Pike River Coal's former hydro mining co-ordinator was previously the under-manager at two Australian mines that exploded, killing 23 men.
George Mason was the under-manager at Moura No 4 Mine in 1986, where an explosion claimed 12 men. In 1994, he was at the Moura No 2 Mine which exploded, killing 11.
According to his written evidence to the Royal Commission of Inquiry today, he voluntarily surrendered his certificate of competency a year after that explosion.
In 2007, he re-entered the industry as a miner, after a stint as a professional fisherman and in an aluminium refinery.
Engineering, Printing and Manufacturing Union lawyer Nigel Hampton QC said Mr Mason did not have his New Zealand competency certificates, although some of the Pike River miners thought he did.
Mr Mason started at Pike River a few months before the fatal explosion 12 months ago. He did not relay an international mining expert's concerns about ventilation to managers.
Criticism after the 1994 Moura blast related to failures to communicate things to management, Mr Hampton said.
Mr Mason, who still works for Pike River Coal (in receivership) as the mining co-ordinator, told former mine manager Peter Whittall during a phone interview for the job that he had no experience in hydro mining but was confident he could upskill.
Once at Pike River, he received no formal training, instead learning on the job.
Before he started work he tried to research it on the internet but could not find much, and management supplied no documents.
Hydro mining was "all very high tech'' and he initially felt overwhelmed and a little out of his depth, although he had no qualms about managing the overall process later.
About half of the crews operating the hydro machine had not yet gone through the formal training but by coincidence, three of the men who died in the explosion - Peter O'Neill, Keith Valli and Allan Dixon - were experienced in it.
Mr Mason thought staff should be familiar with what was happening underground before they started hydro training. He was concerned at the number of inexperienced staff at Pike River.
''[But] they were all placed in there with deputies and other experienced people around them.''
Mr Mason revealed that in the early hours of October 30, three weeks before the disaster, there was a significant rockfall in front of the hydro mining machine. The steel mesh bent down a few metres in front of it, and some rubble fell on the machine.
In early November, while struggling to mine the coal, the company moved to shot-firing to loosen up the coal because the men thought it was too hard.
"That was carried out without my prior knowledge,'' he said.
Gates were locked near the coal face to stop unauthorised men getting inadvertent access to a return airway, he said.
Mr Mason confirmed that international hydro mining expert Masaoki (Oki) Nishioka had relayed to him concerns about the lack of ventilation. Mr Mason said it could be hard to understand him, and he did not pass the concerns on, "because I understood the situation was being addressed''.
All haste was being made to get hydro mining under way, and the main fan commissioned.
Mr Mason said he could not access methane readings because of the computer system. Asked this morning why he did not raise that with management, he said: "pass''.
Mr Mason was working above ground when the mine blew up on November 19. After repairs at the wash plant, the men underground at the time were to start mining coal.
- Greymouth Star
