I think this would really add to the realism of IF and allow the game to take virtual commercial flying to a whole new level on mobile phone.
In synopsis: When looking out over the wing, or any other camera angle that appears to be in the cabin, (i.e. Right Wing, Left Wing View) I think instead of hearing external engine noise, you should hear the engine hum from what it would sound like if you were sitting in the cabin as a passenger.
I hope this wouldn’t be too hard to add, it would just be nice to listen to the ambient cabin noise instead of the blaring engine noise, but the sound would have to differ from that of the cockpit noise, because of the proximity to the engines and the different material of that the cabin is made out of.
This would be really cool to see, and would add a lot to the game with just a simplistic change of audio. It would be awesome to see IF from a passengers point of view and might make the inflight cruising more relaxing (for lack of a better word).