DME Step Down Approaches

[NSEU]

Are these performed by glass cockpit/FMC equipped aircraft or is this purely for steam age aircraft? Perhaps something has to break? (e.g. The FMC or the glideslope transmitter (on the ground)

If still used, would the PNF make callouts at the appropriate altitudes/distances?

Thanks for any insight
Regards
NSEU

[Dash8driver1312]

It is good procedure to call out the height/distance checks. You never know when you'll need it for real, and you should not let your skill set get rusty.

We will sometimes fly VOR or NDB procedures even when the ILS is working for training purposes, for this reason, but not if there is a high traffic situation.

Even somewhere like LOWI, which has a 'glidepath' with a localiser, the GP can be badly affected by snow and temperature variations, so then it's back to step-down call outs anyway.

[BOAC]

NSEU - assuming you mean an actual DME step down rather than DME/altitude tables on an approach, yes, it can be programmed into a 'glass cockpit', but generally there will be an 'imaginary glidepath' that can be flown for the approach, sometimes meaning you may pass somewhat above a particular (early) 'check height' (but not, of course, below). These step downs normally only occur where terrain makes the approach angle too steep initially for a 'normal' approach.

Yes, PNF will call the checks and of course PF will be aware of them. Only by 'mutual agreement' should a block altitude be left for lower at the appropriate DME.

NB As with all things in life, para 1 will have its exceptions and I expect someone will come along with one soon.

[NSEU]

Thanks, gentlemen!

Much appreciated. Although I work in the aviation industry, it's not always prudent to interrogate the flight crew in the middle of their preflight checks about such matters... or when they're about to dash off to their beds after a long flight

Cheers