I've been searching for data about the capacity of sectors for my PhD research but somehow can't find any...the only thing I found is the routes it crosses ....can we conclude that it's the capacity or there is another factors involved. I would appreciate any help
Calculating the capacity of an ATC sector is a complex issue, you should not expect to find one single determining factor.
A few obvious factors come to mind:
- Lateral extend of the sector (size)
- Vertical extend of the sector
- Whether or not surveillance is available (RADAR etc.)
- The route structure, and whether traffic is forced to follow certain airways or not (free route airspace)
- Military areas, their activation frequency and extend
- Type of traffic in the sector
- Uniformity of traffic in the sector
- The actual traffic flow in the sector. Is it mainly an en-route sector where aircraft will enter and leave at the same level, or do a lot of aircraft need to climb/descend within the sector?
- ATC staffing. Is the sector manned by a single controller, or by a pair (executive+planner)?
- Radio coverage, and whether or not CPDLC is available
- Weather - for example, is it an area with frequent thunderstorms?
- Runway configurations of any airports covered by the sector, as well as possible noise restrictions
There is no formula that couples all these factors together. In the end, the capacity of an ATC sector is an estimate based on an evaluation of the above (and probably more) factors, experience and trial-and-error. In many cases, it will be an iterative process.
A fairly simple way to design sectors is to have one per VOR, with the boundaries halfway to the next VOR on each airway. This puts the VOR at the logical center of the sector with lots of space around it for the controller to resolve conflicts between aircraft crossing paths at that VOR.
If traffic levels do not justify having a separate controller for each sector, then multiple sectors may be worked by a single controller during low-traffic periods, or they may be merged into a single larger sector. I've read that the FAA targets 10-15 planes per controller.
Practical factors and experience, such as those listed by @J.Hougaard, would drive refining sector designs beyond what such a simple algorithmic model would indicate, but it gives a starting point—and a possible benchmark to measure how much the real world design varies from the theoretical one.