The National Park Service is continuing its efforts to locate Chad Pallansch, the trail runner who went missing last week after embarking on a solo 28-mile expedition through the Rocky Mountain National Park. The 49-year-old was reported missing on Sept. 28, prompting dozens of people to join in search efforts and officials to close areas of the national park. Investigators shifted their search tactics from on-the-ground scouring to aerial reconnaissance on Thursday. “While weather including snow, ice and wind at high elevations has hampered on the ground search efforts for Chad Pallansch; ongoing investigations as well as reviewing aerial reconnaissance photographs and preparing for a concentrated ground search effort is taking place,” the National Park Service said in a press release. The agency described Pallansch as an “experienced trail runner” who stands at 5-foot 7 inches and weighs 155 pounds.