WHILE JACKING HIS JEEP ON TRACK THE JEEP SLID OFF THE JACK WHILE HE HAD HOLD OF THE JACK BAR. THE JACK KICKED OUT SUDDENLY. DID NOT INVOLVE ANY ASPECT OF COMPLIANCE WITH RULES AND REGULATIONS. MINING SYSTEMS NOT INVOLVED. JOB SKILLS, MINER PROFICIENCY, TRAINING OR PROTECETIVE ITEMS NOT A FACTOR. ATTITUDE COULD BE A FACTOR.