The ever-tighter mismatch between the demand and supply of airport services has triggered policy discussions that bring to the forefront a challenging dilemma for decision makers and the various stakeholding groups in the airport domain: demand management or capacity enhancement? There are two solutions in the effort to reduce gridlock in the air transport system—to expand capacity, and to diminish or handle demand through time and space. One part of the answer lies with technology and operations aiming at building capacity and another with balancing and handling demand. Since the last decade of continuously increasing air traffic congestion, demand management strategies have gained increasing acceptance by airport authorities and policy makers as a potential vehicle of handling demand—by limiting in some way the demand for access to busy airfields or to congested airspace or by modifying the spatial and temporal distribution of demand, or by doing both. A critical review was done of the developments, practices, and research activities in Europe and the United States toward confronting the well-known aviation capacity gridlock. A triplet of analysis formed the base: the current state of affairs pertaining to the demand and growth patterns and prospects vis-a-vis supply-side developments; the discussion of the aviation capacity gridlock; and an in-depth analysis and critical assessment of the alternative demand-side solutions under the spectrum of all potential enhancement aspects (i.e., administrative, economic, hybrid measures).