The mainland’s Civil Aviation Administration activated the last of three branches off the M503 north-south flight path through the strait on Sunday.
The M503 and its offshoots were established in 2015 to connect various cities along the mainland’s east coast. Two of the branches were activated last year and the third, the W121, on Sunday.
At its closest point, the M503 route lies just 4.2 nautical miles (7.8km) from the unofficial line dividing Taiwan and mainland China.
The administration, which made the decision without consulting Taipei, said the “technical adjustment [was meant] to alleviate air traffic pressure and improve safety”.
“Previous changes to the route have improved the operation of cross-strait flights and further facilitated personnel exchanges across the Taiwan Strait,” the administration said.
