If it’s found, what exactly will MH370 black box tell us?

Officials on Tuesday detected two new signals in the hunt for missing plane – but time is running out as the batteries in on flight black boxes are expected to fail soon.

Angus Houston, head of the Australian agency coordinating the search, said the new “pings” would help create a “much more manageable search area on the ocean floor.”

Read more: can underwater robots help find flight MH370's black box?

“I believe we are searching in the right area but we need to visually identify aircraft wreckage before we can confirm with certainty that this is the final resting place of MH370.”

The battery powered black boxes have already reached the end of their 30-day life expectancy, meaning the search teams are now operating on “bonus time”.

If and when the black box is salvaged, engineers will carefully unscrew the containers to locate a computer board with chips that store the plane’s recorders. The recorders are dried slowly and deliberately in a vacuum oven before being analysed for clues.

‘Black’ box

According to National Geographic Channel, all commercial aeroplanes or corporate jets are required to be equipped with a cockpit voice recorder and a flight data recorder. It is these two items of separate equipment which we commonly refer to as a black box.

The flight data recorders and cockpit voice recorders are often used by the authorities to determine what happened to a flight after it crashes.

The cockpit voice recorder may not be so useful as it is likely to only record the last two hours of the flight David Kaminski-Morrow

These recorders are actually painted bright orange with white reflective strips on the sides and contain crash-protected tape or memory modules where the data is stored.

It took two years to find the black boxes from Air France Flight 447, which went down in the Atlantic Ocean in 2009.

The black box recordings showed that plane plummeted 38,000ft in just three minutes and 30 seconds because pilots lost vital speed data.

It also gave a chilling sense of the panic moments before the crash. The co-pilot’s last words were: “Damn it, we’re going to crash … This can’t be happening!”

Flight data recorder

The flight data recorder records the many different operating functions of a plane all at once, such as the time, altitude, airspeed and direction the plane is heading.

Modern flight data recorders are also able to monitor countless other actions undertaken by the plane, such as the movement of individual flaps on the wings, auto-pilot and fuel gauge.

The data stored on the recorders helps authorities generate computer video reconstructions of a flight, so that they can visualise how a plane was handling shortly before a crash.

Cockpit voice recorder

The main purpose of the cockpit voice recorder is to record what the crew say and monitor any sounds that occur within the cockpit.

According to USA Today, the voice recorder captures four channels: the captain, the co-pilot, a general cockpit microphone and potentially an extra pilot.

By law, the recordings are never released publicly, but by the time authorities meet to decide what probably caused a crash, transcripts will have been released.

The recordings carrying the pilots’ final words are often difficult to listen to, both emotionally and for clarity. Whatever chaos is happening to the plane can drown out or blur the words.

Besides hearing what the pilots and air-traffic controllers are talking about, the recorder captures all sorts of noises that can help decipher what happened to a plane.

Two hour loop

TheBlaze website writes that the cockpit voice recorder only retains two hours of recording. That’s the length of time that regulations demand – so anything that happed before that is lost.

So if the plane was hijacked or the pilots lost consciousness, it would be unlikely that we will gather much information from the cockpit voice recorder.

David Kaminski-Morrow, the air transport editor of the Flightglobal publication said: “The flight data recorder will be useful as it will indicate if something had gone wrong with the flight or if, in fact, the flight was a normal one.

“The cockpit voice recorder may not be so useful as it is likely to only record conversations in the cockpit for the last two hours of the flight and so will not tell us about what might have gone on before that.”