DV & others
I can see the issues of the past are seared into everyone's brain - my question is it possible to move on?
I totally agree with " The concept of an“implicit Safety Case” does not comply with Lord Cullen’s concept of a “thorough assessment” of the risks posed by a platform. This is because, in effect, the notion assumes that a legacy aircraft is safe merely because it was built to design and has been operating without mishap for a number of years.
On the other hand IF an aircraft has been operated for many years without mishap there is clearly a body of evidence (or a statistical number) that it is not as unsafe as (say) the F-104G or an Indian Mig-21.
For example the Boeing 777 has many years of safe flying with (perhaps) one airframe incident - it is statistically clearly safe - or safer - than just about any other airliner.
Does the Safety Case have to examine every possible issue and put a risk on it??
And how do we risk the "known unknowns"??
FYI I have been involved with a number of Safety Cases outside the aircraft industry and this is a problem everyone has to deal with when legacy infrastructure & systems are involved- I'm seriously interested in how different people approach this......