A manufacturing flaw, a misplaced cable, even a cigarette.
Those are some of the scenarios put forward by navy veterans and experts as investigators try to determine what activated a firefighting system aboard a new Russian nuclear submarine beneath the Sea of Japan, and why 20 people were killed.
The Akula-class submarine was undergoing sea trials Saturday when its fire-extinguishing system activated in error, spewing Freon gas that suffocated the victims and injured 21 others, Russian officials said.
With little official information emerging yet about the precise cause, experts said overcrowding and human errors may have contributed to the accident and the casualty toll aboard the Nerpa – the worst on a Russian sub since the Kursk disaster killed 118 seamen in 2000.
Never miss a local story.
The vessel, which the navy said was to become part of its fleet later this year, had 208 people aboard when the accident occurred, including 81 seamen. The rest were civilians, many from the shipyard that built the submarine. Akula-class subs normally carry a crew of 73.
Igor Kurdin, a former captain who heads an association of submarine veterans, told the Russian newspaper Kommersant that the fire-suppression system could have been triggered by something as simple as someone smoking a cigarette near a safety gauge.
“Civilians should have undergone training. But it usually is a mere formality,” Kurdin was quoted as saying.
Meanwhile, Kommersant and another leading business daily, Vedomosti, reported Monday that the submarine was to be handed over to India's navy next year under a 10-year, $650-million lease.