Heh........ I'm actually from the Bulgarian side of the pond as well as the British. :(Well I haven't said that GPS is inferior to the old methods. All I have said is that fluency in old and new is what makes a good pilot. GPS is good, but completely ignoring the old navigation methods and choosing to forget them because they are old is a mistake. To be a good pilot one must be able to navigate old school. At the same time ignoring GPS is also a mistake, it is a valuable tool, which provides remarkable benefits. So fluency in BOTH old and new is advisable, why depend only on one method when you can be fluent in more? Also from my side of the pond - the EU is developing Galileo, which is a lot more accurate than the GPS from the USA - http://www.esa.int/esaNA/galileo.htmlEurope is not really far behind at all.

What really matters is overall reliability of the various navigation systems and the common sense approach of not relying on any one system.NASA's General Aviation Aircraft Cockpit Instrument Reliability Analysis gives the reliability of a range of aircraft equipment in Table A1 on page 33. This report is Appendix A of NASA's General Aviation Aircraft Reliability Study. http://ntrs.nasa.gov/search.jsp?R=694874&a...8989%2B251%2B33It was written in 1997 and doesn't give data for GPS systems. The Mean Time Between Failures for some systems (antenna, display, receiver but excluding power failures) are 760 hours for VOR, 1850 hours for ADF, and 750 hours for ILS.How do those compare with GPS?

What really matters is overall reliability of the various navigation systems and the common sense approach of not relying on any one system.NASA's General Aviation Aircraft Cockpit Instrument Reliability Analysis gives the reliability of a range of aircraft equipment in Table A1 on page 33. This report is Appendix A of NASA's General Aviation Aircraft Reliability Study. http://ntrs.nasa.gov/search.jsp?R=694874&a...8989%2B251%2B33It was written in 1997 and doesn't give data for GPS systems. The Mean Time Between Failures for some systems (antenna, display, receiver but excluding power failures) are 760 hours for VOR, 1850 hours for ADF, and 750 hours for ILS.How do those compare with GPS?

Interesting report. Thanks for the link. I guess it doesn't give data for GPS because in 1997 GPS was not that widely used in GA. Pity, it would be good to see some comparison 'Mean Time Between Failures' figures for GPS - in my estimate it should compare favorably with ADF, VOR and ILS. I haven't been able to find any that can be fairly compared to those from the report. While looking I did find these interesting topics regarding GPS though:http://www.defensenews.com/story.php?i=4103132http://www.computing.co.uk/itweek/news/214...rs-plan-outagesIt would also be good to see similar comparison statistics between GPS and INS.

Is there something special about zig-zagging to VOR's, and triangulating a fix between VORs?

There's no zig-zaging if you're a competent and current radio navigator :( Larry knows where I stand on this. GPS is an incredible bit of technology.. I love it, and use it whenever it's available.. But I still won't takeoff on a cross country flight without a radio-navigation plan, and won't taxi out to the runway until the radios are set, any more than I'd takeoff before setting a gyro and altimeter. Radio navigation as a backup, is tough when you're not quick and adept and current in it's use. If you're descending into complex airspace, caint see past the nose, and the GPS fails (all the satellites are getting dangerously old.. one failed recently and the FAA admits that immediate replacements aren't in any country's budget right now).. you're in a world of hurt if you cannot seamlessly transition to radio navigation. From that aspect comes my only disdain for the GPS... in that pilots tend to get complacent and addicted to it.. ala the pilot who turns white when you switch it off...As for simming ? I just don't see any point in setting aside time to sit in front of a computer, and simulate being a pilot.. and then let a GPS do a big part of the piloting FOR me. Following a magenta line is great, and efficient in the real world.. but it renders you little more than a spectator, in a sim.Soooooo.. by all means..use every bit of technology available when flying.. just don't let GPS use be the reasoning for neglecting your other nav skills (as admitted to by "someone" :( )

There's no zig-zaging if you're a competent and current radio navigator :( Larry knows where I stand on this. GPS is an incredible bit of technology.. I love it, and use it whenever it's available.. But I still won't takeoff on a cross country flight without a radio-navigation plan, and won't taxi out to the runway until the radios are set, any more than I'd takeoff before setting a gyro and altimeter. Radio navigation as a backup, is tough when you're not quick and adept and current in it's use. If you're descending into complex airspace, caint see past the nose, and the GPS fails (all the satellites are getting dangerously old.. one failed recently and the FAA admits that immediate replacements aren't in any country's budget right now).. you're in a world of hurt if you cannot seamlessly transition to radio navigation. From that aspect comes my only disdain for the GPS... in that pilots tend to get complacent and addicted to it.. ala the pilot who turns white when you switch it off...As for simming ? I just don't see any point in setting aside time to sit in front of a computer, and simulate being a pilot.. and then let a GPS do a big part of the piloting FOR me. Following a magenta line is great, and efficient in the real world.. but it renders you little more than a spectator, in a sim.Soooooo.. by all means..use every bit of technology available when flying.. just don't let GPS use be the reasoning for neglecting your other nav skills (as admitted to by "someone" :( )

I constantly play with my vor's when flying just for something to do. I don't think I've seen anyone advocate that you should not be able to do radio navigation or even dead reckoning.But I don't follow the if the gps fails argument. I've had vor's fail but never had a gps fail-and that is what raim and gps notams are for anyway-as are vor/ils notams-and vor's seem to go more often out than gps outages. You could also say you are in a heap of trouble if you lose your electrical power which would effect both navigation systems (except my 2 portables gps's that have their own power source). I don't think anyone is advocating that one should not know how to use other equipment than the gps.I could mention that on one of my emergencies when I had a triple whammy-Altimeter was flipping wildly +- 1000 ft., autopilot was trying to follow the altimeter and the prop oversped-I used the altitude readout on my portable gps to keep from hitting some nasty Tennessee mountains below me (I was in imc). I advised atc of my situation and asked them to give me a hollar if my altitude got off by much-they never had to. The vor's wouldn't have done me much good... :( I personally have never experienced a gps outage except my portable 496 loses gps signal when talking to Muskegon approach every time-their freq seems to knock it out-go figure?!As far as the sim-I actually use it to practice with the Reality xp gps mostly. Vor's are easy-twiddling the gps while maintaining aircraft control is hard imho-especially when getting a new full route clearance when you get close to New York airspace in the air-and then they change it every couple minutes. I fly with a friend who has a 430 and I seem to know more about it than he does thanks to the Reality xp 430-and I find the skills rub off on my kln94. As far as following the magenta line-I seldom fly with autopilot on-but I do find it skillful to find and maintain a heading that keeps the dtk right on the money. I also practice that with the sim along with gps approaches mostly.

I don't think I've seen anyone advocate that you should not be able to do radio navigation or even dead reckoning.

Me either (in this thread).. I was just pointing out that I am a GPS proponent, and that THAT type of thing is my only apprehension.. people letting other skills fade..As for failures.. I've only had GPS failures.. One was when one of the zoom buttoms physically wore out and stuck.. the other was when something went nutty in the firmware, and the GPS would only run on it's backup battery; constantly warning me that it was running low. Neither happened at a critical time, though.The worst situation I ever had with a VOR, is when I flew with one that was way out of adjustment.. I suppose if it were at a critical time, that would be a failure.

As far as the sim-I actually use it to practice with the Reality xp gps mostly. Vor's are easy-twiddling the gps while maintaining aircraft control is hard imho-especially when getting a new full route clearance when you get close to New York airspace in the air-and then they change it every couple minutes. I fly with a friend who has a 430 and I seem to know more about it than he does thanks to the Reality xp 430-and I find the skills rub off on my kln94. As far as following the magenta line-I seldom fly with autopilot on-but I do find it skillful to find and maintain a heading that keeps the dtk right on the money. I also practice that with the sim along with gps approaches mostly.

Agreed.. sometimes the GPS can be a handful.. and things happen quickly. Many moons ago, I was flying into Nashville; marginal VFR, ; low ceilings.. using the GPS in the way I use it most (airspace/terrain/tower avoidance).. and as I was fiddling with all the features, I got to where I couldn't get the airpaces to display. It turned out to be a combination of the zoom factor, and the clutter/declutter setting. This was obviously my fault for not fully understanding the equipment, but that's a very common occurence for GPS addicts... you get a button push, and a knob twist away from the moving-map screen, and you're lost. I just had to stay on the north side of a CVK radial, and then follow a BGW radial, right around the tall stuff, to an easy approach/landing. This is where a neat, payware GPS would come in handy,, keeping you comfy and current with even the basic functions, let alone all of the features that we rarely need to use. I still get amazed by being able to pull up frequencies and runway info.. beats the AFD :( Still though (and it's just my opinion).. using a GPS for basic navigation in a sim (approach practice aside).. is boring and pointless.. All you do is watch a line, and follow it :(

It

Geofa,Keep Tuning those OBS's. As said, I have had a GPS Fail in flight. The receivet malfunctioned and that was it - toast. It could have been any other instrument (Other instruments fail as well and I don't hold grudges against the GPS for giving me the finger ;) ) But it's made a point never to rely on one system.You say you have no less than 3 GPS's. That sets you very well for an onboard failure (As you have to backups) as for a sattelite based set of failures? Might seem unlikely (I agree it's very unlikely), most scholars, and the US Department of Deffense will tell you so as well, But the Titanic can sink, It's just the nature of things.That said, I take it upon myself to use 3 Independant forms of Navigation for VFR Cross countries, it's neither hard nor keeps my head in the cockpit too much. the GNS430 has its route programmed, I follow my way on that VOR Radial, and I keep my head outside the cockpit for the visual checkpoints and times I've written down along my Victor airway route. Like I said, I never have to worry about a failure because I have 3 systems (Including dead reckoning that are well set to back me up. On Local flights, I usually don't even touch the GPS, or look at it for that matter :). As always - I've contiinously said since my first post, It's a welcome tool in an Arsenal. If you have a GPS or three, by all means use them for navigation. But the GPS, or a Nav radio, or even your eyeballs (For an IFR Pilot) are nothing you should be afraid to turn off in navigation. You should be fully and 100% comfortable on any of the three on any given day. Because if plan A fails - Plan B is fresh and the flight can continue with no second guess.

This thread reminds me of when I was working on my Amateur Radio/3rd class comm. license back in 74-75.Learning morse code was one of the requirements,even though it was declining in use.My friend and I were using VHF/UHF relay,satellite,making phone calls from a handheld VHF radio and microwave technology(he is an electronics engineer as well as an aircraft owner and pilot).There was a part of the community that insisted that learning morse code was a "must do" because of "what if"..35 years later I,m still waiting for "what if"..Lou N1472Q (With GPS)

As Brett knows, I ran kind of a poll on this subject at another forum (non-sim). Since there was quite a mix of pilots, I got some good responses. Brett prefers to fire up his radio navs before every cross-country flight. Some agreed with him. But most stated, including most airline pilots, that they never set OBS's and follow them. The FMS picks up VORS at part of a three system cross check, but the GPS part of the system was always the highest in accuracy, and that the VOR is only a GPS waypoint.Since Brett has been a flight instructor, there was also some interesting comments from an instructor. He said that he would be happy when the VOR system was dismantled. Then he wouldn't have to teach it anymore, as he no longer cares for it. Some others agreed, but all were aware that radio-nav is still part of recieving a PPL.At the end of the day, this group felt that GPS was more reliable that VORs. Numerous comments were made that VOR outage was more common, and that most GPS problems were around a few specific military installations. They don't buy all this GPS failure stuff either. And I can see why. They've been using GPS for many years, just as I have. I do believe I had an outage around 1994. Lasted a half minute or so. Since then, and with much improved GPS systems.................I have had absolutely none........in the way of loss of signal. No GPS breakdowns either.L.Adamson

http://www.avweb.com/news/avionics/182754-1.htmlMarco

http://www.avweb.com/news/avionics/182754-1.html

Yes, I've read, but it's dated 2003. Seven years has passed, and still no disasters.

http://www.avweb.com/news/avionics/182754-1.htmlMarco

That is a pretty old article-from 2003..Sure something could happen to gps-even a hostile country could shoot down the sats..If you have an ifr approved gps you have raim however which will not only warn you but some units will even predict and warn you if there is going to be a problem in the future along your route. As pilot's we are also supposed to ask for gps notams/outages in our briefings. When I did that 3 years ago the briefers were totally baffled as to what that was-now I notice they will give them to you without asking often.The point is any system can fail and needs a backup. I would have prefered that loran was not decommissioned and for a while at Oshkosh even just a few years ago dual loran/gps units were being talked about as having the ultimate reliability and the future in aviation. In my case I have a panel mounted ifr gps and two portables each with their own gps. The hostile country taking the sats out would be about the only thing that would take me down...I think vor's will be around for quite a while for a backup for gps but at least in the US ndb's are toast. Once they come up with a more reliable backup to gps I bet vor's will be goners too.I have only been flying with an ifr certified gps for 7 years-but it has never failed or lost a signal. I've had crazy readings on a bc/normal localizers and almost every flight of any length have lots of notams of outages of vor's, unreadable radials, and out of service ils/locs. I'll take a waas approach with its' stable needles any time (except my gps doesn't do them :( ).At some point vor's will be finished-along with slant range dme and ndb's/adf. Until there is a reliable backup for gps though they will be the suitable backup. I at least expect though I'll probably never have to use them for primary again. So far that has been the case. There are lots of things I worry more about losing on a flight other than gps......and as a backup if ifr or using flight following-you could always ask the helpful controller for a vector. Before I had a ifr certified gps I was able to fly direct with a handheld gps.I would just ask the controller-how about a heading of xyz degrees until able xyz vor. They gave it to me every time. I would put handheld gps in the remarks section of the flight plan. Each side knew the game. If there was a gps outage-I am sure the controllers would know this and would be very helpful. (I am speaking only of the US which is what I am familiar with).This debate kinda reminds me of the twin/single angle. I went to a seminar once given by a pilot that only flew his twin so that a climb was always possible if an engine was lost. In one case with a full load at gross he took off with 1/4 fuel-flew 15 minutes to another airport to take on another small amount of fuel -and then 15 more minutes further to do the same again, and again,etc. to work his way home.My thought is that is overly backed up. Fact is in a single if you lose an engine you are coming down. If I wanted to backup a single to the same level I would never fly in one again because there really is no backup if your engine quits. For me this is just a little too anal and kinda defeats why one would have a twin in the first place. Fact of the matter is-if I am at gross and high density altitude and I lose an engine I will be doing exactly what a single pilot will be doing-picking a field and landing. I might have a little more time to pick my field though.It is all about comfort level and what one considers is the ratio of safety margin to practical margin to probability margin. It is about risk assesment and everyone has their own personal limits.Me-I do look at gross weights, density altitude, runway lengths, am now am less concerned about alternator/vacuum failure since I now fly a twin(I had failures with both when I had a single and they meant emergency) and perhaps a few others I am not thinking of now.Me-I am not too worried about gps failure-that is very, very,very low on my list of concern.In the words of Mark Twain-there are a lot of things in my life I have worried about-most which never happened.

They're all very valid and agreeable points, but I'll reinstate what I already said: I'd feel less comfortable flying with a pilot who, for years and years, as a matter of fact has always navigated (both VFR and IFR) solely looking at the GPS screen.Marco

They're all very valid and agreeable points, but I'll reinstate what I already said: I'd feel less comfortable flying with a pilot who, for years and years, as a matter of fact has always navigated (both VFR and IFR) solely looking at the GPS screen.Marco

Well luckily that would not be Larry or me.. :( But I bet when ndb's came out there were people that said they would not fly with a pilot that could not do a wind triangle, and when vor's came out there were people that said they would not fly with someone who could not do a good ndb bearing. Probably some that would not fly if you could not do celestial navigating at one point either.One of my friends and mentors was a wwII carier pilot. I asked him once how he found his way back to the boat after flying a mission. He said you had a pad of paper on your knee and wrote I flew 5 minutes this direction and then 10 this-then flew your battle and then when over looked at your paper and retraced your steps and hoped the boat was there. Many didn't find it...He is and was a great pilot-but he uses gps now..