From a sow´s ear-quantitative diagnostic design requirements from anecdotal references

The diagnostic performance of modern avionic systems is widely characterized using anecdotal descriptors. `Forty percent of all failures are due to switch/connector problems´ and `fifty percent of all equipment removed retests okay´ are examples. While they are numerous and bear undeniable elements of truth, it is argued that their imprecision and fragmentary nature impede ready absorption of the information they convey into the diagnostic design process. The author asserts that these descriptors, taken in total, constitute a valuable, timely diagnostic requirements analysis input. He identifies a methodology for exploiting them, provides examples of the anecdotal inputs, presents interim and final analytical results, and proposes an approach to embedding the results into a diagnostic concept