Black boxes: Crucial to air crash probes
Finding black box
On Sunday, an Ethiopian Airlines Boeing 737 MAX 8 crashed, killing all 157 people on board.
The airline said Thursday that the black box flight recorders from the crashed plane had been flown to Paris for analysis by the BEA, France's aviation investigation and analysis agency.
It is uncertain how much of their content can be retrieved as both the aircraft's black boxes, found Monday, were damaged in the crash.
Function of black box
All commercial planes are required to have two of them on board — a flight data recorder and a cockpit voice recorder.
The data recorder stores up to 25 hours worth of second-by-second information including on speed, altitude, engine performance and flight trajectory.
It helps determing what went wrong
The voice recorder picks up conversations by pilots and flight attendants and also other sounds on board, including possible alarms.
All black boxes used in civil aviation function the same way according to a common user protocol, regardless of their make, the BEA said.
The recorders are housed in boxes built to survive extreme shocks, fire and lengthy periods underwater.
Orange is the new black
They each weigh seven to 10 kilogrammes (15 to 22 pounds) and can survive in water as deep as 6,000 metres (almost 20,000 feet) or for an hour at 1,100 degrees Celsius (2,012 degrees Fahrenheit).
To make them easier to find, they are fitted with a beacon which can emit a signal for one month.
Long-haul Airbus A350 and A380 passenger jets will soon come equipped with ejectable black boxes that can float, making them easier to find after accidents over water.
And in 2011, after 23 months submerged at a depth of 3,900 metres in the Atlantic Ocean, the intact black boxes of Air France flight AF447 were found, allowing investigators to determine what caused the 2009 crash.
Lion Air flight JT610 came down in water some 30-40 metres deep and both black boxes were found within 10 metres of each other, authorities said.