Achtually, a gas-powered car isn't that far from an airplane in terms of CO2 emission per kilometer per person. But planes allow for long distance travels that you would never consider doing by car. It also depends how many people are in the car. Planes also produce more non-CO2 pollutants.
If you were to choose between driving X km alone in your car or take a plane to the same destination, both options' environmental impact would be quite close. But with carpooling, the car rapidly becomes a less bad option.

or to get coffee,or lunch, or fly thier pets.