I do not know why this game is no longer in development, it only need updates in certain aspects but ,as a base for a new version, it have a lot of potential.
Well, I have how to make money with 3* and how not to lose too much money with 4* and 5*.
At the moment, the best values I got are:
3* Cost per flight $873, Max Profit per pax: $406
4* Cost per flight $876, Max profit per pax: $-108
5* Cost per flight $896, Max profit per pax: $-462
At the moment I do not found better results in a plane in 3* in this fórum. (Even the other one with "Ryanair" style… My planes get better profits from mine).