Oz, I recall seeing the number of 19 km per liter per passenger for a 75% load 747. Boeing will proudly tell you that is twice as efficient as a solo passenger car.
Thus, "you" consume about 630 liters of jet fuel LAX-SYD. Thus, the surcharge is about 7.5 cents per liter or 28.5 cents per US gallon. Since fuel prices have increased from a budgeted ~$1.25 to above $1.50 per gallon then your fuel surcharge is spot on. Basically, if the spot price (assuming that's what UA pays) is above $1.50 then you are not overpaying. I read that many US airlines budgeted for $1.25 or around there based on 2004 averages.
If you want to look up the current sport price:
http://www.eia.doe.gov/oil_gas/petro...ce/prices.html
On the other hand, better run and non-bankrupt airlines like Southwest don't pay spot prices.
p.s. Holy smoke, the spot price hit $1.92 in LA. It also appears that there is a substantial premium in LA compared to other locales just like for gasoline. Tight refinery capacity in CA, I suppose.