Heavy is a real term and is necessary. Using the term heavy alerts ATC that you are indeed big & heavy. Why do we care?
Every aircraft creates wake turbulence as it flies through the air. The bigger & heavier you are the more aircraft upsetting wake turbulence you create behind your aircraft. Simply explained, a corkscrew stream of air is created behind each wingtip. The oncoming aircraft flies into it and is usually rolled inverted. Typically this occurs low to the ground (on landing approach) with little time to recover. Wake turbulence is scary stuff.
So the term heavy alerts the controller they need to maintain a minimum distance between you and the aircraft behind you. And the 757 is included in the term heavy because it creates a nasty wake turbulence behind it even though it doesn't meet all of the requirements. The FAA figured out that one the hard way.
An with the Airbus 380 coming online it's created a 'super' category requiring up to 10 miles of separation. One major drawback to that is as more come online then fewer aircraft can land per hour creating more flight delays. Funny how things can all be inter-related.
Edited by KTOA (02/08/10 07:39 PM)
Edit Reason: Added A380