I do load planning for a living, and we at times have to block seats or cut frieight or mail because the aircraft are overweight, and people think we're jamming them up. No one ever thinks about the 1500 or 2000lbs of extra fuel need if the weather ( which many think the airlines control ) in your destination airport goes to min/IFR and you're put in a hold by ATC, whom do not work for the airlines, but are employed by the folks elected to office in Washington.
I wonder how ,many people know that the standard weight in the summer time is around 194 lbs and in the winter time its around 180 plus 16lbs for coats, sweaters, etc. Those are numbers and don't qoute me, mandated by the FAA and not airlines in the US. An 1 degree change in temp can increase weight by aboutr 200lbs, meaning on those long internatinal flights in high mountainous regions or even domestic flight in high altitude, hot areas ( Think Denver in the summer time ) it may mean blocking seats, or holding off freight, mail ,etc, whichever is less priority at your company, as you need the fuel to make to your destination, and if the weather in your destination go to crap, then the captain is very likely going to request extra fuel to A. Divert or B. be able to hold.
I often wish the general public could do what we do or see it. It's not as simple as it looks, and airlines aren't trying to nickel and dime people.
So next time you take a flight and they say it's weight restricted and you roll out with 20-30 seats open, there you go, the weight of those passengers may very well be made up in fuel if weather enroute or at your destination requires it. But for the most part it is what you see, those seats are empty because of weight. I can't tell you how many people I've heard say, "what you do mean it's weight restricted ?...."There were 30 opens seat !!!!"
