You will note that it says "The Bad Elf GPS provides location data to any and all apps that use Apple’s iOS Core Location framework.". That is a VERY good thing because the nav apps that are using GPS services do not have to do anything special to use this 3rd party GPS. This is also why this GPS does not require the iOS device to be jailbroken. So that tends to strongly suggest that if you are using a nav app that has moving map functionality with GPS, it will do so with either the built in GPS if it is present, or it will use the external GPS. Now, I have not tried using any iOS devices with 2 GPS options on-line at the same time. So I do not know if iOS gives the user a way to select which GPS will be used. You will notice that they list a lot of specific apps, and they are grouped by category. One of the categories is Aviation.

Also, if you go to the FAQ page, you will notice some questions with interesting answers given our interests.

Note the answers to:

"How accurate is the Bad Elf GPS Receiver?"

"Is the Bad Elf GPS Receiver better than the iPad/iPhone internal GPS?"

"Does it work at the high altitudes and high speeds of aviation use?"

"What do I need to use my iPad or iPod touch for car/marine/aviation navigation?"

An additional point, the App you would be using would need to have the map data locally in the iPads local storage. Since you won't have Internet service over 3G.

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