HRI
Safeware,
Thank you for your clarification re HRI - as a consultant I am always happy to learn. In fact in other areas where I have done some work HRI does indeed stand for, or is used for, Human Risk Index and as far as I can see the definition of probability of the outcome and the results of the outcome are covered in a similar way, but clearly you are correct here, and Tucumseh has also kindly sent me the references to Def Stan 00-56 and the safety matrix.
Turning to your main point the BAES report said, after defining the six potential HRI B risks:
"These above mentioned hazards will require reference to the IPT for consideration as to whether further risk reduction is practicable or whether they shall remain acceptable without further action. The remainder [not defined in the ES I have seen] are recommended as being broadly acceptacle with MOD approval, as being mitigated to a level considered to be ALARP"
I am sure we both agree that ALARP stands for as low as reasonably practicable, and this was the overall rating that BAES gave to the risk of fire/explosion for both the R Mk1 and the MR2 "based on the assumption that (their) recommendations (from the zonal fire/expolosion assessment) be reviewed" - this is obviously a "woolly" position as the page of recommendations which follows is not prioritised and there is no further assessment of what the HRI case will be if the recommendations are not actioned. I do not know what action the IPT took against the BAES recommendations, but, clearly, the 3 I outlined in my last e-mail were never actioned. (Incidentally I have seen the comment that the ER tank fire suppression fit would not provide any cover - the BAES report says the opposite, but I have no idea who is correct.)
As with so many other things the real level of risk may be obscured by differing definitions, or even no definition, of the terms being used. Generally the definitions can anyway only be qualitative not quantitative.
Looking at the safety matrix of "probability of occurence" and "severity of harm" an "A" ie unacceptable (risk) category applies when:
The probabilty of occurence is "frequent" and the severity of harm is "marginal"
The probability is "probable" and the severity of harm is "critical"
The probability is "occasional" and the severity is "catastrophic"
I do not know what conclusions the IPT reached on the BAES report in 2004 or whether the risks were re-considered in the light of the QinetiQ report, but I would have thought that AAR operations with the Mk2 have been firmly in the A category since the loss of 230 - particlarly as the incidents since September 2006 have had inconclusive causes and the BOI has not reported -if the BOI has identified a definite cause one has to assume that even in the absence of the full report some specific engineering actions would have been taken.
My own view, reinforced by the BBC interview with the MOD "put up" spokesman Andrew Brooks, is that the airworthiness chain has been broken for the MR2 by deliberate actions of the IPT and senior management, and the bottom line reason for this is, as always, inadequate funding for people to do their job properly. I would be the first to admit that I am glad I was not put in the position to make these hard decisions, but the fact remains that aviation is very unforgiving of compromised airworthiness standards no matter how great the operational imperatives.
JB