Taiwan’s defence ministry counted 21 People’s Liberation Army aircraft, 10 navy ships and five official vessels between 6 a.m. on 5 September and 6 a.m. on 6 September. Thirteen of the aircraft crossed the Taiwan Strait median line and entered the northern, central, southwestern and eastern sectors of Taiwan’s air defence identification zone. The day before, the same ministry listed J-11 and Su-30 fighters, H-6 bombers, a Y-8 electronic-warfare aircraft and a KJ-500 airborne early-warning jet on a 'joint combat readiness patrol'. Those types do not linger in empty ocean. They work the same map that China Airlines, EVA Air, Starlux, JAL, Korean Air, Cathay and the Gulf carriers use to reach Taoyuan and Songshan. An ADIZ is not sovereign airspace. It is a buffer in which a state demands identification. When fighters and bombers treat that buffer as a daily training ground, civil radar and military radar share the same picture, and the airline dispatch office inherits a variable that used to be exceptional.
Taipei FIR remains one of Asia’s better-run control areas on an ordinary day. The problem is geography. Arrival and departure streams into Taoyuan press north and northeast toward Japan and Korea, east toward the Pacific, and southwest toward Hong Kong, Manila and Singapore. The southwestern ADIZ is the sector the PLA uses most. That is also the door through which a large share of Southeast Asia-Northeast Asia traffic must pass if it is not already routing around the island. East China Sea tracks sit under Japanese and Taiwanese surveillance and under Chinese patrols that have made the median line a memory rather than a rule. Diversion options exist, Naha, Fukuoka, Hong Kong, Manila, Kaohsiung if the northern field is constrained, but a widebody on a Taipei arrival with a fuel plan written for a normal STAR does not carry infinite holding. NOTAMs for live-fire and joint drills arrive. They rarely arrive with the precision a dispatcher wants six hours before pushback. Airlines already treat the strait as a daily operational variable: extra fuel, alternate airports filed, crews briefed on possible vectoring, war-risk underwriters watching the same MND graphic the public sees each morning. Taiwan-based carriers have the least room. Their home hub is the node that would close first if a patrol stopped being a patrol.
This week’s 21-aircraft day is not a 2022-style blockade rehearsal. Trackers put 2026 ADIZ entries well below last year’s pace. That is the wrong comfort. Frequency has become weather. Thirteen crossings in twenty-four hours, across four compass sectors, means civil corridors are being flown around armed aeroplanes that do not talk to the same frequency as a 777 on descent. The next risk is not a headline invasion. It is a misidentified track, a sudden restricted area, a missed STAR and a fuel decision made in a cockpit that expected a civilian sky.