Only four hours after the Pike River blast, Mines Rescue believed all 29 men trapped underground were dead, but it took police five days to reach the same conclusion.
Mines Rescue Service manager Trevor Watts told the Royal Commission of Inquiry today that on the night of the blast Pike River Coal did not even have a current underground map, and had to hand draw the newest workings onto older plans.
Mines Rescue thought the shockwave would have killed most of the men immediately, or left them unconscious. They would then have been quickly overcome by noxious gases or lack of oxygen.
Anyone who got on their self-rescuers and reached the additional ones at the fresh air base would have been able to walk out.
Evidence available on the night of the November 19 blast, including footage from the portal, showed a large explosion which lasted 52 seconds.
The men were trained to escape, not barricade themselves inside the mine, he said. They all had self-rescuers on their belts, and the maximum distance to the fresh air base was only 700m.
However, there had been no communications from within the mine, except from survivor Daniel Rockhouse, who was closer to the portal. A Mines Rescue radio was lowered into the mine that first night; it was not touched.
Air was going down the slimline shaft, so there was fresh air at the bottom.
"If people had been able to walk to the point where Mr Rockhouse survived, they would also have survived," Mr Watts said.
Mr Watts said they knew at 9pm on that first night that the gas levels were unsurvivable.
"We also knew that the second means of [exit] was not available."
Mr Watts said many people had claimed there were air pockets in the mine: "There were no air pockets".
The top section of the mine filled with methane very quickly; it would have filled the roof cavities, and then displaced the air, like water being poured into a room, leaving no gaps.
Mr Watts said the vertical shaft escapeway was of little use after a fire.
Miners were taught if they could not self-escape, to barricade themselves in, he said.
"We always emphasise that barricading yourself in is an absolute last resort. With one breath left in their body, they should head for daylight."
Mr Watts did not agree that Pike River's full emergency plan had been activated.
The mine manager had overall legal responsibility for the site, and under legislation should become incident controller. Instead, the police took control and there was a lot of confusion initially after the explosion.
There were no alarms to indicate there had been a blast, and an evacuation of underground staff was not ordered. There was a 45-minute delay before Mines Rescue was even called.
They could get no confirmation of how many men were missing, where they had been working, of the atmosphere, and whether there were any survivors.
Pike River should have gathered all that information to present to Mines Rescue, but could not, as it had lost all its monitoring systems, he said.
Initially, 36 men were thought to be missing; by 10pm this was down to 27, and it was not until midnight it settled at 29.
McConnell Dowell contractors who left the mine just 1 minute before the blast were allowed to leave the site without being interviewed by the police or Mines Rescue.