Working of Black Box

By   |  Published: 10th Aug 2020  10:26 pmUpdated: 10th Aug 2020  10:28 pm

Airplane accidents are statistical rarities. But when they happen, they’re often fatal, and people want answers as to why their loved ones died. There are usually many unanswered questions as to what brought the plane down. Investigators turn to the airplane’s flight data recorder (FDR) and cockpit voice recorder (CVR), also known as “Black Boxes”, for answers.  Following any airplane accident, safety investigators immediately begin searching for the aircraft’s black boxes. Let’s see how black box works.

The flight data recorder and cockpit voice recorder, or black boxes as they are often called, store data about planes.They can provide vital information in air accident investigations.  Flight recorders are also known by the misnomer black box—they are in fact bright orange to aid in their recovery after accidents.

Invented in Australia

Dr David Warren’s own father was killed in a Bass Strait plane crash in 1934, when David was just nine years old. In the early 1950s, Dr Warren had an idea for a unit that could record flight data and cockpit conversations, to help analysts piece together the events that led to an accident. He wrote a memo for the Aeronautical Research Centre in Melbourne called “A Device for Assisting Investigation into Aircraft Accidents”, and in 1956 produced a prototype flight recorder called the “ARL Flight Memory Unit”.

His invention did not get much attention until five years later, and the units were eventually manufactured in the UK and US. However, Australia was the first country to make the technology compulsory.

Two parts of black box

The “black box” is made up of two separate pieces of equipment: the flight data recorder (FDR) and a cockpit voice recorder (CVR). They are compulsory on any commercial flight or corporate jet, and are usually kept in the tail of an aircraft, where they are more likely to survive a crash. FDRs record things like airspeed, altitude, vertical acceleration and fuel flow. Early versions used wire string to encode the data; these days they use solid-state memory boards. Solid-state recorders in large aircraft can track more than 700 parameters.

Retrieving information

  • If the FDR is not damaged, investigators can simply play it back on the recorder by connecting it to a readout system. With solid-state recorders, investigators can extract stored data in a matter of minutes through USB or Ethernet ports.
  • Very often, recorders retrieved from wreckage are dented or burned. In these cases, the memory boards are removed, cleaned up and have a new memory interface cable installed. Then the memory board is connected to a working recorder. This recorder has special software to facilitate the retrieval of data without the possibility of overwriting any of it.
  • Both the FDR and CVR are invaluable tools for any aircraft investigation. These are often the lone survivors of airplane accidents, and as such provide important clues to the cause that would be impossible to obtain any other way. As technology evolves, black boxes will continue to play a tremendous role in accident investigations.