The missing data deepens the puzzle of what caused the deadly air disaster in Muan, South Korea, late last month.

The investigation into the tragic crash of Jeju Air flight 2216 is picking up pace. The focus is now on carefully extracting data from the plane’s two black boxes. While the initial extraction of information from the cockpit voice recorder is complete,

Korean investigators' efforts to understand the Jeju Air Boeing 737-800 crash at Muan have suffered a setback after both flight recorders failed to capture the final 4min of the accident sequence. The aircraft overran at high speed,