A Volcano Erupted for Thirty Seconds and Closed Jakarta

Anak Krakatau, the island volcano that sits in the Sunda Strait between Java and Sumatra, erupted at 3:53 on Sunday morning and stopped roughly thirty seconds later. The eruption itself was brief. Its consequences were not. AirNav Indonesia closed the airspace around Soekarno-Hatta and Halim Perdanakusuma in Jakarta and four other airports, including Radin Inten II in Lampung. By mid-afternoon the closures had affected 516 flight movements, of which 202 were at Soekarno-Hatta alone, and roughly 22,800 passengers had lost their flights.

Satellite observation found two distinct ash clouds. One rose to about 20,000 feet and drifted northeast over Jakarta, Banten and West Java. A second climbed to roughly 50,000 feet and spread over parts of Sumatra and the Indian Ocean. Volcanic ash is not smoke; it is pulverised rock and glass, and it abrades windscreens, clogs sensors and can melt inside a hot engine and re-solidify on the turbine blades. There is no safe way to fly through it, which is why authorities close airspace rather than slow it down.

The disruption did not stay in Indonesia. Singapore Airlines cancelled at least nineteen services as the Jakarta market shut, and queues formed at assistance counters in Changi. Malaysia Airlines dropped its Jakarta flights, and connections to Kuala Lumpur, Hong Kong, Guangzhou and Doha were caught in the same net. Some passengers reported that airline apps continued to show flights as confirmed after other notifications had told them the flights were gone. By Monday morning another 240-plus flights had been cancelled or delayed, affecting close to 30,000 more people.

Anak Krakatau remains at Alert Level 3 on Indonesia’s four-tier scale, with an exclusion zone of three kilometres around the crater. The disaster mitigation agency has said there is no imminent tsunami threat, and no casualties or evacuation orders have been reported. Indonesia’s transport ministry has named Kertajati, Ahmad Yani in Semarang and Juanda in Surabaya as diversion options. Even once the ash clears, aircraft and crews will be in the wrong places, so anyone travelling through Jakarta this week should confirm with the airline before leaving for the airport.

Sources: Al Jazeera, CNBC