More information on your particular aircraft's QAR data collection setup is available from your friendly ground engineers shop. A look at the supplemental type certificate for the DAU installation may provide some limited info.
There are more than a few pilot unions here in the states that have vociferously fought against performance reviews and sanctioning based solely on these digital witnesses' testimony. The Allied Pilots Association (AA) are one of the more motivated groups in this area.
My reservation is that a pilot could be falsely accused based on qar data.It would be hard to prove that the data is false.
I agree with you completely on this Master Linton.
I know of a fellow 737 pilot who faced sanctions after the aircraft he flew out of Denver later developed a 'premature' hot section failure. Airline had QAR records clearly showing an over-boost with EGT over-limit on his watch. Our man recalled things a bit differently and despite the F/O's recollection of no N1 nor EGT telltale on the day in question, company pressed on. The DFDR data had been long over-written and may not have helped anyway depending on where the discrepancy existed in the recorded data stream.
Thanks to a mechs saved FADEC readout there was finally more evidence that yes - no over-boost happened, at least on that particular day. I would have bought that gent a case of the best were it me. Engineering was rumoured to have later discovered that the DAU retrofit was feeding bad data to the QAR due to a
minor mis-calibration. Imagine that!
