Average 747-400 has 416 seats.
Average A380 will have 550 seats.
747-400 (range 7,260nm) :
57,285 / 416 = 137.70432 gallons per seat
52.721657 seat miles (nm) per gallon
747-400ER (range 7,670nm):
63,705 / 416 = 153.13701 gallons per seat
50.085867 seat miles (nm) per gallon
A380 (range 8,000nm estimated):
81,890 / 555 = 147.54954 gallons per seat
54.219077 seat miles (nm) per gallon
All data from each manufacturer's website.
So, basically, you're gaining two seat miles per gallon over the 747-400 and four seat miles over the 747-400ER, a 4%-8% improvement. On those routes where an airline can fill every seat, the A380 makes more sense.
However, on a route where the A380 would run at 70% full (389 passengers) and a 747 would run at 85% full (354 passengers), the numbers change drastically. The Airbus runs at 210.5... gallons per passenger, while the 747-400 runs at 161.8... gallons per passenger. Airbus efficiency drops to approx 38 passenger miles (nm) per gallon while 747-400 efficiency drops only to slightly less than 44.9 passenger miles (nm) per gallon.
So as you can see, if the A380 is running at the same capacity as a 747, it is more efficient. However, if routes are more appropriate for 747s than A380s in terms of demand, the A380 will actually be a big waste of both fuel and space.
Of course, these numbers are imperfect because we're calculating based upon a) total fuel capacity, not the actual amount of fuel required to travel the max specified range and b) the A380 hasn't yet actually flown, so we don't know what it's actual efficiencies are.
Personally, I think Airbus would have been better off choosing an aircraft with significantly greater efficiency (say, 7E7 material?) than going with a behemoth that needs to be full to beat the competition.
As for the $100,000 price tag, depending on hedging and all, I can easily see an A380 using $100,000 of fuel or more on a given flight. Some flights originating in some cities could easily top $200,000. Fortunately, if that were, say, LAX
, that $200,000 price tag would be shared among the 555 passengers at $360 apiece.
Since the lowest-price fare I could find between those two cities is $1275 round-trip and that's a heavily discounted coach fare, I don't think there will be too much of a problem with all the economy-plus, business and first-class seating available (which is readily bought, I might add!)...
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