GPS Approaches
Joined: Mar 2002
Posts: 2,814
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From: Euroland
IO540, - Except when taking off or landing
Yep, that is what it says in the ANO under Instrument Flight Rules.
However, think of it like this when dealing with GPS -
One can not complete an approach that is not in the databse. There are no approaches in the UK.
Thus when in the UK, most approved GPS units are limited to BRNAV which has an RNP of 5.
Since the unit is only by virtue of the RNP5 certified to be accurate to within 5nm of the indicated position for 95% of the time, you must considder all obstacles within that 5nm unless you can avoid them visually.
Remember that RNP5 is acheived on the ATS routes where the VORs are not more than 100nm appart!!!!...........so when it comes to using the equipment in accordance with the approvals within the UK you are just as good using a VOR 50nm away!!!
Also considder what it says in the AIP about required visual reference before descending below the applicable height that provides the required obstacle clearance.
GPS is very accurate. So is my flying..........but I can't just use that as the basis for flying CATIIIC approaches..........unless the aircraft is approved and the ILS/airfield capable.
Regards,
DFC
Yep, that is what it says in the ANO under Instrument Flight Rules.
However, think of it like this when dealing with GPS -
One can not complete an approach that is not in the databse. There are no approaches in the UK.
Thus when in the UK, most approved GPS units are limited to BRNAV which has an RNP of 5.
Since the unit is only by virtue of the RNP5 certified to be accurate to within 5nm of the indicated position for 95% of the time, you must considder all obstacles within that 5nm unless you can avoid them visually.
Remember that RNP5 is acheived on the ATS routes where the VORs are not more than 100nm appart!!!!...........so when it comes to using the equipment in accordance with the approvals within the UK you are just as good using a VOR 50nm away!!!
Also considder what it says in the AIP about required visual reference before descending below the applicable height that provides the required obstacle clearance.
GPS is very accurate. So is my flying..........but I can't just use that as the basis for flying CATIIIC approaches..........unless the aircraft is approved and the ILS/airfield capable.
Regards,
DFC
Joined: Feb 2003
Posts: 2,042
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From: Oxford
Maybe inadvisable, DFC, but you still haven't shown them to be illegal for private flights. Indeed the CAA published a paper (last year? what happened to it?) discussing two separate issues:
(a) approving approaches at airfields with only a FIS;
(b) making non-approved approaches illegal for all flights;
making it quite clear that at the moment the latter are not illegal. They wanted to tie (a) to (b) as a sweetener for (b).
Or are you suggesting that home-made NDB and VOR approaches are legal, but home-made GPS ones not? Not sure how that could be justified.
Tim
(a) approving approaches at airfields with only a FIS;
(b) making non-approved approaches illegal for all flights;
making it quite clear that at the moment the latter are not illegal. They wanted to tie (a) to (b) as a sweetener for (b).
Or are you suggesting that home-made NDB and VOR approaches are legal, but home-made GPS ones not? Not sure how that could be justified.
Tim
Joined: Jun 2003
Posts: 13,787
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From: EuroGA.org
I think that all the time it is legal to choose freely to go "IFR" outside CAS, they cannot practically outlaw DIY descents through cloud. The best they could do is enforce a minimum MDH of 1000ft - the IFR MSA.
Let's face it, such a pilot isn't going to be flying a normal procedure where one goes overhead a beacon, then straight for 6D or whatever, then a rate 1 turn onto the inbound track, then a stepdown descent when within 5 degrees (of an ADF track which is probably itself some 20-30 degrees out...)
What he will do is fly to a point which is on the extended centreline of the runway, say 3 miles away, get there 1000ft above the terrain, and just fly the GPS-supplied runway-aligned track all the way to going visual.
And if there are no obstacles, that should be as safe as any navaid. The FAA seem to reckon so, and they have far more planes over there than the CAA.
Let's face it, such a pilot isn't going to be flying a normal procedure where one goes overhead a beacon, then straight for 6D or whatever, then a rate 1 turn onto the inbound track, then a stepdown descent when within 5 degrees (of an ADF track which is probably itself some 20-30 degrees out...)
What he will do is fly to a point which is on the extended centreline of the runway, say 3 miles away, get there 1000ft above the terrain, and just fly the GPS-supplied runway-aligned track all the way to going visual.
And if there are no obstacles, that should be as safe as any navaid. The FAA seem to reckon so, and they have far more planes over there than the CAA.
Joined: Mar 2002
Posts: 2,814
Likes: 0
From: Euroland
Does the FAA all ow pilots to fly DIY GPS approach procedures?
or
Does the FAA require that a GPS approach procedure be approved and contained within the database?
Yes, currently DIY "cloudbreak" procedures are permitted by the UK CAA. It can't be called an approach procedure because such a procedure requires ATC.....hence the proposals spoken of above.
If a person decides to design a "cloudbreak" procedure then it is incumbent on them to apply the appropriate obstacle clearances as laid down by the CAA............This usually requires a survey of the area if anything less than 1000ft above obstacles (enroute minima) is used and requires plenty of forethought and planning.
It would be a shame to be completing the perfect GPS letdown at the local club only to colide with the other non-radio guy doing the same in a slower aircraft!!!!!
GPS is super accurate. Home made approaches are full of danger for the unwary..and most of the dangers are unrelated to the guidance system.
Regards,
DFC
or
Does the FAA require that a GPS approach procedure be approved and contained within the database?
Yes, currently DIY "cloudbreak" procedures are permitted by the UK CAA. It can't be called an approach procedure because such a procedure requires ATC.....hence the proposals spoken of above.
If a person decides to design a "cloudbreak" procedure then it is incumbent on them to apply the appropriate obstacle clearances as laid down by the CAA............This usually requires a survey of the area if anything less than 1000ft above obstacles (enroute minima) is used and requires plenty of forethought and planning.
It would be a shame to be completing the perfect GPS letdown at the local club only to colide with the other non-radio guy doing the same in a slower aircraft!!!!!
GPS is super accurate. Home made approaches are full of danger for the unwary..and most of the dangers are unrelated to the guidance system.
Regards,
DFC
Avoid imitations
Joined: Nov 2000
Aviation Qualifications: ATPL
Posts: 15,115
Likes: 1,091
From: Wandering the FIR and cyberspace often at highly unsociable times
tmmorris,
You asked: "Maybe inadvisable, DFC, but you still haven't shown them to be illegal for private flights. Indeed the CAA published a paper (last year? what happened to it?) discussing two separate issues:"
There was an outcry against the proposal by a number of commercial operators. One can imagine why - i.e. folks would be prevented from doing what they have already been doing for some time..... and the CAA, to their credit, are thinking again. There are places in UK where there are "private" letdowns based on GPS, these have been properly surveyed and are known to the CAA.
Hopefully the next step is for the CAA to admit that properly surveyed GPS approaches, flown by properly trained crews, in properly equipped aircraft ARE safe and therefore can be approved and formally sanctioned.
You asked: "Maybe inadvisable, DFC, but you still haven't shown them to be illegal for private flights. Indeed the CAA published a paper (last year? what happened to it?) discussing two separate issues:"
There was an outcry against the proposal by a number of commercial operators. One can imagine why - i.e. folks would be prevented from doing what they have already been doing for some time..... and the CAA, to their credit, are thinking again. There are places in UK where there are "private" letdowns based on GPS, these have been properly surveyed and are known to the CAA.
Hopefully the next step is for the CAA to admit that properly surveyed GPS approaches, flown by properly trained crews, in properly equipped aircraft ARE safe and therefore can be approved and formally sanctioned.
Last edited by ShyTorque; 17th October 2004 at 07:50.
