CHITOSE, Japan -- The Asia-Pacific region is the world's busiest aviation market, but it faces an uncertain outlook due to several major headwinds, industry watchers say.

The region accounted for seven of the world's top 10 international air routes in September by seat capacity, according to the latest figures compiled by travel data provider OAG and presented at industry group CAPA's recent annual conference.

The route between Incheon, South Korea, and Japan's Narita topped the list with 558,000 scheduled seats. It was closely followed by Hong Kong-Taipei. Cairo-Jeddah placed third, while Incheon's connection with Osaka Kansai and the Kuala Lumpur-Singapore hop rounded out the top five. No mainland Chinese city made the list.

Asia-Pacific routes dominated the domestic seat capacity league table as well. Apart from Jeddah-Riyadh, the rest of the top 10 were all in the region, led by Jeju and Seoul's Gimpo and closely trailed by Haneda-Chitose, near Sapporo, where the CAPA conference was held last week. Two Chinese domestic connections -- linking Shanghai Hongqiao with Beijing Capital Airport and Shenzhen -- appeared at the bottom.

Separate data showed that Incheon became the world's busiest international airport for the first time in the first half of 2026. International passenger traffic at the airport reached 38.39 million, up 6%, year on year, surpassing London Heathrow's 37.79 million and Singapore Changi's 34.53 million.

The region's airlines are expanding their fleets. According to CAPA's count through the end of August, Boeing had 47 orders from Asia-Pacific carriers. Korean Air on Sept. 15 held ag ceremony for an additional 103 jets from the U.S. manufacturer, worth $36.2 billion.

Korean Air Chairman and CEO Cho Won-tae, also known as Walter Cho, told the CAPA audience that this was "by far the largest order we made among all our aircraft orders," in the runup to the completion of a long-awaited merger with Asiana Airlines on Dec. 17. He said he wished he had eight 777-8F freighters in the order already, given robust air cargo demand, and expressed "great trust" in Boeing despite its struggles in recent years European rival Airbus' orders in the region far outnumber Boeing's, at 582, including 417 from eight mainland Chinese carriers.

Biman Bangladesh Airlines on Wednesday confirmed an additional order for 10 Airbus jets including four A350-900 wide bodies and six A321neo single-aisle aircraft.

Korean Air Chairman and CEO Cho Won-tae speaks to Adrian Schofield, senior Asia-Pacific air transport editor at Aviation Week, at a CAPA forum in Sapporo, Japan, on Oct. 2. Despite the brisk Asia-Pacific activity, experts remain cautious about the outlook.

During the CAPA event, Adrian Schofield, senior Asia-Pacific air transport editor at Aviation Week, cited five major geopolitical factors that may affect the market, creating winners and losers.

The first: U.S.-China tensions. Two summits between presidents Donald Trump and Xi Jinping so far this year have maintained a trade war truce and the appearance of stability. Nevertheless, aviation capacity connecting the world's two largest economies remains at around 30% of the level in 2019, before the COVID-19 pandemic.

When Trump visited Beijing in May, the Chinese side pledged to order 200 new Boeings but there was no public mention of aviation at their second summit in Washington last month. "We were sort of expecting maybe more Boeing orders, [or] they might confirm those 200 Boeing orders, but nothing more on that," Schofield told Nikkei Asia. He said he had also anticipated that "they might announce more traffic rights between the U.S. and China, but no mention of that either." The limited number of seats flying between the U.S. and China benefits others in the region by allowing them to pick up the slack, "particularly the South Koreans," he said.

The second worry is tension between Japan and China Ties rapidly deteriorated last November after Japanese Prime Minister Sanae Takaichi spoke in parliament about Japan's potential involvement in a Taiwan crisis. Chinese airlines have cut a number of direct flights between the two largest Asian economies, while Chinese visitor arrivals in Japan have fallen sharply. Mainland Chinese carriers have been the clear losers from this, especially Shanghai-based Spring Airlines, which had heavier exposure to the Japanese market "Japan routes have been affected by force majeure," Spring Airlines said in its interim earnings report to the Shanghai Exchange at the end of August, referring to the geopolitical fallout in a roundabout way. It logged an 11% drop in net profit to 1.04 billion yuan ($156 million) for the first half of the year.

Another lingering challenge is Russia's ongoing war against Ukraine and Moscow's counter-sanctions against those supporting Kiev. This has curtailed the use of Russian airspace by flights connecting Asia with Europe. The inability to fly over Siberia is a "handicap for Japanese and South Korean airlines, in particular," according to Schofield.

The war the U.S. and Israel launched against Iran earlier this year, and its ripple effects, is a fourth headache for carriers. Tehran's efforts to disrupt shipping through the Strait of Hormuz has pushed up jet fuel prices, adding to airlines' costs. Only a few players in the region, such as Hong Kong's Cathay Pacific Airways, have weathered the crisis well, thanks to long-standing fuel hedging policies. Many have seen their profits plunge or have fallen into the red.

The fifth issue is even more entrenched. The India-Pakistan confrontation keeps Pakistani airspace closed to Indian airlines, which results in "costly rerouting," Schofield said.

A plane flies over the Arabian Sea near Karachi: Tensions between Pakistan and India forces airlines to fly indirect routes, pushing up costs.

"Geopolitical tensions are big problems for airlines," said Schofield. The "airline industry remains extremely vulnerable to external forces outside its control." The Association of Asia Pacific Airlines (AAPA) recently raised a red flag over the industry's momentum. It said at the end of September that 33.5 million passengers flew internationally in the region in August, down 0.6% from a year earlier.

Although the region's airlines carried 259.3 million international passengers in the first eight months of the year, up 2.1% on the year, AAPA described the situation as "soft," as some carriers are further reducing capacity due to high jet fuel prices and airspace restrictions associated with the Middle East conflict.

Wong Hong, director-general of AAPA, said, "The operating environment remains challenging," as weaker Asian currencies versus the dollar have also elevated costs, since most expenses are denominated in the U.S. currency, and higher fares are weighing on price-sensitive travelers.

Wong maintained a generally positive view but warned, "Geopolitical developments and changes in trade policies add some uncertainty to the outlook for the remainder of the year."