In TWoS whenever a ship is near or a plane, friendly as well as enemy, the game will not go over TC 64. It is modded that way due to game performance and stability.
It prevents CTD's and other trouble, just like not saving your game whenever there are ships present near you saves you from corrupt gamesaves.
The Mod was programmed that way.
So if you cannot go over TC64, be sure someone is in your vicinity somewhere.
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