Flight recorders, commonly referred to as ‘black boxes’, are devices designed to withstand the consequences of an accident. They record a wide range of information related to the flight of an aircraft.
These recorders are not installed on all aircraft, but only on those that are required to be fitted with them by aviation regulations.
Flight recorders are essentially of two types: Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR).
Flight recorders technology is currently based solid state memories. FDRs record flight parameters for a minimum duration of 25 hours. The most modern ones, installed on the latest generation of aircraft, record even more than 2000 parameters.
CVRs store in their memory the audio data of the cockpit: for example, it records conversations between the pilots, communications between the aircraft and the air traffic service, noises and alarms from the cockpit; the recording has a minimum duration of two hours.
These recorders are externally colored orange to facilitate their search in the event of an accident. They are also equipped with an Underwater Locator Beacon (ULB), which is a device that allows the recorders to be found when submerged; this device activates automatically when in contact with water, emitting a signal for a minimum duration of 90 days.
The design requirements of the Crash Survivable Memory Unit (CSMU) provide flight recorders with the capability of withstanding the consequence of an accident. Among those requirements, for example: 3400 G acceleration resistance, 1100° C/1 hour temperature resistance, 6000 m depth equivalent pressures resistance.
FDR and CVR are usually installed in the tail of the aircraft.
The latest generation of recorders often combine the functions of CVR and FDR in a single device (combined devices): in this case, the aircraft installs two recorders anyway, but positioned one in the tail and one near to the cockpit, in order to increase the chances of recovery in the event of an accident.
Recovering data from a flight recorder requires special equipment and specific skills. The information recovered is often of fundamental to the safety investigation.
The ANSV has state-of-the-art FDR/CVR technology laboratories, where data extraction and analysis is done; when requested, the ANSV laboratories also provide support to foreign safety investigation authorities.