This research examined the physical and economic feasibility of using 35mm aerial photos to space access corridors for thinning two overstocked loblolly pine plantations in the piedmont of Virginia. Tree diameters at groundline were predicted as functions of photo-measured crown areas. The capacity of the accumulator on the feller-buncher, an assumed operating swath, and the photo determined diameters enabled the estimation of distances that the machine could travel while thinning before accumulating a full load. Productivities and costs of felling, bunching, and skidding per cord of wood were evaluated with computer simulations for three thinning procedures. The costs of planning the thinning by ground methods and photos were compared so that the least cost planning and harvesting system could be determined. Results showed that row thinning had the lowest simulated harvesting costs with no planning expenses. In the access corridor procedures, the photo planning with newly acquired photos and harvesting in the photo corridor spacing system were more expensive than ground marking and harvesting in corridors 70 feet apart. Photo corridor spacings enabled the feller-buncher to attain higher productivities in the selective thinnings between corridors. Indications were that corridor spacing is stand specific. / M.S.