MDL file is used by Flight Simulator software application. The software is based on simulation of actual existing airplanes.

In order to completely define the characteristics of any specific airplane model the application needs data of that model. The required information for any specific airplane model is stored in MDL file. The MDL file acts as a container file which contains all the geometrical and graphical information of the airplane along with its actual mechanical working pattern. All this information is stored in one single file with the extension of MDL. The contents of the file are extracted when the software is running to load the airplane model.