The heavy aviation cruiser label served passage through the Bosporus

Why are Russian aircraft carriers officially described as heavy aviation cruisers?

The label helps address the legal restrictions on taking a true aircraft carrier through the Bosporus.

The ships' practical identity differs from their official description. In operational terms they are aircraft carriers. The heavy aviation cruiser label addresses the legal difficulty of taking a carrier through the Bosporus. Treaty and transit rules can shape naval classification even when they do not change what a ship actually does.