If you think TrackIR increases immersion that much you
really need to try a VR headset and get your mind blown :)
The 3D vision (a horizon never looks the same on a screen), full 6DOF tracking (you can look over your shoulder, bend down etc), motion controllers with which you can turn buttons.. It feels so real.
Even the way you look out the window to see if it's time for the turn to base, it just looks like how it looks when you do it in a real airplane. Seeing it on a flat screen is really not the same.