EE WAS WALKING ALONG THE BELTLINE BY DRIVE. HE SAID HE SLIPPED OFF PLANKING LAID DOWN FOR WALKWAY, STRAINED LEFT KNEE. CAUSE OF INJURY WAS AWARENESS. COMPLIANCE WITH RULES/REGS A FACTOR. MINER PROFICIENCY MAY BE A FACTOR. SAFETY EQUIPMENT COULD BE A FACTOR. MINING EQUIPMENT/SYSTEMS NOT A FACTOR. FIRST DAY MISSED WAS 1-22-2001.