Say, the plane is flying from country A to B. A cybercrime was committed while the plane was above country C. The attacker hacked into country D. Who has the jurisdiction in this case?
Any or all of A, B, C & D as well as the country of registration of the plane and the country of which the perpetrator and victims were citizens or residents. In addition, there are sub-national jurisdictions (states, provinces etc.) that may be involved.
Just because one jurisdiction has jurisdiction it doesn't mean that others don't also have jurisdiction.