Originally Posted by
Request Orbit
If this had happened in the LTMA the approach controller would have had a flashing alert on the radar that the wrong QNH was set as soon as they were descending through the TL, surprised there’s not similar for CDG.
The Preliminary Report contains the following Safety Recommendation
Implement without delay, a procedure to mitigate the risks of an incorrect QNH setting affecting both altimeters during approaches using the baro-VNAV function, possibly by crosschecking the QNH with another source of information, in particular with the ATIS information when available or by asking the controller for confirmation of the QNH.
which strongly implies that CDG has no current safety-net involving automated detection of incorrect QNH setting.
The BEA makes no reference to the solution adopted by NATS, though it's anybody's guess whether it is simply avoiding being prescriptive as to the solution that it is recommending CDG should adopt, or whether they are unaware of how other ANSPs tackle the issue.