I can see a few with flipping incentives - flight is a subsituable good and a fuzzy one. While not encouraging it for its own sake is fair the alternatives may be worse.

I know of one case where a coworker ended a business trip by taking vacation days and a several day cross Atlantic cruise ship home which was likely worse than even a plane trip to an island as it didn't involve hauling essentially an entire luxury hotel thousands of miles.

I suspect a better idea for encouragement if anything would be subsidizing efficient clear neccessity/better than current baseline transit. Like say if living closer to work was subsidized along with public transit - both replacing or shortening automobile commutes.