Originally Posted by
ethernal
No, all major airlines just use a standard assumed weight for passengers and carry-ons together. In the winter they add something like 5 or 10 pounds to the average based on the idea that passengers have more "weight" on their person and in their carry-ons due to heavier clothes in the winter.
The overall average figure has been revised upward over time, but it may be due for another given the continued expansion of waistlines as well as heavier carry-ons due to checked bag fees. I think the last revision was around 2006.
Not only assumed weight but the assumed weight builds in a huge safety margin. If the carrier used actual weight for everyone + bags (even allowing a large margin of error in weighing), I imagine you would have stayed on (and the flight could have filled more empty seats.