Snoopy wrote:
Is it OEM dependent? For instance (earlier) Cessna G1000 are RNAV1 and Diamond are not? Can it be upgraded?
In principle the difference could be due to different software versions, but I think it is more likely that the installation approvals are what the manufacturer asked for (i.e. needed to provide evidence for) and/or what the particular competent authority agreed to approve.
In the case of Cessna it is the FAA that approved the POH so it is the FAA that would have to be convinced. In the case of Diamond it is EASA or the Austrian competent authority. Recall what I wrote in an earlier post that European authorities used to be reluctant to give RNAV/RNP-1 installation approvals.
An upgrade for the DA40 would most likely be a paper-only exercise but it could cost a lot in money and effort.
the installation approvals are what the manufacturer asked for (i.e. needed to provide evidence for) and/or what the particular competent authority agreed to approve.
Yes, and there is a huge element of “I am an old fart in the CAA and I need to justify my job until I retire and if I just agreed to something – especially something the nasty reckless Americans (who brought us MacDonalds and KFC!!) agreed to – then I need to be stricter, otherwise somebody might realise think I don’t understand how GPS works, and next time I have lunch at the Royal Institute of Navigation I will be taken the p1ss out of” 
Years ago I was at a presentation by a very senior UK CAA official (a “captain”) on GPS approaches. He said you needed a specially approved GPS to fly them (can’t recall the detail; probably RNAV1). Afterwards I pointed out to him that (at the time, at least) France allowed any BRNAV approved installation for flying GPS approaches. Of course this was also the case in the US, with the KLN94 being fully capable, subject to an AFMS. He made a most unhappy face but since nobody else heard the conversation he said “they can do what they like”, turned around and walked away
It was 100% a case of just imposing a higher standard to show that you “know something”.
In the Socata case – getting an AFMS approved by some old fart in the DGAC which prohibited GPS approaches for both the KLN94 and the GNS430 – nobody cared because back in 2002 99% of owners had no idea what an AFMS is (today maybe 95% 
) so they flew them anyway and everybody was happy. AFAIK virtually all American TB owners never knew about the AFMS either and “just flew the planes”. A few got a custom AFMS done by the disti, Socata in Florida; I obtained a copy of one for a template but sent it to a UK avionics shop to do one for me and they lost it
But since pilots like to get strictly legal in every respect we end up debating which exact type of GPS and which AFMS wording can substitute for an NDB
Ultimately “everybody” flies NDB and VOR approaches using a GPS, so the value of this concession comes down to whether you can legally avoid the carriage of an ADF (VOR is not a problem; almost every VHF radio does VOR/LOC/GS) which is a big box which is not reliable, difficult to repair, and forces many to buy replacements from US Ebay and use a hair dryer to move the serial number stickers over Also DME, but DME is awfully useful for ILS approaches which are still key in Europe and are likely to be for many years.
However the value of this concession is reduced because there is no known enforcement; e.g. huge numbers of SR22s came into Europe with no ADF or DME. If hundreds of these pilots had been busted and fined, we would be climbing all over this new EASA proposal.
And unless the ADF can be dispensed with in every scenario, you still have to carry it, so I fail to see the value proposition here. It just seems to legalise what people do anyway and what is utterly undetectable.
johnh wrote:
Seems not to be true any more:It’s somewhat moot anyway since I doubt if there are any approaches which haven’t long since had a GPS overlay.
No it is still the case if the aid is used for final approach lateral guidance. Most US runways have actual GPS approaches (or an overlay which is just a GPS approach that follows a conventional approach track) so as you say it doesn’t matter much there.
In the UK this is a significant improvement due to the prevalence of NDBs in missed approach segments of for example ILS or GPS approaches. But it isn’t a magic bullet and there remains the need to get more GPS approaches in the system.
Airborne_Again wrote:
Jacko wrote:Isn’t take-off/rotation distance a quadratic function of speed, like landing distance (i.e. double the touch-down speed and we roughly quadruple the braking distance)
Sure, but they’re not talking about aircraft performance but rather about what visibility/RVR the pilot needs for a safe take off. That would depend on the time it takes for the aircraft to travel a length of runway and that in turn is directly proportional to takeoff speed.
OK, so they are ignoring the time/distance required to accelerate to Vx or Vy? But to me that’s all that matters.
Perhaps I’m missing something obvious, but I still don’t see where that (arbitrary?) minimum RVR of 150 m came from, unless it’s just regulation for the sake of regulating.
We don’t often get bad weather in Scotland but when I take off from home with a bit of mist or hill fog, I just need to see far enough to back-track sedately to the top of the runway – i.e. 20-40 ft so I can see the runway edge cones. While back-tracking I can clear any dozy sheep or deer out of the way and check that there are no fallen trees or new holes dug by wild boar etc.
Then aim the HSI at 210 degrees, give it full gas, ask the nice lady in the audio panel to “say fuel flow”, lift the tail after 2-3 seconds and fly after another 3 – give or take a few seconds for wind, weight and DA. This is in a typical cheap touring taildragger, but my C150, C172, and C175 cheap touring nosedraggers all performed much the same.
Is it unreasonable to say that if we can’t hold an average HSI heading within +/- 5 degrees for five or ten seconds, we probably shouldn’t be flying in IMC?
What would be wrong with allowing the PIC to determine what minimum RVR she is comfortable with, taking account of all relevant conditions?
Jacko wrote:
OK, so they are ignoring the time/distance required to accelerate to Vx or Vy? But to me that’s all that matters
What matters it the ability to maintain directional control.
Jacko wrote:
I still don’t see where that (arbitrary?) minimum RVR of 150 m came from, unless it’s just regulation for the sake of regulating.
Probably. I doubt they made any scientific evaluation how far you have to be able to see to maintain directional control.
Jacko wrote:
What would be wrong with allowing the PIC to determine what minimum RVR she is comfortable with, taking account of all relevant conditions?
The overwhelming number of fatalities caused by pilots trying to depart with lower visibility, and in particular the carnage of innocent bystanders standing right at the runway edge in fog, of course! [where is the sarcasm emoji?]
At least now the limit is now less than 400m, which is longer than the take off distance for many light aircraft…
150m is very low vis. I am surprised people are complaining about it.
Is 150m now allowed for private ops, in all conditions?
Most airlines can do it.
I could not possibly comment on whether I have ever seen that, but anybody who has seen a departure in say 200m will tell you it is quite spooky. The scene in front of you is the same as you accelerate. Just see what looks the same piece of tarmac. All you see change is the airspeed rising. Then you pull up at Vr and immediately lose all visual references.
If one has been checked on the Pitts and can takeoff+clear 50ft obstacle in 150m in his type then why not? [where is the sarcasm emoji ]
(I am sure most Pitts pilots will ground loop in 150m visibility )
Peter wrote:
Is 150m now allowed for private ops, in all conditions?
No, this is a proposal sent out for comments. Also, the proposal has requirements on runway markings and lights, depending on the visibility.
JasonC wrote:
No it is still the case if the aid is used for final approach lateral guidance. Most US runways have actual GPS approaches (or an overlay which is just a GPS approach that follows a conventional approach track) so as you say it doesn’t matter much there.
Unfortunately, it doesn’t seem there is much to do about this. I checked in PANS-OPS and for NDB and VOR approaches, the narrowest part of the protected area (at the beacon) has a width of 2.5 and 2.0 NM respectively. For an LNAV approaches, the protected area has a width of 2.9 NM. So even of the directional accuracy is totally superior for LNAV — particularly compared to NDBs — there could be a significant obstacle which is not accounted for if you make an LNAV approach that just follows the approach track of a conventional NDB och VOR approach.
