I'm trying to reconcile your numbers with the Wikipedia "Aviation safety” article https://en.m.wikipedia.org/wiki/Aviation_safety

which for 2019 describes "0.5 accidents per million departures" and "40 fatalities per trillion revenue passenger kilometers". Considering that many or most passengers fly close to 800-1000 km/h, we're still quite a bit above above 1 fatality per 100 million passenger hours.

Would a factor of 10 be enough? Suppose we go from one major accident per fortnight to one per five months (10 fortnights). Is that higher than what we have seen in the past thirty years?

My numbers come from conversations I recall with René Amalberti, a notable specialist in the area, having advised, among others, Airbus. The conversations were around 1993-96, when I was doing my PhD, and thus may be a bit blurry by now. Also, it is perfectly possible the reference values and measurement units have evolved since then.

Still your projection shows that both reference indicators and actual values are in the ballpark of the estimates I cited.

My (and Amalberti's) main point is that safety assessment is not just about minimizing the raw number of accidents, but involves tradeoffs between various concerns, including psychological perception and revenue. Otherwise, the safest airline would be the one that does not fly anyone.