AFAIK the navaid calibration flights use ground based augumentation.
The late Dave Philips would have known about this (they got centimetre accuracy) though he would presumably not have posted what his company’s charges were, which is the real topic of this thread.
Interesting that – apart from LPV definitely being totally free – nobody seems to know any real numbers, or if they know they don’t post them. It would illuminate a lot of discussions about IAPs and lack of them.
huv wrote:
In an aviation conference in Copenhagen today with the transport minister and the industry present, the Danish CAA indicated that they finally agree that IFR approaches do not require manned ATC at the aerodrome in all cases. If this materialises, it will realistically allow GPS IFR ops at aerodromes with quite low traffic volumes. At least 4 existing VFR aerodromes have applied, all with some kind of conventional IFR approval in the distant past (2 with ILS, 1 with NDB and 1 with SRE radar).
I am told that special procedures (still to be specified, to separate VFR from IFR) will be required, but saving the AFIS man in the tower will make the crucial difference to the running costs. We have all fingers crossed.
@huv, very interesting information! Please keep us informed about how this plays out.
Airborne_Again wrote:
GLS is actually an ICAO standard and installed at several major airports like Frankfurt (EDDF)
Maybe, but the GLS installed in Norway, and on board in Widerøe aircraft is definitely not ICAO standard. This has caused lots of stuff in the News, because it is literally impossible for anybody but Widerøe to fly these routes today using this particular GLS. Special equipment with special authority. Better to look at it as a kind of fore runner to a standardized GLS system. It was the first augmented GPS approach system in use commercially anywhere, and is now virtually obsolete, only used by Widerøe.
Airborne_Again wrote:
But it’s a bit surprising that Namsos has an GLS installation as (at that airport) it only provides marginally lower minima than the regular LPV does
Namsos can be surprising for the inexperienced, even VFR at clear sunshine due to terrain and turbulence. It is really narrow between mountains. A normal VFR circuit S of the field is impossible, you end up in granite. To the north you are a couple of feet above ground and the runway is short, only 800 m with water (river) in 3 directions.
LeSving wrote:
Namsos can be surprising for the inexperienced, even VFR at clear sunshine due to terrain and turbulence. It is really narrow between mountains. A normal VFR circuit S of the field is impossible, you end up in granite. To the north you are a couple of feet above ground and the runway is short, only 800 m with water (river) in 3 directions.
That comment is in no way related to what I found surprising. Or maybe you are not aware that Namsos also has regular LPV approaches with minima only 35/45’ higher than the GLS minima? Given that the terrain already causes unusually high minima for a 3D approach, I don’t see much point in having GLS. But if what you write is correct then the GLS approaches certainly predates the LPV ones.
GBAS is currently CAT 1 equivalent only as well as SBAS. According to some folks, there is no way to go into CATII/III equivalent with SBAS, only GBAS will allow it. Other people as confident SBAS can do better, make your own judgment. Cost of GBAS ground station is slightly above than the single ILS installation – but can serve multiple runways at a given airport. CAT I GBAS installations are not as wide as expected so CAT II/III GBAS is not expected anytime soon.
Airborne_Again wrote:
I don’t see much point in having GLS
The point is that on these airports it is impossible to install ILS due to terrain. Back then, late 90s, there were no LPV, at least not commercially available. So they made this GLS (SCAT-1 is the real name), which seemed more promising at the time. The system was already obsolete, more or less, at the time of installation because much the same procedures could be made, much cheaper using RNAV approaches. This is what has happened. SCAT-1 is still better, but much more expensive, and all development has stopped. SCAT-1 itself is as accurate as it gets, but surrounding terrain is still the limiting factor for safety of those approaches, especially the slope of climb (I would think). Those LPV approaches are relatively new and came after the GLS approaches.
Problems occurred when DAT (Danish Air Transport) also wanted to fly these routes. They couldn’t get hold of the needed equipment, and managed to make a case through EU against Widerøe. https://www.aftenposten.no/okonomi/i/kaGAgj/esa-mener-at-wideroee-har-brutt-konkurranseregler I don’t know what has come out of this, but Widerøe is still flying all the routes and I have seen nothing about DAT since in the news. Lots about this from 2012-2014,
LeSving wrote:
The point is that on these airports it is impossible to install ILS due to terrain.
Are you deliberately missing my point? I have written several times that I see no point with the GLS at Namsos unless it was there before the LPV which apparently it was. I am very much aware of the siting requirements for ILS GP antennas which can make ILS installations impossible in some places. (This was the rationale for introducing MLS, but it never really caught on and while we have GPS it never will.)
Well, what part of “It was the first augmented GPS approach system in use commercially anywhere, and is now virtually obsolete, only used by Widerøe” did you not understand? The only reason they installed it was the only alternative to ILS, which could not be used. If they could use LPV (as they can today), then why on earth would they install a one off system, at a very substantial cost I would think, that became obsolete a few years later?
In hindsight, it helped them keep Danish Air Transport off their back, so it could very well be it has payed back the cost many times over 
LeSving wrote:
Well, what part of “It was the first augmented GPS approach system in use commercially anywhere, and is now virtually obsolete, only used by Widerøe” did you not understand?
You did not write that until after I had already said that I could understand the point of having GLS if it predated LPV. I actually tend to write other people’s comments carefully before I reply. Everyone should.
I actually tend to write other people’s comments carefully before I reply. Everyone should.
That would create interesting threads
I guess I just didn’t understand your logic. Why would believe someone would use equipment that cost a factor 1k? 1M? more than already existing and good enough equipment exist? (considering LPV is good enough, which isn’t a given).
