There seems to be a worrying aspect creeping into this thread. People seem to be saying that you base your mass on what you can't away with. You are right - those that work like that can 'overgross', as you put it, unwittingly.
I beg you professional helicopter pilots to look at the mass situation for your flight BEFORE you get airborne. That's why the data is made available in the flight manual. It is I know unrealistic to have every kilo or every pound accounted for during certain types of operation but you should at least know how to regulate your mass according to the Density Altitude that relates to the working environment on that day, at that time of day.
Too many out there appear to believe the brochure when it says that because you have 10 seats (example) you can carry 10 passengers and three hours of fuel - don't forget the paragraph that says YES - BUT NOT AT THE SAME TIME.
G.
