Monday, December 19, 2011

Aérospatiale AS 350B2 Ecureuil, Helisika Agricultural Ltd., ZK-HIG: Accident occurred November 23, 2011 in Viaduct Harbour, Auckland - New Zealand


The pilot in last month's central Auckland helicopter crash says he doesn't understand the actions of a rigger who caused the spectacular accident.

The Civil Aviation Authority today released its preliminary findings which showed the November 23 accident was caused by a rigging supervisor jumping to grab a cable from the bottom of the helicopter, causing it to tighten and touch the aircraft's rotor blade.

Pilot Greg Gribble walked away from the accident, which happened as he was helping erect the Telecom Christmas tree on Auckland's waterfront. The crash was seen live on the internet and footage went around the world.

The CAA report said "massive out of balance forces" tore through the helicopter after it struck the lifting line, which was attached to the bottom of the helicopter and the top of a nearby tower.

"After raising the tower, the helicopter descended to hover at about 5m so the lifting line could be detached from its hook by the rigging supervisor on the ground," it said.

"When the rigging supervisor jumped up to grab the line, it instantly tightened and touched the helicopter's main rotor blades. The force of the impact caused major structural damage and the aircraft hit the ground."

Gribble, who had not seen the preliminary report, said he'd had no explanation from the rigger, calling his actions a "massive rush of blood to the head".

They knew what caused the accident but wanted to know why the man had acted that way.

"Nobody knows [why], he's the only guy that can actually tell anyone the reason why he jumped up and grabbed that rope and I'm still gobsmacked."

Gribble, who was interviewed by CAA last week, said the man had refused to speak with him since but told CAA he didn't know why he had done it "which is a pretty shit answer".

He said they had put together a detailed plan with the ground crew from Henderson company Uni-Rigg about how to release the line and were communicating via radio.

Gribble said he could not get the helicopter low enough to the ground to unclip the rope and decided to instead hover above the tower for someone to unclip him from there.

He was pulling up to do that when the accident happened, he said.

Gribble expected the full report would detail exactly what happened and said he would release his own findings once it was all over.

CAA spokeswoman Emma Peel said the reason for the rigger's actions would form part of their investigation along with the suitability of the plans formulated between Gribble and the ground crew.

"It's possible that we may find the rigger was told to do precisely that in which case the actual cause of the event shifts and it becomes about whether or not the actual plan was a good one," she said.

"We know from experience with aircraft accidents that what might appear very obvious right in the early stages can sort of recede in importance as the investigation continues.

"We see that actually, no, although that physically caused the accident, that wasn't the real problem - the real problem was something else and that's why we have a longer, drawn out process to actually get to the real [reason] why this has happened rather than just the initial thought of what happened."

The investigation is continuing with a focus on the pre-flight safety briefings, the pilot's experience and training, health and safety aspects, potential preventative measures that could have been used, and the identification of human factors that apply to the accident.

The full findings could take up to 12 months.

Uni-Rigg could not be reached for comment. 

Read more, video, photos:   http://www.stuff.co.nz

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