Originally Posted by
Cubdriver
Not sure anyone asked, but
mass is a measure of the amount of material in an object independent of any gravity field, while
weight is a consequence of mass occurring in
connection with a gravity field (Earth, Moon). Something has a set mass no matter where it is, but if it goes from the Earth to Moon its weight will vary. The difference becomes academic when the location is set, and we consider variation within a field like the Earth's gravity field to be trivial most of the time although it does vary quite a bit.
Earth's gravity field wiki article
Yes, exactly, and based on the discussion, people are actually talking about mass, however, as most people do, they are using the word weight. So when it was mentioned that the weight would actually change because the lift required would change because the center of gravity changed, then that person was talking about actual weight as a force, rather than weight having it's common meaning which actually represents mass.
So those who said that the weight does not change were correct, as long as they were using the term weight to mean "if you put the plane on a scale at rest", and the term weight was used for the amount of downward force exerted by gravity, the the weight changed.
Usually, when most of the engineers I know talk about this, they use the terms mass and weight, but most non-engineers tend to use these two terms interchangeably and without understanding the difference.