I am planning to do my IR next year and being told conflicting information and hoping for some clarity if possible.
I will be doing the CBIR and ideally want to do it in my aircraft, equipped with 2 × GTN 650s’ but no DME. I’ve been told that in order to do the test, I cannot rely on the GPS DME for a published ILS/DME but i cannot find anything from the CAA supporting this.
Can anyone assist here please. I am UK based.
If the IFR plate reads DME required then you must have an DME else you can’t fly that approach.
If you only have GPS you can only fly RNP or LPV long as it doesn’t say DME required.
DME distance is not same as GPS distance.
They might be same or close, but they doesn’t matter.
Darkfixer wrote:
If the IFR plate reads DME required then you must have an DME else you can’t fly that approach.If you only have GPS you can only fly RNP or LPV long as it doesn’t say DME required.
DME distance is not same as GPS distance.
They might be same or close, but they doesn’t matter.
thank you
The UK has no LPV so the precision part of the test will either need an ILS with no DME mandatory, or you fly LPV abroad.
Not sure if foreign IR tests are allowed (training is) but Alderney is pretty close.
CAP 1926 (linked above) allows RNAV substitution in the UK. That includes ‘fly[ing] a procedure where the chart contains a note requiring a particular type of conventional navaid, e.g. “ADF required”’ – so RNAV substitution can be used for the required DME for an ILS approach. There should be no need to fly abroad for a LPV approach nor the need to find an ILS in the UK without a required DME. Obviously, one needs to do it properly, i.e. not using the wrong fix in lieu of a DME station, or where DMEs do not read zero at the station, resulting in an incorrect distance being displayed.
You need to comply with the requirements of CAP 1926 e.g. not using RNAV substitution for lateral guidance in the final approach segment (so it cannot be used for an NDB approach) nor using it where the AIP (or a NOTAM) notes that RNAV substitution is not authorised for that particular procedure, and in accordance with the criteria in chapter 5 and procedures in chapter 6. You should be prepared to discuss these with the examiner. The ATO should be able to help you understand these requirements as part of your training.
Further on this, I saw today that CAA Standards Document 01 (Notes for the Guidance of Examiners and Applicants taking the Initial Instrument Rating Skill Test) was updated today. Some of the changes relate to RNAV Substitution / CAP 1926. See section 3.9.
that is VERY helpful, thank you! Never a good place to start by arguing with an examiner but that appears quite clear to me, thanks
GPS substitution is allowed but if it is your aircraft in might be appropriate to consider if this is a wise idea for the test and for further flying.
Just a day or two back while doing IR (R) training the GPS gave a LOI warning and went into dead reckoning mode, fortunately the student pilot identified the problem and rectified the problem using VOR & DME but without the DME there would have been a danger of an airspace infringement while probing for radials from the second VOR Box.
Having DME keeps things simple and when the workload goes up simple is good.
