Map Position Error

[Ham_Goulding]

[media]Map Error[/media]

My Skyview map position shows the error illustrated in this photo. On the runway at EINC, south of Dublin, Ireland. The map shows that I am in the sea. Errors of this magnitude make the system of limited use.

I am using the Dynon GPS-250 receiver and I have downloaded the High Res file for Europe.

Any ideas how to correct it? Thanks, Ham Goulding (NG4)

 

[trevpond]

Hi Ham,

Can't see a picture on your message.

regards



Trevor :'(

 

[Ham_Goulding]

Sorry Trevor, Cant get the photo to attach. Have sent it to Dynon Tech Support.

It shows the aircraft symbol in the sea. The airfield is about 300 metres from the shore with a railway line in between so there is a considerable error of position.

 

[dynonsupport]

There are some places where water areas aren't perfect. These tend to be in dry lakebed areas and near shorelines. We have some additional research to do in this area to figure out if there is anything we can do to improve the data. Keep in mind that the primary goal of synthetic vision is to show you a portrait of the terrain out the window so that you can avoid it. Even if you're seeing a portrayal of water where it isn't (or vice-versa), if you're above it visually you'll stay out of the trees/out of the water.

 

[mmarien]

I agree. Rivers are a future detail yet the Saskatchewan Rivers show up on my Skyview. They aren't acurate. See the youtube video.

http://www.youtube.com/watch?v=0o0rgQoqL0M

While I stay the middle of the river, the river slides off the left side of the screen. I don't think this is a big problem. I'm not going to land on the river and it does show up on the display which is a bonus. I would be a bit ticked if the runways are off by that much when I get the Jeppesen data.

What worked well for me was the terrain in the Rocky mountains. I could clearly see the valleys and used the map to fly up box canyons that I would normally have avoided if I wasn't able to see the the terrain on the map.

 

[dynonsupport]

A few thoughts. The terrain database is an absolutely humongous set of data. We don't claim it's perfect, but we do claim it's as good or better than any other competitive product out there. Note that we also publish our terrain information in higher resolution than a lot of the competition does, so this makes smallish errors in the data more apparent. We do think it can save your life in a pinch. Again, the waterlines aren't going to be perfect everywhere, but the altitude data is very robust, and we'd argue that's what you're primarily after. Remember that terrain is supplemental information only, and should NEVER replace proper IFR procedures.

All that said, terrain and navdata are two very different data sets. Though it's not the Jepp data that we'll be offering in the future, note that we do publish the free FAA-derived data, which includes the display of runways on synthetic vision today. Download and install it to see how the runways line up at your airport. In our testing (which again, can't possibly be exhaustive), the runway placement is good enough to fly down to in an emergency (though again, don't do this in IFR. It's not legal.) You can download the navdata and obstacles databases from our website at http://www.dynonavionics.com/docs/support_software_SkyView.html.