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

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,

The Ministry of Land, Transport and Infrastructure said Friday that a flight data recorder from Jeju Air’s crashed Boeing 737-800 will be shipped to the U.S. National Transportation Safety Board (NTSB) on Monday.