Which is a tax on jet fuel, not on carbon emissions. If you raise the tax to cover the negative externalities, you create an incentive to use other fuels that may be less efficient and more harmful but cheaper. If you extend the tax to cover the use of all fuels in aviation, you need a mechanism to prevent people from using fuels bought for other purposes.
Regulation is difficult, especially when you are trying to outwit the market.
There is also sufficient regulation in place to make sure jets don't put random garbage in their fuel tanks. Not that you need it, because it would damage the engines.
I have no idea what you think a passenger jet would switch to?
Not random garbage but fuels the engines are specifically designed to use. After the regulations are in place, in order to circumvent them.
If writing regulations that have the intended effect without significant downsides was as easy as you suggest, tax planning would not be a big business.
How do you define an airline? Especially if the company is active in multiple fields of business. Would a business that operates both planes and trucks have an advantage or a disadvantage under your tax scheme?
How do you deal with refueling at international destinations and possible carbon taxes in the destination country?
Do you actually want to tax carbon emissions or climate impact? A synthetic fuel could plausibly be carbon neutral, but burning it at the cruising altitude would still have an impact on climate change.
I don't need to define an airline. The tax applies to anyone fueling a plane, and I was just saying that airlines are huge and they're not going to hide.
A business with other things has no advantage or disadvantage.
> How do you deal with refueling at international destinations and possible carbon taxes in the destination country?
Pick an option. It won't make much difference.
> Do you actually want to tax carbon emissions or climate impact? A synthetic fuel could plausibly be carbon neutral, but burning it at the cruising altitude would still have an impact on climate change.
We can have that as a possibility. Probably it's worth wording the law so that the tax scales with the remediation cost.
Regulation is difficult, especially when you are trying to outwit the market.