02:09 - Source: CNN
What is a black box anyway?

Story highlights

NEW: Officials say there was some damage to the plane's cockpit voice recorder

Investigators have recovered the black boxes from the Metrojet Flight 9268 wreckage

The Russian passenger jet crashed in Egypt's Sinai Peninsula, killing all 224 people on board

CNN —  

They’ve been fixtures on commercial flights around the world for decades.

And in the inquiry into what caused Metrojet Flight 9268 to crash, investigators hope they’ll provide crucial evidence.

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Here’s a look at what we know so far about the Russian plane’s cockpit voice recorder and flight data recorder, the so-called black boxes, which were found at the crash site on Saturday:

Where are they now?

The flight crashed in Egypt’s Sinai Peninsula on Saturday, killing all 224 people on board. After the crash, Egyptian officials said the two black boxes had been found and were being transported to Cairo for analysis.

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The Egyptian Civil Aviation Ministry released a photo of the boxes on Monday after officials from Egypt and Russia examined them.

01:58 - Source: CNN
Black boxes of Russian plane crash recovered

Were they damaged in the crash?

Data from the plane’s flight data recorder has been “extracted and validated,” Egypt’s Civil Aviation Ministry said Wednesday.

But the cockpit voice recorder was damaged, the ministry said.

“There were some damages to the voice recorder inside the cockpit that require a lot of technical procedure and effort to extract its data,” Civil Aviation Minister Hossam Kamal said. “Any speculation about the content of the audio recording of the cockpit is completely false.”

Russia’s interstate aviation commission said there was “serious mechanical damage” to the recorder.

Investigators from Egypt, Russia and France “are carrying out preparation work to copy the data from it, taking all precautionary measures,” the commission said.

What can investigators learn from them?

Officials say they haven’t had a chance to analyze the data from the black boxes yet. But when they do, investigators hope they will reveal key details about the flight.

The cockpit voice recorder captures sounds on the flight deck that can include conversations between pilots, warning alarms from the aircraft and background noise. By listening to the ambient sounds in a cockpit before a crash, experts can determine if a stall took place and the speed at which the plane was traveling.

Inside a black box lab

The flight data recorder gathers 25 hours of technical data from the airplane’s sensors, recording several thousand discrete pieces of information. Among the details investigators could uncover: Information about the plane’s air speed, altitude, engine performance and wing positions.

“The likelihood,” CNN aviation correspondent Richard Quest said, “is that the black boxes will tell us the cause of why this plane suddenly decelerated very fast.”

But black boxes aren’t perfect. In several cases – like the 1996 crash of TWA Flight 800 or the crash of American Airlines Flight 77 on September 11, 2001 – authorities had hoped to find clues in the black boxes, only to discover that the data inside had been damaged or the recordings had stopped suddenly.

02:13 - Source: CNN AP
The evolution of the "Black Box"

Who will be reading and interpreting what’s inside?

Because the plane crashed in Egypt, authorities there are heading the investigation.

Egyptian President Abdel Fattah el-Sisi has promised Russian President Vladimir Putin that he will allow “the broadest possible participation of Russian experts in the investigation,” according to the Kremlin.

Putin has also ordered Russian Prime Minister Dmitry Medvedev to open an investigation, the Kremlin said.

Aviation investigators from France and Germany, the countries where the plane was manufactured, are also taking part. An Irish team is also participating, because the plane was registered in Ireland.

The aircraft’s engines were manufactured in the United States. If the plane’s engines become a focus of the investigation, the U.S. National Transportation Safety Board will likely dispatch a team to Egypt as well, a U.S official with knowledge of the investigation said.

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CNN’s Salma Abdelaziz, Alla Eshchenko, Jethro Mullen, Susannah Cullinane, Rachel Crane, Rene Marsh, Randi Kaye and John Berman contributed to this report.