Question about WAAS equipped GPS

[piperboy84]

looking at a used Garmin 530 on ebay, it is not WAAS enabled, does this matter for UK based aircraft, Are ILS systems here WAAS equipped?

[Desert185]

Google WAAS.

[cessnapete]

WAAS has nothing to do with ILS. It is a GPS related signal augmentation system which allows suitably equipped aircraft to carry out stand alone GPS approaches to lower limits. Allows the use of GPS derived altitude information for the approach,rather than the less accurate pressure altimeter.
Approx CAT1 equivalent. As usual thousands of these approaches in USA, CAA here still working on ADF!!

[piperboy84]

Pete

Thanks for the explanation, I could not tell from google how prevalent WAAS deployment was her in the UK, sounds like it may be a few years out.

[Fostex]

WAAS will most likely never be deployed in the UK and Europe, EGNOS already is instead and is basically the same sort of satellite based augmented GPS setup, albeit in it's infancy.

[riverrock83]

WAAS and EGNOS are both forms of SBAS (Satellite based augmentation system) and are fully compatible with each other. If you can receive one - you can receive the other. A lot of rubbish on this thread!

EGNOS has been fully live since 02 March 2011.

Officially (http://www.gps.gov/technical/ps/2008-SPS-performance-standard.pdf ):

Global Average Position Domain Accuracy
≤ 9 m 95% Horizontal Error
≤ 15 m 95% Vertical Error

Worst Site Position Domain Accuracy
≤ 17 m 95% Horizontal Error
≤ 37 m 95% Vertical Error

In most conditions, measured accuracy is better than this.
WAAS / EGNOS (or the other equally compatible equivalents) bring this down to 1.5m.

Without SBAS, vertical navigation (ie - glide slope) using a GPS signal would be dangerous, with SBAS, it is possible. Approaches which are using SBAS for vertical navigation are known as LPV approaches. There are a couple in the UK but more are due to roll out soon.
Probably worth a look at http://www.pprune.org/tech-log/499689-egnos-approaches-europe.html
The ICAO agreed that there would be GPS based approaches to all instrument runway ends by 2016, using either SBAS or barometer based vertical navigation, so more and more are going to appear (see EUROCONTROL - Implementing Approaches with Vertical guidance using EGNOS (http://www.eurocontrol.int/eec/public/standard_page/ETN_2010_2_APV.html) although that doc is from 2010)

[piperboy84]

So would a Garmin 530 that is WASS enabled also be EGNOS ready (certified) by default even though the specs for the 530 don't list Egnos.

[riverrock83]

A Garmin 530W (ie - one that can recieve WAAS) can also receive EGNOS.
See Receiver list | EGNOS Portal (http://egnos-portal.gsa.europa.eu/developer-platform/developer-toolkit/receiver-list)
There was a minor software release that allowed it (see Service Advisory 1029 Rev D: EGNOS Activation » Garmin Aviation Alerts and Advisories (http://garmin.blogs.com/aviationalerts/2013/11/service-advisory-1029-rev-d-egnos-activation.html) ).

Note that it says that approvals are needed. However there is a generic LPV approval for non-AOC aircraft in the UK - RNAV (GNSS) - LPV Approach Operations | Air Operations | Operations and Safety (http://www.caa.co.uk/default.aspx?catid=1431&pageid=12818)

They just need to create some more LPV approaches so they can be used!

Should also say - on this topic, see
http://www.caa.co.uk/docs/33/CAP773.pdf
and
EGNOS and LPV [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-477409.html)

[wigglyamp]

Don't forget that the aircraft installation has to be certified for LPV in accordance with EASA AMC20-28 if EU-reg aircraft, with an approved flight manual supplement. The exemption listed above is the operational approval, not the aircraft installation approval.

[Sir George Cayley]

There's a CAA consultation about this at the moment.

Consultation - Proposed New CAP 1122 Application for Instrument Procedures to Aerodromes without an Instrument Runway and/or Approach Control | Consultations and Responses | About the CAA (http://www.caa.co.uk/default.aspx?catid=1350&pagetype=90&pageid=15347)

Maybe the Campaign might actually be doing something positive to introduce "GPS" approaches for all.

SGC

[Fly Through]

At our airfield with cross runways, one of which is ILS equipped, the initial quote for designing & publishing replacement LPV approaches was £60,000. Don't hold your breathe for a rapid roll out!

[piperboy84]

I found this article that explains things quite well for other folks that are struggling to get their arms around this subject like I am, happy reading!
(http://www.jetpro.ca/Article%206.html)


Jet Pro - Edmonton, Alberta, Canada (http://www.jetpro.ca/Article%206.html)

[piperboy84]

Sorry to belabour the point, but i have a questions regarding an approach plate if someone would be kind enough to answer, the plate in question is this one

http://155.178.201.160/d-tpp/1313/00301RY17L.PDF

Under the category and minimums section at the bottom it lists a "DA" for the LNAV/VNAV approach, my question is:

If VNAV is advisory information (not an LPV or RNP precision approach) why does it have a DA like the LPV above it and not an MDA like the LNAV non precision approach below it?

[India Four Two]

the initial quote for designing & publishing replacement LPV approaches was £60,000

Fly Through,

So it is not as simple as re-drawing the ILS plate as a GPS plate? Silly me!

[AviatorTB]

PB84,

I think the answer to your question is found in the AIM (5-4-5). The LPV and LNAV-VNAV approaches are considered precision approaches despite their higher minimums (in the IPHB, they're called semi-precision). Consequently, they are flown to DA's. You see that the OKC LNAV-only approach is flown to an MDA.

Cheers!

TB