But the A380 isn't optomized for this sort of operation. Figure your Average Human is fairly close to the density of water, 7 pounds per US gallon. 150 tons of humans work out to a tad over 6300 cubic feet (apologies - this can't be good for your claustrophobia). The A380 has a cargo volume of 40,000 cubic feet. So you'd need the A380's wing mated to a smaller fuselage - a 757 would probably work out about right. Smaller fuselage means less fuel consumption. Also, the payload would be a few (several?) tons higher since you only need to pressurize the crew compartment.