A flight recorder is a recorder placed in an aircraft for the purpose of facilitating the investigation of an aircraft accident or incident. For this reason, they are required to be capable of surviving the conditions likely to be encountered in a severe aircraft accident. They are typically specified to withstand an impact of 3600 g and temperatures of over 1,000 °C (as required by EUROCAE ED-112). There are two types of protected Flight Recorder, Flight data recorder (FDR) and Cockpit voice recorder (CVR). In some cases, the two recorders may be combined in a single FDR/CVR unit.
EUROCAE ED-112 (Minimum Operational Performance Specification for Crash Protected Airborne Recorder Systems) defines the minimum specification to be met for all aircraft requiring flight recorders for recording of flight data, cockpit audio, images and CNS/ATM digital messages and used for investigations of accidents or incidents. When issued in March 2003 ED-112 superseded previous ED-55 and ED-56A that were separate specifications for FDR and CVR. FAA TSOs for FDR and CVR reference ED-112 for characteristics common to both types.
In order to facilitate recovery of the recorder from an aircraft accident site they are required to be coloured bright yellow or orange with reflective surfaces. All are lettered "FLIGHT RECORDER DO NOT OPEN" on one side in English and the same in French on the other side. To assist recovery from submerged sites they must be equipped with an underwater locator beacon which is automatically activated in the event of an accident.
Early attempts at making flight recorders were made by François Hussenot in July 1941 at the Marignane flight test center, France; they were essentially photograph-based flight recorders. In 1947, Hussenot founded the Société Française des Instruments de Mesure (today part of the Safran group) with an associate, so as to market his invention, which came to be known as the hussenograph. In 1953, Australian engineer Dr. David Warren conceived a device that would record the voices and instruments reading, when working with the Australian Research Laboratories.
Since the 1970s most large civil jet transports have been additionally equipped with a "Quick Access Recorder" (QAR). This records data on a removable storage medium. Access to the FDR and CVR is necessarily difficult because of the requirement that they survive an accident. They also require specialist equipment to read the recording. The QAR recording medium is readily removable and is designed to be read by equipment attached to a standard desktop computer. In many airlines the quick access recordings are scanned for 'events', an event being a significant deviation from normal operational parameters. This allows operational problems to be detected and eliminated before an accident or incident results.
Many modern aircraft systems are digital or digitally controlled. Very often the digital system will include Built-In Test Equipment which records information about the operation of the system. This information may also be accessed to assist with the investigation of an accident or incident.
Such systems, estimated to cost less than $8,000 installed, typically consist of a camera and microphone located in the cockpit to continuously record cockpit instrumentation, the outside viewing area, engine sounds, radio communications, and ambient cockpit sounds. As with conventional CVRs and FDRs, data from such a system is stored in a crash-protected unit to ensure survivability.