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Thread: Using a Car GPS for Flight Navigation

  1. #1

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    Jan 2012
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    Using a Car GPS for Flight Navigation

    I fly an ultralight. Typical altitudes are 500' AGL and navigation is by landmarks. Where I can't recognize the landmarks, or where distinct landmarks do not exist or are far-between, I switch to using uncorrected compass bearings -- good enough, considering the relatively short legs and the mild-wind days I select for flying.

    Recently I installed in my plane a car GPS device (QUE NQ-503) running a cross-country land navigation software. (After all, the difference between 500' AGL and an SUV's 5' AGL is not all that big.) The software is basically a moving 1:50,000 topographic map on which one can add routes and labeled waypoints. To navigate, all one has to do is keep the GPS position marker on the prepared route. Can't ask for anything more.

    For about 10 flight hrs this device performed just fine. Then hardware problems set in which gradually made it useless. I suspect the reason lies in the harsh acoustic and vibrational environment (unbearable without a headset on) that exists on the dashboard where the device has been installed. Indeed, when I moved it back to my car the problems went away.

    My questions:

    1. Anyone out there with a similar experience?
    2. Any suggestions as to how to protect the device from the environment?
    3. Are aviation GPS devices guaranteed to withstand an ultralight cockpit
    acoustic and vibrational environment?
    4. What kind of backup people use in case the GPS malfunctions (apart from
    radio homing)?
    5. Anything else that might be helpful in this respect.

    Thanks for the advice
    Last edited by dov_elyada; 03-31-2012 at 09:07 AM.

  2. #2

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    Well I've never tried a car GPS in an airplane, but I have used a few handheld aviation GPS's and they can and do loose signals from time to time. In my experience with lost signals I find that high-wing airplanes tend to experience that circumstance more often then low-wing. It may be due to a smaller overhead view available in the high wing cockpit vs a low wing design. I have been trying to get a Garmin Pilot III working in our club TriPacer for the past few weeks. It was setup with just a simple top panel mount and the standard "stick" antenna when it did work it was hard to read and harder still to operate while flying. I bought an extended antenna and replaced dead batteries and the unit works fine in my car, but I've only been able to get it into Navigation mode once in the airplane. I have moved antenna locations all over the cockpit trying to get a good view without much luck. I'm going to try it in our club Archer (low-wing) next week and see if that is any better.

    I don't know much about ultra-lights but I always plan flights using charts and ground based radio aids even when flying with very reliable panel GPS installations. I'm guessing that flying an ultralight is mostly flying within 50 miles or less of your base airport where navigation is primarily "looking out the window" and finding local landmarks. If your just starting out I would plan to fly a lot of local or short flights around your base and then just expand your circle as you get familiar with the landmarks.

    Joe

  3. #3

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    There are great... well maybe good deals on used aviation gps out there, I have 3, a garmin pilot III, which is good and something must be wrong with your cause mine has been dandy, I have 2 Lowrance's a 600c (my favorite) and a 1000 (newest addition) that I haven't flown with yet, an external antenna is a must and I see no problem with using a topographical gps in an ultralite or in anyplane, just never, ever rely on them as primary navigation, get the charts out and plan the trip like you have nothing but a compass, it's a skill that requires practice but will save your bacon and give you confidence. As for yours not handling the vibration well such is the way of modern electronics, probably a cold solder joint and the vibration finally took its toll.

  4. #4
    rwanttaja's Avatar
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    What kind of hardware problems did you experience? Loss of GPS signal, loss of display, power loss, etc.

    I doubt the acoustic environment is to blame, but any problems could indeed be due to vibration. My thought is that you have the unit solidly attached to the structure and the engine is causing the problem. Is the problem affected by engine RPM? (e.g., does it stop when the engine is throttled back to idle, does it get worse on full power, is there a particular RPM range where it's worse, etc.)

    If you've got the unit clamped using the same sort of unit as in a car, the vibration in the structure could be getting transmitted directly to the GPS. You need some isolation....some rubber or foam between the mount and the structure.

    I've had vibration problems messing up videos on my airplane, and have cut it back by using such isolation materials. Here's an old shot of a camera mount clamped to the axle. There's a wide strip of inner-tube rubber between the mount and the axle.
    video_axle.JPG
    The materials are cheap, so experimentation is easy.

    I have a hiking GPS in my Fly Baby, but haven't had any vibration-related problems with it. However, it is mounted on an arm that comes up a few inches from the mounting point... this gives a bit of flexibility as well, which probably isolates it.
    fbgps.jpg

    Ron Wanttaja

  5. #5
    These is http://www.oziexplorer.com/ poplular with the Ultra-lights in Oz, you can put digital charts straight in as well, use a windows CE based car GPS.

  6. #6

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    Thanks, Joe.The problems I was complainng about are not of the missing-signals type. This GPS device has only an internal antenna and when it misses too many satelites it just displays a message saying so.As for my range of operations--you may be surprised to learn that this plane (ICP Savannah) at cruise IAS (80 mph) can fly 5 hrs and 400 miles w/o refueling. I never tried it to the limit, and I do not intend to, but 3-hrs continuous flight is standard. Actually, it's an ultralight in some respects (1000 lb MTOW, flimsy construction, taking in rain, no nav aids or transponder, no IFR instumentation whatsoever, true STOL and "bush" performance) and an LSA in other respects (two-seater, 100HP Rotax 912 ULS, Vne=125 mph, 1100 fpm max climb rate.) I have decided I need a GPS as my main navigation method, keeping the chart and compass method as a backup, once I have started long-distance flights accross wilderness areas.

  7. #7

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    Thanks, Racegunz

    As I said, what I was using is just my car GPS (neither a Garmin nor any other aviation brand) transplanted to my airplane.

    I agree with you that plain old chart and compass navigation is a necessary skill, and I do have it, but it's so boring to prepare and then not use. Another problem with this kind of "office flying" is that I do not really have enough "desk space" on my lap to fold, unfold, shuffle and browse through all those papers; they tend to interfere with the stick and block the view of the flight gauges. I did make a special knee-pad (better than anything you can buy at Sporty's) to deal with this hassle, but with so little space it is still a big hassle.

    And one more thing: Flying at 200'-500' AGL you cannot afford to take your eyes off the outside for any appreciable length of time -- you might suddenly find yourself approaching a high voltage power line or a cellular antenna tower, or an uphill slope or a powerful windshear. And where's the fun of flying when you have to wrestle with the papers instead of enjoying the views?

    When I asked the forum what kind of backup people use, I was hoping to hear that some were using a 2nd GPS. That's my tendency.

  8. #8

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    Thanks, Ron.

    There occurred a variety of hardware-looking problems, non of them was related to loss of GPS signal. Examples: (1) The moving map and GPS position marker froze and the on/off button did not respond; since I couldn't use the reset button in flight, I yanked the supply cable out and waited until the battery was used up. (2) The map stopped moving and gradually the GPS position marker went out of the frame. (3) Recurring crashes: suddenly the navigation software would go off and restarting it would keep it going for only a minute or so before the next crash.

    When installing the GPS on the dashboard I did pay attention to vibration isolation. The dashboard itself is padded with foam and vinyl upholstery and the spring clip pressing the base of the pedestal to it is doing so through a thick and soft rubber cushion. That's why acoustic noise was my most likely culprit. Yet the possibility still exists that what I've done to isolate vibrations is not sufficient.

  9. #9

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    Thanks.

    That's roughly what I have, though up-over rather than down-under. So if anyone experienced similar problems, it's probably those Aussies.
    Last edited by dov_elyada; 04-01-2012 at 09:04 AM.

  10. #10
    rosiejerryrosie's Avatar
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    I used to use a simple Garmin 100 (cost at Kmart=$100) in my MiniMax. Worked fine, once I got all the airports and waypoints manually entered, until, one day, it just went dead on me. On landing, it worked fine. After that happened two more times, I contacted Garmin and they recommended that I use ALL the same type of batteries in my unit ie don't mix Everready with Duracell for example. Once I did that - never had another problem. Vibration was not the problem since the unit was NOT mounted to the airplane but suspended from my wrist on a lanyard. Subsequently, I now use a Garmin 196 in my Aeronca, but Judy likes to take along the Garmin Nuvi from the car, because it shows her all the roads that we are crossing over, and she feels more 'oreinted'. It is not mounted either as she holds in in her lap - so vibration is not an issue. Works fine. If your unit is 'freezing' it sounds like it is losing signal for some reason and is not able to update your position as you move..... Antenna?
    Cheers,
    Jerry

    NC22375
    65LA out of 07N Pennsylvania

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