Just the CO2 numbers aren't giving you the right picture, as the other effects multiply the emissions effects of air travel on warming (for example radiative forcing).
That's also why an air travel emissions factor is used by policymakers when talking about its effects.
This is true on a relative basis: flying across the US puts out a lot of CO2 for a single person.
But on an absolute scale, it's pretty tiny: 2% of total CO2, 12% of transportation CO2.