Ash from Anak Krakatau stopped flights at Jakarta's airport

Mount Anak Krakatau, which sits in the water between Java and Sumatra, started erupting late on Friday and was still throwing out ash over the weekend. The cloud drifted across Lampung province in Sumatra and Banten in Java. Jakarta's airport suspended flights from 5:30am to 9:30am on Sunday, and 209 flights were affected, including several international services, Nikkei Asia reports.

Airports close for ash because volcanic ash is nothing like smoke. It is made of tiny pieces of rock and glass. Inside a jet engine, where the air is hot enough to melt it, the ash turns sticky and coats the moving parts, and an engine can lose power. So airlines do not fly through it and wait instead for the wind to push the cloud away, which is why these closures come in blocks of a few hours and can come back the next morning. On the ground the effects were smaller but real: schools called off activities on Saturday after people complained of sore eyes, and fishing boats stayed in port.

Berton Panjaitan, spokesperson for the disaster agency BNPB, asked people to stay calm and stay careful. His advice was practical: wear a mask and eye protection, spend less time outside, cover water containers so ash does not fall in, and take extra care driving. The agency also said there was no immediate tsunami risk, which is a question officials have to answer within hours here, because an eruption in the middle of the sea can move water if part of the island slips into it. A mountain on land does not carry that risk.

Why it matters

If you are flying in or out of Jakarta in the next few days, check with your airline the night before rather than on the way to the airport, because the closures are decided in the early morning when the wind direction is known. For families in coastal Banten and Lampung, the near-term cost is ash in the air and in the water tank, so masks and covered containers matter more than the eruption headlines. Fishing crews lose paid days for as long as the boats stay tied up.