(BRUSSELS, BELGIUM) — Belgian air traffic controllers halted air traffic at the country’s airports on Tuesday, June 2 in an unannounced strike that suspended operations from 12:00 to 19:00 GMT and forced Brussels Airport to cancel all scheduled flights during that period.

Brussels Airport said all scheduled flights had to be cancelled during the strike window. The disruption left air traffic to and from Belgium at a standstill while the suspension remained in force.

Travel advice issued in Belgium gave the same strike window in local time, saying Belgian airports were affected from 2:00 pm to 9:00 pm local time on Tuesday, June 2. It also warned that disruptions can happen at short notice.

The stoppage amounted to a nationwide disruption rather than an isolated airport problem. Air traffic at Belgian airports was suspended across the 12:00 to 19:00 GMT period, with Brussels Airport immediately becoming the clearest measure of the impact after it cancelled every scheduled flight in that span.

The cause was an unannounced strike by air traffic controllers. No advance public notice appeared in the information provided before the halt took effect, leaving airports and passengers to deal with a same-day shutdown.

That short-notice element defined the day’s disruption. Belgium’s travel advice had already cautioned that disruptions can happen at short notice, a warning that matched the sudden nature of Tuesday’s stoppage.

The practical effect of a Belgium Air Traffic Control Strike is unusually broad because controllers sit at the center of aircraft movements. Once traffic was suspended, departures and arrivals involving Belgium stopped moving through the system during the affected hours.

Brussels Airport bore the most explicit cancellation notice in the available information. It said every scheduled flight in the strike window had to be scrapped, turning the airport’s afternoon and evening schedule into a blank board for that period.

Passengers were left facing a disruption measured not in scattered delays but in a full stop. Air traffic to and from Belgium stood still during the suspension period, indicating the interruption extended beyond one terminal or one airline.

The timing also mattered for travelers already in transit on European routes. The strike ran through much of the afternoon and evening in Belgium, from 2:00 pm to 9:00 pm local time, a period that captures some of the day’s busiest airport activity.

Because the strike was not announced in advance, the disruption carried the kind of uncertainty that airports often struggle to absorb quickly. Belgium’s own travel advice pointed to that risk, warning that airport disruptions can emerge with little notice and change plans rapidly.

Tuesday’s stoppage turned that warning into a concrete shutdown. At Brussels Airport, all scheduled flights in the affected window were cancelled, and across Belgium, the suspension of air traffic left the country’s airports effectively frozen for seven hours.

The scale of the interruption also underscored how quickly an air traffic labor action can spread through a national aviation network. Once controllers stopped work, the impact was not limited to one route or a cluster of airlines, but to traffic to and from Belgium as a whole.

Travel advice signaled that further changes around passenger impact and airport operations can develop quickly during this kind of event. That leaves affected passengers watching for updates on which airports are hit, and whether cancellations extend to arrivals, departures, or both.

Tuesday’s unannounced strike gave Belgium’s airports little room to soften the blow. By the time the suspension window opened at 12:00 GMT, the country’s air traffic system had already shifted from routine operations to a standstill.