Flash Recovery Area backup to disk with RMAN

Is it possible to do a RMAN backup of the Flash Recovery Area (FRA) to disk. The standard method by RMAN is that this is only possible with the use of a SBT channel/library. The RMAN command 'BACKUP RECOVERY AREA' works only with SBT channels, meaning a tertiary storage such as tape.

Oracle has introduce an emulator for SBT library to do a backup of the FRA to disk. The RMAN disksbt library, which emulates a SBT library (but it writes the backups to a disk location). This disksbt, can be used to test backup the FRA to a disk location