The problem of decreasing separation distances between aircraft during their takeoffs and landings is investigated. This work presents a general view on the problem under study, whose complexity lies basically in the fundamental impossibility to create a single method and universal tool of investigation. A fragmentary approach is used with asymptotically non-strict splitting of the problem into several subproblems. The formulations of the subproblems are considered, the potentialities of the research tools are assessed, the ways and phases of model refinement are outlined. Some concrete measures are discussed for decreasing safe separation distances between aircraft.