Or any crucifix at all! That's against the GIRM and I battled with my former pastor to have, at least the processional cross displayed during Mass. I tried to rally the parishioners with a petition but they "liked it the way it is". Our Maronite Church has a beautiful, classical Crucifix directly behind the altar, with spotlights shining on it :-). The Tabernacle is to the left and the Book of the Gospels to the right - all illuminated with spotlights. It is heaven on earth.
Here is what our Holy Father says in his book "The Spirit of the Liturgy:"
"Moving the altar cross to the side to give an uninterrupted view of the priest is something I regard as one of the truly absurd phenomena of recent decades. Is the cross disruptive during Mass? Is the priest more important than the Lord? This mistake should be corrected as quickly as possible; it can be done without further rebuilding.”