Simviation Forums

You may remember that I recently discovered that there is no DME on the ILS approach to Rwy 9R at KMIA.  I was so flustered (it was one of my first night landings after a long flight) that I had to log on here to see whether it was my computer or FS.  I think we established that it was a bug in FS.

Well, I just tried to land at Rwy 7 at KJAX and there's no DME there either!

Is this some sort of recurring bug or does MS just hate Florida?

Not all ILS approaches have DME

You might find this site useful:

http://www.airnav.com/

The relevant information for that particular ILS is here:

http://www.airnav.com/airport/JAX/ils/07

No mention of DME though.

I don't understand how an ILS apparatus could not have DME built into it.  How would it know you're on the glideslope if it doesn't know how far away you are?

But I followed your links and you're right - it just seems strange.  Maybe listening to ATIS would at least warn me that Im' being vectored to the active runway of a major airport that has no DME.

Thanks.

The ILS is simply a beam pointing through a widening channel (as represented by the green chevrons on your GPS). If you're not in the area represented by the chevron, your radio can't pick up the ILS beam.

It doesn't know whether you're on the glideslope or not. Your Autopilot does by the angle at which the beam (which points upwards at the exact inclination of the glideslope) is received by the radio. It doesn't need to know how far away you are. It simply tries to keep the beam centred.

For example,

Got it.  ILS does not necessarily have DME built in.

It freaked me the first time it happened because I just assumed it would be there.  But it is true to life and a perfect landing can be made without it, and now I have a link to AirNav.