Anak Krakatau ash closes Jakarta and five other airports, stranding 150,000

Indonesia's busiest airport stayed shut through Sunday afternoon after volcanic ash from Anak Krakatau reached the Jakarta airspace. Transport Minister Dudy Purwagandhi said the paper test for ash remained positive at Soekarno-Hatta and at neighbouring fields, so flights would not resume while the cloud sat over West Java.

InJourney Airports, the state operator, later tallied 764 affected movements at Soekarno-Hatta alone. Those figures mixed cancellations, delays and diversions: 570 domestic passenger flights, 185 international passenger flights and nine cargo services. Earlier in the day the same operator had counted 209 outright cancellations between 1:30 a.m. and 9:30 a.m. Western Indonesia Time, a slice that covered 160 domestic flights, 39 international flights and 10 cargo flights. The ministry put the passenger total around 150,000 and said 467 flights were disrupted across the closed fields, including 58 international services. An earlier Directorate-General of Civil Aviation note said the first Soekarno-Hatta window alone touched 22,798 passengers.

The first halt at Soekarno-Hatta was posted for 5:30 a.m. It was extended to 9:30 a.m., then to 1:30 p.m., then toward 5:30 p.m. after AirNav Indonesia issued a Notice to Airmen on the spread of ash. Purwagandhi inspected the terminals at Tangerang and told airlines not to force a reopening. He named Kertajati, Semarang, Surabaya and Yogyakarta as possible diversion points and told carriers to speed refunds and keep passengers informed so terminals did not clog.

Six fields, one plume

The closed list grew through the morning. Besides Soekarno-Hatta it included Halim Perdanakusuma in Jakarta, Radin Inten II and Taufik Kiemas in Lampung, Husein Sastranegara in Bandung, Budiarto at Curug, Pondok Cabe in Tangerang and Atung Bungsu in South Sumatra. The ministry said each site had returned a positive paper test.

Singapore Airlines cancelled its Jakarta rotations for the rest of Sunday. Qantas reported cancellations on its Jakarta services. Routes toward Doha, Sydney and Kuala Lumpur sat among the international pairs named by the transport ministry. Those three cities are typical long-haul and regional pairs for CGK. A full-day hole on those routes backs up aircraft and crews into Monday even if the ash clears overnight.

Airport staff opened a command post at Terminal 1B and ran a Service Recovery Action protocol: food, light refreshments and hotel buses arranged with airlines. Yudistiawan, Soekarno-Hatta's assistant deputy for communication and legal affairs, said the closure was a safety step because ash damages turbine engines.

What the volcano put in the air

Anak Krakatau, the cone that grew after the 1883 Krakatau blast, sits in the Sunda Strait roughly halfway between Java and Sumatra. It has been erupting since late Friday, 4 September. Indonesia's meteorological agency BMKG, reading Sunday morning satellite images, put ash at about 6,000 metres on the Java side and as high as 15,000 metres on the Sumatra side and over parts of Banten. A commercial jet on climb-out from CGK passes through those bands.

Schools near the strait cancelled Saturday classes after students reported eye irritation. Fishermen stayed in port. The disaster mitigation agency said on Saturday it saw no imminent tsunami risk from the current activity. That statement matters because a December 2018 flank collapse at the same volcano sent a tsunami into the strait and killed hundreds on the Java and Sumatra coasts.

Ash is not smoke. It is pulverised rock and glass. Inside a jet engine those particles melt, coat turbine blades and can shut the engine down. That is why a paper test at an airport, a simple check for grit on a surface, is enough to ground a day's schedule at CGK, which handles the bulk of Indonesia's international traffic.

What reopening depends on

Purwagandhi tied the next decision to two things: the paper tests and the ash dispersion forecast. If the cloud holds over West Java, the airports stay closed. If the plume shifts toward the sea, airlines can restart from Soekarno-Hatta first and feed passengers back from the diversion fields.

The eruption is still young. A Sunday shutdown of this size is already a national travel shock. The question for Monday is whether the plume thins or whether another pulse from the Sunda Strait keeps Jakarta's main runway dark.