Perhaps I did not make myself clear in my previous post.
Following a notional glide path on a non-precision approach that remains at or above all step-down fixes is the best way to do it in a large aircraft. However, the approach procedure is designed to permit the aircraft to descend almost vertically to the MDA at the FAF or last step-down fix as appropriate and then fly level until the MAPT. That is legal and ensures the required obstacle clearance is maintained.
There is no legal or procedural requirement for an aircraft not to follow the "dive and drive" option at Birmingham.
The advice included in the noise abatement procedures for Birmingham to follow the notional glide path on a non-precision approach is a noise abatement procedure alone. If one reads the noise restrictions at Birmingham, one will see that the notional glide path applies not only to IFR flights but also to your average VFR flight in a C150.
So looking at this incident, there is not yet any evidence that the crew did not follow a notional glide-path and as such the discussion regarding those issues may be a red herring. The evidence available seems to indicate that if they did a notional glide path or dive and drive, they would still have ended up at MDA(MDH) 800 (475) when the DME they used said about 1nm.
Unfortunately, it seems possible that the DME that was used was HON.
It is an unfortunate co-incidence that BHX and HON are both to the left of the centerline and the NDB DME 33 final approach track is offset by 5deg from the centerline. Have a think about that and then what you would expect the LOC to be showing when on a 5deg offset.
Again it would be very intersting to find out what was briefed, what was tuned and what was identified. It would also be interesting to hear how ATC positioned the flight and what the approach clearance wording was.
Regards,
DFC