South Korea's government said on Monday it will extend the shutdown of Muan International Airport by a week to Jan. 14, citing the ongoing investigation into the crash of a Jeju Air jet that killed 179 passengers on board.

After overcoming pariah status at the end of the last century, South Korea must learn what caused the catastrophe on Dec. 29 and what lessons to draw from it.

Authorities also raided the regional aviation office in Muan, part of Busan’s aviation administration. Read also: Black box data recovered in South Korea’s deadliest plane crash; another sent to U.S.