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GNSS/SBAS IAP in UK

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GNSS/SBAS IAP in UK

Old 25th Dec 2011, 11:56
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GNSS/SBAS IAP in UK

There are a number of rumours being propogaded in respect of the UK CAA relaxing restrictions on the provision of GNSS/SBAS instrument approach procedures without the need to provide either an APP or APS ATS service.

If in Class G airspace I fully agree with the concept of an ADI/ADV/AFIS provided service at an aerodrome offering the IAP, far better a regulated system to ensure terrain clearance than pilots making up their own procedures.

Can anyone comment on the relaxation of regulation or provide their input to support its implementation if not already in hand.

Merry Christmas to you all.
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Old 27th Dec 2011, 12:06
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To get any iap approved, it needs to be designed by an approved design authority, (NATS Services Ltd will do this) and have a 'safety case' produced; when all this is done it can be presented to the CAA for approval thus enabling it to be used by anyone with the correct qualifications in a suitably equipped aircraft.
What many people designing their own 'private' procedures (ie for their personal or company only use when not operating for public transport) forget is that a missed approach procedure MUST be integral to the design, as obstacles in the missed approach area may have an impact on the OCA/MDA.

Last edited by chevvron; 27th Dec 2011 at 16:22.
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Old 27th Dec 2011, 18:11
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Chevvron

Thank you, more than aware of what is required by DAP to approve an IAP, NATS are the last persons that I would consider to design it, far more economic options available in the real world.

Have a Safety Case ready to go, which recognises and addresses the hazards of an IAP in Class G airspace.

The question is can anyone enlighten me on whether the UK CAA are going to relax the current requirement for the aerodrome to provide an APP or APS service in order to offer the IAP for an aerodrome in Class G airspace?
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Old 27th Dec 2011, 19:18
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There is a rumour (and it is only a rumour) that when the procedure includes an APS or APP unit which will 'filter' traffic so only one aircraft is using it at a time, the CAA might allow it. I believe this is why they have approved the ILS procedure at Walney Island (a FISO unit) ie because Warton ATC only allows one aircraft in the procedure at a time and will hold succeeding aircraft off until the first one has either landed or gone around.
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Old 27th Dec 2011, 21:44
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Sir George Cayley
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25 DME FIX. You are right that change is a comin' and Chevron is also right.

There are a number of obstacles to progress the CAA are addressing and consultation is, I'm told, due in the New Year.

2012 should see progress, especially as several pressure groups are on the case.

But have a think about this scenario. It's a shitty day with a moist warm front across the country. You are IMC in class G at the correct quadrangle rule level. You are in receipt of a basic service but have to get from here to the first intermediate approach fix. You can't get a service which will separate you from other traffic and the AD doesn't operate to PPR.

How will you safely transit from an en route phase to an approach phase in IMC without a separation service?

Answers on a 50 note to the Head of CAA, That London, England.

SGC
 
Old 27th Dec 2011, 22:14
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Sir George, with the greatest respect, you are making the same 'error' that most in the CAA's ATC section do.

Do not confuse:
a) a desire to transition between IMC and VMC (or sufficiently good wx to complete the approach and landing) when approaching an airfield with
b) a desire to be separated from other aircraft in the area or wishing to do the same as you.

If a pilot wants to get onto the ground from a non-visual situation then he/she needs an IAP. If a pilot wants to be separated from other aircraft then he/she needs an ATC Service (or a couple of the UK's curious Flight Information Services might do). If a pilot wants to make an approach and be separated from other aircraft the he/she needs both an IAP and ATC.

Conflating the two concepts (and functions) causes many problems when trying to resolve the current mess.
 
Old 28th Dec 2011, 09:44
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Sir George Cayley
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I love that word conflating.

I'm not confusing the two. It's the particular situation in the UK wrt the airports most likely to benefit from any type of RNAV (GNSS) approach and the current rules.

Those airports that can offer an approach control service and separation of traffic that's in IMC are in many cases not pushing for GPS as they have established navaids that are fit for the purpose of satisfying your b)

Operators wishing to land at an airport without an approach control service or conventional ground based navaids want the airport to, at least, offer an LNAV IAP fo increased accessibility.

The rub is that there isn't a homogeneous (free) radar service across the UK and a lack of airspace of an appropriate class in which to offer separation.

This means that a GA pilot wishing to land at an aerodrome with an RNAV(GNSS) IAP but not much else has to fly most of the procedure (whether IMC or not) in class G - i.e. not a known environment.

The typical T or Y design is quite a big piece in the sky and with the density of aerodromes in this small wet island it means a challenge for the designers.

I don't see it as a mess, I see it as an opportunity for the powers that be to really deliver safety benefits and increased accessibility for all.

SGC
 
Old 28th Dec 2011, 20:09
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Spitoon
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Sir George, I'm not sure I understand your point. You seem, in places, to be blurring the two issues that I mentioned.

The first situation that you describe - airports with ATC and existing conventional ground-based navaids - satisfies both my a) and b). That these airports may not be pushing for satellite-based approaches is probably because they do not see a positive cost-benefit in doing so - i.e., it will cost money to get the approaches designed and the aircraft that they are providing with services can do very well with what's already there.

So that leaves us with airports without an approach control service or conventional navaids. The rub, as you put it, is that the airports will still have to pay to get the approaches designed but the users will be reluctant to pay for this through increased landing fees (or there simply isn't enough traffic to recover the cost in any reasonable period of time). I'm not sure that I see the lack of radar service or contiguous suitable airspace in which separation can be provided in the en-route phase to be in any way connected.

You say 'This means that a GA pilot wishing to land at an aerodrome with an RNAV(GNSS) IAP but not much else has to fly most of the procedure (whether IMC or not) in class G - i.e. not a known environment'. This is going to be true
in most cases - and is sometimes the case at airports with ATC and conventional navaid-based approaches. And, to me, seems to blur the issues of approaches and ATC/separation.

The mess I referred to is more to do with inconsistent and outdated rules which are commonly, if not ignored, creatively interpreted (and powers that be that have trouble recognising this). There's no question that satellite-based approaches offer great potential benefits but to meet the relevant ICAO SARPs may be difficult or costly for many airports. Maybe a better first step might be to try and develop some form of cloudbreak procedure which could be a more viable proposition in some situations.
 

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