Regulators are also considering 53 proposals to improve plans by tapping through-the-earth communication technology and other emerging methods, Chirdon said.

Massey Energy Co. had some of its required new system installed at its Upper Big Branch mine at the time of the April 5, 2010, explosion that killed 29 men. Regulators have said the blast destroyed the system, rendering it unusable during a nearly weeklong search for some of the victims.

Besides gear that can survive accidents, manufacturers are also developing systems that can keep up with miners and machinery on the move, Chirdon said. Some are even adding components that can warn miners about gas and coal dust levels, and when they're in danger of colliding with equipment.

MSHA's numbers show 192 out of the 529 mines lacked a full set of equipment as of February. Most, however, have done part of the work, Chirdon said.

"We're expecting them all to be compliant by June 15," Chirdon told the Associated Press on Thursday.

The numbers are far higher than 2010. At the time, just 34 of 529 mines, or 6.4 percent, were in compliance, Chirdon said.

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Associated Press Business Writer Tim Huber in Charleston contributed to this report.

CHARLESTON, W.Va. (AP) - U.S. coal mine operators fall well short of meeting a 5-year-old congressional mandate to equip underground mines by June with high-tech communication and tracking systems for miners, a federal official told industry representatives Friday.

The figures show 64 percent of more than 500 underground coal mines don't have the required equipment, Mine Safety and Health Administration official Dave Chirdon said at an industry conference in West Virginia.

The required upgrade is supposed to keep near-constant track of miners from the moment they head underground, and enable them to communicate with the surface even after an explosion. Chirdon noted the looming deadline, set by federal law, for mines to install these systems.

"That's a little concerning to us," Chirdon said. "The other 64 percent only have until June of this year, which is only two months away."

The National Mining Association surveyed mines in 2009, and found that nearly all had bought the necessary equipment and had installed MSHA-improved interim systems, spokeswoman Carol Raulston said in an email. She also said that limited suppliers have slowed compliance.

Mines that miss the June 15 deadline face unspecified enforcement action, MSHA spokeswoman Amy Louviere said.

The mandate was imposed after the January 2006 deaths of 12 miners trapped at West Virginia's Sago Mine following an explosion. Rescuers couldn't contact them, nor did they know where to look for them.

All 529 underground coal mines across the country have submitted plans for these systems that MSHA has approved, Chirdon said. About half these plans involve the latest wireless and wired technologies. The other half rely on older, so-called leaky feeder technology, which links hand-held radios through cables stretched through strategic areas of mines and boosted with antennas.

But Chirdon added that leaky feeder systems have improved over time, with a focus on making them better able to withstand accidents. He also noted that federal law requires mine operators to review their system plans at least every six months, and check for technological advances. MSHA will watch for ways to improve these systems as well, he said.

Regulators are also considering 53 proposals to improve plans by tapping through-the-earth communication technology and other emerging methods, Chirdon said.

Massey Energy Co. had some of its required new system installed at its Upper Big Branch mine at the time of the April 5, 2010, explosion that killed 29 men. Regulators have said the blast destroyed the system, rendering it unusable during a nearly weeklong search for some of the victims.

Besides gear that can survive accidents, manufacturers are also developing systems that can keep up with miners and machinery on the move, Chirdon said. Some are even adding components that can warn miners about gas and coal dust levels, and when they're in danger of colliding with equipment.

MSHA's numbers show 192 out of the 529 mines lacked a full set of equipment as of February. Most, however, have done part of the work, Chirdon said.

"We're expecting them all to be compliant by June 15," Chirdon told the Associated Press on Thursday.

The numbers are far higher than 2010. At the time, just 34 of 529 mines, or 6.4 percent, were in compliance, Chirdon said.

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Associated Press Business Writer Tim Huber in Charleston contributed to this report.