becomes somewhat shaded when pre-bingo.

[NefariousKoel]

I get an initial warning when they're at 10% and another when at around 1 or 2. 

I think I noticed that as I was sending some back who were at 9% or so - the percentage seemed to go up if I sent them to a closer airbase than their home one since it wasn't calculating such a long distance back after I changed.[8D]

[ETF]

ok thanks guys must have missed this somehow!!