Pilots at flag carrier Korean Air on Thursday threatened to go on a weeklong strike just as millions of Koreans forward to holiday abroad over the long Chuseok break.

The Korean Air pilots' union said it notified its employer that 390 pilots will take part in the strike.

But the airline is designated as an essential public service, so only a certain portion of its 2,300 pilots can strike at once without risking jail. And the airline must maintain 80 percent of international flights, 70 percent of flights to Jeju Island and 50 percent of domestic flights.

That still leaves a wide margin for chaos and ruined breaks in a country with notoriously short holidays and excessive working hours.

