Korean Air is set to finalize its long-awaited 1.8 trillion won ($1.4 billion) merger with Asiana Airlines Thursday, marking a significant step toward positioning the airline among the world’s top 10 carriers and solidifying its status as the largest in Northeast Asia.

On Wednesday, Korean Air completed payments for Asiana shares to secure a 63.9 percent stake in the smaller rival, putting an end to the four-year-long journey.

The merger marks the end of an era in which the nation’s two largest airlines operated separately, with Korean Air established in 1969 and Asiana Airlines in 1988, respectively.

With the merger, their combined assets stand at 43 trillion won, with Asiana contributing some 12 trillion won. They own a total of 238 aircraft, including 203 passenger flights and 35 cargo planes.

Over the next two years, the two airlines will still operate independently, with Asiana functioning as a subsidiary of Korean Air as they prepare for full integration.

Even though the merger has earned antitrust approval from a dozen countries, including Korea, the Korean authorities say they will continue to closely monitor the merger process to prevent any monopoly issues and consumer complaints.

One of the most contentious issues from the passengers’ side is the integration of the two carriers' mileage programs.

As of June, Korean Air's deferred mileage revenue totals some 2.5 trillion won, while Asiana Airlines stands at 975.8 billion won.

While mileage can be earned in two ways — through credit card usage and travel distance with the airline — the two methods are weighted differently, complicating deciding on a fair conversion rate for Asiana's mileage.

For airlines, unused mileage is automatically recorded as a liability on financial statements, so it is advantageous to encourage customers to use up as much mileage as possible before the merger.

"Aligning mileage programs is more than just mathematics. It’s about retaining customer trust and loyalty," an airline industry official said. "Asiana Airlines' mileage is part of Star Alliance, which differs from Korean Air's SkyTeam, which is another issue to be resolved."

In addition, the combined market share of the two carriers in international passenger transport is expected to reach some 73 percent, raising concerns about potential fare hikes due to reduced competition. To address this, the FTC has mandated that fare increases cannot exceed inflation rates over the next decade. Korean Air has also pledged to maintain competition by making key Asiana routes available to rival carriers.

The high-profile merger comes at a crucial time when uncertainties grow within the tourism and aviation industries about the business impact of the ongoing political unrest triggered by President Yoon Suk Yeol’s short-lived martial law imposition.

The shocking martial law declaration sent the won-dollar rate soaring to a two-year high while prompting major economies to issue travel alerts for their citizens staying in Korea.

Korean Air's share price saw a more than 5 percent decline over the three days following the martial law declaration but began showing gradual signs of recovery starting Monday.

“It is true that we received some cancellations in pre-reservations during the initial days following the martial law order, but this has not resulted in a significant decrease in overall passenger demand,” said a Korean Air official.

In regards to concerns about a sharp rise in oil prices and the need for airlines to repay leased aircraft costs in US dollars, the official dismissed the potential impact.

"Global fuel costs are recalculated monthly, so such fluctuations do not immediately result in increased fuel cost pressure. Regarding our aircraft, nine out of ten are owned and only one is leased, on average. Consequently, the impact of exchange rate fluctuations will be minimal overall," the official explained.