Menu Sign In Contact FAQ
Banner
Welcome to our forums

Can a DME work well enough for the tower monitor but not work for aircraft?

Today I flew the ILS into Lydd EGMD.

No ident and no signal – not even when going around above the runway. I don’t land there; I just phone them with the credit card.

Others e.g. SFD (117.00) and EGKA (109.95) work fine.

I reported it to Lydd tower but they said their status shows “OK”.

Frequency was right

Both NAV1 & NAV2 were dead on 108.15 for DME but both worked for LOC/GS.

So I flew the DME arc etc using the GPS distance There is no terrain whatsoever there.

Nobody was flying today – I was the only fixed wing flight out of Shoreham all day; with winds up to 260G30 almost everything “light GA” except a TB20 is grounded – so I can well believe nobody else tested the ILS at Lydd. Also being the 30th Dec most of the country is p1ssed

Administrator
Shoreham EGKA, United Kingdom

Absolutely sure you hadn’t set the DME to its own local frequency?

EGKB Biggin Hill

I just set 108.15 like I always do. ILDY is my “local”

What is “local frequency”?

Administrator
Shoreham EGKA, United Kingdom

It could be a number of reasons. My betting would be on it having tripped-out – remote monitors in ATC are notorious for not telling the truth about DME status as the ‘monitor’ is actually part of the equipment and not a (independent) monitor in the true sense.

The frequency pairing could also be wrong as the engineers may have set the wrong channel that is meant to coincide with 108.15. The channel should be 18Y which is somewhere in the 960-1215mHz range +/-63mHz. Of course, a pilot doesn’t have any means of recognising that.

Fly safely
Various UK. Operate throughout Europe and Middle East, United Kingdom

Peter wrote:

What is “local frequency”?

Depending on the model: FREQ setting, where you set the actual DME frequency (well, the paired ILS/VOR frequency, in reality) on the DME, or the HOLD setting. Basically, not RMT or NAV1 or NAV2

Last Edited by Cobalt at 31 Dec 16:39
Biggin Hill

I don’t have any way to set anything else to what I have set. I did try both NAV1 and NAV2 on the DME (KDI572) control panel

I never use the HOLD position – it’s a recipe for trouble.

Also, the two SN3500 EHSIs will blank out the DME figure if you have set e.g. NAV1 on the EHSI source but the KDI572 is set to NAV2. Here you see the KDI572 set to NAV1 and the EHSI showing a blanked-out DME value; this is because there is no DME there. If I merely change the NAV1 radio to say 117.00 (SFD VOR/DME) the distance appears in both places.

Even the Shoreham DME could be received from around Lydd… just by setting 109.95.

So I think Lydd did indeed have a duff DME.

Administrator
Shoreham EGKA, United Kingdom
6 Posts
Sign in to add your message

Back to Top