Works well overall for me

Note that there is a manual on the developers website (for the Pro version) that addresses most of the critical comments in other reviews. No stability issues for me on iPhone 4. Not sure about currency of database, but it has good info for the airports near me except for comm frequencies for small fields (not inaccurate, just missing sometimes).

There is a bug with opening the list of navaids, but re-opening the list several times will get it to populate (reported long ago but not corrected).

Overall a very good app. The free version makes a possible backup to a panel mount GPS. Could be used as simple primary GPS for VFR as a supplement to FAA sectionals.

The HSI view is very nice. Setting the CDI needle to align with the runway heading provides excellent orientation when approaching and following a traffic pattern.

2469dhjirvbwl about Air Navigation Free, v2.1.0