[grey_whiskers]

Ignoring the hydrogen atoms (atomic weight 1), 1200 pounds of jet fuel, if all carbon, would result in about 4400 pounds of CO2 produced.

You are assuming complete combustion to CO₂, no CO, and no multiple-carbon products.

Cheers!

[Bob]

You are assuming complete combustion to CO2, no CO, and no multiple-carbon products.

Cheers!

Strictly speaking, you're right, of course. I believe that I used the term "rough calculation" in my original post.

For estimating the difference between the claimed 40 tons and the (roughly) calculated 2.2 tons, though, I really don't think those assumptions are especially harmful to the accuracy.