Question: Shall I blend Obstruction Identification Surfaces (OIS) based on all runways at an airport? Or shall I depict and analyze them independently?

Answer: The system defines the attribute ObstructionIdentificationSurfaces independently for each runway.

Also, per Section of Page 29 of AC 150/5300-18B, “Where multiple runways are surveyed, perform and report the analysis for each runway separately. When an object is determined to be within one or more surfaces, identify the penetration value for each surface. Provide the penetration value (positive or negative) for the most adverse surface (closest to centerline or runway end) in the attribute field penValSpecified and provide the penetration amount (positive or negative) of the secondary surface in the attribute penValSupplemental.”

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