Malaysia plane: What answers will the black boxes hold?
Flight MH17's "black box" flight recorders could yield clues to the fate of the passenger jet, which crashed in the conflict-hit region of eastern Ukraine on Thursday.
The Boeing 777 was flying from Amsterdam to Kuala Lumpur when it disappeared from radar close to the Russian border. A total of 283 passengers and 15 crew members were on board.
Rescue workers say they have recovered one of the plane's "black box" flight recorders, while pro-Russian separatists are said to have discovered the second black box.
The recorders, of which there are two, store key technical information about the flight as well as conversations undertaken in the cockpit.
Here is a breakdown of what the flight data recorder and the cockpit voice recorder - actually coloured a deep orange to aid discovery - could contain.
Flight data recorder (FDR)
The flight data recorder is designed to record the operating information from the plane's systems. Whenever the pilot touches the controls or changes course, the FDR records that action.
International standards usually require commercial aircraft to record a minimum number of "parameters", or types of data, depending on the size of the aircraft.
Parameters recorded by most FDRs include:
- Direction of travel (heading)
- Normal acceleration
- Engine power
- Movement of leading/trailing edge flaps
- Reverse thrust position
- Outside air temperature
However, most modern FDRs are able to monitor hundreds of other actions and warnings, such as the loss of cabin pressure, that can be pieced together by air accident investigators after a crash. This information can even help generate a reconstruction of a flight, enabling better understanding of how a plane was handled before a crash.
Cockpit voice recorder (CVR)
Meanwhile, the cockpit voice recorder, as its name suggests, records conversations between crew members on the flight deck and any other sounds that occur within the cockpit. In commercial aircraft there are usually several microphones sending audio information to the CVR.
Usually located in the plane's tail to maximise its likelihood of survival in a head-on crash, the voice recorder is extremely important to investigators when trying to determine the timing of events.
Although there are different requirements for different planes, the standard CVR can record four channels of audio data, capturing the last conversations and noises on a flight.
In the case of Air France flight 447, which crashed in 2009 on its way from Rio de Janeiro to Paris, the CVR provided investigators a valuable insight into the level of confusion on the flight deck before it plunged into the Atlantic Ocean.