As I analyzed those 55 reports, built my spreadsheets, and did my statistical calculations, I discovered I needed to categorically reject my original supposition as to what I would find. It turns out the mean age of CFIs involved in a fatal accident is 44.4 years. Not even close to my hypothesis of 23. For the statisticians out there who are asking, How sure are you of this figure? I can tell you this; at the 95-percent confidence interval (CI), the mean is 44.4 (+/- 4.6) years. Therefore, the lower limit of the mean is 39.8 years of age for CFIs involved in fatal accidents. Which, of course, is much older than my initial guess. (See Table One at right for a list of the ages of CFIs. You will notice there are 45 ages listed, not 55. This is because in 10 of the accident reports, the NTSB did not list the CFIs age.)
How about the average number of hours of these CFIs? My original hypothesis was a total of about 950 hours. Again, it turns out I was far off the mark. The mean hours is 6257.1, the median number of hours is 2000. At the 90-percent CI, the mean is 6257.1 (+/- 2121.6). Graph One, on page 18, presents information on CFI age and the number of flying hours each person had, according to the NTSB.
