What's next for the black boxes as Ethiopian Airlines investigation moves to Paris

Investigators will be looking into similarities between flight ET 302 and the Lion Air crash five months ago

Men unload a case containing the black boxes from the crashed Ethiopian Airlines Boeing 737 MAX 8 outside the headquarters of France's BEA air accident investigation agency in Le Bourget, north of Paris, France. ReutersShow less

The Federal Aviation Authority, the US aviation regulator, backtracked on its earlier position and grounded Boeing’s best-selling 737 Max jets after evidence showing the Ethiopian Airlines flight that crashed on Sunday may have experienced the same problem as Lion Air’s aircraft that plunged into the Java sea five months ago.

US air safety investigators held intense discussions with their Ethiopian peers on where the black-box recorders from Ethiopian Airlines flight ET 302 will be downloaded and privately pushed to have the devices sent instead to the National Transportation Safety Board's facilities. This was after Ethiopia indicated it wanted to send the flight-data and cockpit-voice recorders overseas and preferred the UK's Air Accidents Investigation Branch as an objective outsider, the Wall Street Journal reported.

Ethiopian authorities, eager to demonstrate that US experts won’t have undue influence over the probe or the investigation's conclusions, decided to send the devices to France for inspection.

The incident raises questions about how investigations are handled in the aftermath of plane crashes.

What happens after a plane crash?

The bodies are recovered, identified and taken away from the aircraft crash site, as investigators recover and account for all aircraft parts. During this phase, the Digital Flight Data Recorder or DFDR, the Digital Cockpit Voice Recorder and air traffic control tapes are recovered and marked as evidence by the crash investigation team. The recovered wreckage is then examined to recreate the last moments before the crash and identify factors that led to the incident.

Who analyses the black box contents and where?

In many cases the data from the devices is downloaded by the local regulator and airline then immediately sent for data analysis which helps determine the last crucial minutes of the aircraft’s flight patterns. The parties involved often include the airline, aviation regulator in the carrier’s country of origin, regulator of country where the jet crashed and a technical team dispatched by the aircraft manufacturer. A computer software downloads the data, helps recreate a simulation of the last pre-crash moments and assimilates readings from the flight instruments, Mark Martin, head of Martin Consulting, said.

What is the black box and what information does it contain?

The black box is a data recorder that has evolved from a needle recording on a wax rotating plate to today's device that looks similar to a computer hard drive installed into a metal box that is resistant to fire, heat, water, pressure and shock. It records all critical parameters that are needed in order to analyse flight patterns: speed, altitude, engine performance, direction, velocity, position of flaps, landing gear, cabin pressure, temperature of cabin and cargo, fuel quantity, GPS position, cockpit alerts and audio recordings.

How long does it take investigators to produce a report?

It may take several days to complete the first readings of the black boxes recovered from the Ethiopian Airlines jet, a spokesman for the French air accident investigation agency conducting the analysis said on Thursday.

In general, depending on the type of aircraft, the condition of the black boxes and purpose of the investigation, it may take anywhere from weeks to up to a year or two to produce an investigation report.

What should victims’ families expect in the coming weeks or year?

Any data extracted and analysed will depend on the extent of damage to the black boxes. Depending on the case, some airlines offer compensation to the families following air disasters and try to return human remains and personal belongings.