09-07-2025
China's change to flight path in sensitive Taiwan Strait raises safety concerns
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Beijing's latest move to adjust the flight path without prior negotiation with Taipei poses a threat to flight safety, experts said.
TAIPEI – China's unilateral move to open a third extension of the M503 air route in the sensitive Taiwan Strait raises safety concerns and challenges Taipei's ability to manage its airspace, analysts said.
The M503 flight path lies just 4.2 nautical miles, or around 7.8km, west of the so-called median line, an unofficial demarcation which for years had served as an informal boundary between China and Taiwan. But Beijing, which claims Taiwan as its territory, has increasingly made incursions across the line as it pressures Taipei to accept its sovereignty claims.
Beijing's latest move to adjust the flight path without prior negotiation with Taipei poses a threat to flight safety, experts said.
'If an aircraft were to deviate from the path due to weather or mechanical issues, Taiwan's air traffic controllers would have only about 30 seconds to respond,' said Dr Su Tzu-yun, a defence analyst at Taiwan's Institute for National Defence and Security Research.
'This poses a risk to civilian aviation on both sides (of the strait).'
The new extension covers an area near Taiwan's outlying Matsu Islands, where Taiwanese holidaymakers fly to for weekend getaways.
On July 6, Beijing announced that it had activated the W121 extension connecting Dongshan in China's Zhejiang Province to M503, a north-to-south air route which goes through the Taiwan Strait.
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It is the third extension after Beijing in 2024 opened W122 and W123 – west-to-east flight paths from the Chinese coastal cities of Xiamen and Fuzhou.
The latest move is aimed at reducing air traffic congestion, ensuring flight safety, and reducing flight delays, said China's Taiwan Affairs Office (TAO) spokesman Chen Binhua.
'Previous changes to the route have improved the operation of cross-Strait flights and further facilitated personnel exchanges across the Taiwan Strait,' he added.
But Taiwan's Mainland Affairs Council (MAC) slammed the unilateral decision, saying that it not only disregarded past cross-strait understandings and public opinion in Taiwan, but also increased regional instability.
The MAC added that China's international air passenger traffic has not returned to pre-pandemic levels, and pointed out that W121 is not part of any cross-strait flight route. 'How can it be said that it would facilitate cross-strait personnel exchanges? Such claims are obviously unjustified,' the council said.
This is not the first time the M503 flight path has been a source of controversy.
China had first established the path and its three connecting routes – W121, W122 and W123 – in 2015, provoking opposition from Taiwan.
A bilateral agreement was reached later that year to allow for only southbound flights on the path, with the three extensions closed until a consensus was reached.
However, China in 2018 unilaterally opened the M503 route to allow for northbound flights.
In January 2024, Beijing broke agreements once more, activating the W122 and W123 extensions. China also shifted the route 6 nautical miles eastward and brought it substantially closer to the median line of the Taiwan Strait.
This, analysts said at the time, was part of broader Chinese efforts to erase any understanding of the median line, as well as a show of displeasure at the election that same month of Taiwan President Lai Ching-te, whom it distrusts.
Now, Beijing's activation of the W121 comes just days ahead of Taiwan's annual Han Kuang military and civil defence drills, held to simulate a Chinese blockade and invasion of the island.
'The move is also an angry response to Lai's '10 talks' speeches,' said Assistant Professor Lin Ying-yu, a defence analyst from Taiwan's Tamkang University.
In June, Mr Lai kicked off a series of 10 speeches to 'unite the country', sparking debate and drawing ire across the strait. In his first speech delivered on June 22, he said that
Taiwan is 'of course' a country , adding that China lacked both the historical evidence and legal proof to back up its sovereignty claims over the island.
In response, China condemned Mr Lai's remarks as a 'declaration of Taiwan independence filled with 'heresies'', and accused him of inciting separatism and 'leading Taiwan towards war'.
Taiwan legislator Chen Kuan-ting, a member of the Foreign Affairs and National Defence Committee in Parliament, warned that 'China is engaging in 'grey zone' warfare under the guise of fulfilling civil aviation needs'.
Grey zone tools are coercive actions designed to intimidate while stopping short of a conventional war. For instance, China has sent balloons and drones into Taiwan's air-defence identification zone, aimed at intimidating the public and undermining the morale of the military.
Dr Su, the defence analyst, noted how Taiwan should demand accountability from China while raising the issue internationally.
'The situation highlights the necessity for Taiwan to keep making a push for it to join the International Civil Aviation Organisation (Icao),' he added.
Taiwan is not a member-state of the United Nations and thus cannot join ICAO, the agency that oversees global aviation standards and practices, despite being a significant hub for air traffic.
In a July 6 statement, Taiwan's Civil Aviation Administration said it has asked air traffic controllers to closely watch flights on the W121 route to ensure safety in the region.
'We ask China to quickly communicate with us on this matter in accordance with the mutual agreement reached in 2015,' it added.
