Anak Krakatau eruption disrupts hundreds of flights

An eruption of Indonesia's Anak Krakatau volcano has caused major air traffic disruption, forcing the temporary closure of Jakarta's primary international airport. The volcanic ash plume reached 50,000 feet, directly affecting airline cruising altitudes.

According to Indonesia's Directorate General of Civil Aviation, the closure of Soekarno-Hatta International Airport (CGK) on Sunday impacted 209 flight movements. The authority stated that 22,798 passengers were affected during the closure period.

Flight cancellations and delays

The disruption included 16 cancelled international flights, seven delayed flights, and five rescheduled flights. Airlines cancelled services to destinations including Kuala Lumpur, Singapore, Hong Kong, Sydney, Seoul/Incheon, Doha, and Amsterdam. Four domestic flights were also cancelled, with another diverted.

Singapore Airlines and Malaysia Airlines were among the carriers that cancelled their Jakarta services. Qantas reported disruption to a number of its flights. Other international routes affected included services to Singapore, Kuala Lumpur, Doha, and Sydney.

Ash plume poses serious hazard

The primary aviation concern is the altitude and extent of the ash plume. The Darwin Volcanic Ash Advisory Centre reported continuous volcanic ash reaching approximately 50,000 feet. The high-level plume was moving west at around 30 knots.

Lower-level ash was reported up to 20,000 feet and moving towards the south and southeast. The advisories were based on Himawari-9 satellite imagery and dispersion modelling.

Volcanic ash is a serious hazard to aircraft. It can be ingested by jet engines, where it can melt and adhere to hot turbine components. This can potentially cause engine damage or a loss of thrust. Ash can also damage windscreens, sensors, and other critical aircraft systems.

Airport closures and diversions

In response to the spreading ash, Indonesian authorities suspended operations at several airports across western Indonesia. They identified alternative airports for possible diversions where operationally feasible. These included Kertajati, Ahmad Yani, and Juanda airports.

The eruption followed increased volcanic activity from Anak Krakatau. The volcano, located in the Sunda Strait, has been at alert level 3 since July 2. It has a notorious history; its 2018 eruption triggered a tsunami that killed more than 400 people. No tsunami threat has been reported from the current activity.

With further eruptions recorded on Sunday, airlines and Indonesian aviation authorities continue to closely monitor the movement of the ash cloud. Normal operations will resume only when it is safe to do so.