Why do two drives appear when I insert the recorder’s SD card into my computer’s card reader?

The recorder’s embedded software contains the Appareo Virtual File System (AVFS). One drive on your computer represents the physical SD card and the other represents AVFS (assigned to drive M or later).

Raw, unpartitioned data is recorded to the SD card. AVFS converts the raw data into viewable flight data based on when the file was recorded and what type of data is represented. For this reason you can only access and use data from the AVFS (instead of from the physical SD card drive).