How many of us have run the tanks dry whilst sitting on the pad before this ad?
I can only report what I saw.
Have I taken the fuel system apart and crawled around in it? No.
Where did the fuel go, I have no idea.
The collective opinion amongst my colleagues is it's syphoning.
Why would it be uphill????? Aircraft is parked level.
The nub of it all IMHO is where does the XFER pump deliver the fuel to? Does it pour into the supply tanks or does it deliver to the bottom of the supply ?