This is not a thing that has to be a high priority right now.
But I think that here in the community are certainly many plane spotters. And the PAX in the game have the need “fun”. Maybe you can do something good for both, and offer an observation deck as a terminal object.
Since it is a 2D game, it will not be able to have a big function, but it will increase the fun factor of the PAX and make the upper buildable floors even more meaningful.
And could be a nice gimmick without a lot of development expenses.