All-PRNAV airports

[IO540]

Just noticed that Prague (LKPR) has every SID and STAR PRNAV-only.

How does this work in reality?

They must just turn a blind eye to most of their traffic.

[soaringhigh650]

Isn't this stuff illegal?

That shuts out the majority of light aircraft IFR for a start.

[FlyingStone]

Flying to LKPR comes with ~200€ bill, plus the airport is co-ordinated, so you need a slot for arrival and departure - this basically kills most light aircraft at the beginning.

Considering P-RNAV, you can always say that you are "unable (P)RNAV", but I believe it is up to ATC whether they will permit you depart or arrive via radar vectors.

Extracts from Czech Republic AIP AD LKPR:

2.22.3.2.3 RNAV procedures
2.22.3.2.3.1 P-RNAV certification is required for RNAV arrival
routes.
2.22.3.2.3.2 Aircraft not certified for P-RNAV can also utilize
STARs with certification for B-RNAV. Aircraft not certified for
RNAV may incur delays and/or extended routing during peak
periods.
2.22.3.2.3.3 Only a pilot-in-command of an aircraft not
certified for B-RNAV shall inform the ATC when establishing
the first radio contact.
2.22.3.2.3.4 For aircraft not approved for RNAV operations,
necessary number of conventional procedures or vectoring
will be provided.

2.22.3.3.9 RNAV procedures
2.22.3.3.9.1 P-RNAV certification is required for RNAV
departure routes. Separation on parallel departure routes (for
example RNAV SID from RWY 24 to the north) is provided by
ATC service.
2.22.3.3.9.2 Aircraft not certified for P-RNAV can also utilize
SIDs with certification for B-RNAV. Aircraft not certified for
RNAV may incur delays and/or extended routing during peak
periods.
2.22.3.3.9.3 Only a pilot-in-command of an aircraft not
certified for B-RNAV shall inform the ATC when establishing
the first radio contact.
2.22.3.3.9.4 For aircraft not approved for RNAV operations
vectoring will be provided.
2.22.3.3.10 Aircraft not equipped in accordance with
requirement 2.22.3.3.9 for RNAV departure routes will be
radar vectored to exit points of relevant departure routes.

[FlyingForFun]

RNav has been mandatory in the UK above FL100 for quite some time, and is now (or very soon, I can't remember the exact date) mandatory for almost all UK airways. The reference is in AIP ENR, somewhere near the beginning. If I get time later on, I'll try to dig it out unless someone beats me to it.

I'm not familiar with Czech rules, but this is the way IFR flying is going in the UK, and presumably worldwide.

FFF
----------

[what next]

Hello!

I'm not familiar with Czech rules, but this is the way IFR flying is going in the UK, and presumably worldwide.

In ECAC airspace B-RNAV capability requirements were introduced in 1998. That is thirteen years ago (see: EUROCONTROL Navigation Domain - B-RNAV (http://www.ecacnav.com/RNAV_Applications/B-RNAV) ). The Czech Republic joined the ECAC states in 1991, therefore the B-RNAV requirement was introduced there in 1998 as well.

[FlyingForFun]

The reference for UK airways is AIP ENR 1.1.1 (http://www.ead.eurocontrol.int/eadbasic/pamslight-3A0C86E2D3F9856BAB812272B3F829AB/7FE5QZZF3FXUS/EN/AIP/ENR/EG_ENR_1_1_en_2011-01-13.pdf), paragraph 2:2.1 In accordance with ICAO Annex 11, the following prefix designators are used to indicate European Regional RNAV Routes, L, M, N, P and for non Regional RNAV Routes Q, T, Y, Z. Routes designated with these prefixes are compulsory RNAV at all levels except when otherwise notified, eg sections of certain ADRs in the Scottish FIR.Having checked the list of Lower ATS Routes (http://www.ead.eurocontrol.int/eadbasic/pamslight-3A0C86E2D3F9856BAB812272B3F829AB/7FE5QZZF3FXUS/EN/AIP/ENR/EG_ENR_3_1_en_2011-03-10.pdf), I've found that every single airway has a prefix which indicates mandatory RNav. Many Advisory Routes do too, although there are 8 Advisory Routes which are not mandatory RNav. There are occasional notifications of exemptions, for example Q41 between SAM and ORTAC below FL95.

I haven't been able to find anything that says what level of RNav is required - it may be that B-RNav is sufficient, in which case this may be (slightly) less relevant to your Prague query than I originally thought. [Edit - crossed posts with What Next, who has all but confirmed this.]

FFF
------------

[IO540]

Aircraft not certified for P-RNAV can also utilize
STARs with certification for B-RNAV. OK, that would be normal, but is this printed on the plate? Nobody reads the AIP.

Aircraft not certified for
RNAV may incur delays and/or extended routing during peak
periods.Well, a non RNAV capable aircraft won't get to LKPR in the first place because the whole IFR enroute system has been purely RNAV for at least 10 years ;)

Only a pilot-in-command of an aircraft not
certified for B-RNAV shall inform the ATC when establishing
the first radio contact.There won't be many of those since BRNAV has been mandatory for yonks, FL095+

RNav has been mandatory in the UK above FL100 for quite some time, and is now (or very soon, I can't remember the exact date) mandatory for almost all UK airways. The reference is in AIP ENR, somewhere near the beginning. If I get time later on, I'll try to dig it out unless someone beats me to it.Actually BRNAV has been mandatory for FL095+ in Europe.

RNAV is merely the capability to fly direct to virtual waypoints, which is how the IFR enroute system has been working for yonks. VOR/NDB or any other navaid navigation has not been used for at least a decade.

Indeed they are proposing reducing the FL095 level.

I'm not familiar with Czech rules, but this is the way IFR flying is going in the UK, and presumably worldwide.RNAV is the way flying has been for many years.

BRNAV is a certification level for the IFR GPS (in the GA context).

So nobody should have the slightest issue with RNAV or BRNAV which are the de facto only way to get about (IFR GPS). It is PRNAV which is the worrying bit because not only it is very hard to get (esp. under EASA where it is a major mod) but also it excludes most of the older avionics, regardless of having RNAV capability. It also involves crew certification.

Realistically, any IFR GPS can fly to PRNAV accuracy but without the paper approval for the aircraft, you "cannot go there". In the past, when I saw airports publish PRNAV-only procedures, there would normally be 1 or 2 non-PRNAV ones which one could use. But Prague seems to have done away with that.

What obviously happens is that 99% of the time one is radar vectored anyway (for departures too, IME) so no need to tell ATC your plane/crew are not PRNAV approved. And the rest of the time? I can't see anybody bothering; just fly the procedure as published. It's 100% GPS anyway which is easily accurate to RNP0.3 which is what PRNAV is.

Yeah, Prague is pricey these days for landing but not too bad for the odd visit. Not like LGW at £500 a pop.

I don't think LKPR is PPR BTW. They always told me to just file a flight plan (as if I was going to fly there without one :) ).

[FlyingStone]

Nobody reads the AIP.

Well, I don't think this is wise actually, considering other countries you overfly may have entirely different sets of rules - Czech Republic for example doesn't allow flying VFR on top (coverage 4/8 or greater), unless you hold an IR and you fly aircraft, which is equipped for IFR flight, etc. Germany on the other hand has a legal (AIP being used as a legal basis) requirement for the PIC to seat in the left-hand seat (if not otherwise stated in the AFM), etc. In your case, check Jeppesen plate 10-1P4 for LKPR and you will see that your PRNAV issue is taken care of by the Jeppesen people...

[FlyingForFun]

I'm with you now, IO540.

Originally, I had missed the significance of the "P" in the P-RNav in your original post, but it clicked as I was writing my reply, and I now see exactly where you're coming from.

I think P-RNav is likely to become more and more common, though, with more RNav approaches popping up all over the place, and ICAO wanting to have an RNav approach on every instrument runway within a few years (I think 2018 was the target?).

But the aircraft I fly are all P-RNav-approved, it's easy for me to talk about a P-RNav world and forget the very valid point you make about the cost of the approval.

FFF
------------

[IO540]

Well, I don't think this is wise actually

I get your drift :) but operationally speaking that's how the world wags...

Czech Republic for example doesn't allow flying VFR on top

That's undetectable and thus unenforceable, and irrelevant in this context which is Eurocontrol IFR procedures :) But, yeah, I didn't know that... so they join the UK among the very few places where VFR above a OVC is not allowed without an IR.... trust my old countrymen to be anally retarded. They had to employ all the old workplace spies in some way...

Germany on the other hand has a legal (AIP being used as a legal basis) requirement for the PIC to seat in the left-hand seat

I wonder how they deal with flight instruction where the student is not legally capable of being PIC in the airspace in question? Not that it's relevant here, either. Anyway, one would just swap seats when enroute, surely? ;) Might be interesting with a girl student... one of the fringe benefits of instructing, hey?


In your case, check Jeppesen plate 10-1P4 for LKPR and you will see that your PRNAV issue is taken care of by the Jeppesen people...

Well spotted :ok: In the past this occassionally used to be a note on the plate itself.

I think P-RNav is likely to become more and more common, though, with more RNav approaches popping up all over the place, and ICAO wanting to have an RNav approach on every instrument runway within a few years (I think 2018 was the target?).

RNAV is OK. I don't have an issue with that, because as I said RNAV is de facto necessary just to fly in the IFR enroute system.

Equally, RNAV (GPS) approaches are a non event.

It is the gradual creepage of PRNAV which concerns me, and many others, for GA.

The funny thing is that PRNAV is a boat which left the port many years ago because GPS/RNAV approaches are equiv to RNP0.3 (on the final approach track) which is what PRNAV is enroute, but an EASA GPS approach approval is a minor mod, whereas a PRNAV approval is a major mod (under EASA) :) So basically PRNAV is an idiotic thing to be pushing now. 15 years ago, yes. But it's past its time.

Obviously somebody bent EASA's ear, several years ago, and told them that unless they make the RNAV approach approval a minor mod, GPS approaches will for ever be dead in the water in Europe.

But nobody has yet told the arrogant t0ssers sitting in their bunkers that PRNAV will kill IFR GA if it is allowed to spread, especially to any enroute airspace. I suppose, mind you, that transiting PRNAV airspace will never be checkable (practically, within the present-day ATC framework).

On an N-reg, PRNAV is more doable - if you have a Gamin 430/530/W. I don't know the details (my own GPS does approaches but is not PRNAV-paperwork compliant anyway). And US FSDOs do 337 approvals FOC. You just need a US agent to submit the approval for you because the NY IFU has stopped doing 337s.

But the aircraft I fly are all P-RNav-approved, it's easy for me to talk about a P-RNav world and forget the very valid point you make about the cost of the approval.

What do you fly? Jets I assume.

[M609]

Next week the 3 Oslo airports will get a completely new airspace structure that uses P-RNAV in the terminal area. That's ALL P-RNAV :)

Lots of NDBs gets switched off

Non-RNAV traffic will be given vectors

More:

http://flyger.no/arkiv/filer/ANSPbrosjyreendelegversjon.pdf

[Sir George Cayley]

UK SITREP

Base of B-RNAV FL095 today. Consulted recently to lower to (I think) 3500' AMSL. Expect this in due course.

P-RNAV in the UK is coming but oh so slowly. LTMA first. UK PBN Policy document due out later this year.

Withdrawal of en-route NDBs, and later some VORs, tied to introduction of P-RNAV.

Concerns about access to:

Mr M Robinson
AOPA
London.

Sir George Cayley

[BackPacker]

Germany on the other hand has a legal (AIP being used as a legal basis) requirement for the PIC to seat in the left-hand seat
I wonder how they deal with flight instruction where the student is not legally capable of being PIC in the airspace in question?

My initial reaction was "WTF???" But it's true. From the German AIP, ENR 1.1 Section I Para 2:

(1) The provisions of the Aviation Regulation (LuftVO) concerning
the rights and duties of the pilot shall apply to the pilot-in-command,
irrespective of whether he is operating the aircraft himself or
not.
(2) Aircraft shall be operated by the pilot-in-command during flight
and on the ground. He shall take the seat of the pilot-in-command
except during training, familiarisation and test flights or, in the case
of paragraph 3, if the operator has decided differently.
(3) If several pilots entitled to operate the aircraft are on board, one
pilot shall be appointed as pilot-in-command. The appointment
shall be made by the operator or his legal representative or, in the
case of a legal person, by the authorised agent. On a par with persons
in charge according to sentence 2 are those entrusted with
the management or supervision of the other person's company or
those explicitly entrusted by the latter to make the appointment
according to sentence 1 at their own responsibility.
(4) If, contrary to the provision of paragraph 3 no appointment has
been made, the person operating the aircraft from the seat of the
pilot-in-command shall be responsible. If the seat of the pilot-incommand
is not specifically designated in the flight manual or in
the operating instructions of the aircraft, the following seats shall
be regarded as the seat of the pilot-in-command:
1. the left-hand seat for aeroplanes, powered gliders and gliders
with a side-by-side seat configuration,
2. the seat to be occupied during a solo flight for aeroplanes,
powered gliders and gliders with a tandem seat configuration,
3. the right-hand seat for rotorcraft.

[My bold]

A whole new meaning to the word "Gründlichkeit" as far as I'm concerned.

Anyway, sorry for the thread drift. Back to the topic now.

[IO540]

P-RNAV in the UK is coming but oh so slowly. LTMA first. UK PBN Policy document due out later this year.

Yes; I have heard this. I am hoping that if it is delayed some more years everybody will realise it is no longer relevant to any flight and will quietly drop it :)

Also I don't see the UK CAA allowing IFR GA to be screwed. Other countries might do it without thinking.

The average cost of PRNAV compliance for GA would be at least £10k per aircraft and probably nearer to £20k by the time you do it properly, ensuring avionics interoperability with the new bit of kit you had to put in.

[Jwscud]

I don't have references immediately to hand, but I was under the impression that PRNAV was RNP1 en route whereas approach certification (IAPs not SID/STAR) was RNP0.3?

Happy to be corrected if I'm wrong

[S-Works]

But the aircraft I fly are all P-RNav-approved, it's easy for me to talk about a P-RNav world and forget the very valid point you make about the cost of the approval.

Out of interest how as that achieved, I thought your fleet were all the usual, pipers and Duchess?

[IO540]

Correct; PRNAV (http://www.ecacnav.com/content.asp?CatID=201) is RNP 1.0

From the above link

this level of navigation accuracy can be achieved using DME/DME, GPS or VOR/DME.

I'd like to know how you are going to get a < 1nm cross track error by VOR tracking ;)

A lot of the PRNAV stuff on the Eurocontrol site is suspiciously old. This doc (http://www.ecacnav.com/downloads/P-RNAV30-07.pdf) is 2003.

Page 19 6.2-1 of the above PDF is an intriguing piece of text, suggesting that an aircraft with a primary IFR GPS should be automatically PRNAV compliant :)

And 7.1-1 is an old chestnut... the "mandatory EHSI" requirement. The UK CAA agreed, several years ago, after some flight tests with a PPL/IR member, that this is not necessary. I wonder what the latest on that one is?

[englishal]

PRNav capability can be gained by installing something like a 430W installed as an IFR fit. You don't even need to have auto slewing HSI's. In an N reg, you are now PRNav approved in the USA.

To get PRNav approval in Europe you need a LOA issued by a FSDO in the USA, which will normally be issued by bringing your aircraft documents in and showing the FMS and test results (all checklists supplied by Garmin with a 430W). I can see no mention of crew training or anything else like that, and AFAIAA that is all that would need to be done to be PRNav approved.

In a G reg you'd probably have to have pink underpants, and have a funny handshake though....

[FlyingForFun]

What do you fly? Jets I assume. No, Beech Duchesses. I work as an instructor teaching CPL and IR.But the aircraft I fly are all P-RNav-approved, it's easy for me to talk about a P-RNav world and forget the very valid point you make about the cost of the approval.Out of interest how as that achieved, I thought your fleet were all the usual, pipers and Duchess? No Pipers, just Duchesses. And one Beech Sierra. But they all have approved Garmin 430 installations.

The CAA started testing candidates on RNav approaches a year ago, on condition that the school stated in advance that they would train their candidates on RNav approaches, and the aircraft the candidate tests in has an approved installation.

So we had a big drive to get them all approved. I wasn't involved in that process, so I don't really know too much about it - I just saw the certificate that came out the other end. Englishal - my boss (and the aircraft owners) may well have a funny handshake, but I really don't want to know what colour underwear they had to wear to get it to happen!

We the first school at Bournemouth to have candidates tested on RNav approaches, and they were very popular with the examiners, presumably because the examiners very rarely got to see RNav approaches themselves! I think the novelty has worn off now, though - it's been a while since any of our students have been tested on them. But they are all trained on them.

FFF
--------------

[IO540]

No, Beech Duchesses. I work as an instructor teaching CPL and IR.

They might be BRNAV approved but they definitely won't be PRNAV approved.

The total # of PRNAV approved GA pistons in all of Europe is prob99 well under 10.

BRNAV is a piece of cake. My TB20 was BRNAV off the shelf, ex factory, 10 years ago.

[bookworm]

They might be BRNAV approved but they definitely won't be PRNAV approved.

You should come to more PPL/IR Europe meetings, IO540. Weren't you at Cambridge when Paul and Anthony explained how they got the PRNAV certification?

By the way, PRNAV is (more or less) RNAV1, not RNP1. There is no requirement for on-board performance monitoring and alerting.

[FlyingForFun]

They are approved for non-precision RNav approaches. All of the CAA Staff Examiners at Bournemouth have flown RNav approaches in our aircraft after having inspected the approval.

Surely the approval for approaches (RNP0.3) will also cover PRNav (RNP1.0)? I'm not 100% on that, because we don't fly any PRNav procedures, but not only does it logically make sense, it's also implied in CAP773 (http://www.caa.co.uk/docs/33/CAP773.pdf):a system that meets the PRNAV certification (flying in the terminal area on RNAV SIDs and STARs) is required to be accurate to within 1 NM for 95% of the time, however, this still does not meet the required navigation performance for use in NPA operations(Therefore, by implication, a system which does meet the required navigation performance for use in NPA operations, such as ours, also meets the requires for PRNav?)

If that's not right, I'd be very curious as to why it's not right. I'm still fairly new to all of this, I've just about managed to get my head around the terminology used in the various types of RNav approaches, but I don't have any experience of RNav departures/arrivals, etc, and I'm ready to learn if my assumptions are wrong.

FFF
--------------

[IO540]

They are approved for non-precision RNav approaches.OK, now it makes sense.

Your FTO has got its fleet approved to fly GPS/RNAV approaches :)

That is an EASA Minor mod - easy. The procedure is similar to BRNAV and has similar equipment (annunciator location, etc) requirements to BRNAV. Similar tests for VHF interference, etc.

Surely the approval for approaches (RNP0.3) will also cover PRNav (RNP1.0)?:) :)

That kind of progressive thinking will never get you a job at Eurocontrol. As you have just discovered, this king has no clothes, and has not even had a pair of pink underpants for more than a decade.

Of course PRNAV is total bollox, when you can get a GPS approach approval.

But you must be a good citizen and think of all those poor failed ISO9000 quality managers who are pushing PRNAV. They have families to feed.

As regards a serious answer, I think it is in several parts. Your GPS needs an LOA from the mfg and not all IFR GPSs (all of which are OK for a GPS approach approval) have this LOA. Then, under EASA, it is a Major mod (4 figures). It is an AFMS under the FAA which is also a Major mod, done with a 337, but the FAA has a straight process for flight manual supplements (well, in the USA, anyway...).

N-regs also need an EHSI for PRNAV, if doing it today. G-regs don't.

You should come to more PPL/IR Europe meetings, IO540. Weren't you at Cambridge when Paul and Anthony explained how they got the PRNAV certification?That's two planes. I haven't been to the meetings for a few years.

I gather from someone in the business that they got in before the EASA clampdown. Last year a friend had a major (£30k?) avionics job done, with PRNAV paperwork, but the allegedly promised paperwork never turned up, and the last I heard from him was that he was still waiting for it but then he died - around middle of 2010.

So there are probably just two in Europe; maybe a few more around. I know loads of European IFR pilots and none of those I know appear to have the masochistic tendencies required to do this now.

It used to be quite doable on the N-reg, before the NY IFU washed its hands of avionics 337s. We both know one chap who got his plane done, in the very early days before anybody knew what this was about, by burying the FSDO under so much paper they rubber stamped it all just to be able to breathe again. Now, you have to use a "different route"...

The basic point however is that it is irrelevant to IFR flight. It's a pure job/activity creation scheme.

[bookworm]

Surely the approval for approaches (RNP0.3) will also cover PRNav (RNP1.0)? I'm not 100% on that, because we don't fly any PRNav procedures, but not only does it logically make sense

You're not the only one to use the word "logical" in that context -- so does ICAO in its PBN manual. Unfortunately...

1.2.5.3 Understanding RNAV and RNP designations
1.2.5.3.1 In cases where navigation accuracy is used as part of the designation of a navigation specification, it should be noted that navigation accuracy is only one of the many performance requirements included in a navigation specification — see Example 1.

1.2.5.3.2 Because specific performance requirements are defined for each navigation specification, an aircraft approved for an RNP specification is not automatically approved for all RNAV specifications. Similarly, an aircraft approved for an RNP or RNAV specification having a stringent accuracy requirement (e.g. RNP 0.3 specification) is not automatically approved for a navigation specification having a less stringent accuracy requirement (e.g. RNP 4).

1.2.5.3.3 It may seem logical, for example, that an aircraft approved for Basic-RNP 1 be automatically approved for RNP 4; however, this is not the case. Aircraft approved to the more stringent accuracy requirements may not necessarily meet some of the functional requirements of the navigation specification having a less stringent accuracy requirement.

[Jan Olieslagers]

The whole discussion is unlikely to be relevant for me, seeing I fly microlights that are generally supposed to stay clear of controlled airspace. Still, out of sheer curiosity: what is al this BRNAV and PRNAV and what not?

[bookworm]

That's two planes. I haven't been to the meetings for a few years.

It was a small fleet of aircraft, in fact. But the point is that it was the [i]same[i/] fleet of aircraft, the Duchesses and Sierra, that FFF flies, about which you said:

They might be BRNAV approved but they definitely won't be PRNAV approved.

Overall, I'm not disputing your point. Obtaining PRNAV approval is pointlessly, and therefore dangerously, difficult.

[FlyingForFun]

Right, I think I've got it:

- Approval for RNav approaches does not automatically include approval for PRNav
- Approval for BRNav and for RNav approaches is quite easy to get
- Approval for PRNav is more difficult to get, for no real reason except beaurocracy
- IO540 assumed, because my aircraft aren't jets, that they're not PRNav-approved
- Bookworm has attended a talk by my boss, and, based on what was said at that talk, believes my aircraft are PRNav-approved

Now that I'm at work, I've been able to dig out a couple of the certificates. In fact, IO540 and Bookworm are both only partly correct - of the first two certificates I looked at, one aircraft is PRNav-approved, and the other isn't! I'm not sure about the other two Duchesses, I'll have a look at their paperwork later.

Thanks! All is now clear as mud!

FFF
-----------

(PS - Jan, I started typing a reply to your question then lost it by mistake, haven't got time to re-type it now. I'll answer it later if no one else gets in first.)

[IO540]

Indeed it would totally amaze me if a UK FTO pushed its piston fleet through PRNAV approval, at a cost of perhaps £5k-10k per aircraft, for the paperwork (totally irrelevant for any IR training purposes, anywhere in Europe AFAICT) but a zero functional improvement.

OTOH if doing a significant avionics refit anyway, only a fool would not absolutely insist on less than PRNAV. And very very few UK shops can actually deliver that at present.

Aircraft approved to the more stringent accuracy requirements may not necessarily meet some of the functional requirements of the navigation specification having a less stringent accuracy requirement.I don't know what they are talking about. If they mandated an EHSI (enabling a multi waypoint route to be flown hands-off, with the course pointer always showing the current track, thus ruling out a mechanical HSI with GPSS retrofitted, because the CP on that does not move, compromising situational awareness) then it would make some sense. But they don't.

and therefore dangerously, difficult. "Dangerous" assumes operational relevance, no? ;)

I'd say that a Major mod requirement for TAWS would be dangerous. (it probably is, but EASA/Eurocontrol are nothing to do with aviation; it's just a nice retirement number for failed ISO9000 quality managers and other assorted control freaks).

Right, I think I've got it:

- Approval for RNav approaches does not automatically include approval for PRNavYes.

- Approval for BRNav and for RNav approaches is quite easy to getYes, generally. Subject to VHF-GPS interference checks - see AC 20-138A (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/8a2ae2491c85226f86256e35004c638b/$FILE/AC20-138A.pdf) or a similar EU spec (which I have as a PDF but the URL is now dead).

- Approval for PRNav is more difficult to get, for no real reason except beaurocracyYes.

- IO540 assumed, because my aircraft aren't jets, that they're not PRNav-approved
- Bookworm has attended a talk by my boss, and, based on what was said at that talk, believes my aircraft are PRNav-approved

Now that I'm at work, I've been able to dig out a couple of the certificates. In fact, IO540 and Bookworm are both only partly correct - of the first two certificates I looked at, one aircraft is PRNav-approved, and the other isn't! I'm not sure about the other two Duchesses, I'll have a look at their paperwork later.Amazing. I wonder why any FTO would bother at all.

[SNS3Guppy]

RNAV is OK. I don't have an issue with that, because as I said RNAV is de facto necessary just to fly in the IFR enroute system.

That's definitely not the case. GPS, RNAV, and little magenta lines aren't necessary to operate in the enroute environment. They're nice toys, but they definitely aren't necessary.

[IO540]

That's definitely not the case. GPS, RNAV, and little magenta lines aren't necessary to operate in the enroute environment. They're nice toys, but they definitely aren't necessary.

One day, Guppy, we will all work out which part of the known universe you fly in, IFR, enroute, Eurocontrol airspace.

It's not Europe, for sure.

Without BRNAV you are illegal anyway, in any practical flight. Personally I wouldn't write about doing it, just in case you get rumbled one day.

[SNS3Guppy]

It's illegal to fly using a VOR on an airway from A to B in Europe?

It's certainly not that way throughout the rest of the world. Perhaps if you'd suggested that one can't fly without RNAV in your small corner of the world, you'd have been more accurate.

Imagine, the ability to move from A to B without a magenta line. How fantastic and mystical that must seem to you.

[IO540]

1) On a private flight (i.e. non-AOC, so there is no company procedures manual approved by the national CAA) you are allowed to use any means of navigation you wish, including the proverbial tuna sandwich (https://groups.google.com/group/rec.aviation.ifr/browse_thread/thread/c4f89da4e362617/896021daae66139e?hl=en&ie=UTF-8&q=%22tuna+sandwich%22+aviation#896021daae66139e)

2) In Euro airspace, the carriage of a BRNAV approved navigation receiver is mandatory. In the context of currently manufactured civilian avionics this can be met only with a) INS or b) an IFR GPS.

3) ATC watch you like a hawk and expect precision performance. When they say "DCT XYZ" and 20 seconds later you are still pointing 10 degrees away, they are onto you, even though at that point your lateral track error is probably only a mile or two. Evidently they watch the computer-extrapolated track...

So, in Europe, "total RNAV" is a done deal and the only question is whether you are doing it with an FMS (with DME/DME or GPS corrections) or directly with a GPS. It's obviously very easy and effortless to fly this way.

If you lose RNAV capability you need to advise ATC, and they will either give you vectors, or give you some VOR-able route.

BRNAV does not (currently) apply below FL095, but if you want to see the feasibility of developing valid routes around Eurocontrol-land below FL095, download a copy of this (http://flightplanpro.eu/Home.html) and have a little play, setting the max level to FL095, and see how far you get before you run out of juice ;) Actually it works in some places, like France.

PRNAV is something else....

[SNS3Guppy]

How exactly does one navigate with a tuna sandwich?

[Final 3 Greens]

He didn't say you can navigate with a Tuna sandwich, he said you are allowed allowed to.

Any fool knows that a smoked salmon bagel is the navtool of choice.

[IO540]

The key is that in the private flight context

equipment required to be carried

is not the same as

equipment actually used

So it is legal to navigate with a smoked salmon roll (I agree BTW, though parma ham is even better) but you have to carry a BRNAV approved GPS.

No kidding.

[SNS3Guppy]

I believe both the Tuna and the Smoked Salmon Bagle methods are only appropriate for water routes, or routes within 150 nautical miles of a bona fide salt water body.

Christie Brinkley doesn't count.

[bookworm]

Indeed it would totally amaze me if a UK FTO pushed its piston fleet through PRNAV approval, at a cost of perhaps £5k-10k per aircraft, for the paperwork (totally irrelevant for any IR training purposes, anywhere in Europe AFAICT) but a zero functional improvement.

The paperwork cost was in this case quite low, because the approval was sought in conjunction with GPS approach approval. It was a single mod at the time. From memory, it was nothing like as high as the costs you mention.

"Dangerous" assumes operational relevance, no?

No it just assumes that money, concentration and time spent on pointless certification could be spent on something that makes a genuine difference to safety instead.

[IO540]

I recall a post by a well known avionics shop man saying that the PPL/IR examples got in as a minor mod but that EASA have within the past few months blocked that route.

A pure RNAV approach approval remains an EASA minor mod.

(FWIW, on an N-reg I don't know of a way of getting the 337+AFMS approved. I have some contacts but nothing concrete. It's probably done by submitting the papers to a US FSDO via a contact in the USA).

I agree regarding the safety angle, of course. But I don't see any evidence that EASA policy runs on safety. Everything I see is driven by blatent in-your-face work creation. It may just be a coincidence that work creation and safety go hand in hand but why is the work creation angle always so obvious while the safety angle remains so non-transparent?

[421C]

FWIW, on an N-reg I don't know of a way of getting the 337+AFMS approved. I have some contacts but nothing concrete. It's probably done by submitting the papers to a US FSDO via a contact in the USA


This is a problem for IFR approval in general for the N-reg (where you do need a 337) but not for PRNAV where there is an existing IFR approved GPS and it is PRNAV compliant. You do not have to have a Flight Manual Supplement, TGL10 permits a compliance statement. Therefore it is just a matter of documenting TGL10 compliance (iaw AC90-96A) and applying to the NY IFO for an LoA. I am not aware of this requirement for an EHSI - where did this come from?

[IO540]

You do not have to have a Flight Manual Supplement, TGL10 permits a compliance statement.

Doesn't TGL10 apply only to EU-regs?

Interesting... obviously one needs a Garmin x30/W or similar to get the LoA.

I am not aware of this requirement for an EHSI - where did this come from?

Travis posted it.

I never found any mention of it in the US "pilot hangouts" but then I wouldn't because the FAA grandfathered all N-regs with an IFR GPS to PRNAV compliance, in US airspace, and 99.x% of US private pilots never leave US airspace especially for anywhere where anybody knows what PRNAV is.

[wigglyamp]

The requirement for an EHSI comes from Section 7.1 of TGL-10, box 1.

The course selector of the deviation display shall be automatically slaved to the RNAV computed path.

EASA have accepted that for smaller Part 23 aircraft of relatively low speed (we have suggested max cruising below 150kts initially), that an auto-slewed H.S.I may not be required as the pilot will have time to adjust the course pointer manually at a leg change and re-position the aircraft to the new track without going outside PRNav limits.

[Johnm]

Already doing it with GNS430W and a CDI connected to autopilot in heading mode and it works perfectly. Is it legal? Don't know don't care.

[IO540]

EASA have accepted that for smaller Part 23 aircraft of relatively low speed (we have suggested max cruising below 150kts initially), that an auto-slewed H.S.I may not be required as the pilot will have time to adjust the course pointer manually at a leg change and re-position the aircraft to the new track without going outside PRNav limits.

There is also the "alternative means of compliance" text, later in the same para :)

All very much debated over the years :) PPL/IR have banged on the CAA about this for years, including doing flight testing with a CAA official who accepted that an EHSI is not required.

[englishal]

EHSI is not required under the N reg to get a LOA as far as I am aware.

[421C]

The requirement for an EHSI comes from Section 7.1 of TGL-10, box 1
As IO says, at the end of TGL10 7.1 box 1, it says:
"An acceptable alternative is a navigation map display readily, visible to the flight crew, with appropriate map scales and giving equivalent functionality to the lateral deviation display, except that scaling may be set manually by the pilot"

[IO540]

Gosh, that is really clever. That is a moving map GPS. How much did some ex ISO9000 quality manager get paid to compose that Shakespearian description? Must be careful though; Germans take ISO9000 deadly seriously so JAA probably had to pay him loads of euros to lure him away from his previous cushy number. I bet he never knew he would be immortalised as the first man (or possibly a woman?) to invent a whole new name for a moving map GPS.

Anyway, the full unedited garbage of TGL10 is here (http://www.ecacnav.com/downloads/TGL10%20rev.1.pdf) and the relevant text is in the middle of page 8 of the PDF.

[Immortal]

I was searching info about PRNAV and came acros this thread. Found this website at Eurocontrol: EUROCONTROL Navigation Domain - Approval Status (http://www.ecacnav.com/content.asp?CatID=208)

The Garmin 400 - 500 series is listed as compliant to JAA TGL10.

So I assume that makes al the Garmin 430 installations on a IFR platform PRNAV approved. Or do I miss something here?

[peterh337]

The 430/530 GPS is PRNAV approvable.

The installation is not however. There is a process for doing that, which the status of the GPS itself merely makes possible.

I don't know any more detail. I think there are some documents on PPL/IR (http://www.pplir.org) about it. This PRNAV thing has been going back and forth for years now and I have stopped following it.

The number of GA planes that are PRNAV approved can be counted on your fingers. The pilot also needs some kind of approval.

It's all a load of Euro bollox.

[micsve]

We went thru the PRNAV process 6 years ago, the approval in itself was just a matter of showing our CAA the appropriate documents and wasnt very expensive, less than 200 Euros if I remember it correctly. We did this after we had made a major upgrade to the panel (100kEuro), since it was a major mod we already had all the documents they were asking for. And since EASA requires a typerating and HPA for the PA46 we as pilots were already approved since the HPA included it... So all in all I believe the approval was a nonevent, uppgrading the aircraft however was a whole different story with avionic shops trying to dig really deep into your pockets by not telling you the small things like the fact that you can get a PRNAV approval flying manual so you really dont need that approved rollsteering computer for the AP...
By the way this was in Sweden, UK CAA I have no experience with.

[peterh337]

That's interesting. Especially that your local CAA demanded (or the avionics shop demanded) roll steering.

There were "easy" avenues years ago, before the powers to be got their heads around it. I know somebody on the N-reg who got PRNAV approval from the FAA by basically burying them with documents on how well equipped his aircraft is and how experienced a pilot he is, courses attended, ect (AIUI). Today, the FAA process is not hard and I know of somebody who claims he can arrange it for $600 - provided you have the correct equipment installed. There are claims going around that the FAA requires course pointer auto-slew (which is not the same as roll steering but the end result is similar for autopilot operation) but I now gather that is not true.

The FAA gives automatic PRNAV approval to all aircraft which are IFR approved (e.g. for flying GPS approaches) which makes completely logical sense since PRNAV is RNP1.0 (IIRC) whereas GPS/RNAV approaches are RNP0.3, but this is not valid in EU airspace, in which the air is different (it's thinner) so the airplanes fly less accurately due to the higher AoA.

EASA is something else. It's a Major Mod allright but I don't know the details.

Incidentally, why did you go for the approval?

[micsve]

We went for it to save time.... When our bird was in the avionics shop (took 2 months) we chartered a jet, and with the jet we never got to fly the long STAR that we always got with the PA46. I asked about the reason and the answer was that if you had PRNAV the controller was able to give you a different route, so we looked into the possibillity to get the approval and since it wasnt any big things we needed to do we went for it...We have been saving roughly 20 min flying time every week since then...Huge cost saving for us :ok:

The rollsteering is needed if you want to be able to fly on AP, we didnt know at the time that you are allowed to fly PRNAV manually. In the jet we always flew on AP so we never questioned it...However another PA46 in Sweden got the approval with the restriction to fly manual, CAA had something against his S-TEC AP, we have King.

[GWYN]

For what it is worth, and it is of no consolation whatever, GA and lighties are not the only ones with these PRNAV problems.

It really is, (put Single European Sky, mandatory ADSB, CPDLC etc. etc in the same category), a load of Euro bollox. Those were Peterh's words, I could not possibly bring myself to use such words about the dreams of the inhabitants of the ivory towers.

Airlines also are faced with HUGE bills and logistical / equipage problems owing to this nonsense. Imagine a jet plying the airways to many ports in Europe many of which suddenly have only PRNAV approaches. That means the FMS database has to contain all the approaches and waypoints for all the European PRNAV airports to which it is likely to fly. Sadly the FMS in these aircraft, have unbelievably limited memory. Including all these procedures exceeds the capacity of the box. So it requires amongst other things an FMS upgrade at a few $100K a pop. Then there's the crew training etc., etc. Then consider, all these aircraft in Europe need access to an avionics shop but guess what? The time required for all these refits will stretch way beyond the mandatory compliance date. Oh Bugger! Oh, and who do you think will pick up the bill? One guess!

I actually believe that the Euro (aviation) dream has overstretched itself, specifically with the ETS fiasco where it is about to be challenged by the world's major developing power, (China). Sooner or later someone is going to stand up to these people and say, "NO!" and the whole edifice will come tumbling down. The EASA/Eurocontrol zealots seem to be hell bent on making aviation, both private and commercial, all but impossible.

I can only say, I guess the eleventh commandment applies!

[peterh337]

I guess the eleventh commandment applies! which makes me ask...

and with the jet we never got to fly the long STAR that we always got with the PA46. I asked about the reason and the answer was that if you had PRNAV the controller was able to give you a different route,how did ATC know you have PRNAV approval in the jet?

In theory there is a database of PRNAV approved aircraft, which in theory is accessible to ATC, which in theory could be done in real time.

If you look at e.g. Zurich, which last time I looked was totally closed to all non PRNAV IFR traffic, how does this work? It's obvious that ATC there don't operate the system anyway.

Airlines also are faced with HUGE bills

Why don't the airlines get together and tell Eurocontrol to get stuffed? I went to a Eurocontrol "navigation workshop" a few years ago (a complete farce, basically) in which they claimed that they are under huge pressure from the airlines to reduce the route charges, so they wanted to dismantle the radar network and replace it with ADS-B. Notwithstanding the absurdity of this "solution" it did appear they are concerned about what airlines tell them... or so it looked.

[micsve]

how did ATC know you have PRNAV approval in the jet?


Well I dont know for sure but I have always assumed it was be because we gave them that info in the flightplan.(P in field 10 equipment) But if it works in some other way please enlighten me :O

[peterh337]

Hadn't thought of that :E

So, what stops anybody from just putting the P in their flight plan?

[M609]

Nothing, but you might feel like a prat when ATC is telling you off for not following a P-RNAV transition accurately.... :ok:

In reality the oposite is more common, biz jets forgettin to put the P in.

[Denti]

A big driver of going the PRNAV way is ATC procedure design. It simply costs way too much airspace designing those nifty arrival transitions and departure routes within the limits of BRNAV (which is equivalent to RNAV5). If the transition downwind and inbound are 3NM (heard 5NM somewhere) apart they are PRNAV compliant, to design the same in BRNAV requires 5 times more space.

But yes, it does hurt airlines as well, however they do have some more or less clever ways around it. We had to get PRNAV approval on our 737 classic fleet for its last 3 years, which required us to get new FMC boxes at around 100k$ per plane (to upgrade the memory from 192kb to around 1MB). There is simply no business case to make up that kind of money within 2 or 3 years, but there is the possibility to lease those boxes, which is what we did.

[peterh337]

It simply costs way too much airspace designing those nifty arrival transitions

How often do ATC operate the published arrival procedures?

IME (light GA) the answer, in N Europe, is "never". One may be assigned a STAR but then one gets radar vectored to the localiser.

In southern Europe, e.g. Greece, they tend to operate the STARs, but it seems to depend a lot on whether there is a radar controller.

[GWYN]

Peterh you are of course absolutely correct. The STAR is seldom ever actually flown. One of the most commonly heard phrases in ATC: XX cancel STAR turn left / right heading YYY. So the design of the SID/STAR is practically immaterial.

I would also be interested to know why the careful design of the PRNAV STARs has resulted in procedures which complete about three S-shapes before intercepting the final approach track, and which are about 3 times the length of the conventional STAR. It rather smacks of the bureaucracy creating something which in a year or two they can tidy up and then claim credit for reducing the mileage and hence carbon emissions and "Hey, European Commission, aren't we clever boys, and can we have some more funding please?" Just a bit like the meeting in Morocco this week: the Moroccans introduced some 'directs' to improve routings out of the Canaries. But, hey that wasn't Eurocontrol's idea so the routes get rejected by IFPS. So now it will be Eurocontrol's idea and all in Brussels will add it to their KPIs and claim credit for carbon reduction.

As for PRNAV, yes it is indicated by a P in field 10 on the flight plan form. How many controllers actually know what all those different letters mean on the flight plan form? Not many, I would suggest. They rely on the pilot saying, "PRNAV unable" and then of course they will do what they always do and vector the aircraft to the ILS.

Peterh, yes, many of us have been to these Eurocontrol meetings/workshops and yes there are some of us for whom the Emperor has no clothes. Sadly there is a core group of 'meetings men' who spend their whole time trekking around Europe attending one of these meetings after another. I could mention the man from AB who does nothing else. It is in their interest to perpetuate all these meetings or else, God forbid, they may have to stay in the office and do some work. One or two others, like you and me, drift in and out and vow never to waste our time going to another one of these farces again!

[10W]

How many controllers actually know what all those different letters mean on the flight plan form? Not many, I would suggest. They rely on the pilot saying, "PRNAV unable" and then of course they will do what they always do and vector the aircraft to the ILS.


Many controllers have Flight Data Processing Systems which tell them the aircraft equippage for each flight. We certainly do for RVSM, 8.33, and PRNAV capability, all of which comes from the flight plan.

[GWYN]

Thanks for that 10W.

Are you able to tell us the separation standards for PRNAV and non-PRNAV equipped aeroplanes?

[M609]

I don´t know any airspace where separation standards are connected to RNAV.

But: When working PRNAV flights there is less need to lock aircrafts on headings during "close" crossings etc. In our TMA I can climb one aircraft on a SID that is 6nm from a STAR without having to lock anyone on headings, i.e it is less workload intensive. (separation in such situations 5nm, not 3)

Same situation last year, before we went all PRNAV, you could not trust aircraft to stick to the SID/STAR centerline, and you had to radar vector much more, and by that creating much more workload.

[peterh337]

you could not trust aircraft to stick to the SID/STAR centerline

In purely technical (avionics) terms, I cannot understand that.

Both DME/DME corrected INS, and GPS, are capable of keeping you (on autopilot) within a few tens of metres of the programmed track.

PRNAV does not in the slightest way affect lateral navigation accuracy.

Is this some ATC-procedural thing? Or perhaps you had airliners which were flying non-RNAV sids/stars using some old FMS which used VOR/DME as the nav source?

[GWYN]

Thanks for your input M609.

I don't understand, notwithstanding what Peter says, why a conventional or RNAV SID/STAR should require you to "lock anyone on headings" any more or less than the PRNAV version.

[10W]

In domestic European airspace there is generally no different separation standard between aircraft based on their navigation capabilities. This is because they will either be separated or monitored by using radar (which is not dependent on aircraft fit), or by route structure (which is dependent upon the RNP value designated for the route).

Radar separation varies from 2.5NM on final approach to 10NM en route, or sometimes even greater.

Route separation is mostly based on BRNAV at the moment, which is RNP-5.

For radar monitored parallel RNP-5 routes, ICAO suggest a minimum distance between the route centre lines of 10NM-15NM. In practice, I think our UK designers go for 12NM. If it is that spacing or more, then monitoring is all that is required. If it is less, then the routes are not deemed separated and our rules usually say that appropriate radar or vertical separation must be provided.

For RNP-5 routes which are separated procedurally, and the only 'surveillance' is from pilot position reports, the ICAO recommendation is 16.5NM between the centre lines for uni-directional routes and 18NM for bi-directional routes.

PRNAV equates to RNP-1. I have not seen any formal confirmation yet, but previous concept documents I have seen were suggesting that for radar monitored RNP-1 routes, the spacing would be 7NM and for procedural routes would be 10NM.

In TMA airspace, even lower RNP values might be achievable, but by interpolation of guidance material, would still only offer a slightly decreased route separation value, which in any case could never come below the separation standard value of the surveillance equipment being used. If you went for RNP-0.3, the minimum route separation for routes which are monitored by surveillance would be in the order of 3.6NM for uni-directional routes. You would then of course have to assess the risk of being able to pass a corrective action in the event of a deviation between aircraft only 3.6NM apart in enough time to prevent a collision. Fortunately that kind of decision is way above my pay grade :ok:

[M609]

Or perhaps you had airliners which were flying non-RNAV sids/stars using some old FMS which used VOR/DME as the nav source?

Nope, not as long as you don't count RJ85s, ATRs and such as old.

Our "old" stars where conventional with RNAV overlay, and even on straight sections of stars some customers often wandered off centerline 2-3nm, and when asked said they where "on magenta line". Back then we did not focus much on the RNAV status on the aircraft, but surprise-surprise when we went PRNAV last year, the handling of BRNAV flights singled out some customers, and the "offenders" was all among them.

You are right that many BRNAV a/c are fully capable of flying very accurately, which is nice for us, but as long as some don't, we can't count on it.

And that brings us to what GWYN asks about.
On BRNAV procedures experience shows that a/c often overshoots turns with several miles, even on fly via points, not all the time, but several times each day. On PRNAV procedures my experience is that a/c nail the turns rolling out on the next segment each time.

(When it happens nowadays, the crew mostly confess to having gone into heading mode or some such, and not trusting the box. Or cancelling the procedure in the FMS, and wandering off whilst trying to put it back in, without telling ATC :D)

When i have a SID that turns parallell to a STAR with say 7nm, any overshoot on that turn will mean a loss of separation, so with BRNAV you would never design them that close, or you would use vertival separation until the turn was observed to be accurate, or turn the departure onto the desired heading earlier to assure separation. Hence increase worload.

With PRNAV procedures that are properly designed, you can IMHO shift more aircraft in a given volume of airspace with the same staff and ATM equipment.

But: For GA IFR you will as peter correctly states seldom fly a SiD or STAR, and the issue is speed. Modern terminal procedures are designed to manage a even flow of aircraft, i.e capable of flying arrivals at speeds in the low 200s in clean config. Departures will often see the use of "prop" SIDs for turboprops, since performance is more diverse in climb.

In your GA hotship tourer you will often be the slow boy, even for prop departures, and ATC want to move you away from the flow.

[peterh337]

M609 - I think what you describe by e,g,

and even on straight sections of stars some customers often wandered off centerline 2-3nm,is something pretty weird going on, and it either creates big questions about how crappy nav gear they have in [some] airliners, or the pilots weren't using it.

I know that INS (without GPS corrections) can easily be a few nm off track on oceanic routes but this should never happen over mainland Europe.

Basically, when the procedure track is loaded (either from the database or by manually loading the waypoints) the aircraft should be within about 1/4 mile on all sections where major turns are not taking place. That is where I would be, with a crappy mid-1990s GPS and a late-1990s autopilot.

And I have no GPSS / roll steering. All modern jets (those that can fly holds on autopilot for example) ought to have computed turns.

Something very weird is going on...

What seems to have happened for you with PRNAV introduction is not really PRNAV introduction but a change of cockpit procedures to actually use the stuff they have had for many years. Even with VOR tracking one should not be 2nm off track (at say < 30D) unless somebody is not paying attention, or they are using a dodgy avionics shop :)

PRNAV is a boat which left the harbour about 15 years ago. The fact that GPS/RNAV approaches are equivalent to RNP0.3 makes PRNAV, with its massive costs, a pointless exercise. Even at GA level, PRNAV cannot be done for less than 5 digits and for most IFR aircraft it will mean a huge retrofit - for no extra functionality but just to get the "boxes" for which the manufacturer has produced the PRNAV LoA (etc). But in this business there are always people who are looking for work and PRNAV is a good gravy train to jump on. Almost as good as AIDS research...

[GWYN]

Interesting stuff. Thanks M609 for your explanations. Peterh, I'm with you all the way up to the AIDS research. AIDS, Malaria etc. are still serious diseases and deserving of research and the type of fundamental research involved often produces discoveries and benefits not necessarily related to the original research subject. Now if you were to start talking about the general level of panic and hysteria surrounding AIDS, BSE, Avian 'flu, SARS, Volcanic Ash, etc., etc., and the predicted mass fatalities resulting, I would definitely be with you on that as well.

I still don't understand the claimed benefits of PRNAV though. M609, you state that, "With PRNAV procedures that are properly designed, you can IMHO shift more aircraft in a given volume of airspace with the same staff and ATM equipment." I respect your opinion as one who is apparently involved at the 'sharp end' of this but you do say that this is only your opinion. Is there any real evidence that this is the case and if so I still don't really understand how.

You also however say that, "(When it happens nowadays, the crew mostly confess to having gone into heading mode or some such, and not trusting the box. Or cancelling the procedure in the FMS, and wandering off whilst trying to put it back in, without telling ATC." So even with PRNAV there is, of course, still no guarantee that aircraft will be where the procedure says they should be. So all of the design to put tracks closer together seems simply to be a degradation of safety.

Surely, "When i have a SID that turns parallell to a STAR with say 7nm, any overshoot on that turn will mean a loss of separation, so with BRNAV you would never design them that close, or you would use vertival separation until the turn was observed to be accurate, or turn the departure onto the desired heading earlier to assure separation. Hence increase worload. " if the tracks are that close, then it would be foolhardy in any case, PRNAV or not, to not have an element of vertical separation for just the reason which you describe.

As a related remark in all this I could mention at least one airline, which while PRNAV equipped and approved, chooses not to put the "P" on the FPL as the PRNAV procedures add so much extra track mileage that it would add significantly to costs.

While we are on this type of subject and have M609's attention, perhaps you would give us your take on another of the dreams of the 'Gravy train committees,' the 'point merge' procedures? What on earth is that all about?

10W, you make exactly my point: there is no difference in separation standards and in European airspace aircraft are continuously radar monitored. So what is the benefit of PRNAV, RNP - and ADSB in Europe, come to that?

Back when I were a lad and things were simple(r), they larned I at skool, that an airway was a corridor of airspace whose limits were defined vertically and which extended five miles either side of the centreline, i.e was 10nm wide. I am still unclear as to whether this has changed or what effect all this RNP stuff actually has in practice. I still don't really see how it improves 'flight efficiency' which is another of the committees' 'metrics.' I hope you appreciate my use of all the jargon!

It is interesting that, 10W, you also state that, "In TMA airspace, even lower RNP values might be achievable, but by interpolation of guidance material, would still only offer a slightly decreased route separation value, which in any case could never come below the separation standard value of the surveillance equipment being used." So you agree that what is really important is the surveillance equipment being used, i.e. radar, not so much what is on the aircraft or what it is called. Ultimately the limits, particularly in a congested TMA, are mostly defined by physical constraints, particularly separation required due to wake turbulence requirements and no amount of mandating upgraded on-board equipment is going to change that. Only a change in aircraft design or maybe the laws of physics! As to procedural separation, I would be interested to know where, in European non-oceanic airspace, there is normally en-route procedural separation.

[mad_jock]

creates big questions about how crappy nav gear they have in [some] airliners

Its a statement of fact, its not uncommon for the old **** haulers to have one beam bar showing of to the right by half a dot and the other one showing half to the left in VOR mode and the GPS showing you going plumb up the middle. The VOR tracking mode on the AP is the work of satan and the thing wanders "S"ing up the radial. Everyone has a play with it and then never uses it apart from VOR approaches. And I could well imagine it deviating by 2-3 miles.

If your in heading mode, basically crew cockup, turn points are missed, wind changes arn't spotted and the tracking goes off. Alot of the machines you can't slave the AP to the GPS or if you do you use the VOR capture mode which I have already said is the work of satan and would make me feel sick never mind the punters in the back.

The only thing that will sort this is by tightening up the instrument limits and having a third party instrument C of A every 12 months which the airlines will lobby like :mad: not to have. If say you report a 5 knts split between airspeed indicators they won't actually fix it because the limit is 6 knts each ASI is allowed +- 3 knts. And then you get the sodding machine does something different in the air than it does on the test rig on the ground.

There are several levels of LNAV in my experence.

1. Go get straight line only which the controllers will spot because they get to a point then turn if the crew are leaving the machine to do its own thing.

2.You get circular nav which means they can fly dme arcs and holds etc. But will still go to the point then turn

3. And then you get the predictive turn ones which have logic to swing by points and start turns before you get to the point and will also vary the distance to the point when the turn is wound in depending on the GS and angle to be turned through.

Sometimes it can be the same hardware but with a different software level. But they won't upgrade it because that would cost 50k.

Then there is training, some training folk say you can't start turning until you with x amount of a point this can vary between 0.5 miles and 5. I have looked for a reference for this years ago but couldn't find it. Then you have crews taking the piss and cutting the corner edging round it from 10 miles out.

[peterh337]

OK, an interesting lesson on supposedly crappy airliner avionics (I would have my two VOR receivers adjusted if they were more than 1 degree out on the 30 day FAA mandatory VOR check; it is a simple matter of getting an IFR4000 tester and removing one of the four fixing screws) but I don't see the connection with PRNAV improving things for ATC because the aircraft must be BRNAV approved and you cannot do that with just VOR receivers.

My comment about AIDS research was flippant, GWYN :) Just referring to how many people would be out of a job if the problem was ever solved.

[GWYN]

Actually one or two bits of my contributions are a little bit tongue-in-cheek as well. I leave you to guess which!

[mad_jock]

BRNAV is for area navigation not terminal navigation. Basically below FL100 your not meant to use it (but we all do). SIDS and STARS will all reference a radio aid if you do a PRNAV SID and STAR the points can just be abstract points in space with no reference to a radio aid.

Thats my understanding on it anyway.

Without PRNAV they have to expect that the aircraft will deviate to the max of the allowed instrument error so each nav aid will have a one dot cone coming out of it which is the max deviation. Then from the edge of that cone they then seperate to the max edge of another cone.

Which is actaully where some noise planners fall foul because they prescribe routes which are outside the nav tolerances of the aircraft.

[peterh337]

BRNAV is for area navigation not terminal navigation. Basically below FL100 your not meant to use it (but we all do). .I don't understand that.

BRNAV is a certain level of lateral accuracy. It is available to you whenever you are flying according to some form of track guidance.

Are you saying there are passenger or cargo jets flying in Europe which fly using the FMS (i.e. INS with DME/DME or GPS corrections) when enroute, and after they cross the terminating waypoint of the enroute section, and if flying a non RNAV STAR, they track VORs until the IAF?

If so, who is doing that and what in?

If that is really common then I can see PRNAV is a huge spanner in the works because they will all have to rip out most of their panel.

Any half decent GA IFR tourer can auto-fly (perhaps with the pilot hand turning the course pointer, if he has a mechanical HSI and doesn't have GPSS) the whole enroute and terminal path with ~ 1/4nm lateral accuracy all the way to the IAF and then intercept and track the ILS to 200ft AGL.

SIDS and STARS will all reference a radio aid if you do a PRNAV SID and STAR the points can just be abstract points in space with no reference to a radio aid

Only non RNAV sids/stars reference navaids for the entire track to the IAF. RNAV ones don't (for the most part of the track distance) and same for PRNAV ones.

[GWYN]

BRNAV is for area navigation not terminal navigation. Basically below FL100 your not meant to use it (but we all do). That's a bit of a surprise. Where did that come from?

This is all very entertaining but apart from M609's considered opinion, we don't seem to be unearthing the underlying benefits of PRNAV and how it is going to unlock capacity.

Mad jock (is there another sort??? - only joking! Please take it as such.) also touches on another point: increased accuracy in flying the SID can have the effect of concentrating the noise. This has already happened: where noise was acceptable because it was spread, increased adherence to the precise SID has meant that the same (groups of) houses are always receiving the whole noise benefit of jets at full chat.

[peterh337]

I was talking to a fairly senior ATCO at LHR during an ATC visit at West Drayton (several years ago) and he said PRNAV is a load of crap because ATC will always radar vector traffic.

He explained (and this has also been written by other ATCOs known to be senior on the UK scene) that if radar failed, the capacity of all these airports would instantly collapse to a fraction of the present. So they have very good backups for their radars.

That makes complete sense, but it beggars belief that so much effort has been expended into designing 42 STARs (just counted them) for LHR, which are probably never actually flown, and 32 SIDs which are probably partly flown before radar vectoring takes over.

Interestingly, none of the LHR STARs are RNAV, never mind PRNAV. So what is it that has driven the all-PRNAV airports when Heathrow, which is claimed to be the busiest on the earth / the universe / etc seems to manage with procedures which you could fly in a stock 1970 C150 :)

Could it be that the LHR STARs are never actually flown as published, whereas at say Vienna they have gone for ludicrously convoluted RNAV transitions (but I notice they still retain radar vectoring for "non RNAV" aircraft)?

Do they have a different class of aircraft going into LOWW which can perfectly self-separate by flying at 220kt +/- 1kt (or whatever), all tracking the RNAV tracks with perfectly computed and wind-corrected fly-by and fly-through waypoint performance? I know s0d-all about airline autopilots but I understand that even the new ones do not fly precisely calculated wind corrected track intercepts. I know the capability exists on fairly modern avionics to do this in zero wind...

Or, just perhaps, has somebody created a lot of work by designing all these procedures which, should they actually have to be operated for real, the said airport's capacity will collapse?

When I last flew into Zurich (another similar place) they assigned me a PRNAV SID which I refused but they just said "fly the overlay". No overlay is published but the message was clear (ATC there couldn't care less).

increased adherence to the precise SID has meant that the same (groups of) houses are always receiving the whole noise benefit of jets at full chat.

But surely this issue will not go away, because most jets fly mostly on autopilot and navigation with modern kit is now so accurate that one jet could fly into the back of another one, if timed procedural separation (as over e.g. Africa) failed.

[mad_jock]

Define FMS though your NG's and new airbuses have them and heavys but most of your regional stuff doesn't have them. I don't know what the Q400 and Saab2000 has they are as about as new as you get for regional TP kit.

The 146 etc don't have them.

Normally you need the VOR up for setting up the hold as you come to the end of the star.

Heading into a procedural field you would have the vor up on primary again for joining the hold and for your outbound. You can't decend until you get half scale deflection.

Certainly the 15 departure from BHX heading north was always a flurry of DME holds and VOR's getting tuned in.

LHR ATC are not always the best ones to ask because they are working in a very controlled enviroment. Ask a controller from Newcastle,Leeds or the like and you will get a different responce. Its a very British thing to radar vector everything. The likes of Helsinki or Oslo you will get given an approach and you will complete it without another word said once cleared for it apart from QSY to tower.

[Denti]

Saab 2000 new? Its out of production for 10 years now. The 146 even longer. Both are basically gone in most of europe, nowadays its jungle jets or Q400s, the odd ATR inbetween. Most of those have a full FMS and are of course completely PRNAV aproved.

Anyway, while vectors are common, transitions are widely used now as well. And some airports use quite a lot of their STARs as well. As mad_jock says many scandinavian airports use STARs and only very rarely use vectors. Even though major german airports do not use STARs they do use transitions, which have usually two opposite directions which are pretty closely spaced, oh VIE does as well. Was quite surprised on my first approach to gothenburg to get nearly 80NM out a clearance for SID and ILS, next was the frequency change to tower and a landing clearance there. Very quiet approach, but worked very nice.

[GWYN]

But surely this issue will not go away, because most jets fly mostly on autopilot and navigation with modern kit is now so accurate that one jet could fly into the back of another one, if timed procedural separation (as over e.g. Africa) failed.

I thought someone would pick up on the converse and say that surely if these procedures are so accurate, then surely that means the noise can be concentrated in the (maybe uninhabited) other areas. Swings and roundabouts, I guess.http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif

You are of course correct on both points: it will not go away and also, yes your other point is correct too, although it doesn't necessarily need a failure of procedural separation. See http://www.pprune.org/rumours-news/246031-mid-air-collision-over-brasil.html, GOL 737 vs Legacy over Brazil. Head-on rather than into the back of the other but you will understand my point.

I say again, though: this is all very entertaining but apart from M609's considered opinion, we don't seem to be unearthing the underlying benefits of PRNAV and how it is going to unlock capacity. I have added 'point merge' to that question now as well.

The rest of the discussion is interesting but does not really answer the question, "What's it for Mister?"

[peterh337]

The basic point is that you don't need PRNAV to end up with an avionics fit where your autopilot can track a preloaded arrival track.

My old KLN94 (http://www.sea-avionics.com/lc/cart.php?target=productDetails&model=KLN-94&substring=kln94) ($5k or so when new) can do all this, except it doesn't have the RNAV procedures whole in its database (it has the waypoints by name). An almost equally ancient GNS430 (http://www.sea-avionics.com/lc/cart.php?target=productDetails&model=GNS-430&substring=gns430) does have them (AFAIK) so that's you done and dusted.

No need for PRNAV.

[MIKECR]

MJ,

The Saabs(2000 as well as 340) all have full FMS. PRNAV too. The Q400, ATR, Dornier 328 have all full FMS as well.

[M609]

The Saabs(2000 as well as 340) all have full FMS. PRNAV too. The Q400, ATR, Dornier 328 have all full FMS as well.

Aircraft CAN have it yes, but far from all of them do. All ATRs and Saabs we handle on a daily basis are BRNAV only. We even have some A320 series pitching up without PRNAV, but they are often chartered stuff flying for weird airlines no one has heard of.

peter: As far as the "fly the overlay" is the easy way for ATC to guide you into the terminal area, as it saves them a lot (potentially) of verctoring. They still have to consider you "wandering off".

The way we shift BRNAV aircraft is to route them via the TMA STAR entry fix, and DCT another fix further into the TMA, then vectors from there. The feeder sectors will give that as standard, and it is in our LoA. Still means I have to consider them deviating from that track, and they do, whatever you might think.

As far as it being reckless designing procedures close together in PRNAV, even when we see some deviations: The point is that deviations from PRNAV A/C are very rare, and some freak deviations we have to expect, and react to tactically. The procedures are designed for the best strategic result.

As for Point Merge System, what do you want to know? It works well in many traffic situations, escpecially in high traffic load.
And I have first hand experience, as one of around 25 controllers in the world that use it with live traffic :ok: :ok:

Yes, it has drawbacks, and our procedures need some tweaking, because there are some things you can only find working real airplanes. Simulators cannot replicate everything, and that´s the price for being "launch customer".

Point Merge is not for every airport, or every set of airspace.

[MIKECR]

If they dont already have it M609, then most I believe will do. Our FMS's are all upgraded and ready.

[mad_jock]

Fair enough and doing a search it appears that the GNS/XLS is counted as a FMS these days and is also PRNAV (with a software upgrade). I have a reasonable bit of time on them.

I always took FMS to be able to do VNAV and link into the vertical modes of your AP.

Well you live and learn. Any box of tricks that can do LNAV and drive your flight director is now a FMS.

[silverknapper]

Very surprised if Saab 340 operations are PRnav approved.

[peterh337]

Still means I have to consider them deviating from that track, and they do, whatever you might think.

But surely any aircraft can deviate from that track - whether it is a brand new 737, the Apollo 11 lunar module (which had two INSs), or my TB20 :)

Any box of tricks that can do LNAV and drive your flight director is now a FMS.

Well, yes.

What is an FMS? It is the principal user interface for the navigation sources, with other goodies like fuel metering, loading, and whatever other stuff I know nothing about. Apart from the goodies it is not significantly different from a high-end GA GPS from a decade ago (not Garmin though).

But we are getting nowhere, chaps.

All that M609 is basically saying, if I understand him correctly, is that equipment in the old Tupolevs ;) has improved.

You still do not need PRNAV to autofly a programmed lateral track :) Shall I paste my last post at this point, again? :)

[mad_jock]

Silvernapper during my searches there are a whole heap of software upgrades for old ****e bits of kit to be PRNav approved. But there is a crew training overhead as well even if the kit is good to go.

And M609 I wouldn't be suprised if your aircraft are PRnav approved now but some gimp in OPS hasn't bothered there arse changing the RPL's or they are waiting for the training cycle to include all the crew going through the sim.

And Peter a FMS to me is whole different ball game to whats being discussed which as you say is just a box of tricks which is like a GPS on steriods. Takes nav data and creates a magenta line. Depending on the box it may join striaght lines or it might give you curves as well and do the holds for you.

FMS will do your trim
All your performance calcs including speeds
Fuel burn. predicted burn and take care of landings weights etc.
Taking the wind levels into consideration will plan your decent to the runway including any speed/level restrictions.
It will drive the vnav to get the previously calculated profile.
It will manage the plane in flight to achive a cost index.
It will work out your most economic cruise level etc

I am sure you get my drift.

Oh and Peter during my searches there is something about PRNav point names being 32bit something or other and your box of tricks needs to be compliant other wise it misses them and can send you off to another airfield halfway through the procedure. ( I really don't have a clue, this is by far your special subject)

[GWYN]

M609, what I 'want to know' is, have these new procedures released a lot of latent capacity in the airspace or improved safety? Are you now able to handle a lot more movements per hour with fewer controllers? I admit, I don't really understand what point merge is, which is why I ask the questions. Does it really achieve anything that a good Flow Controller would not, in terms of sequencing traffic?

Yes, these are all nifty new procedures, but I (and I believe Peter) have not yet seen any evidence that they lead to any real enhancements in traffic flows, safety, or (sorry!) Flight Efficiency.

I try to keep an open mind on all these things, but that also means that I am not necessarily convinced that something is an improvement just because it is new - or because it is mandated by Brussels.

[mad_jock]

EUROCONTROL - Point Merge for Oslo, Dublin and Rome? (http://www.eurocontrol.int/eec/public/standard_page/EEC_News_2008_3_PM.html)

And from oslo

Point Merge System - new regulations for air traffic at Oslo Airport Gardermoen - YouTube


Basically you wang it round an arc until you get to your radial and then head towards a center fix until you get Loc established.

[GWYN]

Oh, and mad jock referring in a derogatory manner to "some gimp in OPS" does display a rather poor attitude to those who are probably your colleagues or customers. Hardly likely to endear you or make for a good working environment wherever you may work. In my experience there are individuals who might fit that title in all walks of life, and that includes on flight decks, sitting in front of radar screens and many others.

Indeed if you read my previous posts you may realise that far from being the omission of 'some gimp in Ops' (RPLs??), it may even be 'company policy' to not admit to being PRNAV.

[GWYN]

......and thanks for posting the Avinor video. I'll have to look at that tomorrow!

[Denti]

All your performance calcs including speeds


If you mean take off and landing performance calculation, that is something most airliners still need an EFB for (or paper if they're still stuck in the last century).

[peterh337]

Yeah, I am still searching for the reason why PRNAV is "needed" for its lateral accuracy. For example, these four track fragments, which I captured with my ancient kit

http://www.peter2000.co.uk/aviation/sn3500/intercepts.jpg

are all within 0.5nm of the track, except the last where the overshoot (I did that one with turn anticipation disabled in the GPS) is 1nm i.e. within PRNAV limits.

This is a more typical arrival sector performance

http://www.peter2000.co.uk/aviation/sn3500/gps-rnav-approach.jpg

Yet, for me to get PRNAV approval I would have to rip out all this perfectly working kit and put in other kit which won't deliver anything different to the controller.

It should be readily apparent that PRNAV is something devised back in the great days when a Tupolev from the Peoples Republic of Upper Volta could land with 1 engine out at LHR and depart as it came :)

But where there is money, there is a gravy train running on it, and there is no shortage of people trying to jump on it. The avionics installers love this. How much does it cost to upgrade some regional turboprop to this "capability"?

And there is a lot of certification work involved in this, which keeps the nice people at EASA at work. What goes around comes around :)

[Denti]

All your performance calcs including speeds


If you mean take off and landing performance calculation, that is something most airliners still need an EFB for (or paper if they're still stuck in the last century).

[mad_jock]

That could be a fair comment when working for BA netjets or any major.

The rest of us have to put up with no hotel rooms booked, no hire car, no flight plans, bizarre flight planning, impossible scheduals and then when you phone they have legged it as soon as they get an arrival message. And our crews lives constantly screwed about because of thier piss poor planning and attention to detail.

Gimps in ops can run an airline into the ground far faster than any other deptment.

And BTW I have worked as ops I know exactly what it takes and what a bastard of a job it is. I am not expecting anything other than what I would provide myself.

But as you say if by not being PRnav approved gets them out of doing the point merge system it may very well be a tatical omission that they can do it.

Certainly most aircraft seem to have an upgrade to allow you to do it. How much that upgrade is (I should imagine alot) I don't know. Although thankfully the trusty trimble approach plus doesn't :-)

Peter from my searches tonight it appears that most of the kit can do it already with a software upgrade. I think you can also do it with twin G530's but I don't have a reference for that. It was an option for the 8.33 capability which also got you PRNav as well.

Fair enough denti I got a jump seat on 777 years ago am pretty certain they pulled them out and then cross referenced them against the paper books. But it was a few years and before I had any clue what was going on in a CAT cockpit.

[M609]

have these new procedures released a lot of latent capacity in the airspace or improved safety

Safety: Yes, when the system is operating at max capacity I belive safety is much improved. The reasoning for that has several focuses, but the main one for me is that R/T loadinng on all sectors are greatly reduced. (When using the PMS fully, aircraft get few instructions, because all the vectoring is gone, and because vi can count on a/c performing the turns published inside the merge points, there is less need for step decends for safety.)

Our setup is one Director (DIR) managing the PMS arcs, and one Final (FIN) doing speed control and vectors of BRNAV aircraft once turn and decend from the arc is done.

The R/T call sequenc can be as minimal as:

1.Checkin DIR
2.Reply
3.Turn instruction from ARC
4.Readback
5.Descend instruction and freq. change to FIN
6.Readback
7.Checkin FIN
8. ILS clearence via transition or DCT fix
9.Readback
10. Speedreduction to 180kts
11.Readback
12. Speed reduction to 160kts and freq change to TWR
13. Readback

We estimate that is a reduction of approx 40% from the old vectoring system, which means the controller has more spare capacity.

As for the departures/arrival conflicts, done at the two TMA sectors (east/west), the R/T loading is down as well for the IFR traffic, due to the designs outlined in the video there are less level offs of departures. This is not all down to RNAV and PMS, but some. SIDs can accuratly be turned of the "inside" of arrival routes, closer to the airport, and contineous climb departures are the norm.

I estimate 95% of all jet departures get cont. climb to cruise. (Segregated arrival and departure routes in the AOR was allso part of the redesign)

Staffing:
For the TMA we run one more sector with the same number of people, that says something about the workload. Before the redesign it was very close to becoming unsafe when we operated at max capacity, because of high R/T load and "everthing" on radar vectors. Today we can run more traffic, with no drama at all, and I don´t see the need for adding sectors for some time.

I stated earlier that PMS are not for all airports, and this is where it becomes interesting. Oslo got a PMS system that is a bit to large, and it will be downsized in the 2.0 version. (We often have to shortcut befor traffic reach the system, and to long level flight segments are not popular with the customer. That will be improved, see my "launch customer remark")

One problem when using PMS in the terminal enviroment is that if you make the arcs too big, and/or place them too far from the RWY like we have to a certain degree, you don´t get to save on staffing as much as possible.

For Oslo we had planned to run DIR and FIN bandboxed for more of the time than we do, but has found that the number of trackmiles from entry onto DIR freq to THR can bring to many a/c onto one freq.
But: Since the Arr/dep conflicts are less, we can now bandbox the 2 TMA sectors much more. We could NEVER bandbox them before.

As for PMS on a European level, the use as enroute sequencing tool is interestring, and it is a really good way to merge 2-3 flows of tfc into 1.
The French are going that route I belive.

There are however some factors that you need to get the most out of PMS, at least in the terminal airspace, and the main one is a working automatic arrival manager (AMAN). PMS is great for absorbing short delays, ut på ca 4-5 pr aircraft. It is just as useless as radar vectors if the TMA gets overloaded with aircraft.

http://www.barco.com/barcoview/downloads/OSYRIS_AMAN.pdf

I know NATS had some issues with their AMAN, but we are fairly happy with ours. They use it a little different to us, but then again it was designed for our kind of use. (We have the same system from Barco, NATS bought our HMI after us, and went live BEFORE we did, that might be some of the problem as well.....)



One the subject of aircraft types that could/should be PRNAV equipped. We used to have less BRNAV customers. The company that flew mail for the national mail service, West Air Sweden had PRNAV for most of their ATPs and all the CRJs. Then they decided to shaft their staff, so they created a new company based in Luxembourg, called West Air Luxembourg, bid on the same mail contract based on lower salaries for the pilots. They won.

Now NONE of the ATPs are PRNAV. And yes, it´s the same airframes! Progress?

[GWYN]

Thanks for the detailed explanation, M609.

I have to defer to your knowledge and experience on the point merge and as someone who is actually operating the system, I have to accept your vote of confidence in it. I still don't really fully understand though why, a) PRNAV is required for this and b) why the 'amount of controlling' is less. I don't see why conventional STARs cannot be flown without a lot of vectoring. After all the STARs are designed for that reason are they not, in order that the aircraft can be assigned a STAR and left to fly it, including any level changes? Surely that can also be flown in most cases as a CDA?

Anyway, good luck with the new procedures. I hope with the fine tuning it does release capacity, but also you, but more importantly, Eurocontrol have to accept that PRNAV is a huge financial burden to impose on airlines at an inappropriate time. APD (in the UK), European carbon taxes etc, all add to the price of a ticket and this is in danger of making flying something which is out of reach for many people.

[peterh337]

It is IME (GA only) unusual to fly a STAR using own VNAV. Even if one is flying a named STAR whole, the vertical part is according to ATC direction. Most STARs do not have clear vertical levels assigned to the different bits.

And I cannot see why PRNAV is necessary for this. All one needs is the ability to fly a programmed track on autopilot.

Maybe PRNAV has been used as a stick to beat the "old hardware" airlines into upgrading their avionics, on the pretext that the improved lateral accuracy is necessary?

[LYMANGOOD]

Very surprised if Saab 340 operations are PRnav approved.


The Saabs with UNS1k/1L (Incl. K+/L+ models) installations are P-RNAV approved since 2008 if you have the supplement 37 from Saab :ok:

[M-ONGO]

All well and good as long as you have an approved manual for P-RNAV.