Authorities have said black boxes holding the flight data and cockpit voice recorders stopped recording around four minutes before the crash.

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

The two flight recorders on board a South Korean airliner stopped working before the jet crashed during an emergency landing and subsequent crash that killed 179 of the 181 people on board, officials said Saturday.

The nation’s transport ministry reviewed structures near airport runways after the deadly crash of a Jeju Air flight late last month.

A Jeju Air jet in South Korea crashed last month due to bird strikes, leading to 179 fatalities. Investigators found bird feathers and blood in its engines. The crash occurred after overshooting the runway,

A total of 179 died in the crash, with just two crew members surviving in one of the nation’s worst aviation disasters.

South Korea said it planned to improve the structures housing the antennas that guide landings at its airports this year after December's fatal crash of a Jeju Air plane, which skidded off the runway and burst into flames after hitting such a structure.