By RYAN GORMAN
Commercial aviation disasters usually only have one survivor -- the plane's black box -- but very few people know why the device is so important.
The black box actually refers to two devices, a cockpit voice recorder and a flight data recorder. All commercial airplanes are required to have the devices, which are not actually black, but blaze orange with reflective strips to make them easier to locate.
AirAsia Flight QZ8501's black box will partly tell the story of how the plane crashed into the ocean.
Investigators located the wreckage of the doomed Singapore-bound flight Tuesday morning off the coast of an island in the Java Sea. Three bodies have reportedly been recovered along with luggage, a plane door and other parts, but the black boxes have yet to be found.
As boats and helicopters begin the grim process of recovering bodies and debris, another team is already at work looking for the black box.
Black boxes are virtually indestructible. They provide the data necessary to help investigators piece together the flight's final moments.
The cockpit voice recorder continuously logs the last 30 minutes of conversation between pilots and air traffic control. It cycles over until the end of the flight, be it a safe landing or a catastrophic crash.
The flight data recorder logs information from the host of instruments used by pilots to fly the aircraft.
Speed, elevation, atmospheric conditions, fuel levels, weight and every adjustment made by a pilot is logged inside the black box.
Aviation experts have theorized that Flight QZ8501 went down after the engines stalled while trying to climb above a violent monsoonal storm.
Data from the black box can help to confirm or refute those theories. But it is only useful if the device is found.
The vital data is located by sonar devices scanning for an ultrasound beacon emitted by the black box that can be detected in depths of several thousand feet. Those pulses are usually emitted for about 30-days.
The Java Sea location where Flight QZ8501 crashed is believed to be about 100-feet-deep. Locating anything at that depth is not considered by investigators to be difficult, especially a device emitting a homing beacon.
Those ultrasounds can be picked up by ships, submersibles or even aircraft.
The search for the doomed AirAsia flight's black boxes continues, but is not expected to last very long.