JAKARTA – Flight disruptions between Singapore and Jakarta could continue even after airports reopen if further eruptions occur or airlines decide it is not yet safe to fly, aviation experts warned.

Additionally, whether flights can operate will depend not simply on whether Anak Krakatau, a volcanic island located in the Sunda Strait, continues erupting, but on how much ash it produces, how high the ash rises and, crucially, where winds carry it.

“An airport can be closed, then reassessed, reopened, monitored, and if conditions deteriorate, restrictions can be imposed again,” Polana Pramesti, an aviation analyst from the Indonesian Aviation Association, told The Straits Times.

Even after an airport reopens, schedules may take time to return to normal.

“Reopening an airport is not as easy as just restoring a schedule,” said Susanna Jenkins, associate professor at Nanyang Technological University’s Asian School of the Environment.

“Aircraft and crew end up in the wrong places, crew duty-hour limits kick in, and there is a backlog of displaced passengers competing for seats on flights that were already busy,” she added.

Singapore was the international route hardest hit by the initial closure, ahead of Hong Kong, Sydney, Seoul, Doha, Amsterdam and Kuala Lumpur, according to Indonesia’s aviation authorities. All 33 flights scheduled to depart Singapore for Jakarta on Sept 6 were cancelled.

Seven Indonesian airports, including Jakarta’s main Soekarno-Hatta International Airport and Halim Perdanakusuma Airp...