Originally Posted by
DaveReidUK
Realistically, that's not setting the bar very high ...
If you must worry about CO2 rather than fuel cost.
Take aircraft type, normal fuel burn for flight, divide by number of miles flown, divide by number of revenue pax. Most modern twins will return better than 120mpg per revenue passenger.
No infrastructure is needed to be built
and maintained between departure and destination - no rails or tarmac
Other 'incidentals'
Cost of passenger time traveling is also reduced.
Some journeys are only practicable by air.