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Any reason NOT to remove an ADF than has gone u/s?

There is quite a bit of discussion about ADF’s but most are 3-4 years old and the last post that I can find is in this thread from June/16: “Peculiarities with latest UK LPV approach”. Most recent posts on it are not specifically ADF-related.

My C172 has a dual WAAS GPS/NAV/COM plus DME and ADF. The ADF is an old Cessna ARC 300 R546E unit and it has now gone u/s. I’ll be having some work done on the aircraft and will need to add a CB.

Does anyone have any argument at all against removing the ADF? Other than the UK, would I miss it? What about the UK? Specific examples? The above-mentioned thread (and others) seem to imply that not having an operation ADF could have disadvantages in the UK. I haven’t used it for ages and would like to just pull it, take the W&B improvement, and spend my money elsewhere. I know that none of the Cirrus have one, and clearly one can manage even in the UK without. Just looking for any disadvantage of not having one, that I haven’t considered.

LSZK, Switzerland

There are some ILS approaches — also outside of the UK — that require ADF.

ESKC (Uppsala/Sundbro), Sweden

Examples? Under FAA ops, a GPS can be substituted for an ADF to identify waypoints such as locator beacon, hold fix, etc.

Last Edited by chflyer at 15 Mar 07:22
LSZK, Switzerland

Some airports only instrument approach is an NDB eg carlise

chflyer wrote:

Examples?
ESOE ILS 19
Under FAA ops, a GPS can be substituted for an ADF to identify waypoints such as locator beacon, hold fix, etc.
That’s not legal in EASA-land. Or at least I have never seen any regulation approving it. OTOH, I don’t think anyone has seriously argued that there is a safety risk in doing so. It’s different with substituting for a DME.

ESKC (Uppsala/Sundbro), Sweden

Under FAA ops, a GPS can be substituted for an ADF to identify waypoints such as locator beacon, hold fix, etc.

That’s not available outside the USA, not even in an N-reg.

There are some ILS approaches — also outside of the UK — that require ADF.

There are many approaches in Europe which are either wholly NDB based or they have an NDB specified.

That’s the strict position. You do need to carry an ADF to fly these because Europe has no GPS substitution concession like the USA has. The reality is that there is probably something approaching a four figure number of e.g. SR22s in Europe which don’t have an ADF, and there are no known prosecutions.

Also almost nobody (apart from IR tests) uses the ADF to fly these approaches. People set up the NDB as a GPS waypoint, etc.

In the UK, currently, there are difficulties doing an IR test without an ADF. It used to be absolutely impossible until very recently because the aircraft would not meet the CAA standards doc. Now AFAIK it is possible if you “arrange” the test to use airports which don’t have NDBs but have other navaids to meet the nonprecision test requirement (VORs). I don’t know if this issue exists in other countries but in any case it is relevant only if you need to use the plane for IR tests (or possibly revalidations which need to be done each year).

I know many people replace faulty ADFs with units bought on US Ebay and there is no logbook entry This should work if the serial numbers of the boxes are not checked regularly. But also some transfer the serial number stickers, with a hair dryer.

Luckily my KR87 ADF is still working after 15 years and I have a complete spare kit on the shelf, bought from a US pilot who ripped out a lot of stuff a few years ago. Otherwise, I doubt I would replace it if it failed.

Administrator
Shoreham EGKA, United Kingdom

There will be a CAA statement very soon (we have been told before the end of the week) about NCO operations using fix substitution in all but the final approach, which will mean no NDB final approaches without an ADF, but everything else (procedures, holds, missed approach), and DME substitution in DME arcs, will be OK.

PPL/IR Europe have been pushing for that for a long time (we would have liked to have seen final approach as well, but one step at a time.)

I imagine that it will only cover the UK initially, but these things have a way of spreading.

Last Edited by Timothy at 15 Mar 08:22
EGKB Biggin Hill

That would be good news.

However I have no plans to remove the adf or DME from my aircraft. Firstly it works and I also find it an excellent training aid. I also can’t afford to replace it with say a second had Garmin 430 and even if I could I couldn’t afford to keep the database up to date.

Plus although not the lowest of minima I can’t think of a single airport that I have ever visted which doesn’t have a ndbapproach.

Still a very positive move.

Timothy wrote:

PPL/IR Europe have been pushing for that for a long time (we would have liked to have seen final approach as well, but one step at a time.)

Even in the US you can’t substitute an NDB final approache segment without an actual overlay approach. This is excellent news and another great initiative from PPL/IR. Is it for non commercial ops or ops under part NCO (ie will it also apply to Part-NCC)?

Last Edited by JasonC at 15 Mar 09:58
EGTK Oxford

Good news Timothy. I understand that to mean that standalone NDB approaches (without GPS overlay) aren’t exempt, but any non-NDB approach that contains an NDB/LCTR fix can substitute GPS for NDB fix. Correct? That’s one to track closely.

Peter wrote:

There are many approaches in Europe which are either wholly NDB based or they have an NDB specified.

Peter, do you know of any online source of a list of these? And how many don’t have an RNAV alternative? I understand the UK IR test req’t for ADF equipment, but in my case (N-reg) that’s not a consideration.

France seems to be rapidly adding RNAV approaches to airfields that previously only had NDB approaches (e.g. Blois LFOQ). In the mentioned example, the RNAV has lower mins (300’ LPV DH) vs NDB (520’ MDH) and the NDB is not aligned with the runway while the RNAV is. I don’t expect the NDB approach there gets much use these days.

I would certainly fix the DME if it broke, as it is good backup assistance for VHF nav if GPS reception goes out. There are also other threads here that discuss risks in certain situations (and even accidents) when substituting GPS for DME due to slant range or fix confusion when substituting.

The bottom line is the cost/benefit analysis of keeping and repairing a broken unit. I already replaced mine with a unit from eBay a few years ago (after having an avionics shop check it and sign off as airworthy, to be legal). I think the situation has changed today, and your comment about your KR87 indicates you likely concur, especially since that is a much more modern model than my old ARC unit.

LSZK, Switzerland
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