HOW MUCH INFORMATION IS AVAILABLE?
The capacity of flight recorders has been debated for years as authorities weigh improvements against the cost and the risk of inadvertently creating other problems, such as drawing power from other systems needed in an emergency. Cockpit monitoring has also been a sensitive topic with pilot unions.
FDRs must record at least 88 essential parameters but modern systems can typically track 1,000 or more additional signals.
The CVR usually contains two hours of recordings on a loop but this is being extended to 25 hours.
Implementing such regulatory changes can take years.
A spate of accidents in which recorders stopped working when onboard electrical power was lost, including an Egyptair flight from New York to Cairo in 1999, led the US National Transportation Safety Board to recommend enough backup power to provide 10 minutes of extra recording.
The Federal Aviation Administration proposed the change in 2005 and it was adopted for new planes delivered from 2010, eight months after the 737-800 involved in the Jeju crash left the Boeing factory, according to data from FlightRadar24.
Pressure to lengthen the loop of voice data to 25 hours to reflect trans-oceanic flights began with French recommendations following the crash of Air France 447 in 2009, and accelerated after the disappearance of Malaysia’s MH370 in 2014.
Last year, the US Federal Aviation Administration Reauthorization Act included the 25-hour requirement for cockpit voice recorders, echoing previous decisions in Europe.
