Squiffy- Yes, I think the travelling public is on the receiving end of some very good work over the decades. I think in flight safety work, some sources of "comfort" are justified, such justifications to be found mainly in the data. For example, the data has justified ETOPS work yet serious, (in my, and others' view) questions remain regarding an actual vs. planned diversion under worst circumstances, (pressurization failure, arctic/polar/trans-Pacific routes, etc). Like the case under discussion, reliability has justified the approach taken. And of course, we all know and accept that the risk of failure is always present but has been examined (and hopefully constantly re-examined).