Anak Krakatau ash closes eight airports and strands 170,000 passengers

Indonesia shut eight airports after Anak Krakatau sent ash across western Java and southern Sumatra, leaving about 170,000 passengers unable to fly. The Transport Ministry counted 1,558 delayed or cancelled flights on 6 and 7 September. More than 900 of those services were to or from Soekarno-Hatta, the country's main international gateway more than 150 kilometres from the volcano.

The closed fields were Soekarno-Hatta and Halim Perdanakusuma in the Jakarta area, Husein Sastranegara in Bandung, Radin Inten II near Bandar Lampung, Budiarto in Curug, Pondok Cabe in South Tangerang, and Taufik Kiemas and Atung Bungsu in Lampung. Transport Minister Dudy Purwagandhi named Semarang and Surabaya as alternate landing sites. Bali's Ngurah Rai stayed open but lost dozens of domestic connections as airlines rerouted around the plume.

The geology agency said Anak Krakatau erupted on Saturday with a lava fountain and noise heard tens of kilometres away. Two further eruptions were logged on Sunday. Ash reached Soekarno-Hatta's airspace even though the cone sits in the Sunda Strait. AirNav Indonesia runs concentration tests before a field can reopen. A Sunday evening attempt to restart Soekarno-Hatta did not clear those tests. A later window toward 23:59 local time on Monday was listed as the next try.

Singapore Airlines and Malaysia Airlines cancelled Jakarta flights for Sunday. Scoot, AirAsia and other regional carriers cut or moved services. Routes to Singapore, Kuala Lumpur, Doha, Sydney, Hong Kong, Seoul and Amsterdam were among those hit.

Anak Krakatau grew from the caldera of the 1883 Krakatoa eruption and has been restless for years. Authorities had already raised the alert to Level III, the second-highest of four, on 2 July after ash emissions increased. Copernicus Sentinel-2 imaged a northward plume over the strait that day. The September events turned a monitoring file into a capital-city aviation stoppage.

Volcanic ash melts inside jet engines. That is why airports close on a satellite read and a concentration number, not on whether the terminal looks dusty. Soekarno-Hatta handles on the order of 54 million passengers a year. Two days of ash over that field backs traffic into Bali, Surabaya and every airline's crew-hour ledger.

Tsunami risk is a separate watch. The 2018 partial collapse of the cone killed more than 400 people along the strait. The geology agency has not, in the public notes around this eruption, reported a flank failure. Masters in the Sunda Strait still sail under that memory.

Reopening depends on wind and on AirNav's next test. Until the number falls, the eight-airport list stands and the 170,000 people who bought tickets for those two days remain a queue, not a flight.