The operators of Incheon International Airport and other regional airports kicked off emergency operations ahead of unionized workers' planned strike on Friday.

The Incheon International Airport Corporation and Korea Airports Corporation(KAC) said in a news release Thursday that they would mount an all-out response and activate emergency systems to minimize passenger inconvenience during the action.

The Incheon Airport operator, which has been running an emergency countermeasures headquarters since last month, intends to raise its crisis alert level for relevant subcontracted firms from "caution" to "serious" starting at 6 p.m. Thursday and reinforce its monitoring of operations.

The KAC, which operates Gimpo International Airport and 13 others nationwide, has been conducting on-site inspections since last Thursday and has established an on-site team to monitor the situation in real time. 

The companies will dispatch replacement personnel and keep passengers updated on the situation via on-site guides, notices and banners.

The Incheon airport chapter of the Korean Public Service and Transport Workers' Union and an umbrella union for airports in the country, which together represent 15-thousand subcontracted airport employees, announced in a news conference last week that they would launch a general strike on Friday to demand improvements to their working environments, including changes to shift schedules and additional hiring.