what is the .air file doing in the aircraft folder, is this where the "flight caracteristics" are modelled?i have succesfully added contrails to all planes, when i fly them in specific temp i can see them, and i used different effects. My question is when i fly online (ivao) i cant see contrails, when i fly the same aircraft they have contrails. How is this modelled/triggered, i mean the temp triggers the effect but why is the mp aircraft not having condense trails?Rick

.air files are more for flight dynamics. effects such as contrails are in aircraft.cfg under the [effects] heading. Contrails are triggered above 30000 ft. for jets. It may just be that contrails don't work online. Having never flown online, i wouldn't know.