This has got to be, single-handedly, one of the BEST examples of determined bug-hunting I have ever seen over my entire career as a software engineer.
It is a fine example of the ART that can result when you mix simple, thoughtful reasoning, patience, and a deliberate approach, with strong domain knowledge (in this case, of general aviation).
You just taught a master-class, and I am lucky to have witnessed it first-hand.