Ian W,
Some good points there but:
- Does the A300-600 have the gear to be RNP-AR (or indeed LPV or LNAV/VNAV) capable;
- Why doesn't KBHM 18 have a glideslope? I suspect cost or terrain (which was collided-with) prohibits (could also preclude an RNP-AR approach).
- RNP LNAV works well when the aircraft can use the FMS database-coded approach slope/VNAV (even if just following it with VS/FPA or handflying), but aircraft must be capable.