Originally Posted by
Geoff Fairless
....
Good explanation.
There's only one hick-up... IFR and VFR is not separated in class D airspace. The separation the tower controller is responsible for is the "runway separation", which means he shall make sure there's only one aircraft on or over the runway at any time (which is not entirely correct, but can do as a rule of thumb). VFR and IFR will be provided traffic information about each other.
At the moment you establish a control tower, you can have one controller working at very low density airports. But still consider that the person would need breaks etc. Furthermore, the staffing need to be higher, since that one person would still need days off, vacation etc. So you'd need maybe 3 controllers to staff a unit.... On top of that you'd need an approach setup at the centre, which technically can be done by the sector covering the area, but still it's a task someone has to do etc. etc.
Setting all this up is not just one controller cheap and easy.