In some of my aircraft.cfg files for project AI, I have atc_heavy=0 and in others it is atc_heavy=1. I assume all project AI aircraft are considered 'heavy'.

'Heavy' is only a designation due to an aircraft's GTOW. All aircraft certified above 299,000 lbs. GTOW are clasified as 'heavy' by ATC. This includes the Boeing 757 as well. The reason behind this is wake turbulence. This way ATC can space arrivals and departures accordingly.Cheers,John

if heavy=1 ATC will say like Speed Bird 333 Heavy.747, 757, 767, 777, A300, A310, A330, A340, A380 are heaviesRest are nothttp://img2.ranchoweb.com/images/svedude/jpsig3.jpg