When taxes are placed on objects such as international aviation this sends a message to either improve the efficiency of the airplane engines are incur more cost. Granted, these cost may be passed on to the consumer, but there is a limit that consumers will incur before they move to another company; one that uses more efficient equipment as well as being better for the environment.
Yes, an aviation tax would provide an incentive to make airplane engines more efficient, because inefficiencies would cost money. The aviation industry would have to become more efficient in order to maximize their profits. Efficiency would mean more miles per gallon and fewer flights, which would help the environment as well as make the industry better.