Economies of the -400 vs. the A340.?
We were discussing this on the flight deck the other day so I had a look at a couple of Flight Plans to LHR on the same day - 1 x A343, 1 x B744. For accuarate comparision I used Corr/1000kg LDG wt to get both plans up to MZFW (i.e. max payload).
Back of the envelope result:
B744 burn 132.8T payload 64.9T Time 11.43, kg fuel used/kg payload = 2.04
A343 burn 91.7T payload 47.0T Time 12.18, kg fuel used/kg payload = 1.95
i.e 3-4% difference at max payload. Then you have to account for all the other costs e.g. cost of crew spread over 385 pax vs. 250-280 pax, Time cost of the extra 30+ mins flight time, pax preferences (particularly F & J class etc.), maintainence cost etc. etc.
Also note that 3-4% is often the difference between 2 aircraft in the same fleet due to performance degradation.
Therefore I suspect any decison to get rid of one or the other will be demand based - are lots of people still flying therefore needing high capacity aircraft? Will there be a cutback in demand meaning smaller planes are the answer?
Of course the B773-ER beats the pants of both of them on fuel economy.