Ok, let's sum up: there's an official AD limiting the use of fuel, but on the NG only.
On classics and originals there's no limitation : we are allowed to burn routinely ALL center tank fuel.
Although we can takeoff with all 6 pumps on, it is customary here to takeoff with the center pumps off if the tank contains less than 1000 kg , to avoid uncovering them because of the acceleration and body angle involved while taking off.
That's simply to avoid a nuisance blinking light, which would be no big deal anyway.
We turn the pumps on again following the completion of the After takeoff cklist.
I say again, this is customary only and based upon an unofficial tradition.
All this in my understanding.
Questions: Is this practice the same elsewhere?
If yes, do you take 1000kg as a reference or 1000 pounds?
That was my original question, and regards classics.
Thanks.