Gleision deaths: Mine was not inspected for 16 months
A mine where four people drowned following an explosion had not been inspected for 16 months, a court heard.
Tony Forster, who was a Health and Safety Executive inspector at the time, told Swansea Crown Court some visits had been thwarted by bad weather.
He added Gleision drift mine was not always in constant operation so regular contact was not always possible.
Former pit manager Malcolm Fyfield and owners MNS Mining Ltd deny manslaughter charges.
David Powell, 50, Charles Breslin, 62, Philip Hill, 44, and Garry Jenkins, 39, all died in the mine when 650,000 gallons of water gushed into the area they were working in September 2011.
The miners had blasted into a flooded old section of the mine near Pontardawe causing 17 tonnes of contaminated water to fill the area they were working in within six seconds.
Mr Forster, who is also the lead investigator in the Gleision incident, told the jury the last inspection of the 100-year-old drift mine was in May 2010.
He said he intended to return three months later in August and again in December, but snow had prevented access.
Elwen Evans, defending Fyfield, told the court Mr Forster had made regular visits to the nearby Aberpergym, Unity and Tower mines between 2009 and 2011, but said that did not happen at Gleision.
Mr Forster replied: "There is qualification here. This mine wasn't constantly working.
"It was periodical, it started, it stopped, [Gleision] didn't present itself with the opportunity to have the kind of regular contact.
"They [the other mines] were bigger mines with a bigger potential for catastrophe. These are gassy mines with the potential to blow up or catch fire."
Mr Fyfield, 58, denies the gross negligence manslaughter of the four men while MNS Mining Ltd, represented by directors Maria Seage and Gerald Ward, deny four counts of corporate manslaughter.
The trial continues.