Originally Posted by
TangoAlphad
The transponder of modern aircraft send huge amounts of data including the hull registration. I'd hazard a guess that is where it is taking the data from.
I don't think that's what the OP is referring to.
FR24 often shows, for a given aircraft registration, flights that are planned hours, or even days, in the future.
I've often wondered, too, where that information comes from, as it often turns out to be wrong - its clearly not from a transponder.