One of the key things when doing procedure design is to remember that obstacles are not points, we get a lot of them just as surveyed positions but they actually have an area.
Following image illustrates obstacles that by their position are out but reality is those blades are inside the areas. It’s amazing how we still deal with a lot of these things in basic terms of points, instead of trying to have a more detailed model and also how many of procedure design techniques are modelled in 2D space instead of using 3D models and go for more of a 3D intersection similar to cut/fill (volumetric areas) as done for railways and roads.
For many years when drawing areas by hand PANS OPS talked about adding horizontal and vertical accuracy (offset) to account for innacuracies in the data, as we moved to digital tools we though the inherent innacuracy can be disregarded but we actually have just changed the drawing and analysis tool not the flawed method. We can’t consider an obstacle a point any object has an area, even if we add a horizontal offset (I’m not focusing on vertical in this post) we can see that it may not be enough to really cover the case.
The above is just one case, but what above power lines where the actual line connecting high transmission towers is not modelled? Overall Procedure Design is safe inherently because of the many safety margins (maybe sometimes luck?) but the idea of this post is to think really as a designer that our world is not made of points, lines and areas, sometimes we need to think in what way something may be affected and for sure validating the used data is one way to go.
Update 2: Sometime Google doesn’t win
Google left – Bing Right