How do the airlines determine how far certain planes can fly? I always look at the ranges on Airbus and Boeing airliners to see how far they are capable of flying and find that they're capabilities far exceed the ranges they fly. For example, I heard Delta is suspending the ATL-HNL route because the 764 has trouble making that flight with full capacity, and yet I look at the Boeing web site which says the range on the 764 is 5,635nm which is about 1,000nm more than the distance between ATL and HNL. If that's it's real range, what's the problem? Are there regulations that don't allow the airlines to utilize their aircraft?