Anak Krakatau eruption grounds Indonesian airports, disrupting 373 flights

The Indonesian Directorate General of Civil Aviation reported 373 disrupted flights as of the 10.35am local time update. Closures are issued in stages of several hours and extended based on ash readings.

Six airports shut, including four serving Jakarta

Jakarta’s Soekarno-Hatta International Airport was first closed under NOTAM A3341/26 between 01.30–05.30 WIB after a paper test between 00.35–01.05 detected volcanic ash on the runway. A second test between 06.05–06.35 returned positive again, prompting NOTAM A3344/26 to extend the closure until 09.30, then 08.30–13.30.

Five other airports followed, according to the Indonesian Directorate General of Civil Aviation advisory published on 6 September:

• Halim Perdanakusuma (Jakarta) — closed until 14.00 WIB

• Radin Inten II (Lampung, Sumatra) — closed until 14.00 WIB

• Budiarto (Curug, Tangerang) — closed until 13.30 WIB

• Pondok Cabe (Jakarta) — closed until 14.00 WIB

• Husein Sastranegara (Bandung) — positive test, NOTAM closure notice pending at time of advisory

Disruption totals included 202 movements at Soekarno-Hatta, 29 at Halim Perdanakusuma and 8 at Radin Inten II. In Jakarta, 167 flights were cancelled, 16 delayed, 7 rescheduled and 4 diverted. An earlier count at 05.30 cited 209 movements and 22,798 affected passengers for Soekarno-Hatta alone — a figure initially circulated that did not cover later hours or other airports.

Most affected international routes

Among flights departing or arriving at Soekarno-Hatta, Singapore was the most impacted destination with 11 disrupted services. Domestically, the route to Makassar in South Sulawesi saw the most cancellations at 16 movements.

At peak closure, 170 aircraft were grounded on the three terminals’ aprons.

The Indonesian civil aviation authority advises passengers to check their airline for real-time updates and to avoid travelling to the airport during closure windows. Carriers are required by Indonesian regulations to care for passengers stranded during closures.

Geological agency assesses eruption status

The Anak Krakatau volcano, located in the Sunda Strait between Java and Sumatra, has been at level III (Siaga) since 2 July 2026. Badan Geologi, the geological agency under the Ministry of Energy and Mineral Resources, issued a special report on 5 September describing continuous eruption activity, including lava fountains, flows and ejecta blocks.

This episode of continuous eruptive tremor began on 4 September at 23.07 WIB and ended on 6 September at 00.04 WIB — about 25 hours. The head of the volcanology centre warned the alert level remains at III and that the potential for further eruptions in the near term remains high. The exclusion zone is set at 3 km around the crater; residents, visitors and trekkers are barred from entry.

The weekend episode’s end does not close the case. Airport closures hinge on plume direction and wind shifts; new ash clouds passing over runways could prompt new suspensions at any time.

Ash cloud extends far beyond the Sunda Strait

The BMKG meteorological agency has issued 18 SIGMET warnings since the eruption began. A 6 September 08.00 WIB satellite analysis identified two ash plumes: one drifting east to 20,000 ft, the other west to 50,000 ft, covering Banten, Jakarta, West Java, Bengkulu, Lampung, the Sunda Strait and the Indian Ocean.

This spread explains why airports more than 150 km from the volcano were closed. Volcanic ash abrades turbine blades and can extinguish engines; authorities ground airspace at the first positive residue test, without waiting for intensity measurements.

What this means for travel to Indonesia

Entry formalities remain unchanged: visa-on-arrival, e-visa and the electronic arrival card stay in force. Indonesia’s immigration authority has not issued measures related to the eruption. Disruption is purely aviation-based.

A cancelled or delayed flight due to volcanic ash falls under the carrier’s obligations under Indonesian civil aviation rules. The impact isn’t limited to the six closed airports; the airspace block over Jakarta ripples across the archipelago, notably affecting Jakarta–Bali connections. Direct arrivals to Denpasar are unaffected, but connections routed via Jakarta are impacted while the alert remains in force.

Vulnerable routes include flights to Radin Inten II in Lampung and the Sunda Strait crossing, given their proximity to the volcano. BMKG places both Banten and Lampung, along with regional beaches, ferries between Java and Sumatra, under the ash plume envelope.