One of a series on the growing demand for energy, this report examines the potential for reducing the energy requirements of the U.S. commercial airlines, with emphasis on the certificated-route air carriers. The four strategies examined are (1) raising airline load factors as high as practicable without adversely affecting service quality; (2) reducing aircraft cruising speeds to the point of minimum fuel consumption; (3) preventing terminal-area aircraft delays from exceeding 1971 levels; and (4) substituting less energy-intensive transport modes in short-haul routes. Measures yielding benefits in both the short and long term are considered and their conservation potentials are quantified relative to present and future energy requirements. 94 pp. Ref.