JPH wrote:
Tauno Voipio wrote:

Steven P. McNicoll wrote:

"Bob Moore" wrote in message
. 122...

Well Steven, why don't you just come right out and tell them
about the Middle Marker?



Because they're disappearing.




There should be a co-located (and associated) DME if
there are no markers, and in can be used instead of the markers.

In the USA, the MM used to be a required part of the ILS system. Now,
nothing is required to replace the MM (not even DME), so most have been
removed.


It's a weird interpretation of the ICAO rules, but that would
not be the first time FAA does not respect the internationally
accepted rules.

I'll check from the relevant ICAO docs as soon as I get to
the office.

AFAIK, there should be at least either operative outer
and middle marker or a co-located DME. The markers are
positioned so that outer marker is roughly at the crossing
of the intermediate approach altitude and glideslope
(the point where glide starts) and middle marker at
the crossing of glideslope and MDA.

--

Tauno Voipio
tauno voipio (at) iki fi