1. When I make mistake and put dot instead of comma the app does not send error message and you cannot understand that something is wrong.
2. I would upgrade it by having the airport code/cities and countries auto prepopulate or drop down option , that way you cover in some way encode decode.
3. In the direction column (east/west etc..) the header is point – I think it should have a another definition .
4. We need to try and squeeze in more option for encode decode