The restriction spans an area twice the size of Taiwan, blinding civil aviation until May 6 in a move experts call an unprecedented military flex.
April 9 — China just locked down 73,000 square kilometres of sky. They didn’t say why.
Civil aviation is now banned across a massive stretch of the Yellow and East China Seas. The restriction, quietly slipped into the global aviation system via a US Federal Aviation Administration (FAA) notice, holds for 40 days. It ends on May 6.
Nobody saw it coming. The Notice to Air Missions, or NOTAM, went online on March 27 at 1150 GMT. It took effect just hours later.
The scale is staggering. The blackout zone is roughly twice the size of Taiwan, sitting a few hundred kilometres north of the island. It slices directly through highly trafficked international corridors.
But what exactly is Beijing doing out there?
“There is no possible use other than military,” Benjamin Blandin, a maritime security expert and researcher at Taiwan’s Institute for National Defense and Security Research (INDSR), told AFP. “It could be to fire missiles, carry out air exercises, etc. We don’t know.”
The geography of the ban tells a specific operational story. The closed airspace isn’t a single, solid block. It’s fractured. Two zones sit squarely over the Yellow Sea, wedged between China and South Korea. Three more stretch across both the Yellow and East China Seas, sitting between China and Japan.
They left exactly one door open. The closed zones are separated by a narrow air corridor about 100 kilometres wide. That sliver of sky allows commercial traffic to continue funneling into Shanghai from the Yellow Sea. Everything else is a no-go.
And the altitude parameters are just as extreme. Aviation and defence consultant Xavier Tytelman noted that the restriction is entirely out of the ordinary. It isn’t just the sheer size or the 40-day duration. It’s the total lack of altitude limits, high or low.
In practical terms, Tytelman said, it means “the government is reserving a zone for itself.”
This isn’t business as usual for Beijing. China frequently conducts military drills, but they typically come with defined perimeters, public warnings, and clear justifications. This didn’t.
Blandin called the move unprecedented. It is the very first time China has choked off access to its airspace in a way that is “so sudden, geographically extensive, prolonged over time, and so poorly documented.”
So why do it? The target isn’t just the airspace. It’s the neighbours.
Blandin sees the unannounced closure as a direct signal aimed at deterring US allies in the region. It’s a calculated flex designed to weaken American military influence in the Indo-Pacific. It forces Japan, South Korea, and Taiwan to navigate around an invisible wall erected strictly on Beijing’s timetable.
This NOTAM isn’t an isolated administrative anomaly. It fits a larger pattern. Blandin describes the sudden airspace restriction as part of a “continuing series of access denials.” It is the latest tactical escalation in what he calls China’s strategy of “nibbling away at the land and sea borders of its neighbours” over the last 15 years.
By cordoning off the sky without a word of explanation, Beijing proves it can disrupt regional logistics at will. They don’t need a declared crisis to lock down a sea. They just need a NOTAM.
The sky opens back up on May 6. But the precedent is already set.
