Cockpit Voice and Flight Data recorders (CVR/FDR) recorders are designed to protect data in extreme environmental conditions to ensure reliable access to cockpit voice and flight data following an incident. They are mandated for many aircraft, and desirable for many others, but not all aircraft have a suitable data stream available to output the required information. There is also a trend towards using the flight recorder system as an active component in aircraft maintenance, expanding its role to include applications such as Flight Operations Quality Assurance (FOQA) and Condition Based Maintenance (CBM).