Microsoft Flight Simulator 4.0b

Version 4 of Microsoft Flight Simulator was released in 1989, and brought several improvements over MSFS3. These included, amongst others, improved aircraft models, as well as an upgraded model of the Cessna Skylane, programmable dynamic scenery (non-interactive air and ground traffic on and near airports moving along static prerecorded paths). The basic version of FS4 was available for Macintosh computers in 1991. Like FS3, this version included an upgraded converter for the old subLOGIC Scenery Disks into SCN files.

Source: TheGamesDB