If a plan was made to repatriate it, chances are this will happens slowly over years, possibly decades. A lot of it might not even be "moved", but rather "swapped" for gold physically in the EU by means of various vehicles: such as selling gold at a slight loss in the US, and buying gold in the EU. Doing so might be cheaper than arranging for physical transport of large quantities.

When large quantities of gold are actually transported "at once", it usually happens in secret on warships. Maybe military planes would be used nowadays? Who knows. Good luck anyhow.