As it is now, there's a little dilemma with aircraft types: Sometimes your records might show a general type (737, A300), sometimes more detailed information (737-300, A300-600). Now, how to enter this?
If you enter the subtype (where available), you end up creating many artificial plane types under 'Analyze'. So it distorts the stats. In the Top 10, you may have 10 flights on 737 (unspecified), 6 on 737-200, 5 on 737-400 and 2 on 737-800, while I think all this should actually count as 737 (main category).
On the other hand, if you decide to leave out the subtype, it means you discard some potentially interesting information.
So when entering a new flight, there should possibly be two separate fields for aircraft type: a) main type and b) subtype.
In the statistical calculations, the numbers for the subtypes would be merged into those for the main types, and only the latter would be displayed.