Philippine firefighting officials are investigating whether calcium hypochlorite that was not properly secured had leaked and combined with asphalt aboard the local Ro-Pax ferry June Aster.
Investigators from the Bureau of Fire Protection (BFP) believe this may have triggered the fire that killed 77 people on board the vessel off Coron municipality in Palawan province on September 9.
BFP officer-in-charge Fire Chief Superintendent Wilberto Rico Neil Ang Kwan Tiu presented the agency's preliminary reconstruction at a briefing on Friday, October 16.
Eight people who were on the ferry remain missing and 43 were injured. Of the 77 dead, 63 have since been identified.
The calcium hypochlorite had been placed at the back of the cargo deck. Blocks of asphalt were beside it, with the engine room behind it and the engine's hot-air exhaust outlet nearby. Investigators found the chlorine containers had not been firmly secured.
The BFP believes rough seas may have caused the containers to move or overturn, bringing their contents into contact with the asphalt.
The agency also identified a faulty ventilation system discharging hot air that may have contributed to ignition.
Calcium hypochlorite is a strong oxidising agent that can intensify combustion. Asphalt is combustible, particularly when heated.
The fire broke out at around 18:30 local time on September 9 while the ferry was in the Strait of Coron. Tiu said that combustion produced highly toxic smoke and that passengers who had settled into their bunks after dark may have suffocated before they felt the heat, which could explain the death toll.
The voyage had been delayed by four days, and loading continued during that period. While underway, fuel line repairs delayed the ferry by around two hours and 45 minutes.
The captain allegedly ordered increased engine revolutions to reach nine knots. Investigators said this may have raised exhaust temperatures near the cargo deck.
The BFP said the vessel operator’s management, the captain and crew, the stevedore responsible for cargo arrangement and the Port of Baseco in Manila could face liability if negligence is established.
Separately, the Philippine Department of Labor and Employment has issued work stoppage orders on six other vessels owned by Atienza Inter-Island Ferries, the operator of June Aster. Inspections on these vessels identified a lack of safety programmes, emergency response plans and trained safety officers, inadequate personal protective equipment, and underpayment of wages and benefits.
Philippine Labour Secretary Francis Tolentino said that the orders would remain in effect until the company complied. Crew must continue to be paid during the stoppage, and the company has until October 23 to respond.
June Aster was already engulfed in flames when Philippine Coast Guard responders arrived. The coast guard completed its search of the vessel's interior on September 15.
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