West Virginia ? The first wireless system designed to help rescuers track and communicate with trapped coal miners was approved Thursday for use in the state’s 177 underground coal mines.

The approval of the equipment manufactured by Ontario, Canada-based Varis Mine Technology Ltd. comes a year and a half after the Sago Mine disaster that killed 12 miners. Investigators said poor communications and uncertainty about the miners’ location hampered rescue efforts.

The state Office of Miners’ Health, Safety and Training also gave conditional approval to three other tracking and communications systems and two that offer only tracking.