They usually get told before boarding starts if they can spread them out or not. Usually led by how much baggage/freight is in the rear hold.
And most company's have a zone head count just to check people haven't moved if the aircraft has a problem with being trim sensitive.
So you would get a bit of paper with the aircraft and zones depicted and the number of seats full in each zone. Then you just check that you have the required number in each zone.
A lot of load controllers just take what's given and if its inside the envelope they release it. Where as crew want the weight further back. So tell the CC to chuck a few to the rear trim zone. Each type will have a rule of thumb with what movement causes what amount of index change.
Last edited by mad_jock; 3rd Dec 2013 at 18:39.