Primarily for general aviation discussion, but other aviation topics are also welcome.
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By AlanM
#1839370
PeteSpencer wrote:Y’know, on reflection with the type and amount of flying I now do I’m not gonna miss it one iota . ILSs for IR reval from
now on ! :wink:


ILS’s won’t be around forever - most airfields (if they have one) with it due for replacement in the next 3-10 years is already planning not to have the CAPEX in the Long Term Plan. The cost of design, installation and ongoing maintenance staff is huge.

For an aerodrom operator, compare that with LPV.
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By johnm
FLYER Club Member  FLYER Club Member
#1839378
@DavidC This is the safety of life elements of EGNOS which is the equivalent of WAAS.

The Galileo and EGNOS facility are the equivalent of GPS and WAAS and they will be available for all practical purposes but the SoL aspects and some of the more “added value” services require formal contractual agreements which the UK has declined to enter into.
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By AlanM
#1839381
DavidC wrote:Could someone explain why if we don’t have any agreement with the USA DoD to use GPS then why we do we need an agreement to use EGNOS?


As @johnm says - it is ultimately the descending element of the flight profile. The RNAV 1 airways structure is not affected in the UK.

As aren’t combine harvesters, UAVs, cars etc etc etc
By riverrock
FLYER Club Member  FLYER Club Member
#1839386
The WAAS signal only covers N. America. EGNOS provides the equivalent info for Europe.
However someone has to pay for it, and UK Gov thinks price is too high. Was different when much of the infrastructure to run it was based in the UK.
By AlanM
#1839391
Any Non-EU TCO can negotiate and pay for an EWA. The UK seemingly didn’t want to.

Short sighted v Long term independent plan. You be the judge!
By Lefty
FLYER Club Member  FLYER Club Member
#1839397
We will still have access to the American GPS system for lateral navigation and it is accurate enough to give you lateral navigation on an instrument approach - but it is not accurate enough in the vertical plane to be used for vertical navigation - eg on an instrument approach.

This inaccuracy in the vertical plane is caused by the “slant angle “ of the GPS signals as they reach the earth’s surface

To get the accuracy needed for vertical guidance one has to provide a mechanism to “Augment” the standard GPS system vertical accuracy. The generic term for this Augmentation is “WAAS” - Wide Area Augmentation System.

One can place an extremely accurate GPS receiver at an (extremely) accurately surveyed position on the earth’s surface. A computer then compares the (accurate) known position - to the position being computed from the GPS signals and produce a correction factor. This correction factor is then fed up to the EGNOS and GALLELEO satellites which simply rebroadcast the correction factor to all of our WAAS capable GPS units - and allows them to produce both a horizontal and vertical accuracy that is sufficient for both horizontal and vertical guidance on an instrument approach.

The “RIM” stations (two of which are in the UK) are the earth based GPS receivers that calculate the GPS error (at that particular location) and transmits the correction factor up to EGNOS to be rebroadcast back down to us.

These correction factors are “acceptably” accurate with a radius of approximately 250-300nm from their location.
In parts of the world, without EGNOS / GALLELEO coverage - or for tactical military purpose it is relatively easy and cheap to set up a “RIM” type unit and transmit the corrective signal from the ground (outwards and upwards).
However this solution is limited by line of sight. Eg someone on the other side of a hill or mountain, can’t receive it.
This is why SBAS was invented as the correction factor can be received almost anywhere within line of sight of the SBAS (EGNOS/ GALLELEO) satellites.

So in theory, the UK could fairly easily setup its own SBAS system. We already have two RIM stations. We would need perhaps another one or two for redundancy , plus 2-3 Satellites in geostationary position over the UK. However as it is a safety critical system, it would need to both redundancy and constant accuracy monitoring, to send a signal to our GPS receivers saying “this GPS position is not accurate enough for vertical guidance” - and automatically disable vertical guidance whilst the situation continues.

However as others have said, the more pragmatic solution is to negotiate access to EGNOS.
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By riverrock
FLYER Club Member  FLYER Club Member
#1839399
@Lefty a few corrections.
The genetic term is SBAS ( Satellite Based Augmentation Systems).
EGNOS and WAAS are regional versions of SBAS
EGNOS is broadcast from 3 dedicated geostationary satilites.

Galileo and GPS ( and GLONASS) are global navigation satellite systems (GNSSs). They broadcast the timing signals which can be used to triangulate your position. Each is a constellation of satellites in low earth orbit.
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By johnm
FLYER Club Member  FLYER Club Member
#1839412
We can receive all of the standard signals since nobody has switched them off. However the use of Safety of Life and other "added value " elements of Galileo/EGNOS requires an agreement and payment. It is this last that the UK has decided not to engage with.

It isn't really possible to discuss the issues further without trespassing on the "no politics" rule.
By Lefty
FLYER Club Member  FLYER Club Member
#1839417
Flyin'Dutch' wrote:There is no cogent argument for not partaking in projects like Galileo, Euratom, Erasmus etc

Agree 100%
(no political content)
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By Sooty25
#1839428
Flyin'Dutch' wrote:There is no cogent argument for not partaking in projects like Galileo, Euratom, Erasmus etc


Assuming you don't mind remaining under the control of the EU. It was clear the two can not be separated.

Personally, I'd rather see the creation of "UKAS". Lets face it, we have the technology and ability to do it.
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By Flyin'Dutch'
FLYER Club Member  FLYER Club Member
#1839433
Sooty25 wrote:
Flyin'Dutch' wrote:There is no cogent argument for not partaking in projects like Galileo, Euratom, Erasmus etc


Assuming you don't mind remaining under the control of the EU. It was clear the two can not be separated.

Personally, I'd rather see the creation of "UKAS". Lets face it, we have the technology and ability to do it.


The UK remains a part of ESA, because it is not part of the EU, but does not longer partake in EGNOS/Galileo but remains in the Copernicus*

The UK has left EURATOM, although that is not an EU organisation.

Participants in Erasmus are also the following countries, under control of the EU; Switzerland, Norway and wait for it, Russia...

I defy anyone to explain the logic in any of the decisions to remain/leave the various programs.

*link to UK.GOV page here: https://www.gov.uk/guidance/uk-involvem ... -programme

Screenshot relevant part below:

Image
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By GrahamB
FLYER Club Member  FLYER Club Member
#1839434
If the UK were to implement its own SBAS solution, I assume it would potentially mean we’d be dependent on the avionics manufacturers to implement the option to select it.

Garmin and the like might be reluctant to do that for the legacy boxes where software development and support has ceased and the teams may not even exist any longer.

London Control: ‘G-SBAS, contact Lille Approach on 120.275; select EGNOS at RINTI' :lol:
Last edited by GrahamB on Sat Apr 10, 2021 10:16 am, edited 1 time in total.
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By johnm
FLYER Club Member  FLYER Club Member
#1839436
As @Flyin'Dutch' pointed out there is no rational basis for the decision to exclude engagement with Galileo and EGNOS and a number of other EU initiatives which also involve other third countries but not the UK.
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