The wording in Part NCO is “the aircraft systems required for the type of approach are operative”.
Make of that what you will.
“Required”, to me, means the aids named in the AIP.
“Operative”, to me, means existent, switched on, tuned in and giving usable indications.
The wording in Part NCO is “the aircraft systems required for the type of approach are operative”.
Looking for the reference, I did a google on the exact phrase and it’s quite amusing where it turns up – all over the place. No wonder most people can’t find the latest EASA reg for anything!
This is one, but it says it is a “draft”.
This is a Word doc and is from 2012.
“Operative”, to me, means existent, switched on, tuned in and giving usable indications.
IMHO “tuned in” is over-interpretation, and “giving usable indications” even more so. But hey when has this ever been tested? EU law is truly rubbish in so many areas. In the UK nobody would draft a reg so obviously meaningless, because everybody knows they will never be able to prosecute anybody under it.
I was referring to NCO.OP.110 (c) (2)
Peter wrote:
Do you have a reference for that, @Airborne_Again?
I don’t need one… When you are navigating using a radio aid, you are using the indications to check that you are on the correct track. How you actually maintain that track is immaterial. So if you fly an NDB approach using a HSI driven by your GPS, while at the same time monitoring the ADF for adherence to the correct QDM/QDR you are obviously legal.
That’s one interpretation, but what if the ADF wants you to turn 20 degrees off the GPS track?
Happens a lot on approaches, especially at coastal airports.
Peter wrote:
That’s one interpretation, but what if the ADF wants you to turn 20 degrees off the GPS track?
You mean the ADF shows a QDR/QDM that is 20 degrees off (when you are not close to the beacon)? Then you abandon the approach.
Airborne_Again wrote:
I don’t need one… When you are navigating using a radio aid, you are using the indications to check that you are on the correct track. How you actually maintain that track is immaterial. So if you fly an NDB approach using a HSI driven by your GPS, while at the same time monitoring the ADF for adherence to the correct QDM/QDR you are obviously legal.
I agree that this is correct in the US and has always been the case. However, many questioned the FAA wording, particularly in the AIM and AC 90-108. So the issue was brought up in the Aeronautical Charting Forum – Instrument Procedures Group. Finally the FAA individual agreed to clarify the wording in the AIM and in the AC. The Aim wording has been updated and is now available in section 1-2-3 (c.) (5.). It is a clarification and not a real change in FAA policy.
Old Wording:
Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID.
New Wording:
Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable. The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment.
In both cases, the underlying NavAid (NDB) must be operational, the equipment must be installed (ADF), and the pilot must monitor the RMI or other course indicator while on the final approach segment. So if there is a disagreement of sufficient duration and indication, the approach should be abandoned. Otherwise the GPS guiding the autopilot is a pilot choice.
In the case of the certified operator’s opspec, the Navaid (NDB) need not be operational, the equipment need not be carried (ADF), and the RMI indication need not be used.
You mean the ADF shows a QDR/QDM that is 20 degrees off (when you are not close to the beacon)? Then you abandon the approach.
Every time at EGKA or EGMD then, at a few nm away 
I used to have the ADF on a KI229 RMI and now have an ADF needle on both EHSIs so I do see this.
Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable. The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment.
Is there a limitation on e.g. just US airspace on this?
So if there is a disagreement of sufficient duration and indication, the approach should be abandoned.
Is there anything on how much disagreement is allowed?
Peter wrote:
Is there a limitation on e.g. just US airspace on this?
Yes, this is only applicable in US airspace.
Peter wrote:
Is there anything on how much disagreement is allowed?
Not that I am aware of, but if the indications would have caused you to abandon the approach just using the ADF or VOR indications, you should still do so. With a VOR, more than half scale would be my limit, except close to the VOR. It has been so long (17 years) since I removed my ADF, I am not as sure, but probably a sustained bearing error of 5 degrees comes to mind, again accounting for the normal fluctuations of the system and distance to the NDB.
dylan_22 wrote:
This is how it done in a non-ADF Cirrus.
Seriously??? I really hope nobody does it that way. The video was intended to show how you can practice final approach tracking with a bearing pointer instead of a CDI, why would anybody in their right mind do that for a real approach, instead of the CDI?
