According to this article about Netanyahu visiting Hungary, ICC signatory states are technically supposed to arrest Netanyahu if he visits their country, but some have said they would and some have said they wouldn't.
Does the same apply to overflights? Hungary is landlocked and all the surrounding countries are ICC signatories. Would he have had to fly over countries that had said they won't enforce the warrant? Or at least validate that they were ok with an overflight even if they would arrest him if he landed?