dspp wrote:A rule of thumb I have seen is that cattle class are packed 3x as densely as biz-class, who are in turn packed 3x as tightly as first class. The revenues and profits flow similarly. If you take the airframe mass (and hence fuel fraction) as being apportionable to the area occupied - which is a fair approximation, given that airframe selection is also a variable in play - then the mass fraction allocated to each seat will follow the revenue, and in turn the energy consumption, and in turn the carbon footprint. (For simplicity I am ignoring premium economy). Remember that as a generalisation we know that airline profits are 80% business+first. You can find stuff online that gives the decimal points behind this if you want and try and understand what you are all looking for
One report I read had it a bit different i.e. that business class is the most profitable. First is less profitable. That is a big part of why many airlines do not have First any more. BA still does (but it is fairly crap). Virgin hasn't had it for years, if ever. The US airlines have abolished it except for AA Flagship, which is crap. Air France and Lufthansa have it, maybe Swiss (not sure) too but the other European airlines do not. Which leaves First as mostly Asian airlines and, inevitably, the over-the-top ME3.
Also, whether a passenger in F or J is producing more carbon depends on how you argue it. A BA Club World seat probably takes the space of 3 passengers in Economy. So if I fly CW am I producing more carbon than 3 passengers and their bags? Maybe if only because the CW seat is very heavy but I am not certain about that.
In BA First you are taking the space of 6 economy passengers. I can construct a reasonable argument that an "All F" BA Dreamliner or A350 might be the most carbon-friendly plane in the sky.