Three South African navy personnel die in submarine accident at sea

Cape Town [South Africa], September 21 : Three South African Navy personnel lost their lives on Wednesday after seven crew members of a submarine were swept off its deck by big sea waves as a helicopter attempted a "vertical transfer" of supplies, reported Al Jazeera, citing the Department of Defense. 
According to the defence department, the accident happened as an Air Force Lynx helicopter was attempting a vertical replenishment, known as "Vertrep" of supplies to the SAS Manthatisi submarine on the ocean surface off the coast of Cape Town. 
Following the accident, the operation was immediately called off and a rescue effort was launched, reported Al Jazeera. 
All seven crew members of the submarine were recovered during the rescue operation, however, three were found dead and one of the senior officers was in critical condition. 
Moreover, a crew member from the helicopter who was dispatched as a "surface swimmer" to assist in the rescue operation was also recovered. 
He was hospitalized along with the other four injured submariners, Al Jazeera reported. 
The National Sea Rescue Institute and other emergency services were immediately called in to help in rescuing the submariners, the Department of Defence said. 
According to Al Jazeera, there will be an inquiry into the failed operation and the resulting deaths in the accident. 
According to the South African National Defence Force, comprised of all the armed forces, noted that a female officer with the rank of lieutenant commander was among the three who died, Al Jazeera reported. 
Since last weekend, Cape town and other areas on South Africa's south coast have been hit by extremely rough seas, caused by a phenomenon known as "spring tide".