What is a Black Box?
What is a Black Box?(Photo: Altered by The Quint)
  • 1. Are Black Boxes Really Black?
  • 2. Survival of the Sturdiest?
  • 3. You Ask The Questions, The Black Box Has The Answers
  • 4. Not All Black Boxes Are Found
Why Are Black Boxes So Crucial in Air-Crash Investigations?

With the recent crash of an Ethiopian Airlines Boeing 737 Max 8 plane, the term ‘black box’ has been making headlines again as investigators try to decode what caused the plane to crash shortly after takeoff. This incident comes not long after a Lion Air plane of the same make crashed in a similar fashion in October. The why’s and how’s of the crash are usually contained in what are commonly called ‘black boxes’.

This ‘black box’ contains data crucial to piecing together what happened on the plane before and during a crash.

Early designs of the black box or the Flight Data Recorder included copper foils on which instruments indented the recordings. This design, which could withstand extreme heat and pressure, was built by Len Harrison and Vic Husband. Magnetic tape voice recorders date back to the World War II era.  Modern-day black boxes, however, are solid-state drives which store all the flight data.

  • 1. Are Black Boxes Really Black?

    What is a Black Box?
    Black Box of the Ethiopian Airlines 737
    (Photo: AP/BEA)

    What is commonly called the ‘black box’ is in fact two orange-coloured boxes, one is the Flight Data Recorder (FDR), the other is the Cockpit Voice Recorder (CVR). As the names suggest, CVR stores the last two hours of voice recording from the cockpit and the pilots’ headset microphones on four channels. The CVR also records ambient noises such as the turning on and off of switches, thuds and other noises.

    Modern-day FDRs record the operating data from the plane’s systems. Sensors placed in different parts of the plane are connected to the Flight Data Acquisition Unit, which sends the data to the FDR. Hence, any change in the plane, any switch turning on or off of a switch, all the data is recorded. The FDR captures 88 different types of data, for the last 25 hours till the recorder loses power.

    Parameters recorded commonly include:

    • Time
    • Pressure altitude
    • Airspeed
    • Vertical acceleration
    • Magnetic heading
    • Control-column position
    • Rudder-pedal position
    • Control-wheel position
    • Horizontal stabiliser
    • Fuel flow

    Data from both the components are stored in memory boards inside a Crash Survivable Memory Unit.


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