Malibuflyer wrote:
It’s not only on the approach – but you need to be at least RNP-5 to legally fly IFR in most parts of European airspace system. And a Com-Radio can hardly be claimed as RNP-5 …Also if we apply common sense: What the regulator intended to ask for is that no failure of a single piece of equipment should constitute an emergency. Lack of own means of navigation and being dependent on radar vectors from ATC is an emergency.
Therefore one might argue that IFR in VMC is legal with just one navigator, IFR in IMC is pretty clearly not!
You can fly it radar-vectored, which means it’s legal. Don’t forget you can get GPS signal problems anyway, does not mean you are in emergency. More like PAN-PAN.
Last time I checked that is why you need VOR or some other method to navigate in case of GPS issues.
And yes, you can theoretically fly to RNP-5 using VOR, what’s the problem? TSE (total system error) of 5 nm is absolutely flyable by hand on VOR.
“What the regulator intended to ask” – could not care less, sorry. Primarily because different people that submitted proposals to NCO/SERA/… meant different things.
Therefore, if I can interpret regulations my way, I will.
Malibuflyer wrote:
This statement could be misleading: There are obviously types where the type certificate and/or the certified POH says “VFR (day) only”. And in those planes IFR flight is obviously not allowed even if the equipment would be sufficient.
That’s what I wrote in the sentence after the one you quoted, wasn’t it…?
arj1 wrote:
And yes, you can theoretically fly to RNP-5 using VOR, what’s the problem?
Sorry but the discussion was not if a VOR-receiver is a legal backup for a GPS (it obviously is) but if a com radio only would be one.
Malibuflyer wrote:
Also if we apply common sense: What the regulator intended to ask for is that no failure of a single piece of equipment should constitute an emergency. Lack of own means of navigation and being dependent on radar vectors from ATC is an emergency.
I wouldn’t go as far as “no failure of a single piece of equipment should constitute an emergency”. I think it’s more “no failure of a single piece of equipment should have a high likelihood of resulting in an accident”.
As part of the AWO project, some of the provisions in Part-NCO have been revisited, as published in NPA 2020-02. In the subsequent review of comments, for various reasons, draft GM to NCO.IDE.A/H.195(b) was developed and shared at the consultation workshop last month. I expect it to be published (for information, not as a Decision) with the AWO Opinion in Q1 2021.
Malibuflyer wrote:
It’s not only on the approach – but you need to be at least RNP-5 to legally fly IFR in most parts of European airspace system. And a Com-Radio can hardly be claimed as RNP-5 …
You mean RNP5 or RNAV5? while both have same tolerances the former has onboard integrity monitoring….
You can still fly RNAV1 & RNAV2 on VHF comms & transponder under radar vectors and let-downs (e.g. PARs/SRAs)
At least in the UK you can fly the “en-route airspace system” under RNAV5, so radar vectoring is way more than enough to comply, although en-route ATC will hate you if you turn up with non-IFR GPS (e.g. the guy asking for vectors after each direct 
), but it’s practically useless as you still have a problem flying IFR in approaches/departures/arrivals which are RNP1 or RNP0.3(RNP APCH)
Ibra wrote:
You mean RNP5 or RNAV5? while both have same tolerances the former has onboard integrity monitoring….
Whatever was intended, the requirement is for RNAV 5.
Ibra wrote:
You mean RNP5 or RNAV5?
Sorry – obviously RNAV-5
Would an ADF be counted as acceptable back up?
This sounds like one of the sleeping dogs nobody wanted to wake up.
I suspect it is unclear. Obviously the coffee grinder ADF degraded the simplicity and accuracy of the four course range :) and we can be certain it is not RNAV 5 compliant.
