Ash from Anak Krakatau shut two of Indonesia’s busiest airports overnight

A string of explosive eruptions at Anak Krakatau sent volcanic ash drifting across the narrow strait separating Java and Sumatra in early September, forcing Indonesian authorities to ground flights at two of the country’s busiest airports overnight. The shutdown disrupted travel for hundreds of thousands of passengers just as the young volcano, born from the wreckage of one of history’s most destructive eruptions, entered its most active stretch in years.

An eruption that kept building through the weekend

Anak Krakatau began erupting late on the evening of September 4, producing a fountain of lava and booming detonations that residents reported hearing from as far as 700 kilometers away, according to Indonesian disaster officials. The country’s meteorological and geophysics agency, BMKG, measured ash columns reaching roughly 20,000 feet on the Java side of the strait and as high as 50,000 feet on the Sumatra side and over parts of Banten province, altitudes that sit squarely inside the cruising range of commercial jets. Two additional eruptive pulses followed on September 5, and the national geology agency warned that the probability of further eruptions remained elevated into the start of the following week, which is why authorities kept the exclusion zone and airspace restrictions in place well after the initial blast had passed.

Soekarno-Hatta and Halim close through the night

Soekarno-Hatta International Airport, Indonesia’s busiest hub and the main gateway to Jakarta, and Halim Perdanakusuma Airport, the capital’s secondary field, were both ordered closed until 9:30 a.m. local time on September 6, according to an alert issued by the U.S. Embassy in Jakarta. Lampung’s airport, which serves southern Sumatra on the opposite side of the strait, stayed shut until 10:00 a.m. that same morning. The closures followed ash drifting into the airspace over both islands, a hazard that can sandblast jet turbine blades, contaminate fuel systems, and cut pilot visibility to near zero. Airport operator Angkasa Pura extended several of the shutdowns further into the following week as the volcano kept producing intermittent bursts, a pattern that repeatedly reopened and then reclosed runways whenever shifting winds carried fresh ash back over approach paths.

More than 270,000 passengers stranded across eight airports

Eight airports across Java and southern Sumatra halted operations over the weekend, and Indonesia’s Transport Ministry reported that more than 270,000 passengers had been stranded by the disruption, according to Al Jazeera’s coverage of the shutdown, which drew on AFP and Reuters wire reporting. Roughly 1,558 flights were delayed or canceled across the affected fields, with more than 900 of those tied to Soekarno-Hatta alone. On the Monday morning after the eruption, airport officials said nearly 30,000 passengers were affected by cancellations and delays in that single morning. Jakarta closed schools and moved classes online as ash settled over the city, and authorities in Semarang and Surabaya prepared their airports as alternate landing sites for diverted flights while the main hub stayed dark.

Airport officials apologize as passengers camp in terminals

With thousands of travelers unable to rebook or reroute quickly, Soekarno-Hatta’s own spokesman, who like many Indonesians uses a single name, Yudhistiawan, acknowledged the scale of the disruption directly, saying in a statement that the airport understood the situation was affecting passengers’ travel plans and that staff had focused on meeting passengers’ needs from the start of the temporary closure. The Transport Ministry described the cumulative passenger and flight figures as covering the period since September 5, meaning the tallies grew each day the closures dragged on rather than reflecting a single-day snapshot. A small regional airport in South Sumatra was the first to resume flights, reopening Monday morning at 9:00 a.m. local time even as the larger Java hubs remained closed.

No tsunami risk, but a volcano with a violent history

Indonesia’s national disaster mitigation agency, BNPB, said there was no imminent tsunami risk from the eruption and announced plans to seed clouds over the region to trigger rain that would help wash accumulated ash from streets and rooftops. BNPB chief Suharyanto told a news conference during the shutdown that sufficiently heavy rain would quickly wash away the volcanic ash that had been disrupting daily life in the region since the eruption began. That reassurance carries weight because Anak Krakatau’s history includes exactly the kind of catastrophe officials were working to rule out: the volcano rose from the sea in the 1920s inside the caldera left by the 1883 eruption of Krakatoa, one of the deadliest volcanic events ever recorded, and a 2018 eruption triggered a partial collapse of its crater and a tsunami that killed more than 400 people along the coasts of Java and Sumatra. Maritime authorities barred vessels from approaching within a three-kilometer exclusion zone around the volcano as a precaution while the latest activity continued, and ships transiting the strait were told to stay alert for sudden changes in sea conditions.

Ash remains the harder problem for aviation

Unlike lava flows or pyroclastic surges, volcanic ash is a hazard that travels far beyond the immediate danger zone, which is why the airport closures reached hubs many miles from the eruption itself. Fine glass and rock particles suspended in an ash cloud can melt inside a jet engine’s combustion chamber and re-solidify on turbine blades, a failure mode that has caused engine flameouts in past encounters between commercial aircraft and ash plumes elsewhere in the world. That risk is the reason regulators favor extended, precautionary closures over reopening the moment visible ash appears to clear, and it explains why Indonesian officials kept several fields shut even after the most intense phase of the eruption had passed on September 5.

This article was created with the assistance of AI and reviewed by an editor.

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