Airborne
"In theory, a signed RTS indicates that, accepting as yet unknowns, the airframe being inflicted upon the crews is safe and fit to fly. That the various systems function as advertized and, as far as can be reasonably tested, they don't interfere with the proper function of the other installed systems. It also lays down limits on how it should be flown and those limits allow for some "flex" to build in a safety buffer. There's the baseline of your "safety" right there."
The problem is that "safety" is not absolute
If you asked an aeroengineer in 1920 what he considered "safe", it would be very different than if you asked one now.
Every shift in the baseline may save lives in accidents, but compromise effectiveness, so this needs to be incredibly closely monitored.
As I said before, the easy safety measures that were good bang-per-buck went a long time ago. We have just been throwing money and effectiveness down a well for 30 yrs.
I believe that the baseline of "safety" across all areas needs a very dramatic reset left.
The sine wave of safety has swung from very poor in the middle of last century where were were losing our ability to fight due to constant lose of men and machines, to a position now where we are too hamstrung to field competetive aircraft in affordable numbers.
Some of our platforms have become a shadow of what they could be due to regulatory silliness.