South Korea’s aviation sector continues to exceed its relative scale, and nowhere is this more striking than on the world’s busiest airline route. Jeju International (CJU) – Seoul Gimpo (GMP) tops OAG’s global rankings for the busiest domestic route in December 2025, with 1.46 million seats, and grew at the fastest rate among the Top 10 busiest domestic routes.

Using three airline capacity data points from November 2025, this blog explores the dynamics shaping South Korea's air travel landscape today.

SOUTH KOREA’S COMPETITIVE AIRLINE LANDSCAPE

The market in South Korea is characterised by robust demand and fierce competition, with low-cost carriers (LCCs) playing a significant role. Total airline capacity in South Korea reached 14.5 million seats in November 2025: 62% international capacity and 38% domestic capacity.

The first of our charts illustrates the major players operating in South Korea’s airline landscape.  Whilst the domestic market appears competitive, with nine airlines vying for passengers, the reality is that one airline group now dominates.

• The Korean Air and Asiana Airlines merger finally completed in December 2024, and the combined position of both carriers and their LCC subsidiaries (Jin Air and Air Busan) gives the Korean Air Group 77% of total capacity in South Korea’s domestic market. 

THE JEJU-SEOUL GIMPO SUPER ROUTE

The second chart highlights the domination of the Jeju International (CJU) to Seoul Gimpo (GMP) flight route in the domestic market. In November 2025:

• 7 carriers operated
• 209 daily return flights
• 1.4m seats
• Asiana operated 57 return flights, Korean Air 55 return flights, and Jeju Airlines 41 return flights on the route

Jeju appears as a destination in seven of South Korea’s Top 10 domestic routes. It is an island tourism hotspot, and unlike many busy routes that compete with high-speed rail or buses, flying is the only practical option for getting there.  With multiple low-cost carriers competing and average economy one-way fares of USD$33, prices are extremely affordable for most Koreans.

LOOKING OUTWARDS: STRONG INTERNATIONAL RECOVERY LED BY JAPAN AND SINGAPORE

• South Korea’s international capacity reached 9 million seats in November 2025, +4.7% compared to 2019.
• 84 carriers operate in the international market:
  • The Korean Air Group now has the largest combined share, with 43% of total capacity in November
  • Jeju Airlines is the next largest operator with 8% of total international capacity
• Korean domiciled carriers operate the largest share of international capacity, amounting to 68% of total international capacity in November 2025.  

The international market is driven by distinct regional trends:

• Japan: The largest international market With 2.61m seats in November 2025, capacity has grown by 89% since 2019.  This short haul market is highly competed by low-cost carriers, boosting both inbound and outbound travel demand.  Post-pandemic, Japan's air travel has rebounded earlier and more smoothly than countries such as China.
• China: Slow recovery amid weaker outbound demand. Despite ranking second largest international market with 1.57 million seats, China remains below 2019 levels. Sluggish outbound tourism and geopolitical tensions have pushed Korean LCCs to shift capacity elsewhere for better yields and load factors.
• Singapore: Premium demand meets K-culture travel. Capacity to Singapore is up by 44% compared to 2019, driven by strong business links and premium travel opportunities combined with tourism growth in both directions.  Leisure interest in South Korea has surged with the growth in Korea’s cultural popularity, from food tourism to holidays to K-culture.
• The US: Diaspora travel, business and education-related travel, joint ventures. The market is up 21% since 2019, supported by a large Korean-American population, robust business links, and the Korean Air-Delta joint venture that continues to strengthen Seoul Incheon’s role as a transpacific hub.

A combination of legacy carrier scale and low-cost agility is driving growth across South Korea’s domestic and international markets, positioning it as one of Asia’s most dynamic aviation landscapes.