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UK CAA RNAV approach manual


I think this publication is recent. However, from a first quick glance, it contains a lot if blabla and not much of any real interest.

Interesting that this publication comes from a CAA that has, AFAIK, not introduced a single one RNAV approach at any airfield that did not previously have some kind of instrument approach procedure…

Mainz (EDFZ), Germany

How would the CAA know anything about RNAV approaches?

EGTK Oxford

I reads like somebody went around the CAA house and asked everybody what they knew about aviation, and wrote it all down.

It’s not a bad document (on a quick look I didn’t spot anything actually inaccurate) but coming as it does from a regulatory body one wonders what a lot of it means. This is one gem which must have been made up on the spot (notwithstanding the fact that somebody actually doing that is going for the Darwin Award)

and here is another astonishing piece of aviation wisdom which is sure to save countless lives

The training summary on page 47 onwards is interesting, in case mandatory training for GPS approaches arrives. Currently the UK doesn’t require that but my last recollection is that EASA are going to require it at some stage, as a part of a quid pro quo in some other areas.

The extensive stuff about PBN shows how much effort has gone into job protection after GPS did to navigation what the CD did to vinyl records It’s almost like the Royal Institute of Navigation owned 51% of the CAA. Never before in the history of human endeavour has so much bullshit been written by so many for the benefit of so few.

Interesting that this publication comes from a CAA that has, AFAIK, not introduced a single one RNAV approach at any airfield that did not previously have some kind of instrument approach procedure…

Very true… however it has to be said that with UK instrument approach design having to be paid for by each airfield (not by the national CAA as the case is in the rest of the universe) an airfield is not going to spend the approx. 30k per approach unless they can see a payback.

And if there is an NDB/DME/VOR/whatever procedure, everybody with a brain is already flying that using a GPS. So the benefit is just in the shorter flight path (no outbound track and coming all the way back). And if the airfield has an ILS, there is even less point in doing anything.

Current UK regs require an approach controller, which practically speaking (given the way ATC is funded) translates to full-ATC in the airport tower, and AFAIK all UK airfields that have full ATC but no IAP of any sort have only fairly short grass runways, which is a problem for any IAP. Also runway lighting required for any IAP is likely to cost even more than the 30k IAP design.

So it’s down to £££££ as usual…

Shoreham EGKA, United Kingdom

Well you could certainly say this document is thorough! Quite a bit of repetition and plenty of “parental advice”.

A few points worth highlighting though (some gross simplification to keep it short)
- Terminology will evolve:
PBN (Performance Based Navigation) is the new name, of which GNSS is only one element (although in practice, it’s the key one).
B-RNAV has been renamed RNAV5
P-RNAV will be renamed RNAV1
RNAV (GNSS) approaches will be renamed PBN APCH

- Strong recommendation for training on GNSS approaches
Appendix with suggested theory and flying syllabus. Encourage much should be done in simulators. Checklist for pilots flying such approaches

- Lot of stuff about older, unsuitable kit
Some really old GPS receivers have hardwired Selective Availability permanently turned on
Some old kit might only be able to display En-Route rather than Terminal – giving wrong impression of accuracy or cross track error
Lot of reminders about RAIM checks, NANUs, NOTAMs etc
(I suspect that most if not all PPL/IR pilots outside flight schools would be flying WAAS/EGNOS (ie SBAS) kit by now, so this is probably fairly unusual)

- Reminders about legal limitations
Can only fly an RNAV approach if your POH says so
LNAV/VNAV can only be flow to minima if you have Baro-VNAV fitted (extremely unlikely), so should only be flown as LNAV non-precision (ie ignore the glideslope)
LPV approaches officially can’t be used on any IR skill test or proficiency check for either precision or non-precision. An LNAV without glideslope is permitted on test. (This is an EASA regulation, not UK CAA)

In summary, this is a good sign that the CAA has finally awoken to discover that GNSS is relevant. Perhaps they’ve been poking around too many flight schools and have a view that most GA GPS kit is pretty antiquated. It probably is, given that it’s not been part of the syllabus. You can’t really blame flight schools for not investing in the kit up to now.

I suspect we should brace ourselves for some mandatory GNSS differences training (although hopefully grandfather rights would apply).

I’d like to see the restriction on LPV in a skill/proficiency test removed ASAP. We do now have 2 in operation in the UK: Exeter and Bristol (plus one at Alderney).

Re approaches at non-ATC airfields, the CAA did publish a separate document on that last year. I’ve heard that there’s been lots of talk and probably quite a bit of behind the scenes activity, but still not seen evidence of an impending new approach published. There is some European money available to help, but airfields themselves must contribute and want to progress it.

EGBJ, United Kingdom

There is grant funding from the body that is promoting EGNOS which pays a large proportion of the approach design costs. I am not sure how many applications are successful, but I know airfields that have applied. Perhaps Booker is one of the beneficiaries?

Darley Moor, Gamston (UK)

@DavidC Are you sure about:
LNAV/VNAV can only be flow to minima if you have Baro-VNAV fitted (extremely unlikely), so should only be flown as LNAV non-precision (ie ignore the glideslope)”?

That goes against what is written in this EASA document.
“CM on the use of SBAS for LNAV/VNAV”:

Section Database
“The requirements of AMC 20-27 paragraph 7.1 item 3 remain applicable, with the additional
requirement that for systems that provide VNAV based on SBAS/GNSS geometric altitude,
the flight crew should only be able to retrieve an approach to LNAV/VNAV minima when the
approach has been appropriately coded, i.e. and indication ‘A’ in the ARINC 424 coded
Navigation Database (see note below).

In order for an approach to LNAV/VNAV minima to be flown with VNAV guidance based on
SBAS/GNSS geometric altitude, the angular nature of the guidance should have been taken
into account in the procedure design. States publishing the approach should explicitly
declare whether or not angular guidance has been accounted for in the approach design.
Where approaches with angular guidance can be used, this is indicated by the database
provider by coding an approach with the character ‘A’ in the ARINC 424 coding of the
navigation database. This is not visible to the flight crew. However, if the coding of the
approach indicates that the approach cannot be flown with angular guidance, the flight crew
should not be able to retrieve the approach from the Navigation Database."


To answer my to my own post above.

How is it possible for the EASA and the NAAs to make “GPS use” (RNAV, PBN APCH, etc.) so bureaucratic?
Imagine what the ADF licensing and training requirements would be if it was invented today!

CAP 773 is clear on that aircraft with SBAS receivers may not fly approaches to LNAV/VNAV minma:

I really thought that in the UK SBAS EGNOS receivers could be used to fly approaches to LNAV/VNAV minima when certain conditions were met.
Some years ago NATS said this in a presentation:


Does anyone know wich regulation in the UK that prohibits the use of SBAS receivers to fly approaches to LNAV/VNAV minima?


A few quotes from the GNS530W AFMS, it only applies to US airspace, but there are no restrictions on flying an RNAV (GPS) approach using WAAS for vertical guidance if it is in the database and the approach is inside the service volume of WAAS vertical guidance.

1.2 GPS/SBAS TSO-C146a Class 3 Operation

The GNS complies with AC 20-138A and has airworthiness approval for navigation using GPS and SBAS (within the coverage of a Satellite Based Augmentation System complying with ICAO Annex 10) for IFR en route, terminal area, and non-precision approach operations (including those approaches titled “GPS”, “or GPS”, and “RNAV (GPS)” approaches). The Garmin GNSS navigation system is composed of the GNS navigator and antenna, and is approved for approach procedures with vertical guidance including “LPV” and “LNAV/VNAV” and without vertical guidance including “LP” and “LNAV,” within the U.S. National Airspace System.
2.6 Approaches

Instrument approaches using GPS guidance may only be conducted when the GNS is operating in the approach mode. (LNAV, LNAV+V, L/VNAV, LPV, LP, or LP +V)

NOTE: Advisory vertical guidance deviation is provided when the GNS annunciates LNAV+V or LP +V. The controlling minimums remain LNAV or LP even when
advisory vertical guidance is provided. Advisory vertical guidance information displayed on the VDI in this mode is only an aid to help flight crews comply with altitude restrictions. When using advisory vertical guidance, the flight crew must use the primary barometric altimeter to ensure compliance with all altitude restrictions in accordance with the LNAV or LP approach procedure

From the current Instrument Practical Test Standards for the Instrument rating:

Note: A localizer performance with vertical guidance (LPV) approach with a decision altitude (DA) greater than 300 feet height above terrain (HAT) may be used as a nonprecision approach; however, due to the precision of its glidepath and localizer-like lateral navigation characteristics, an LPV can be used to demonstrate precision approach proficiency (AOA VI TASK B) if the DA is equal to or less than 300 feet HAT.

Also from the FAA:

As of January 8, 2015, there are 3,522 Wide Area Augmentation System (WAAS) Localizer Performance with Vertical guidance (LPV) approach procedures serving 1,730 airports. Currently, there are also 583 Localizer Performance (LP) approach procedures in the U.S. serving 424 airports.

There are 906 LPV approaches with a HAT of 200 feet! I haven’t had a need to use an ILS in over 6 years other than for practice. There are only 1276 Category 1 ILS in the approach inventory. Most of the runways served with an LPV don’t have approach lights unless the runway is already served by an ILS. Minimums for an LPV to a, runway without approach lights require a 1/4 SM visibility penalty. There is also very little use for LNAV/VNAV, even though the WAAS GPS is authorized to fly them, most RNAV approaches have LPV on the same procedure as better option.

KUZA, United States
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