A flight recorder is a device placed in aircraft that records data that might be helpful in determining the circumstances surrounding a crash. Many aircraft have two devices: a cockpit voice recorder and a flight data recorder. Flight recorders often are referred to as "black boxes," even though they usually are painted bright orange.
Cockpit voice recorders are one type of flight recorder. As the name implies, cockpit voice recorders are located in the cockpit of an aircraft. They record at least 30 minutes of audio from the cockpit. This recording might include crew conversation, alarms, noise from the engine and other audible feedback.
A flight data recorder is another type of flight recorder. This type of recorder makes a record of various parameters associated with the flight in progress. Legally, the number and type of parameters that are required to be recorded vary by locality. Some items that might be recorded are altitude, airspeed and acceleration.
Both types of flight recorders are used together to provide investigators with the critical details of a crash. Many times, the flight recorder is the only item that survives a crash intact, so it is understandable that it is sought after almost immediately. Without it, key details that might unlock the mystery of the crash might be left undiscovered.
Through repeated use and advances in technology, manufacturers are learning that not only can flight recorders be used to provide details surrounding a crash, they might also be used to prevent accidents before they happen. Data recorded during flights can be analyzed and used to make better-performing aircraft. In addition, the data might be used in the training of pilots about ways to react to changing conditions during a flight.
Flight recorders also are used to monitor the health and safety of an aircraft. The data recorded by a flight recorder might be analyzed to let the aircraft manufacturer or operator know when maintenance needs to be performed, whether something is not working as it should or whether an item needs to be replaced. All of this might do much in the way of preventing future accidents.
Crashes involving deep water or that were so terrible that a flight recorder was smashed to pieces led manufacturers to develop recorders that could be self-ejected during a crash. Some even make use of sonar or radio technology to help investigators locate the recorder. This has helped make it easier to find out what happened in a variety of crashes.