GARMIN SALES MANAGER KILLED IN AIRPLANE ACCIDENT

[Brad Brady]

Probably....but it gives you terrain not trees, towers, ect..... .....Brad

Yes it does give you towers.

Bruce,
With wind turbins going up here in central IL every day.......they can't keep up with the topo.....belive me....I know...Brad

[170C]

Know what you mean Brad. In places down here what was an open field a few months ago is now a forest of wind turbines. Tree huggers have been upset about birds flying into them. I think it may be our birds that need to be careful about low flying in unfamiliar areas.

[c170b53]

On the way back from Branson, I was northwest of Yellowstone (Cody) and just north of Red Lodge my Lowrance 2000c with terrain indicated that I could slip through a small valley on route to Big Timber then I planned direct to Bozeman M. When I rounded a corner in the small valley and could see the valley's end it was obvious that my altitude was too low to clear the end yet the GPS indicated the terrain in green. I turned and went back down the valley and turned East to gain altitude and by the time I had gained sufficient altitude I had a more direct route. Other than the lumps, the weather was perfect otherwise I would have stayed clear of that type of terrain, so it was no big deal. Previous to that experience I had total faith in the box, now I wonder.

[jrenwick]

GPS is much more accurate for horizontal position than for vertical. It has to do with the geometry of satellite positions, I believe. I don't thnk it's unusual for non-WAAS handhelds to be off by 100 feet or so in altitude.

There's a big difference between a handheld GPS, even a WAAS-enabled Garmin 496, and an IFR-certified WAAS unit like a Garmin 430W (I have both). The IFR-certified unit can tell you if the satellite solution isn't good enough for vertical guidance on an approach; the handhelds don't do that.

[Bruce Fenstermacher]

John the Garmin hand held will tell you if you have enough satellite resolution for vertical navigation, it's just not an automatic feature. The automatic feature, RAIM will look at satellite resolution and predict whether it will be good enough to execute an approach safely. That is one of the differences that make the panel mount meet the TSO for IFR certification.

[jrenwick]

Hi Bruce,

John the Garmin hand held will tell you if you have enough satellite resolution for vertical navigation, it's just not an automatic feature....

Where is that feature? I've never found it, unless you're talking about the 2D vs. 3D navigation status shown on the GPS status page. That's quite a different thing from RAIM, as you know. As far as I know, the 496 doesn't offer VNAV on approaches. I get that only from the WAAS 430.

I don't use the 496 in approach mode, because when I call up an approach on the 430, that approach automagically crossfeeds to the 496 (through the hardwired power cable) and replaces the current route. For that reason I seldom even enter a route into the 496 -- I put it in the 430 instead. Avionics porn!

John

[Bruce Fenstermacher]

The 496 does have vertical nav but since it doesn't have approaches or approach mode it is not used for that. You could fake an approach with vertical nav if you set it up right though.

Yes the accuracy I was talking about is displayed on the status page. It can also be displayed on any other page that you have information displayed in data fields. Yes it is different than RAIM. RAIM uses an algorithm to look at satellite reception and predict whether or not you will have adequate reception to successfully navigate the approach within the tolerances required.

BTW the 496 is WAAS capable and is just as accurate as the 430.

[Brad Brady]

Know what you mean Brad. In places down here what was an open field a few months ago is now a forest of wind turbines. Tree huggers have been upset about birds flying into them. I think it may be our birds that need to be careful about low flying in unfamiliar areas.

Ole Pokey,
I think things are going to get out of hand around here....The company I drive for...for the time being....isn't going to charge anything extra for flying around wind towers......But one of the other outfits I mechanic for is going to charge a surcharge.....even if the owner of the land doesn't own a tower.....just if he has to go around it.......It's going to make being GREEN interesting here in Central IL. ........Brad

[jrenwick]

The 496 does have vertical nav but since it doesn't have approaches or approach mode it is not used for that. You could fake an approach with vertical nav if you set it up right though.

Yes the accuracy I was talking about is displayed on the status page. It can also be displayed on any other page that you have information displayed in data fields. Yes it is different than RAIM. RAIM uses an algorithm to look at satellite reception and predict whether or not you will have adequate reception to successfully navigate the approach within the tolerances required.

BTW the 496 is WAAS capable and is just as accurate as the 430.

OK, now I think I understand you. The point I was trying to make is that we really don't have electronic devices that would prevent you from hitting terrain or obstructions on a cross-country flight at low altitudes where terrain or obstructions would become a factor. The obstacle databases in GPS units aren't perfect, and GPS isn't really designed to give you vertical precision with consistent accuracy -- except in a special case like a WAAS-aided VNAV approach with an IFR-certified unit, and even then you might find out in real time that the unit isn't getting the signals it needs to go to VNAV minimums. And if they do, the VNAV minimums still higher than you get with many ILS approaches.

I'm not putting down GPS or handhelds -- I love them. But we've got to keep in mind what they can and can't do. The old principles of flight planning, altitude management and judgement of weather that we learned years ago still are valid, IMHO.

[Bruce Fenstermacher]

John, yes we do have a device that can help stop you from hitting the ground. Yes it is any of the Garmin products with the terrain and obstacle data base. True the database is not perfect and new towers may not be in the data you have. But I've found the data to be amazingly accurate. And true at any time any of the GPS units might not have good enough resolution to navigate. Here is how accurate different GPS can be right from the Garmin site.

100 meters: Accuracy of the original GPS system, which was subject to accuracy degradation under the government-imposed Selective Availability (SA) program.
15 meters: Typical GPS position accuracy without SA.
3-5 meters: Typical differential GPS (DGPS) position accuracy.
< 3 meters: Typical WAAS position accuracy.

So typically they are within 100 meters and probably as accurate as 15 meters. When a WAAS unit is receiving a WAAS signal the accuracy is typically less than 3 meters.

When I'm flying 700 ft above the ground at night as I often am in my job and any of the Garmin units I have available to me tells me I'm about to run into a tower or the ground it gets my attention and I believe it and adjust my flight accordingly. No I do not and would not fly at 700 ft in any weather and rely souly on the Garmin or any other product to miss the ground or towers. But if I did find myself in a low and limited visibility situation I'd rather have the Garmin and terrain and obstical data as an aid than not have it.

[GAHorn]

If that Garmin fellow had flown at 700' AGL then he wouldn't have hit the ground either.

[jrenwick]

Bruce,

I don't think we're actually disagreeing. It sounds to me more like a "glass half-full vs. glass half-empty" conversation.

...
100 meters: Accuracy of the original GPS system, which was subject to accuracy degradation under the government-imposed Selective Availability (SA) program.
15 meters: Typical GPS position accuracy without SA.
3-5 meters: Typical differential GPS (DGPS) position accuracy.
< 3 meters: Typical WAAS position accuracy.

Technically, I think this applies to horizontal position information, not vertical. The satellite geometry doesn't provide the same accuracy for vertical position as for horizontal.

When I'm flying 700 ft above the ground at night as I often am in my job and any of the Garmin units I have available to me tells me I'm about to run into a tower or the ground it gets my attention and I believe it and adjust my flight accordingly. No I do not and would not fly at 700 ft in any weather and rely souly on the Garmin or any other product to miss the ground or towers. But if I did find myself in a low and limited visibility situation I'd rather have the Garmin and terrain and obstical data as an aid than not have it.

This works for me too, and I even get audible warnings from my 496 through the power cable. But as you say, one shouldn't depend solely on this (or even a sectional chart!) and go scud-running through obstacles. That's the point I was trying to emphasize.

Best Regards,

John

[wingnut]

FYI, I accasionally check the NTSB report for the status of this investigation, just out of curiousity. They have recently published the propable cause, link below for those interested.


http://www.ntsb.gov/ntsb/brief2.asp?ev_ ... 054&akey=1

[GAHorn]

Too early to jump to (inappropriate) conclusions, but if I read it right... it appears to be an engine shut-down (for unknown reasons) while scud running resulted in a forced/crashed landing that produced a fire, and the cause of death was a heart-attack while attempting to excape the wreckage?

[wingnut]

That's kinda what I'm readin in to it too, but I'm still having a hard time coming up with any logical explanation for 22k plus hour career pilot scud running, in these mountains, with all the high tech avionics, and not filing a flight plan?
Carb ice maybe? Over confidence in himself, and his panel?