There are at least 7 commercial passenger flight suicides in history (plus the four on 9/11, though that's arguably a closed vector now, and some others on non-revenue flights). There are around 100K pilots working today in commercial aviation [not all Part 121 (airline)], so perhaps 500K, and surely less than 700K, total over the course of time. If we posit a successful suicidal action rate of 7 in 700K, that's only "five nines" over the course of their shortened career or 99.999%, but could become seven or even eight nines on a per-flight basis.
I'm 100% with you on the desire to not have ground-link control (and, for me, to keep two crew in Part 121 operations); I just figured I'd estimate the math.
I had a feeling someone would try and do this calculation. :) I would calculate it instead based on the number of flights rather than the number of airmen. It doesn’t make any sense if the units for the numerator are “number of successful suicide flights” and the demoninator is “number of airmen”.
I would not count the four flights in 2001, personally. Those are not suicide by flight personnel.
If you look at an average of say 25m flights per year since the year 2000, then you would have about 550mm flights. Even if you include the 4 tragic flights of 9/11 in the numerator, my 7 nines are very conservative.
I'm 100% with you on the desire to not have ground-link control (and, for me, to keep two crew in Part 121 operations); I just figured I'd estimate the math.