The 757 is also included as a 'heavy' now, due to the incidents of following aircraft a few years back
Truth'sfriend wrote:
The term "Heavy" refers to transport category aircraft over a certain weight threshold. Aircraft in this category include (among others) the 767,777,747,C5, C17 and the A340.
ATC will include in an aircraft's ID the additional description of "Heavy", when communicating with the aircraft, to alert other aircraft. "Heavies" have additional separation requirements from other aircraft because of a larger wake turbulence "foot print".