An experienced helicopter pilot has told of his terror as his aircraft went down in Porirua Harbour, saying at one point he didn't expect to survive. Rick Lucas was flying his BK117 twin-engine helicopter lifting power poles when he felt something was wrong on Tuesday morning. "I just experienced a medium-frequency vibration, but this just increased and continued to amplify and something went bang and the helicopter started to rotate so it was a total failure of some description," Mr Lucas, who has more than 35 years of flying experience, says. Emergency services were called to the scene in Browns Bay just north of Wellington where they found the aircraft was in knee-deep water and lying on its side. Mr Lucas says the entire incident happened quickly and he tried to manoeuvre the aircraft into a position where he'd most likely survive. But the impact into the relatively shallow water was still significant and the worst crash he'd experienced.