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Operating cost (to the airport) of VOR DME NDB or ILS, and LPV?

More and more air carrier aircraft are capable of flying RNAV approaches. Whether an airline is authorized by their Opspec is a different matter. All recent Airbus and Boeings are capable. Most recent air carrier aircraft use an FMS that uses GPS as an input and don’t fly raw signals for VOR or NDB type approaches. Virtually none of the air carrier aircraft are equipped to fly WAAS procedures such as LPV as the airlines have not seen any financial benefit. In the US, this is mostly a GA capability. At best two US minor airlines have the capability, I know Horizon does (have you ever heard of Horizon?). The newer aircraft are also equipped to fly RNAV (RNP AR) approaches where the lateral is GPS and the vertical is Baro-VNAV, although this requires special crew training and authorization.

KUZA, United States

The procedure for obataining appraoch approval is quite the same for N-Reg. and EASA-reg

That doesn’t seem to be true.

My aircraft’s installation to my knowledge fully complies with TSO C129 and AC20-138. Therefore it should have been possible to get an N reg AFMS allowing nonprecision approaches.

Now according to JAA ACJ20X5 you need to, besides TSO-C129, additonally prove your navigator complies with C129a paragraphs (a).(3),(xv).5 and (a).(6).

(a).(3).(xv).5 is essentially this: “The GPS equipment shall detect a pseudorange step error greater than 1000 meters, including steps which cause loss of lock for less than 10 seconds.”

Now it might make sense to include such a requirement in a general standard (if someone ever has the idea of building a least squares type GPS receiver for aviation use), but for the standard search and track type receivers used in aviation (and elsewhere), a pseudorange step means the receivers’ DLL looses lock, and this is such an important event that no GPS receiver firmware will miss it.

Now JAA requiring this in practice means TSO-C129 receivers can’t be used for approach in europe, because nobody will likely put up the money to prove this paragraph, even though all existing C129 navigators are likely ok.

LSZK, Switzerland

My recollection – never investigated it in detail – was that GPS/LNAV approach approval became an EASA minor mod approx 2006.

They realised that GPS approaches would be dead in the water otherwise.

Last I heard, you throw a few hundred € at an EASA 21 company.

Until I got the KLN94 approach approved, I flew the published NDB/DME ones but using the GPS (see below). So frankly I don’t think many people tear their hair out over this “lack of capability”. You just fly a longer track, on a procedural approach.

IFR will simply never come to airfields which don’t have a certain number of movements or a certain attractivity for either AOC or business flights

It will also not happen in the UK because

  • the airfield needs full ATC (c. £1M/year for daylight hour cover) and nearly all of those that have ATC already have some sort of conventional IAP (required to “legalise” AOC ops, and support instrument training) and everybody with a £50 GPS from a camping shop can fly that IAP, while requesting the published one
  • the airfield has to pay the survey, c. £30k

This creates an impossible financial barrier unless a really big FTO sets up there.

The “full ATC” can actually be a US-style remotely located approach controller (still needs to a full ATC pay grade however) but there is no way to get taxpayer funding in the UK, so that will never happen either.

There have been many proposals to change the system, with various encouraging noises emanating from various places, but AFAIK nobody has actually made any progress. Replacing an ATCO-grade controller with an A/G-radio one would change things dramatically (you “just” need to find the ~30k then) but that would be political dynamite.

Last Edited by Peter at 16 Feb 14:10
Administrator
Shoreham EGKA, United Kingdom

Now according to JAA ACJ20X5 you need to, besides TSO-C129, additonally prove your navigator complies with C129a paragraphs (a).(3),(xv).5 and (a).(6).

@ Tomjnx
Tom, I found an “or” between those above cited requirements, that would change the pseudorange step error detection proof ?

from JAA ACJ20X5 :

5.4 Additional Criteria for Stand-alone GPS equipment only.
The following points need to be taken into consideration as part of the airworthiness approval:
(a) For IFR operations, Class A equipment, is required to be approved to either:
(i) FAA TSO-C129a or
(ii) FAA TSO-C129 and the additional paragraphs (a).(3),(xv).5 and (a).(6) of TSO C-
129a.

Last Edited by nobbi at 16 Feb 14:43
EDxx, Germany

There are differences between TSO C129 and C129a. Most GPS units are certified to TSO C129a. I would interpret the “or” if they are certified to the earlier version of the TSO, that they must also meet the requirements identified in the latter specification. However, having the GPS meeting the requirements of the TSO are one thing, but the installation has to meet additional specifications for an IFR installation. The FAA uses AC 20-138a or later for IFR certification. Example it requires an external CDI in the primary view of the pilot. A stand alone TSO box does not meet this requirement. It must be installed in compliance with the manufacturers installation manual which typically includes requirements for IFR installation that specify a pressure altitude source (typically an encoding altimeter) and other requirements that don’t apply for a VFR installation. In addition, an AFMS is required as are certain ground and flight tests. This is easy if there is an STC with an AML as the AFMS is already pre-approved. If not, then an AFMS needs to be edited to match the installation and should have the same limitations as the approved version being edited. In the US, the AFMS is submitted with a 337 to the local FSDO requesting it be field approved.

KUZA, United States

I was talking about 5.4(a)(ii).

Obviously, if the navigator complies to C129a, it will comply to all paragraphs of C129a, including (a)(3)(xv).5.

LSZK, Switzerland

My recollection – never investigated it in detail – was that GPS/LNAV approach approval became an EASA minor mod approx 2006.

Today I found the CAA.UK regulation regarding the a.m. problem – it’s in CAP 773 and says:

2.6 Existing Installations
Those installations that meet the requirements of Part 1, paragraph 2.4, but that are not certified in the AFM/POH in accordance with Part 1, paragraph 2.5, may be the subject of an application to EASA (for changes to an aircraft’s type certificated standard) via an EASA Form 31 or 32.

EASA Form 31 or 32 are major modification or minor modification which means to

throw a few hundred € at an EASA 21 company

Last Edited by nobbi at 17 Feb 22:40
EDxx, Germany

Some interesting reading here on the US situation.

over 80% of the 967 VORs in the NAS inventory are past their economic service life and cost the FAA more than $110M per year to operate. Likewise, replacement parts are becoming increasingly difficult to obtain. The replacement of all of the VORs would cost over $1.0B

110M/967 comes to $113k/year for a VOR.

One might assume that like a lot of things in aviation it is going to cost 2x as much in Europe… That’s a huge amount of money. You could build a nice 4 bedroom house for that.

Last Edited by Peter at 01 Mar 09:13
Administrator
Shoreham EGKA, United Kingdom

Can anyone come up with any actual figures between LPV and ILS?

I understand the survey cost is similar.

Does LPV need the same regular calibration flights as an ILS?

Administrator
Shoreham EGKA, United Kingdom

Dave Philips?

Last Edited by Neil at 14 Aug 14:33
Darley Moor, Gamston (UK)
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