I have watched and read this thread with a great deal of interest, both as an ex Nimrod engineer, and now as a Safety Engineer. Some of the comments made on the thread show a real lack of understanding of the whole airworthiness and safety engineering process.
Safeware, who I know very well, has come in for a lot of stick from people who quite obviously do not know what they are talking about, despite their claimed thousands of flying hours etc. It may not have come across in the best possible way, but what Safeware has said is indisputably correct.
Where does all this nonsense about aircraft being as safe as possible come from ? How many of you commenting on here are familiar with JAR25, CS25, ARP4754, AR4761, DO-178B/ED109, DO-254/ED80 JSP553, Def Stan 00-970, Def Stan 00-56 etc, etc ?
Ask yourself if you understand the ALARP principle, its background, the difference between broadly acceptable, tolerable and intolerable. Do you understand how an ALARP judgement is made, how disproportionality has to be demonstrated, and how the ratio varies according to the risk.
Do people really believe that aircraft are built to be as safe as possible ? Some of these people appear to be very experienced, and probably formerly fairly senior, aircrew. Can they be that niaive ?
I would suggest for some of the idiots (and you know who you are) who have posted on here, that they download EASA Compliance Specification CS25 (formerly JAR25), it’s free ! Then read clause CS25.1309, and then read clause AMC25.1309 in the Acceptable Means of Compliance (AMC). This will give you a very good idea of the safety targets that large civil aircraft have to meet. Some of the principles are basically the same for the military, but we have also thrown ALARP in to make things more subjective.
I would like to add this to the discussion though. In my experience it is often very difficult for an IPT too properly demonstrate that they should not incorporate major safety modifications. However, in many cases they don’t understand what they are doing, they don’t have the money and they will make some very odd assumptions, particularly those relating to the remaining life of an aircraft, which will have massive implications on the cost benefit analysis.
There is some very good discussion on here particularly from the likes of Safeware and Tucumseh, as ever, but others seem to think that they can just bully others into submission with ill informed rubbish and abuse, dragging a serious debate into disrepute.
Safety_Helmut
Senior Safety Engineer
MSc (Safety Critical Systems Engineering)