THE SELECTION OF LANDING APPROACH SPEEDS

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONMEMORANDUM I0-6-58AA FLIGHT EVALUATION OF THE FACTORS WHICH INFLUENCETHE SELECTION OF LANDING APPROACH SPEEDS*By Fred J. Drinkwater III and George E. CooperSUMMARYThe factors which influence the selection of landing approach speedsare discussed from the pilot's point of view. Concepts were developedand data were obtained during a landing approach flight investigation ofa large number of jet airplane configurations which included straight-wing, swept-wing, and delta-wing airplanes as well as several applicationsof boundary-layer control. Since the fundamental limitation to furtherreductions in approach speed on most configurations appeared to be asso-ciated with the reduction in the pilot's ability to control flight pathangle and airspeed, this problem forms the basis of the report.A simplified equation is presented showing the basic parameterswhich govern the flight path angle and airspeed changes, and pilot controltechniques are discussed in relation to this equation. Attention is givento several independent aerodynamic characteristics which do not affect theflight path angle or airspeed directly but which determine to a largeextent the effort and attention required of the pilot in controlling thesefactors during the approach. These include stall characteristics, sta-bility about all axes, and changes in trim due to thrust adjustments.The report considers the relationship between piloting techniqueand all of the factors previously mentioned. A piloting technique whichwas found to be highly desirable for control of high-performance airplanesis described and the pilot's attitudes toward low-speed flight which bearheavily on the selection of landing approach speeds under operationalconditions are discussed.INTRODUCTIONAviation progress, as measured by the increased speeds and altitudesof flight, has led to concurrent increases in landing speeds. Furthermore,*Title, Unclassified