IGh;
We have also several cases where the DFDR was, or some parameters were, inoperative but the QAR data was reliable (given the understandings in the thread) and used for investigation.
The Concorde accident was the most poignant example of using the QAR vice the FDR and it assisted greatly in the investigation.
In fact, we have more often had the case where the legally-recognized systems (AIMS, DFDR) have failed and the QAR/FDA system has been able to provide data and information on correcting/fixing the DFDR. Validation once per year does not always seem adequate.
Understand your comments on filtered data. I am making the assumption that this would not necessarily automatically apply to QAR data as such filtering is either downstream of, or on a parallel stream to, the FDR where such filtering occurred.
While I know this is somewhat rhetorical and doesnt' require a response, all this begs the question, why hasn't legislation caught up with technology in terms of accepting QAR information on the same basis as FDR information?