Hi you guys,
all of your posts were correct, but the "heavy" is just the wake turbulence category, which results of the weight!
There is light, medium and heavy. It is important for separation between the aircrafts. A 737 needs to be separated of a minimum of 2 minutes behind a heavy. Otherwise it can encounter these severe wake turbulence, which can bring you in unusual attitudes!! Like we saw on the AA
300 in NY! The encountered wake turbulence of e preceding 747 and we know what happened.
The B752 is also heavy, although its weight is not above the limit for the wake turbulence category, but the 752 has short wings and these short wings need to produce a lot of lift! And with this lift the wake turbulence are even worse! So a 752 is heavy!
In ATC Communication they use the word HEAVY to make sure, that there is sufficient separation between the aircrafts...