1000 feet should be fairly safe, much below that you can find oil rigs and wind turbines.
But are you sure of your QNH ?

Galaxy,
My point was not if you should observe these limitations or not but the definition of safety, and that safety is not a black and white issue but a variable. Good airmanship dictates that you select the least risk option, generally that will mean you do not descend below MSA, but there can be situations where that may not be the safest option!

You're quite right, but my point is that as far as the GPS is concerned, an approach is just a sequence of waypoints. Whether those form part of a published approached, or whether they're user-defined ones that you made up as part of your home-brew approach, it neither knows nor cares.

I'm not recommending home-brew approaches, just saying that it isn't too hard to figure the mechanics of how to fly one.

Last time I did it, 125ft on the Rad Alt, but that was 50+ miles north of Iceland with no diversion. These days I would never descend below MSA without an approved IAP or radar vectors.

Actually the GPS does know and care, very much.

With a published approach loaded the GPS will scale at the FAF from 1 mile to 0.3 mile full scale deflection and a TSO 146 GPS will scale to full scale deflection of 2 degrees inside the final fix down to 350 feet at the missed approach point.

A homebrew approach cobbled together using just a sequence of waypoints will be scaled to 1 mile at best and could be as much as 5 miles full scale.

I know what I'd want to use for an approach and it sure ain't some dodgy homebrew one.

Good point, I'd forgotten about that (although of course it pops up on the GPS every time). It's another good argument against using a homebrew approach, as if any more were needed.

It will be scaled to whatever you set it to. The more significant aspect is the integrity: the horizontal alerting limit may be significantly higher than for a procedure retrieved from the database

For those thinking of GPS and synthetic vision are infallible, have a read here.

https://www.caa.govt.nz/Accidents_an...-SML_Fatal.pdf

I certainly don't think any of this stuff is infallible, but you can hardly lay this at the GPS. Yes, the terrain database was inaccurate, but presumably the aircraft had an altimeter. This is like truck drivers getting stuck under low bridges or people driving into rivers because they "followed the GPS".

Slightly off topic, but recently upgraded our G430 t0 430W. I have been amazed at the accuracy and stability of GPS approaches carried out. Even an LNAV/V with only advisory glideslope, (i.e. Shoreham) if flown accurately takes you to the Rwy numbers. Pity that unnecessary regulatory bulls..t prevents this great safety enhancing aid being stifled in CAA land.

Cessnapete
I will be doing the same upgrade on my 430 later this year, what was the ballpark cost if you don't mind me asking?

Anything to do with aeroplanes, not cheap! C182Q
£2300 to Garmin UK to upgrade the internal hardware/software, quite a big mod apparently, new faster processor etc.
Then about another £2000 for avionics shop.
New GPS aerial and cable to G430 box.No new holes to cut as all new upgrade parts fit into present positions in aircraft. And nice new thick Garmin manual to teach you how to use it!
Includes a 'royalty' fee to GAMA Avionics for their time, expertise and paperwork for the mod in UK.
All done expeditiously and efficiently by RGV Glos.

I just upgraded my 530 to a 530W, and replaced my 330 transponder with an ADS-B 345. Total cost including parts and labour was about $16K. Ouch.

I agree with pb84 - LPV approaches are a pleasure to fly.

Hopefully you would be sat in your arm chair at home having carefully studied the weather forecast and realised that the forecast conditions were not suitable for your aircraft/qualifications.

I flew maritime patrol for a living with a previous company. We would not decend below an absolute minimum of 1300ft on the forecast regional QNH if we had not become VMC as obstacles could be up to 299ft without being shown on a chart.

Ideally yes, but if you have never been caught with an incorrect forecast you probably have not got too many hours under your belt, It is also very different operating commercially in light aircraft than someone who can choose to only fly in CAVOK conditions.

This thread is amazing! There are dead bodies and wreckage strew all over the place, well qualified professional pilots saying flying a DIY approach is a stupid thing to do and a bunch of plonkers saying it's OK. To those who think flying a home brewed approach is OK, may make one request please: Fill in a donor card. Your brain, although unused, will not be involved in any transplant.

PM

Shame they normally are beyond recovery by the time the ambulance gets to them...

This thread is making me feel as though there hasn't been enough lobbying to the UK CAA to allow GPS instrument approaches at uncontrolled airfields to be more widely accepted / cheaper (re: paperwork / CAA application fees).

Surely if the UK CAA had a duty of care, and had to ensure safety was paramount - all airfields in the UK would have GPS approaches.

I've got a copy of a 'discrete procedure' for Wellesbourne - looks like it originates from 1995 and uses the HON VOR and DME. Is this the same as an unpublished approach? I've only ever used it during my IMCr training and I'm a bit unsure about what it is really!

My understanding is that this is a training procedure, only to be used in VMC, another interesting one is the VOR procedure at Goodwood - this USED to be a published procedure but got withdrawn, so how many would use that down to its (once) published minima?

Foxmoth
Flew the old GWC VOR/DME NPA and Hold on my last IR renewal. Worked a treat, and free!

My understanding is a discrete procedure is supposed to be for a specific company to use and approved only for them (with an AOC?). Not sure if the Wellesbourne VOR procedure is strictly one of those - like you I used it in training.

Putting aside the wisdom or otherwise of using non-published procedures, the legalities for a private operation seem to allow it (in the UK).

I.e. the minima for IFR in the ANO and SERA do not apply when taking off or landing without any mention of following a defined procedure.

So it would seem reasonable that a procedure established and maintained to the same standards as a published one should offer a similar level of safety. The arguments about separation from other traffic are not much different from those for operating IFR outside controlled airspace except that you are in the vicinity of an airfield and hence more likely to encounter other traffic.

So, I agree using a hastily home-brewed approach carries increased risk, but a well thought out one done to the prescribed standards should be legal and relatively safe.

ANO:

Nice try. But ignoring for a moment the issue that the ANO is not applicable to the operation of EASA aircraft, the 1000 ft rule for IFR in SERA is not part of aerodrome operating minima.

I'm still waiting for some one to come up with a persuasive list of examples of the "dead bodies and wreckage" attributable to unpublished let-downs. Most of those the examples I've seen cited are accidents that did not seem to depend on whether or not an approach was published or approved.

I know of accidents where pilots messed up published IMC let-downs and others where pilots attempted to let down without any sort of pre-planned procedure. However, I can only think of one accident where an "unpublished" let down resulted in an accident and that occurred because the procedure wasn't followed at all accurately. Paradoxically, and sadly, a CAA Ops inspector was on board and perished along with the crew.

The same organisation suffered another, more recent and well publicised accident during an attempted IMC departure by a relatively inexperienced crew.

Bookworm, I was replying to this:

It's a thread, if you can follow it.

Shy;

Is this the one you're refering to? http://www.aaiu.ie/node/11 The late great Spotty Muldoon was the examiner on board.

Another, more recent one: https://www.gov.uk/aaib-reports/aaib...y-s-76c-g-wiwi I think we both knew the crew from that, and we both definately knew this guy:https://www.gov.uk/aaib-reports/agus...3-october-2010

SND

Hmm. All rotary.

Indeed if you are referring to G-HAUG, the primary cause was the deviation from the planned procedure. In the conclusions:

3.1.20 No evidence was found that would indicate that the aircraft would have experienced any difficulty in following the selected route, MOIRA - WARRN - MAP - B, if the aircraft had been operated throughout in the fully coupled mode, with Nav Capture, and allowed to fly the selected route without manual intervention.

There is an argument that a PANS-OPS compliant procedure would have offered more margin for error. But in general, deviating more than 1.3 miles from an RNP 0.3 final approach segment of a published procedure is also bad news.

Hear hear. After all:

NCO.OP.110 Aerodrome operating minima — aeroplanes and helicopters

(a) For instrument flight rules (IFR) flights, the pilot-in-command shall select and use aerodrome operating minima for
each departure, destination and alternate aerodrome. Such minima shall:

(1) not be lower than those established by the State in which the aerodrome is located, except when specifically
approved by that State; and

(2) when undertaking low visibility operations, be approved by the competent authority in accordance with Annex V
(Part-SPA), Subpart E to Regulation (EU) No 965/2012.

So whether you operate iaw the ANO or Part-NCO, you may only descend below your minumum safe altitude in IMC if you are following an approved procedure.

Your logic eludes me. Did you highlight the bit on "low visibility operations" for a reason? Where do you get "minimum safe altitude" from?

Clearly.

According to Skybrary, "Minimum Safe Altitude is a generic expression, used in various cases to denote an altitude below which it is unsafe to fly owing to presence of terrain or obstacles. An ICAO definition of the term "minimum safe altitude" as such does not exist." It is just a piece of jargon that a lot of seasoned pros would understand, like 'platform altitude' or any number of other phrases. Sorry it threw you.

Oggers,

I think you are reading more into that than is actually intended. It is about operating minima, as it says.

Your quote does not include any reference to descent below MSA or approved procedures.

Shy, have a read of this:

It is pretty clear to me that whatever discretion private operators had to exploit homebrew approaches back in the day no longer exists.

ROTFLMAO. :)

Oggers, it refers to the bit at the end of an approach, no reference to MSA.

ShyTorque

Yes the approach. That is what gets you down from safety altitude to minimums. I have shown you the regs. You are interpreting them differently from me, so here is some further guidance from the CAA:
It is in the ANO, it is in Part-NCO, it is spelled out in CAP773. You cannot descend below safety altitude in IMC unless you are using an approved procedure.
.

No matter how much you wish to kill yourself.

^^^^^^^^^^^^^^^^:ok:

All right. I've recovered my composure enough to type again… :)

Aerodrome operating minima are established for aerodromes for take-off and landing. They consist of a decision height or minimum descent height and an associated visibility condition for each approach. Aerodrome operating minima may be published by the state, although these days the UK simply adopts what it says in the corresponding part of the EASA Air Ops Regulation, in this case Part-NCO.

The rule that you want to apply as "MSA" is in Part-SERA.

SERA.5015 Instrument flight rules (IFR) — Rules applicable to all IFR flights
(b) Minimum levels
Except when necessary for take-off or landing, or except when specifically authorised by the competent authority, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State whose territory is overflown, or, where no such minimum flight altitude has been established:
(1) over high terrain or in mountainous areas, at a level which is at least 600 m (2 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft;
(2) elsewhere than as specified in (1), at a level which is at least 300 m (1 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft.

The 1000 ft mentioned in (b) is not part of "aerodrome operating minima". It is a generic rule for IFR flight that applies except when necessary for take-off or landing.

Descent below the levels addressed in SERA.5015(b)(2) when taking off or landing is not to be taken lightly. The best way of mitigating risk is to use a PANS-OPS compliant instrument approach procedure if available. Almost all CAT operations manuals will require that if relatively conservative minima for a visual approach are not met. But there is no requirement that a published procedure is used to meet the requirements of SERA.5015(b) when operating under Part-NCO.