Airspeed Ambassador- the NAS steps do not work for jets intending to remain A to C and of course their airways clearance applies A, C and E. They hug or slip out of the steps so companies may need to adjust descent profiles per location.
At certain locations they must transition A to E to D (eg no-RADAR Alice) where there is quadruple Whammy (without adding any reduced viz due PO etc):
No RADAR
Lower use or availability of transponder
E airspace - unannounced VFR (including at FL's)
No talking - naughty naughty,
Still counting,........