BoeingBoy

Other than the capacity of the fuel tanks which is a fixed number, there are two other limits on fuel load:

1 - One most of y'all know enough fuel is required to fly to the destination, make an approach. miss and fly to the alternate, plus another 45 minutes of reserve fuel. Less than this is a violation of the FARs.

2 - No more than needed to fly to and land at the destination with alternate and reserve fuel still on board. More than that and the plane can't land without circling to burn extra fuel and that extra fuel is part of the required alternate/reserve fuel required to be on board if you land at the destination.

While rare, it is possible on short segments that the FAR fuel minimum is too much to allow the plane to land at the destination because too much fuel remains making the weight higher than max landing weight. Note that this has nothing to do with the maximum fuel capacity - it could carry enough fuel to go around the world yet encounter the same problem. It's strictly a function of the two fuel requirements and the FAR required fuel being enough higher than destination fuel.

If this problem rears it's ugly head, the only solution is to reduce weight (take off passengers and/or baggage/cargo). Lowering takeoff weight lowers landing weight at the destination and solves the problem of being faced with too much fuel to land.

In a sense they were restricting carry-on bags. A carry-on is normally included in the passenger weight, but if it must go in the cargo bin it is counted just as another checked bag and the standard checked bag weight is added to the total weight.

Jim