Outbacker,
You asked a very good question. I haven't got any numbers for the 748 and haven't had the privilege to fly one, but have a little time on the 777 and the 380. Two compare a 77W with a 380 on a low yield route like BNE-LHR-BNE would look like this.
77w
Total Fuel burned- 344.2t (so $344200 at $1000/t)
revenue from PAX using EK website return prices (AUD):
1st- 8pax = $80000
j - 42pax= $252000
y -320pax= $640000
total = $972000 less fuel cost = $627800
380
Total Fuel burned- 525.5t (so $525500 at $1000/t)
revenue from pax using EK website return prices (AUD)
1st- 14pax = $140000
j - 76pax = $456000
y - 389pax = $778000
total = $1374000 less fuel cost = $848500
Result is the 380 earns about $220000 extra on these sectors with low yield fairs. The margin would be greater when compared to a cx 77w as they don't cram the pax in like EK 777s and have some 54 less seats.
Now the 77W is TOW limited out of BNE-DXB (return) and would be limited to less than 8t Cargo. The 380 would carry about 10t on these sectors. The 380 DXB-LHR-DXB carries an extra 27 pax in Y, and still about 13t cargo. The 77W would carry about 18t to 20t of cargo on the DXB - LHR - DXB sectors.
On the DXB - LAX - DXB of about 16hr sector length, the 77W carries 37t of revenue for a fuel burn of 138t, or 3.74kg/t revenue, and the 380 will carry 56t revenue for a fuel burn of 207t or 3.69kg/t revenue. Both aircraft are TOW limited on this pairing.
The Don