Blacksheep;
Many thanks - superb and very helpful post.
I think I have what I came looking for.
Checking the QAR data with the DFDR is not practical due to the fact that QARs typically have far larger dataframes and the parameters captured therein do not exist on the DFDR. That said, concurrence and reasonableness is achieved through daily detail analysis and on occasions when an incident occurs and both the QAR and the DFDR are available for examination. I think your 2% figure is spot on.
With increasing use of QARs in investigations and with critical safety and commercial decisions being increasingly made based upon FDA/FOQA data, many now believe that it is time for regulators to adopt the same approach to QARs and FDA Programs that have applied to DFDRs for decades. As it stands, some operators use the notion that the data is "unverified" as an excuse to ignore the data when it points to costs but seemingly take the commercial information at face value.
Again, thanks for your very helpful input.
PJ2