9-3 The General Aviation and Commercial Division located in Washington, DC provides for the evaluation and approval of ATDs.  Advisory Circular AC 61-136,  FAA Approval of Aviation Training Devices and Their Use for Training and Experience  provides the  criteria for ATD approvals and use, and further divides them into two categories; Basic or Advanced ATD approvals  (BATD/AATD). The letter of authorization provided by the FAA to the manufacturer specifies the training credits or experience  requirements that can be acquired using that model trainer. These training devices are predominately used by general aviation flight  schools providing flight training under 14 CFR part 61 or part 141 regulations. ATDs cannot be used for airman practical tests or type  rating training requirements.  Figure 9-2.  A Level C simulator.  Figure 9-3.  An example of a Level 6 Flight Training Device (FTD). 