IMC

[W2k]

IMC is one thing, but GPS is greatly useful to pilots under VFR as well. I'm working on my PPL(A) right now and all the instructors I've flown with advocate using GPS for general navigation.

Of course I'm also learning to use the old nav aids as is required for the PPL, I can find my way using VOR, ADF or map-and-stopwatch no problem, but quite frankly, I consider those to be (cumbersome) backups for when the GPS fails, just as the turn indicator can be used as a substitute gyro horizon in a pinch.

GPS is here to stay. Possibly supplemented by other satnav systems to provide redundancy, but I for one won't be shedding tears when they turn the last power-hogging NDB off.

[TurboJ]

IO540

and the reference that this organ has the slightest legal significance is......... where?

Are you suggesting I teach the use of GPS contrary to a CAA safety publication?

I also refer you to CAP773: Flying RNAV GNSS Approaches in Private & GA Aircraft which states that the required approval of the GPS equipment to fly GNSS/RNAV approaches should be clearly stated in the AFM. This, I believe, is also true of en route GPS navigation.

I believe GPS is great, I use it every day, I am not stuck in the dark ages, or dragging myself kicking and screaming into 2010; I also don't believe GPS is evil or illegal;

However, if you are teaching GPS to students who fly GPS approaches or use GPS for en route navigation, then they should be taught that the equipment they intend to use is to be approved for its intended use or it should not be used as a primary means of navigation. I don't believe this is uneducated tosh -

En route nav: RNP is 5
Terminal nav: RNP is 1

[Katamarino]

I've been looking at FAA RNP. Guess it must be different...5nm seems pretty poor precision.

[Duchess_Driver]

The problem with GPS is the inherrent inability of MOST owners to keep the database up to date - and despite protestations to the contrary, things do change from time to time.

Gents, the truth of the matter should be that we use ALL available facilities to maintain our positional and situational awareness. Who really cares whether GPS is primary or not.

DD

[TurboJ]

Who really cares whether GPS is primary or not.

The CAA investigator when you're sat in front of him facing an infringment interview !!

When London City airspace changed a few years back it caught a lot of GPS happy PPL holders out who were flying fat dum and happy with their out of date databases, using GPS as sole means of nav.....cos their instructors probably told them it was such a great piece of kit....

[S-Works]

TurboJ, Do me a favour and show me where a Safety Sense leaflet is enshrined in law? I am struggling to reconcile your claim with the legal position and just want to make sure we are talking from the same book.

[IO540]

I've been looking at FAA RNP. Guess it must be different...5nm seems pretty poor precision.

Yes... all that "RNP" stuff goes back to the goode olde days when pilots were real men with sextants, and a jet pilot coming off the oceanic route was doing damn well if his INS drifted off by just 5nm.

Today it is basically meaningless, because both INS with GPS or DME/DME fixing yields accuracies of a fraction of a nm (equivalent to RNP 0.3 or better).

A Garmin 496 is RNP0.0-something and that's before you get EGNOS..... The funniest thing being that a handheld is allowed to receive EGNOS whereas a certified unit isn't

But there is such a huge army of assorted well paid hangers-on around the national regulators safeguarding "RNP" based performance specs, and all the associated avionics certification garbage, and turkeys have never voted for xmas.

BRNAV is RNP5 I think. PRNAV is RNP1, I think. GPS approaches are RNP0.3 or something like that, which is why PRNAV (which requires weird equipment and crew certification, despite being less accurate than GPS approaches for which even EASA has a straight path today) is now completely irrelevant. But does that stop the PRNAV machinery in its tracks? No way. It will be 10-20 years before they realise that the "RNP" boat has left the port (sunk, actually) a few years ago.

The problem with GPS is the inherrent inability of MOST owners to keep the database up to date - and despite protestations to the contrary, things do change from time to time.

I am sure that's true but have not seen evidence that this statistically features in CAS busts. Let's face it, the CAA VFR charts update once a year, and they are as "official" as you can get... And the typical handheld, with its fairly hopeless Jeppesen mapping, needs to be used together with the printed chart anyway.

It's different and more critical for airways/IFR where all nav is 100% GPS and ATC are constantly feeding you waypoints. I should update the KLN94 database every 28 days but in practice I don't bother if I am not flying airways in those 28 days, so I skip that cycle and save myself a few bob. I did one airways flight 2 weeks or so ago and the next one will be to Germany on 9th April and I see there is a download becoming valid on 8th April so I will grab that one.

[Duchess_Driver]

Which is why we should have all available systems on and tracking.

I'm not pro GPS or anti it....I couldn't care less....but I do teach my students GPS/VOR/NDB/DME navigation and the use of an integrated approach to navigation. In VMC, I even advocate looking out of the window

DD

[mm_flynn]

Originally Posted by IO

BRNAV is RNP5 I think. PRNAV is RNP1, I think. GPS approaches are RNP0.3 or something like that, which is why PRNAV (which requires weird equipment and crew certification, despite being less accurate than GPS approaches for which even EASA has a straight path today) is now completely irrelevant. But does that stop the PRNAV machinery in its tracks? No way. It will be 10-20 years before they realise that the "RNP" boat has left the port (sunk, actually) a few years ago.

The RNP is about how close the aircraft is to where it is supposed to be, not about how accurately the nav kit measures the actual location.

So RNP 0.3 means you are within 0.3 nm 95% of the time and, I think, 'never' (ie. 99.999% sure) be more than 0.6 nm from your programmed track. This needs to be true for all of the supported profiles (turns, DME arcs, etc.) this is why there was the debate on PRNAV if autoslew HSI was requried

(How many people can make a 45 degree course change in IMC never moving more than 0.5 mile from the specified flight path using an NDB or VOR?)

The US version of PRNAV is called RNP xxx. It is on trial in Alaska with IMC approaches consisting of multiple fly past waypoints weaving up mountain gorges all below the mountain ridges.


The use of GPS ranges from the use RNP SAAAR approaches, through WAAS approaches, into normal GPS approaches, RNAV, GPS monitoring, VFR situational awareness with a quality aviation moving map (with up to date data) down through a hacked car GPS with a 5 year old map on down to a camping GPS with a lat lon display. So making any comment about Good/Bad on 'GPS' is not very illuminating with out contexting the type of equipment.

[IO540]

The RNP is about how close the aircraft is to where it is supposed to be, not about how accurately the nav kit measures the actual location.

Indeed; however one has the same issue with a standard T-shaped GPS approach, with a fly-through IAF and a fly-past later on. The accuracy required is pretty high.

America seems to be relaxed about it - for private GA in its own airspace.

[TurboJ]

I don't believe I have stated that a safety sense leaflet is a legal document.

Where does it say you can go and use a handheld GPS to fly an instrument approach?

Where would you stand at the board of enquiry when a person you have taught has crashed their plane because you didn't teach them the pitfalls of GPS and the need to have equipment approved and certified before use?

[IO540]

Where does it say you can go and use a handheld GPS to fly an instrument approach?

Where does it say you can't?

Of course only an idiot would fly an ILS using a GPS...

To fly a nonprecision approach (VOR or NDB) using a GPS, one really needs one with OBS mode and few handhelds have got that. Most modern pilots fly them with an IFR GPS's OBS mode.

Where would you stand at the board of enquiry when a person you have taught has crashed their plane because you didn't teach them the pitfalls of GPS and the need to have equipment approved and certified before use?

Nowhere. It would not arise. In the UK, there is no comeback on an instructor. If there was, many would be out of a job, following accidents of former students.

[TurboJ]

Where does it say you can't?

CAP 773

Legal document or not, its a reference document produced by the UK CAA.

I'm not going to ignore a UK CAA document cos some guy on pprune says so.

[S-Works]

I'm not going to ignore a UK CAA document cos some guy on PPRuNe says so.

Which is entirely your perogative, however your previous posts were ethusiastically trying to convince the rest of us that it was against the rules to use a GPS as primary navigation equipment when I clearly pointed out that in order to meet BRNAV and PRNAV in light aircraft a GPS is the only means of complying. Therefore it is somewhat at odds about your claim that you are not allowed to use GPS as primary navigation.

As IO540 quite rightly points it there is no legal requirement for any type of PRIMARY navigation. The CAA safety sense leaflet is primarily aimed at those who think it is a great idea to use a car or walking GPS or the in the bottom of the bag brigade who generally don't have a clue how to use them and when they actually need them do more harm than good.

The use of an aviation GPS even a handheld one for VFR flying if properly trained for and used is a huge benefit to situational awareness and safety. It can be used on its own or if the pilot is prudent as a part of blend of navigation tools.

For IFR cruise and approaches then an approved panel mount is the way to go and used by the majority of GA IFR traffic this day. Even our work Turbines are being fitted with Garmin stuff now to replace the old FMS. The FMS was also the PRIMARY means of navigation for us in the past, however it is not unknown for me to stick the 496 up on the dash to watch the world go by.

[TurboJ]

Maybe I should have phrased it slightly different.

GPS can only be used as a primary means of navigation if the equipment and installation is approved and certified and correctly indicated in the POH/AFM in accordance with EASA AMC 20-5. Otherwise it may be unsuitable for RNAV/GNSS operations.

I am not going to teach a student anything to the contrary.

In the UK, there is no comeback on an instructor.

So my FTO is paying a fortune for instructor liability insurance for......??

[IO540]

GPS can only be used as a primary means of navigation if the equipment and installation is approved and certified and correctly indicated in the POH/AFM in accordance with EASA AMC 20-5. Otherwise it may be unsuitable for RNAV/GNSS operations.

Correct for BRNAV, but not a lot of your students will be going IFR, FL095+ which in the UK is Class A anyway, and in virtually all cases an IR is needed

(I say "virtually" because there are a few places in the UK one could go IFR on the IMCR alone at FL095+ but one would be hard pushed to find non-Class A CAS )

Not applicable to normal private flight, however.

So my FTO is paying a fortune for instructor liability insurance for......??

You are paying that in case one of your instructors is involved in an accident, and the student (or his estate) sues, or there is a ground damage claim. Or some spurious personal assault claim which has to be defended... a possibility when one is spending a lot of time alone in a plane with the student.

There is no known case of a comeback (in the UK) against an instructor simply for poor teaching methods.

[mad_jock]

There is no known case of a comeback (in the UK) against an instructor simply for poor teaching methods.

Prestwick I forget the details but a student crashed after getting himself IMC and the instructor was sued by the arab parents and the instructor had to pay sizable damages. It wasn't just poor teaching methods (by teaching methods I also include the process of sending someone solo and the duty of care if the student isn't hitting the grades)

[IO540]

It wasn't just poor teaching methods (by teaching methods I also include the process of sending someone solo and the duty of care if the student isn't hitting the grades)

Exactly. If the instructor ticks all the boxes, there isn't going to be a comeback purely on bad teaching methods.

Anyway, we are talking about instructor being gone after after the punter is qualified. Establishing liability would be almost impossible - provided the paperwork was straight.

[Fuji Abound]

The FMS was also the PRIMARY means of navigation for us in the past, however it is not unknown for me to stick the 496 up on the dash to watch the world go by.

So how did the FMS derive position?

[mad_jock]

My FMS uses 6 DME/DME cross hatchs then down grades to VOR/DME then GPS . It throws up all sorts of warnings if it goes into GPS only mode.

yep agreed on that one IO