South Korea’s leading low-cost carrier, heavy with debt and its stock already near record lows, is now facing intense public and government scrutiny.

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

The two black boxes on the Boeing jet involved in the worst aviation disaster on South Korean soil stopped recording about four minutes before the accident, the transport ministry said on Saturday. South Korean investigators previously said the flight data and cockpit voice recorders were key to finding out the cause of last month's crash that killed 179 people.

After initial analysis of the devices, the US National Transportation Safety Board concluded that both the flight data and cockpit voice recorders stopped working about four minutes before the crash

The black boxes of the Jeju Air plane involved in last month's fatal crash has been found to lack data from the final four minutes before the explosion.

The black boxes from the Boeing (NYSE:BA) jet involved in South Koreas deadliest aviation disaster stopped recording four minutes before the crash, according to the transport ministry. The tragedy claimed 179 lives,