DME is not required to fly this procedure unless you elect to fly the ARC
initial approach segments. In that case, you have to be able to receive the
DME from the VOR at the same time you are receiving the LOC. It is a
boilerplate note they put on anytime the DME is not frequency-paired with the
ILS.
But, you're right, you could easily fly the ARC, then use the lead radials to
change to the LOC. The note serves no real purpose on this IAP.
Don Faulkner wrote:
Hi folks. I've got a bit of a puzzle here.
First off, I'm a student pilot, so maybe I haven't gotten to this yet.
Take a look at the ILS 18 plate for Springdale, AR (ASG):
http://myairplane.com/databases/appr...l/ASG_ir18.pdf
First, note that the approach is "ILS RWY 18"
---
Next, read in the notes section:
Circling NA east of Rwy 18-36, inoperative table does not apply.
DME from RZC VORTAC
Simultaneous reception of I-ASG and RZC DME required.
---
So, the way I read this, DME is not required, since the approach is ILS
not ILS DME, but it is required since "simultaneous reception ... is
required."
I guess my real question is, "Is this approach authorized for an aircraft
without DME? And if not, why don't they call it ILS-DME?" but read on for
my thinking...
Looking at the chart, here are the uses of DME that I see:
1. DME arcs to intercept the localizer
2. A 3.8 DME non-precision MAP (my Jepp plate shows a non-precision decent
with DME 3.8 as the MAP)
3. WESTY intersection, 18 DME out, which can also be identified by a
cross-radial from the DAK VOR.
Now, this is how I reason (i.e. rationalize. 
my way out of these:
1. I tune the RZC VORTAC and fly the DME ARC, but once I turn to intercept
the localizer, I no longer care about the ARC, so I don't need DME anymore.
2. DME would be helpful here, and simultaneous reception would be
required, but I could also time from the FAF to identify the MAP.
3. I can swap VOR receivers once safely established on missed approach, so
I shouldn't need this for the inbound part of the approach.
To my thinking, #2 is the shakiest logic. Still, if DME is required, why
don't they just call it an ILS-DME approach?
--
Don Faulkner, KB5WPM |
(This space | "All that is gold does not glitter."
unintentionally | "Not all those who wander are lost."
left blank) | -- J.R.R. Tolkien