The clock is ticking to find an Indonesian Navy sub with 53 people on board, which has now been missing for more than 24 hours. The last contact came around 3am Wednesday as the sub was completing a torpedo drill north of Bali. Officials believe the crew, led by Marine Lt. Col. Heri Octavian, will only have enough air to survive for another 72 hours, putting the deadline at 3am Saturday, reports the Jakarta Post. A helicopter, six warships, and some 400 people are searching for the sub. The US, Australia, France, and Germany have offered help, while Singapore and Malaysia have sent ships to the area. Singapore, which has a submarine rescue pact with Indonesia (and with the US), sent a specially built submarine rescue vessel, reports Al Jazeera. The search is focusing on an oil slick spotted at 7am Wednesday near where the KRI Nanggala-402 sub was last known to be.
The Navy said the slick—which is not definitely linked to the sub—could be a signal from the crew, or a sign of damage to the sub's fuel tank, per the BBC. An internal Indonesian Navy report notes the sub is thought to have sank as deep as 2,300 feet, per Al Jazeera. French navy vice admiral Antoine Beaussant tells AFP that the sub—built in 1978 and retrofitted roughly a decade ago—can't handle such a depth and "the likelihood is it would have broken up." The sub had an emergency button which would've allowed it to resurface, but the Navy report notes it would've been ineffective in case of a blackout, which would also make the sub uncontrollable. AFP rounds up other recent submarine disasters, attributed to everything from torpedo explosions to poisonous gas. (Argentina's military lost a sub carrying 44 people in 2017, before finding it a year later.)