Needs a vertical speed gauge that indicates maximum safe landing speed. Maybe an auto-level as well? The throttle and angle of attack have too coarse a granularity - you can't actually manually keep a flight level, it's always ascending or descending by at least a few feet a second.
Fewer faults in the air would be nice... maybe grant the first level of mechanic by default? Or at least make it so that the engine failing in the air is quicker to restart - the props are still spinning, so it's not like it's a cold start.
Everything else is good - the art, the soundscape, the money progression, whathaveyou.