On Monday, January 7, 2013 4:20:53 PM UTC, son_of_flubber wrote:
A standalone PNA relies solely on GPS position and stored map data.



What does a standalone PNA do poorly without flight instrument data?



What information does a PNA obtain from flight instruments?



What does a PNA do better because it has flight instrument data? To what extent do these improvements enhance performance and/or safety? Is the improvement relevant to recreational flying, or is the degree of improvement small and only relevant to competition and record-setting?

It has been mentioned that wind calculations are more accurate if the PNA receives air mass data as well as GPS data, which affects all calculations which depend on wind, including final glide and time to task completion. Most flight software nowadays also offers thermalling assistance. In my experience (mainly Winpilot Pro and SeeYou Mobile) this works quite well with connection to flight instruments but is useless without.

Connection to your external instruments may enable you to declare tasks, and to download approved ICG files.

In my opinion, if you have an instrument which can provide air mass data to your PNA you should certainly connect it. But the extra information provided over a standalone PNA with an internal GPS is fairly limited.