A major eruption of Mount Anak Krakatau disrupted air travel across Indonesia on Sunday, Sept. 6, forcing the temporary closure of eight airports — including Jakarta’s main international gateway — and affecting about 1,558 flights and 170,000 passengers, according to Indonesian authorities.What happenedAnak Krakatau erupted repeatedly, with two significant bursts early Sunday. One lasted about 30 seconds at 3:53 am, followed roughly three hours later by another eruption lasting about 16 seconds.The volcano had shown increasing activity since Friday, Sept. 4. Indonesian authorities described the latest eruption as the strongest phase of its current activity.Ash clouds rose as high as 50,000 feet (about 15,000 metres), putting aircraft at risk and prompting aviation authorities to suspend operations. Ash spread toward Jakarta, western Java and Lampung province on Sumatra, depending on wind direction.Airports affectedThe disruption expanded beyond Jakarta. The affected airports included:Soekarno-Hatta International Airport — Jakarta/TangerangHalim Perdanakusuma Airport — JakartaRadin Inten II Airport — LampungHusein Sastranegara Airport — BandungBudiarto Airport — CurugPondok Cabe AirportTaufik Kiemas AirportAtung Bungsu AirportIndonesia’s Transport Ministry initially reported about 150,000 passengers and 467 flights affected, but the figure subsequently rose as the disruption spread, reaching about 1,558 affected flights and 170,000 passengers. At Soekarno-Hatta alone, more than 900 flights were affected, according to reports.International flights hitThe ash cloud disrupted routes linking Jakarta with major regional and international destinations, including:SingaporeKuala LumpurDohaSydneyHong KongSeoulAmsterdamSingapore Airlines, Scoot, Malaysia Airlines, AirAsia and other carriers cancelled or adjusted services.The danger is not simply poor visibility. Volcanic ash can damage or disable jet engines, contaminate aircraft systems and severely reduce visibility, making continued operations unsafe.