Guys, all these years with this lovely B757 and I just now quite figured it out : I became tired of beeing able to load the aircraft via ACE putting full pax and full cargo and still beeing able to have almost full tanks and still within limit of the MTOW. I just knew this is not real as all aircrafts have limitation between either full payload / full fuel. (heck even a Piper PA-28 Archer has such limations) So I did some research over the internet and I found out that the ACE is not doing a good job at computing the max payload for this aicraft (not at the defaut unit weight of the cargo container "ULD" found in the ACE) But the good news is that this default unit weight can be modified be the user. So I made a "guide" with various figures for the 2 main scenarios I'm mostly interested when I fly : a) fly at full fuel and max payload b) fly at full payload and max fuel. The part that needed research over the internet was the full payload figure, and I found them for all variants in several Boeing documents. The full payload added the the empty weight gives you the MZFW, which is the figure I found in the Boeing documents. SO here we go...