Pike River safety and training manager Neville Rockhouse, who lost a son in the West Coast coal mine disaster, tried to stop the main ventilation shaft being made an escape exit and when staff attempted the ascent, they became too exhausted to make it to the top.
Mr Rockhouse was on site when the November 19 blast happened.
He helped his son Daniel after he staggered out of the portal. Another son, Ben, died in the disaster.
Mr Rockhouse said the decision to make the ventilation shaft a second escape exit was very contentious. After phase one of the Royal Commission into the explosion, mine chief executive Peter Whittall told the Campbell Live television programme that Mr Rockhouse had deemed it satisfactory for a second escape route.
"I totally refute that statement ...I was always concerned," Mr Rockhouse said.
He said he did everything he could to prevent it being declared the official second escape.
"At no time did I ever accept this as being a satisfactory means of exit from the mine in any type of emergency situation."
The second escape way was to let technicians access the main fan when bad weather prevented helicopters from reaching it. He understood a new, second egress was to go out to the west.
Then, he said, things went wrong: Part of the main ventilation shaft collapsed, mine manager Kobus Low resigned. Then they hit a stone graben, and the tunnel headed north.
About this time, it was ruled the ventilation shaft was to become the second escapeway. He was excluded from the meetings when this decision was made, and could not say who made it.
"It was a very strenous climb. Once I found out about this plan, I proactively began to fight against it."
It had no mechanical hoist to pull injured people. There was a 50m vertical ladder with no platforms, which at one stage leaned back. A static wire rope and harnesses would instead be used. Only eight sets were purchased as it was originally intended for maintenance.
If there was a fire or explosion, miners would not be able to climb 50m up an incline, then up another 50m ladder. He said he told all department heads of his concerns. "You did not send people to a bottleneck in an emergency," he said.
At shift change, there could be up to 60 people underground. The ladder could take eight.
A year before the blast, four people were to test the ascent. The first two were so exhausted that no one else even wanted to try. Neither made it as far as the surface.
Mr Rockhouse said he tried to convince Mr Whittall to buy a refuge station.
With no official sign-off on the second escape exit, other safety measures were delayed, including smokelines to navigate to safety in a smoke-filled tunnel.
Mr Rockhouse said that in late 2009, he asked Mr Whittall if he could train the management team on the emergency system. Mr Whittall refused and said he was comfortable with the company's ability to respond.
Earlier today, footage of the second massive explosion on Tuesday, November 23 was shown in court. It later emerged that an army robot weighing 300kg was blown 100m.
On the Wednesday there was a third, smaller blast and on the Friday, one week on, a fourth, similar one. It dislodged part of a surface fan 'avasy' weighing 6-7 tonnes, by 3-4m.
Flames indicated a fire in the shaft, or from the bottom of the shift, where there was coal.
Commissioner Stewart Bell said it seemed odd there had been no prohibition notices issued in the life of the mine, over six or seven years.
The hearing continues.