My grandfather, who I called Pop, could navigate by the stars. He would grab a sextant and gaze skyward and in no time at all he would have his position on the earth to an amazing degree of accuracy. It is one of my great regrets that I never got him to teach me how to do that before he left this mortal life.
These days we fly navigating by satellite to a breathtaking accuracy. It is not uncommon for the GPS system to have my plane to an accuracy of 8 m with better than 95% confidence. Wow!
Now on casual inspection that would seem like a good thing. And most of the time that level of detail is great. All of the logistics planning and time management activities of modern aviation benefit from this accuracy.
The sky is vast but like roads planes fly on designated tracks and quite often these “roads” in the sky have opposite direction traffic on them separated by different heights of course. This brings me back to my Pop and his sextant – with both planes at sextant accuracy the chances of these two aircraft being laterally close was remote if not nearly impossible however with GPS now guiding planes the unintended risk is they are both perfectly on track.
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