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Unpublished let-downs

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Unpublished let-downs

Old 21st Jan 2017, 20:48
  #21 (permalink)  
 
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Homebrew approaches, what an extremely stupid idea. Either fly IFR and carryout a promulagted approach or fly VFR, don't go making up your own procedures.

I'm sure there are a few clever people who can figure out something, then there are the rest of us who are not so clever and miss an important item.

One thing you cannot incorporate in a home brew GPS approach is the scaling required to give the accepted scaling requirements that occur in a promulgated GPS approach.

Isn't the problem with GNSS approaches in the U.K. more the requirement for approach trained controllers? Whereas the USA allows you to shoot an approach to a non-towered or closed airfield with a clearance from a controller many miles away, so the only cost is the survey and approach design (and many early GPS approaches were overlays).
Isn't that so quaintly British, find a difficult solution to a simple problem. What benefit does the controller provide?

In New Zealand, (and I suspect it's the same in the USA) no controller clears you for an approach located outside of controlled airspace. You will be cleared out of controlled airspace and then you will carry out the approach as promulgated in the AIP. No controller input required.
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Old 21st Jan 2017, 21:41
  #22 (permalink)  
 
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I just want to clarify my earlier post that may be misinterpreted.

i'd rather take my chances shooting a homebrew approach with a non certified but extremley feature rich and flexible gps like a garmin 496 than i would with a cumbersome and purpose built certified unit like a 430. In fact i'd rather use an ipad with sd than a 430.
this was purely hypothetical, i haven't and would never do approaches this way and would strongly advise anyone considering it not to.
I was merely commenting on the user friendliness of different guidance systems.
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Old 21st Jan 2017, 21:45
  #23 (permalink)  
 
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Originally Posted by tmmorris View Post
Question: is ILS to an airfield nearby followed by 5-10nm of scud running safer than a home made approach flown using a proper approach certified GPS direct to the runway?
It seems to me that would be a choice between two alternatives, both of which are inherently unsafe.

Descending on a published approach to a point from which you are able to proceed VFR to destination is acceptable provided you are sure you will be in VMC until you land, but I would not call that scud running.

Originally Posted by 27/09 View Post
What benefit does the controller provide?
An out if you mess up, particularly if they have radar. Suppose you lose visual reference after the MAP? The serious incident in Gibraltar with a Monarch 757 comes to mind.
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Old 21st Jan 2017, 23:01
  #24 (permalink)  
 
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A controller would be a great bonus - yes. But should a controller be REQUIRED? I think not...

Since when do we need full ATC support to shoot an approach. In NZ it works marvellously well to just announce yourself, and follow the procedure. What happens in the UK when controllers become unavailable? Would elf n safety make them go elsewhere? Or would they just follow the procedure and land anyway?

In the case of the monarch flight - as well as a couple more recent incidents, ATC is useful to catch people's mistakes, but surely that is always pilot error is it not? That will always happen, even with ATC!
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Old 22nd Jan 2017, 07:51
  #25 (permalink)  
 
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Sillert,V.I: An out if you mess up, particularly if they have radar.
It would seem just having an available approach without a controller provides a level of accessibility and safety far in excess of not having an approach because you need to have a controller. One third of airfields in New Zealand that have scheduled IFR services do not have ATC of any sort. There's also plenty of others with no ATC that don't have scheduled services.

Sillert,V.I: Suppose you lose visual reference after the MAP?
Carry out the missed approach procedure, or, if more appropriate from a obstacle clearance point of view, carry out the promulgated IFR departure for that runway.

Unless it's a circling approach, I'd have to say in my experience, it would be very very unusual to lose visual reference after the MAP.

Last edited by 27/09; 22nd Jan 2017 at 08:31.
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Old 22nd Jan 2017, 08:39
  #26 (permalink)  
 
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Find a nearby airfield with an ILS if your aircraft is so equipped. Fly a few ILS approaches in VFR until you are 'competent'. If you get caught out above 8/8 clag, divert to said airfield, fly the ILS ( be prepared to explain if you are non- IR) and get a taxi home.
Don't fly below MSA in IMC unless you are qualified. Don't "scud run". It's not fun and you could kill yourself very easily!
If you expect conditions below 3-5miles vis/1500 cloud base - think "DO I REALLY WANT TO DO THIS?".
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Old 22nd Jan 2017, 09:56
  #27 (permalink)  
 
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Isn't the problem with GNSS approaches in the U.K. more the requirement for approach trained controllers?
No. The advent of CAP1122 in the UK provides for IFR approaches at locations without Approach control. However, as it stands, AFISOs are a prerequisite as Air/Ground only is (currently) unlikely to get approval according to said document.

(And it's Alexander Pope - 'A little learning is a dangerous thing.')
Nice to see the focus on the really important aspects of this safety related debate.....
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Old 22nd Jan 2017, 11:47
  #28 (permalink)  
 
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Good news, actually that does ring a bell but has any airfield got even near an approach with an AFISO yet?

As for Pope - why let an inaccurate fact go unchallenged, ever? I agree it has nothing to do with safety. It's a mindset.
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Old 22nd Jan 2017, 12:16
  #29 (permalink)  
 
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Nice to see the focus on the really important aspects of this safety related debate.....
Nice to see that we can focus on this really important facet as well..........
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Old 22nd Jan 2017, 14:08
  #30 (permalink)  
 
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Originally Posted by tmmorris View Post
Good news, actually that does ring a bell but has any airfield got even near an approach with an AFISO yet?

As for Pope - why let an inaccurate fact go unchallenged, ever? I agree it has nothing to do with safety. It's a mindset.
The Sherburn application is, I understand, at an advanced stage with the CAA.
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Old 22nd Jan 2017, 15:44
  #31 (permalink)  
 
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Originally Posted by tmmorris
Good news, actually that does ring a bell but has any airfield got even near an approach with an AFISO yet?
Campbeltown, Barra, Islay, Walney Is, Tiree all published. Wolverhampton well advanced but still in the pipeline.

Lands End is Twr only; no App.

Last edited by Downwind.Maddl-Land; 22nd Jan 2017 at 15:58.
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Old 23rd Jan 2017, 11:09
  #32 (permalink)  
 
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Firstly - you can't put unpublished GNSS approaches into IFR GPSs - they simply wont accept them. Its part of their certification.

So you are left with doing home brew approaches based off VFR GPSs or other navigation beacons.

A let down over the sea is still pretty safe. CFIT isn't a risk, so long as your altimeter is set. If you can get a traffic service from ATC, all the better.

Over land - your minimums are going to be pretty high for an unpublished approach. It doesn't take a rocket scientist to descend on a radial after crossing a VOR / beacon.

I wouldn't use GPS/ILS or some other app to go anywhere near the sorts of minimums I would on a published approach using a certified GPS. GPS altitude ambiguity and other issues (no alarms from a phone when it isn't getting an accurate GPS fix) mean it shouldn't be trusted, certainly for height info.

Some CAT operations have had their own approaches for years (I believe that there are unpublished GPS based approaches to places like Barra in use) but those are professionally created.
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Old 23rd Jan 2017, 15:43
  #33 (permalink)  
 
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Originally Posted by riverrock83 View Post
Firstly - you can't put unpublished GNSS approaches into IFR GPSs - they simply wont accept them. Its part of their certification.

So you are left with doing home brew approaches based off VFR GPSs or other navigation beacons.

A let down over the sea is still pretty safe. CFIT isn't a risk, so long as your altimeter is set. If you can get a traffic service from ATC, all the better.

Over land - your minimums are going to be pretty high for an unpublished approach. It doesn't take a rocket scientist to descend on a radial after crossing a VOR / beacon.

I wouldn't use GPS/ILS or some other app to go anywhere near the sorts of minimums I would on a published approach using a certified GPS. GPS altitude ambiguity and other issues (no alarms from a phone when it isn't getting an accurate GPS fix) mean it shouldn't be trusted, certainly for height info.

Some CAT operations have had their own approaches for years (I believe that there are unpublished GPS based approaches to places like Barra in use) but those are professionally created.
"A let down over the sea is still pretty safe"
Is "pretty safe" a positive or a negative statement? It's either safe or unsafe, and MSA is MSA whether you are over sea, land, or mountains which run down to the sea!!
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Old 23rd Jan 2017, 16:38
  #34 (permalink)  
 
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It's either safe or unsafe
Totally disagree, lying in bed is generally thought to be safe, but if thats all you do you will suffer all sorts of problems - and it is where most people die!
Aerobatics by a trained but inexperienced aerobatic pilot is relatively safe at 3,000'+ but less safe at 2,000' and progressively less safe the nearer he gets to the ground and similar could said of many aspects in aviation!
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Old 23rd Jan 2017, 17:23
  #35 (permalink)  
 
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Originally Posted by foxmoth View Post
Totally disagree, lying in bed is generally thought to be safe, but if thats all you do you will suffer all sorts of problems - and it is where most people die!
Aerobatics by a trained but inexperienced aerobatic pilot is relatively safe at 3,000'+ but less safe at 2,000' and progressively less safe the nearer he gets to the ground and similar could said of many aspects in aviation!
Therefore, using that logic it's safe to descend below MSA in IMC conditions! I disagree.
However, if one decides to do so, I agree it's less risky to descend over the sea, notwithstanding that there are less masts and aerials about than over the land, unless one encounters a ship! Risk management is an important element of safety, but safe/unsafe are viewed by most people as "black and white". Not grey!
As for staying in bed, that's not for me! Far too dangerous!!
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Old 23rd Jan 2017, 17:41
  #36 (permalink)  
 
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you can't put unpublished GNSS approaches into IFR GPSs - they simply wont accept them. Its part of their certification.
Actually, you can if you really really want to; it's fairly obvious how, but I wouldn't do so myself and don't intend saying how you can do so here.
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Old 23rd Jan 2017, 18:15
  #37 (permalink)  
 
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It's so obvious that surely anybody could work it out for themselves... just enter the sequence of waypoints. Of course you'll have to manage the altitudes yourself, and you won't get LPV or LNAV - just like a Mk I GPS approach.

The GPS approach to my own home airport (KPAO) always has to be manipulated along these lines, because ATC never, ever, ever uses the official IAFs. So you have to select one of them, then manually to "direct" to the IF they use. (If you care to look it up, the official IAFs are SAPID and LICKE, but you are almost always given directions to DOCAL, very occasionally vectored onto the ABSIW-PUDBY segment - even when my flight has taken me right through SAPID I've still been given "direct DOCAL").
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Old 23rd Jan 2017, 19:07
  #38 (permalink)  
 
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Therefore, using that logic it's safe to descend below MSA in IMC conditions! I disagree.
That is not what I said at all - the point is that it is not safe or unsafe it has a level of safety, even staying above MSA cannot be said to be safe per se, if you are have an MSA of 2,000' and you go from 2,001' to 1,999' have you REALLY gone from safe to unsafe, what you can say is that, generally, remaining above MSA is going to be relatively safe, if you go higher than that you are safer and if you go lower you are less safe, and the further you get below MSA the more unsafe it becomes, but even that has variations, for example if you are sitting in a light single at 2,500' in icing conditions with an MSA of 2,400' and you get a pirep that the cloud base is 2,350' what is the safer option?

Last edited by foxmoth; 23rd Jan 2017 at 19:33.
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Old 23rd Jan 2017, 19:48
  #39 (permalink)  
 
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How low would you descend to over the sea??
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Old 23rd Jan 2017, 21:24
  #40 (permalink)  
 
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N5396S,

Two different animals here, a non-TERPS'd home designed approach versus a usual ATC procedure to an operational advantage, that is, expedite traffic.

foxmoth,

While your example has some validity, air discipline requires as accurate as possible observance of established minima. If 1,999' is ok is 1,900'? When does one stop descending? All the errors in the error budget are not terrain, but instrument error, Venturi effects over mountainous terrain, ground reporting errors, etc.

GF
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