RNAV1 "mandatory" to fly an ILS - a novel idea...

On the side question: The very same as you are supposed to do with the loss of any other means of navigation during flight.

First of all you fly the aircraft. Make sure your AP is configureds the right way (HDG-Mode might be the best idea in the beginning) and you are on a safe track
On a SID in almost all cases it is most practical next step to tell ATC that you have lost navigation and request vectors. You will always get them.

Then you have time to analyse the situation: Do you have enough navigation capabilities left to conduct the flight or is it safer to fly back to the departure aerodrome with vectors. Obviously one important part of answering that question: Can you fly visual or do you need an instrument approach? If you do: Does the departure airport have an instrument approach that you can still use w/o the required GPS accuracy? If not, you need vectors to an alternate that either has an instrument approach you can use or is in VMC.

Malibuflyer wrote:

First of all you fly the aircraft. Make sure your AP is configureds the right way (HDG-Mode might be the best idea in the beginning) and you are on a safe track
On a SID in almost all cases it is most practical next step to tell ATC that you have lost navigation and request vectors. You will always get them

Yes I agree it’s fly airplane stick a heading and asking for help, especially if it goes “no GPS signal” but LOI flag on SID only means you lost RNP1 integrity, you can still have a magenta line to track it’s just not reliable, GPS will go from TERM to ENR (just like when you are flying 50nm away from your FPL airports on OBS mode), it’s no drama just like when LOI LPV goes LNAV during approach, you keep flying the sh**t of it dead in middle above 1000ft agl on higher minima or go-around (most likely on ENR annunciation rather than TERM), why above 1000ft agl if LOI SID goes ENR, I would do anything differently? bellow 1000ft agl with VMC, I may go freestyle back to the circuit and fly again when it’s back to normal

SID is mainly designed in places where you don’t have tower/departure ATC to help with radar, you will not be on the SID for very long if you can have vectors unless it’s lost comms procedures:
- If you go visual navigation then accuracy is likely +/-10nm, it’s worse than SID but at least you won’t hit anything or you will see it first
- If you go radar navigation then accuracy is likely +/-2nm, it’s probably worse than LOI RNP1 SID with aircraft dead in middle of ENR

My main question was mainly for bellow 1000ft agl or MSA with LOI on SID going ENR in IMC, I would not go back to my departure airport for GPS IAP approach for sure best is just to keep going up to above MSA on some conventional radial and higher to get nice GPS signal reception, then I may ask ATC to go back fly an ILS but most likely I will just pretend nothing happens to the signal and fly to destination, signal is likely to be better there…

Ibra wrote:

SID is mainly designed in places where you don’t have tower/departure ATC to help with radar, you will not be on the SID for very long if you can have vectors unless it’s lost comms procedures:

My experience is the very opposite. SIDs are used at the airports with the most traffic which certainly have tower and departure ATC. In Germany, all IFR airports have SIDs.

Airborne_Again wrote:

My experience is the very opposite. SIDs are used at the airports with the most traffic which certainly have tower and departure ATC. In Germany, all IFR airports have SIDs.

Yes I agree there are load of airports with SID but I was not referring to having SID but the act of practically flying them in full all the way in Sweden/Germany? I am sure we asked this question in another topic and the conclusing was yes they are flown fully in no COM & no TXP & no ATC scenarios? but I am still not sure about no GPS scenario for RNP1 SID?

Note that the same thing can be asked for NDB SID or VOR SID when the ident music stops !

On actual SID flying, it’s simple the moment you reach MVA/MSA with radio & radar contact you will get a vector or direct away from SID bellow that you won’t get it, AFAIK, even in emergency you are supposed to “extract yourself” to MVA/MSA before getting ATC to help, did anyone ever asked ATC for vector or direct bellow MVA/MSA after they lost GPS on RNP SID departures?

Anyway, the requirement to have RNP1 for ILS or SID but not for go-around & missed MAP probably comes from the house of dinosaures, it’s the same as UK CAA department who require NDB overhead or radar ATC for GPS approaches, these guys are usually found reading Daily Mail on effect of nuclear EMP on GPS navigation for GA aircrafts and the effect of 5G antennas on people with a PPL (same guys who put HIRTA zones in VFR maps as it’s an imagined vulnerability of GPS and VOR/DME while these have internal integrity checks for RAIM/SBAS and have passed severe FM immunity tests, in they other hand, they ignored the major effect of radio waves on their preferred ways of navigation, paper map DR and old NDB antnenna, where pilot heads gets hot, paper maps burn and ADF with AM/FM radio stations goes crazy meanwhile the neaxt department guy is happy for one to depart IFR from a non-RNP SID aiport with no ATC/no IAP in 10ft ceiling with runway heading to track some coastal NDB 20nm away or using paper map and paper PLOG as long as you avoid CAS

In case someone does not know

High Intensity Radio Transmission Areas (HIRTA)

HIRTA are areas of defined dimensions within which there is radio energy of an intensity that may cause interference or damage to communications or navigation equipment and may be injurious to health. Pilots should be aware that these transmissions can give false indications on navigation and systems monitoring equipment; GPS is particularly vulnerable. Details of the major sites are listed at UK AIP section ENR 5.3 and are depicted on UK CAA Aeronautical Charts. Reference to specific HIRTAs can be found in the ENR 5.3 section of the AIP.

RNP 1 is rarely used on RNAV SIDs or STARs, only RNAV 1 is the US standard. The only time RNP 1 is required is when the RNAV SID or STAR includes an RF turn. Hybrid and RNAV (GPS) approaches don’t require RNAV 1 in the US, “RNP APCH” is the PBN navigation specification. The only time RNP 1 or less is used in the US is with RNAV (RNP) approaches which use the “RNP APCH AR” PBN navigation specification.

NCYankee wrote:

RNP 1 is rarely used on RNAV SIDs or STARs, only RNAV 1 is the US standard. The only time RNP 1 is required is when the RNAV SID or STAR includes an RF turn. Hybrid and RNAV (GPS) approaches don’t require RNAV 1 in the US, “RNP APCH” is the PBN navigation specification. The only time RNP 1 or less is used in the US is with RNAV (RNP) approaches which use the “RNP APCH AR” PBN navigation specification.

I think in Europe it is all RNP1 now, I’ll that for others to correct.

arj1 wrote:

I think in Europe it is all RNP1 now, I’ll that for others to correct

That is correct, it’s RNP1 but it’s unecessary, RNAV1 would be more than enough (at least it’s equivalent to ATC RV), the US applied way too much common sense when it comes to PBN topic: RNP is only relevant when going to touch the ground, to tell you to go-around

Going away from the ground should not require RNP, you will keep going toward the sky when RNP is lost !

arj1 wrote:

I think in Europe it is all RNP1 now, I’ll that for others to correct.

I’m baffled by this and Ibra’s response. The EHRD plate that started this thread clearly says “RNAV1 required”, as do EHRD’s SID and STAR plates. I think this is typical. Where is RNP1 required? RNP1 seems rarely used. RNAV5 is more common for STARs, though an increasing number are RNAV1.

The only real difference between European and US policy seems to be in hybrid approaches. I don’t think there is a separate hybrid approach concept in Europe, and the emphasis on on nav specs hence the designers choose an RNAV1 nav spec.

@bookworm, so it is RNAV1 required, but RNP approaches?
Sorry, I’m now confused with terminology.