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A passing thought on GPS nav....

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Old 9th September 2007 | 19:11
  #21 (permalink)  
 
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Nope.

I would rather see GPS taught as an integral part of the PPL and used as a primary navaid with the map and conventional aids as a backup. I have had plenty of conventional equipment failures but can count the number of GPS errors on a couple of fingers and I would bet I have a lot more time navigating using them than most.

I do think anyone using a single method of navigation is a lunatic and requires some remedial training. There is no excuse for not having a map with a route drawn on it.

The problem with VOR/DME, NDB navaids is in the general GA fleet they are not FM immune, rarely maintained or properly calibrated despite the requirements for an avionics annual. They stop working at a moments notice, but the BIG problem is they do not wor very well at the alts that the average GA flyer operates. I flew back from the Guernsey Rally today at FL110 and only got SAM at about 60nm and that is on a perfect condition Garmin. GA heights over the see the coverage is much worse even after accounting for VHF signal propagation.

I am a great advocate of GPS and think it is a powerful PRIMARY tool. However even though I am permitted to use it as my PRIMARY source of navigation data for my flying I still draw the route on either the map or the airways chart.

The problem with incidents of this type is it just brings out the map and stopwatch/anti GPS lobby. We have to move with the times and GPS is part of this. You only have to look at the airlines move towards GPS driven FMS and the future of 4D FMS/GPS navigation to realise that GA is stuck in the dark ages.

Sooooooo.... GPS is a great tool, any idiot who has no backup plan for any type of primary nav is a fool. So lets not turn this into a GPS debate, Again..........................
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Old 9th September 2007 | 19:45
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backup instruments .. .. ..

poppycock

two GPS, one to backup the other.
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Old 9th September 2007 | 20:19
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Was that aimed at me Fuji? I always fly with 2 GPS, GNSx and 496. I was trying to be charitable with the conventional aids.

It is however possible to lose the GPS signal and in the case of the pilot under discussion he had a VOR which would have backed up the GPS and Map.

I love GPS but at the same time if other tools are in the cockpit use them all.
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Old 9th September 2007 | 20:20
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two GPS, one to backup the other
Presumably with two separate antennae and cables. And in the event of a GPS signal failure (e.g. local jamming, which the MoD keep experimenting with)...
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Old 9th September 2007 | 20:58
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Was that aimed at me Fuji? I always fly with 2 GPS, GNSx and 496. I was trying to be charitable with the conventional aids.
I promise you - not at all.

Just my sense of humour.

I fly with a G1000 so I am the last person to complain about GPS, and thinking about it I have two hand held GPS in my flight bag - a G195 and an iPAQ. Then again I also have an iCom with VOR.

Mind you I agree with you Bose, I have had just about everything fail, although never the GPS touch wood, other than on one occasion when it was blatantly my fault.
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Old 9th September 2007 | 21:02
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gcolyer,

I suspect you missed my point. He had to get a crash course because he couldn't instigate the basics. There are generic get out of trouble skills that are unrelated to what equipment may or may not be available at any given time. Would that scenario be an issue for you if radio nav was not available?
 
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Old 9th September 2007 | 22:23
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GPS may be the most wonderful navaid ever, I'm quite sure all those Lysander pilots of WW2 going to some obscure field in France would have loved it. BUT, "signal failure" how often do we hear this? To not do the basics with the chart / wind / sums for when it all turns to worms, is, in my opinion, utterly dumb. I thought it was a legal requirement to carry an up to date chart of the area? No excuse, ground the prat for gross incompetence!

Edit
D&D should charge him for the nav lesson.
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Old 9th September 2007 | 22:41
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while we all know, what we'd like, gps being taught to all, untill such time, I will follow CAA guide SRG_GAD_SSL25.pdf
gps as a backup
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Old 9th September 2007 | 23:13
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What the !!!!'s to stop you using GPS and Chart simultaneously?
I find it soothing to follow the magenta line but I do look out the bleedin' window all the time and match stuff on the ground with stuff on the chart and stuff on the GPS.
But I also before I go anywhere programme waypoints on the steam driven 8-waypoint RNAV.
Soooooooo..... I believe in triple redundancy but prefer to follow the high tech to the map and stopwatch.
These long drawn out GPS bashing threads give me the willies but while the rules are that GPS is for back up only , the detractors will always have the moral (and probablylegal) high ground.
Safe (and triple redundant) flying
Cusco.
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Old 10th September 2007 | 01:43
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wobble2plank

Ah, interesting read this, we heard the same conversation as you on 121.5 and it did sound a bit alarming that a GPS failure, close to destination, seemed to have led fairly swiftly to a call for help on 121.5, despite the aircraft having other navaids...glad it worked out OK but wonder what happend to pilot nav as I was taught it and as I taught it...closing angles, 1 in sixty rule and all that....
At least the guy had the good sense to get onto 121.5 and there was a happy ending.
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Old 10th September 2007 | 06:32
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My point for discussion is that this was a good VMC, VFR day
I didn't hear the conversation on 121.5, but I did hear the preceeding request on London Info and did share the bus on Guernsey with the pilot. I was also flying to the CI (Guernsey Air Rally) and the visibility between SAM and ORTAC was pants with no horizon at all for quite a while. I have no idea how experienced the pilot is, but had I made thr trip a few years ago I would have been working very hard indeed for a while.
Ian

Last edited by IanSeager; 10th September 2007 at 08:16.
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Old 10th September 2007 | 07:24
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Half the people here have not read the first post and don't realise the chap was over water, so the stuff about map reading is nonsense

What made me curious was that there was indeed NO backup for the GPS and the pilot in question seemed to be having difficulty with the rudimendary details of the VOR beacon.

One is not (IME) taught VOR tracking in the PPL. All I did (year 2000) was a VOR/VOR fix. VOR tracking is trivial enough but I bet you most PPLs currently flying have never been taught how to use the thing at all.

The stuff about loss of signal is rubbish. I've had about 2 mins in 800hrs. With VOR nav, one can easily be out of range of any VOR much of the time and that is over UK mainland (if flying low, at the typical GA levels of 2000ft or lower).
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Old 10th September 2007 | 08:16
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while we all know, what we'd like, gps being taught to all, untill such time, I will follow CAA guide SRG_GAD_SSL25.pdf
gps as a backup
It's just a GUIDE you know, not the law or even a rule. And written by the anti GPS brigade at the CAA.

If people actually bought proper GPS units fit for purpose it would solve 90% f the problems. Instead we are always seeing the discussions on what is the cheapest GPS to buy (to keep switched off for an emergency in the flight bag of course...). This usually ends up being some crappy hiking or road GPS or one of the tiny aviation GPS that you then start trying to put your own waypoints into and not bothering to keep database up to date.

If you are going to us a GPS, buy a proper aviation database with a big clear moving map, and keep it updated. Use the database waypoints and cross check the route on a map. Get it mains powered and external antenna.

I have a panel mount GNS and portable 496 and have managed to not get lost or bust airspace for in over 2000hrs. I can count the GPS signal loss from the portable unit on 2 fingers and in durations of less than a minute. I have NEVER had signal loss in the panel mount unit.

AS long as people view GPS as a backup rather than a primary and refuse to learn to use them properly we will continue to have these problems. I wonder if early aviation had the same problem with NDB, VOR, Decca, LORAN etc.
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Old 10th September 2007 | 08:16
  #34 (permalink)  
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Half the people here have not read the first post and don't realise the chap was over water, so the stuff about map reading is nonsense
Incorrect, a chart is entirely relevant. A fix is a fix. With a chart a sensible heading can be established in moments avoiding horrid airspace along with a distance and hence an ETA. Once on the heading, at a unhurried pace you can re-examine your, chart and look for radio aids that might be useful. I'm not even sure if mid-Atlantic or mid-channel would change the process much for the same scenario.

With regards to the primary vs secondary debate: My view is that the primary means is the one where the buck stops, not the one that you maybe referring to most frequently. If some doubt arises over the 'active' method (GPS, rad nav, whetever), then one would work back to a known last point, GPS maybe 99.999% reliable but this is only 100% reliably possible with a chart, so a chart would still be the primary aid.
 
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Old 10th September 2007 | 08:22
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From: Ask OPS!
IO540, I don't think having a chart over water is exactly rubbish, most people, when transitting water, usually select a direct track (oddly enough as there is very little to see!).

By using standard navigational techniques a clock and a compass with a correctly annotated chart can give you an accurate position at the other end, i.e. your coast in point. Having an Equal Time point written down along with a Point of No Return will reduce your workload (and that of London Centre) by giving you vital information that you now need to continue or that you are indeed closer to your destination. Correctly worked out winds (CRP5) and groundspeeds followed by accurately flown speeds and headings will get you there in the event of a loss of signal or in a degradation in the weather.

All that GPS is doing, and it is an excellent nav aid, is allowing some pilots to leap airborne without correctly planning a nav route and flying off into the wild blue yonder totally unprepared.

This discussion was never meant to be 'should GPS be your only nav aid' it is supposed, looking back on it, to ask 'should GPS replace proper pre-flight planning and aircraft knowledge'. I feel that most, if not all, on this board would agree that it should not, irrespective of your views on GPS as a primary aid.

(My systems uses 2 independant GPS receivers feeding an INS with DME/DME, DME/VOR, VOR/VOR backups. RNAV capable to 0.3 Nm )
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Old 10th September 2007 | 09:54
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A friend at my airfield pointed me to this great thread as he knew it was about my recent trip...

So there I was, having just got my PPL. I thought I don't want to be one of those pilots that never goes more than 20 minutes from my home base, so I'll set out to improve my skills and do a cross channel trip. I did all my planning, based on using ground turning points, just like I'd been taught. I was using a PA22 that belongs to a friend which I'd flown with an instructor to get the hang of, doing the usual handling, circuits etc.

I had my GPS turned on all the time and was following my track on that. I was pleased because all my timings had been spot on as I headed toward the coast. There wasn't much of a horizon over the water, so I concentrated really hard on the AI and keeping the thing straight and level. It was freaking me out a bit to be honest and I think I got a bit fixated on the AI. I was getting the leans and having to fight really hard to counteract it. The instrument appreciation stuff I'd done in my PPL didn't make me feel any better and the turning and leaning sensations I was feeling made me feel scared and unwell; it was so different to be in actual poor viz conditions - my instructor had insisted on only flying on perfect VMC days and the hood I wore for instruments didn't simulate this at all!

Then, my GPS lost its signal. It is an aviation handheld with an up to date database. I use an external antenna stuck on the inner windscreen, but I think maybe the sucker let go as they sometimes do and the antenna fell down a crevice. I was calming down a little bit from the problems of a poor horizon and I hoped that my passenger could sort out the GPS. Aviate navigate and communicate had been banged in to me from an early stage in my training so I followed that advice.

A few minutes later I got a bit worried, because I'd not had a position check in a while - kind of tricky when used to using ground based turning points! One thing I had constantly in my mind was that everyone says you should call D&D sooner rather than later. I pressed on a few minutes, because I was kind of ashamed to call them. I figured if anyone heard me making the call they'd call me a moron, so I just ploughed on it out for a bit. In the end I decided that it was best to follow the advice I had repeatedly received; call when you need help - D&D won't mind. So I called them. I didn't lie and say I was temporarily unsure of my position - I came clean and told them my GPS had packed up. They asked about other nav equipment and I again was honest and told them there was a VOR in the aircraft, but I was unfamiliar with it and was struggling to fly and didn't want to divert attention from that. ANC I kept saying to myself.

I was getting a bit flustered. By this point my passenger was freaking out - she'd announced she couldn't fish the antenna out and she was getting really scared. She started saying how she'd never speak to me again after this, let alone fly with me. I told her to shut up and let me concentrate but she was so scared she couldn't help herself. D&D asked me a few more questions. I now realise they were asking if I had a chart, though at the time I didn't get this straight. It seemed an odd question to be asking so I thought they meant did I have a chart I could use to fix a position. I thought "I am over the water, how can I fix my position on a chart!" so I said "No". Still struggling in the haze (damn my instructor for only flying in "all the 9's"!) I gave as much attention as I could as D&D helped me figure out the VOR.

My passenger was calming down a bit because it was clear we were going to be okay as soon as I could find the damn button which toggled the VOR frequency from one display to the other. Just as I got that sorted the GPS came back online. Everything settled down and I was comfortable so I told D&D I was happy to proceed.

In the end we had a great day out and I learned a lot. I was really proud of myself that I'd traveled all this way on my fresh new PPL, I was proud that I followed the advice repeatedly given by those in the know to call D&D sooner rather than later and most of all that I followed the advice of Aviate Navigate Communicate.

I decided when I got back that I'd do an IMC rating. I did read somewhere on here that it might be scrapped quite soon but I guess what I really want is just an appreciation for instrument flying and navigation, which obviously you don't get on a PPL. I'm also going to find an instructor who is willing to come along with me and let me experience flying in what legally is still VFR - I can't believe how different it was from what I'd seen during initial training.

Thanks for all the great advice on this thread. That's the great thing about flying isn't it? Despite all the NIMBYs, the beuracratic nonsense, the huge cost and so on, we're all happy to help each other out, be given the benefit of the doubt and encourage one another to keep on flying and learning. If people on this thread had slated me for having a bit of a panic a bit when the going got tough I think I might have given up flying! But the aviation community is small enough as it is, so when everyone praised me for calling D&D and sticking to ANC I was really happy. The beers are on me!
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Old 10th September 2007 | 10:06
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This is like to old exam addage about first working out what the question is about.

This is about good old "situational awareness" is it not, not about whether the pilot was trained to use a VOR? This means knowing where you are, where you have just been, where you expect to be in the next 6, 12, 15 minutes, which way you have to turn at any particular time for your alternate, possible diversion airfields at any given time, what your max drift is expected to be etc., and the instruments you will use to get you there.

Most of this information should be either on the chart or your flight log or even both. It may be that I have just not been trained in the correct use of GPS, but now that I am flying an aircraft with a wonderful modern colour GPS fitted I now spend more time with my head in the cabin than looking out. I start to loose that sense of awareness of where I should be at any point because I pay less attention to flight time and comparing estimated position with actual. At the first hint of uncertainty I look at the GPS rather than doing the mental analysis. The danger to me is that the basis mental skills are going to attrophy with lack of use. At least using a VOR is more in tune with conventional navigation as you will often be flying on or to a radial and DME distance fix, calculated in advance.

All my own fault of course, but clearly I am not alone.
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Old 10th September 2007 | 10:17
  #38 (permalink)  
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Southern Fly Guy,

Well it isn't very often that we get to read the other side of the story, it is very interesting and a reminder that all is not as it sometimes seems I also hope your passenger is cool with it now.

The issue of the antenna is just one of those hard to predict buggeration factors that crop up. A reminder that one must simply assume that a GPS (or whatever) will fail without considering the list of possible reasons.

The issue with the chart is simply that with DR, if you fly the correct heading for a set amount of time, you will be roughly where you calculated you should be. It simply will not work out any other way, even if the wind is in a completely different direction over a 30nm leg you will probably only be about 6 nm off course at 100kts and a 20kt wind and 30nm is a long. So long as you keep the distances between legs within a sensible time frame, you won't be far off. The notion of a fix over a featureless sea is valid and one may as well get those fixes from the GPS whilst it has a signal.

The more I hear about other people's training experiences, the more I realise how fortunate I was to fly in near marginal conditions before being let loose. During one of my very first lessons I was taken over the sea and given control. I could feel everything getting light, but I could not tell what way was up, and the experience of suddenly 'loosing it' has stuck with me and has been of immense benefit. On the other hand it could be argued that it gives one more confidence to get into trouble. I don't agree, I think I learnt to see trouble coming.

Last edited by High Wing Drifter; 10th September 2007 at 13:32. Reason: Add a "probably" rather than have it sound so black and white.
 
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Old 10th September 2007 | 10:24
  #39 (permalink)  
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Well done SFG . You recognised the problems, correctly rememberered ANC priorities, and in the end sucessfully completed the flight.

Seems to me that those who are critisising your failure to recall VOR training have failed to recall their Human Performance & Limitations training.

I suspect most of the fiercest critisism on here has come from those who've never found themselves in the mental overload situation you described.

Cross Channel flying will get easier with experience, and next time you get a nav problem (whether GPS or any "traditional" means), you'll be better equipped to deal with it.

Incidently, I often find my GPS loses its signal from abt 30 miles to 10 miles S of Cherbourg for some reason.
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Old 10th September 2007 | 11:37
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SFG,

Thanks for a very candid reply. I could hear from your RT that you were having a hard time and I think that London Centre handled your situation excellently as you did as well for a relatively in-experienced pilot.

The decision to call on 121.5 is a very difficult one at times and, as an ex SAR pilot, one that is often not called enough. It is far better to get help early than to let a potentially dangerous situation develop where assistance is made far more difficult. All to often I have been out to scenes that could have been prevented by early RT and assistance from LC.

The really good news about the whole incident is that you have learnt from the experience and decided to continue your training to avoid it in the future.

Safe flying and I hope the pax wasn't tooooo freaked out ;-)

W2P
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