Interesting...
Hmmm... I wonder how such thing might apply to other items that remain unclaimed for a long period of time...
There's periodically litigation relating to treaties with various tribes over land ownership/treaty issues, but that's a legal track.
The oldest "controversy" that comes to mind is the negotiations between Israel and the Vatican over Jewish artifacts looted by the Romans, though that will be predated if Egypt does in fact file their lawsuit against Jews worldwide over possessions taken from Egypt by the Jewish people during the Exodus. Of course they lost that one in Alexander's court, so maybe they won't try again.
England has, over the years, sent polite notes to Tokyo whenever Japanese businessmen propose salvaging HMS Prince of Wales and HMS Repulse.
The text of said notes mentions that Her Majesty's Government would regard such salvage as "an unfriendly act." Kindly recall what that statement means in the subtle, nuanced discourse of international diplomacy...
Incidentally, if there were fatalities in the aircraft crash, the aircraft is considered to be a gravesite.