Under U.S. Bureau of Mines Contract jo133925, ESD Corp. developed the high angle mining system (hams) as a method of extracting coal from seams varying widely in thickness and pitch. The system would normally be employed to extract coal lying beyond the economic limit of a strip or open pit highwall. A surface-controlled operation involving no underground personnel, the hams can significantly increase the reserve base of coal that can be economically surface mined. A number of open pit or surface mines that have moderately or steeply pitched seams were visited and studied. Existing technology was reviewed to identify systems or system components that merited further consideration for the development of the hams concept. Conventional and innovative approaches based on augering and two approaches based on slackline excavation were developed in sufficient detail to enable comparison on the basis of operational limitation, recovery ratio, productivity, and economy. The slackline excavator concept employing a projectile bucket was selected as the best approach. The capability of economically mining pitched seams of coal with the hams was demonstrated.