Bill,
Adding an external GPS will only make the signal "stronger".

  To get your position on approach plates you need to subscribe to a service that provides "geo-referenced plates for the iPad.  The only one I know of is WingX who uses plates from Seattle Avionics.  Their service is a little pricey as they charge $98 a year for their service, plus another $99 for the Seattle Avionics plates.  The reason for georefferenced charts is that they are different scales, unlike a sectional.  So, each plate needs at least two points with a firm lat - long position.  I have both fore flight and wingx, I keep hoping fore flight will get geo-reffed plates, the rumor is that they are working on it.  

Wingx works fine, but I think fore flight is better for planning, and they have moving map sectionals, low and high altitude IFR charts.

My 3G IPad works great with both Foreflight and WingX.  Your position on an approach plate is great for situational awareness, you still need to watch the needles to shoot the approach.

Bob Mitchell

Sent from my iPad

On Dec 4, 2010, at 6:59 AM, billhogarty <billhogarty@hughes.net> wrote:

> Does anyone know if adding an external GPS (bad elf) to a 3G IPAD would give you
> a moving map position on an approach chart?  Thanks
>
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