Theoretical distance is not arrival margin
A fictional sailplane worksheet gives an available height loss of 4000 feet and a glide ratio of 40 to 1 in still air. It defines one nautical mile as 6076 feet and asks for theoretical distance when no height remains. The task deliberately excludes turning, wind, sink and any arrival or traffic-pattern allowance. A learner reports the computed number as a guarantee that an airfield at that distance can be reached and landed at safely. Another distinguishes the geometric model from a practical plan. The exercise provides no actual field elevation, surface, obstacles, airspace or current weather. A complete answer must show the unit conversion and identify the information and margins excluded from the model rather than infer a flight authorization or an acceptable landing site.
1. Calculate the theoretical model distance.
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Horizontal travel is 4000×40=160000 feet. Dividing by 6076 gives approximately 26.3 nautical miles, with zero height remaining under the stated ideal model.
2. Does that establish a practical safe range?
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No. Arrival height, actual wind/sink, maneuvering, destination elevation and site suitability are excluded. They must be assessed separately using actual conditions and aircraft data.