I recently read that Cathay Pacific has started trial non-stop flights between Hong Kong and Toronto. In order to make this non-stop flight possible, they have to restrict passenger numbers to around 200 (i.e. about 50 seats empty). What I don't understand is why the weight of 50 passengers is so important. Even if we assume each passenger is 300 pounds (incl luggage), that will only mean an extra 15 000 pounds -- surely insignificant compared to the weight of the plane itself (airbus gives the weight of an A340 as 608 200 pounds)
Secondly, what is the longest range plane currently in the market. Aribus and Boeing all claim that their planes have the longest range (A340, 777-200ER and 747-400 respectively). Does anyone know for sure which one is really capable of flying longest non-stop? If so, which submodel is it (i.e. 340-200 or 300, 777IGW or 777ER?)?