He is a leading authority on altitude illness, high altitude climbing, wilderness medicine, and the effects of altitude on people living and working in the mountains. Dr. Hackett is also a board certified Emergency Physician. His pioneering work at High Camp on Denali and Mount Everest dramatically increased understanding of high altitude physiology and methods for coping with life-threatening conditions such as cerebral and pulmonary edema. Dr. Hackett's recreational activities of high altitude mountaineering, skiing, and living at altitude have lent him a personal understanding of altitude physiology.