Airspace is divided into different classes and areas depending on several factors, such as the aircraft movement complexity and density, level of safety required, etc... Depending on the type, different services are provided.
In total there are 7 different airspace classes (A-G), but they can be grouped into 2 larger categories: controlled and uncontrolled airspace.
- Controlled: Includes classes A, B, C, D and E. In here, air traffic control service is provided. A clearance is required in all of them except for Class E.
- Uncontrolled: Includes classes F and G. Here, only Flight Information Service (FIS) is provided and thus all aircraft are responsiible for their own separation.
Even though clearances (and consequently flight plans) are not required in all airspace classes, on the online environment it is up to each VACC to request a flightplan to be filed or not, as well as contacting an online controller before starting with a flight.
Further comparisons and descriptions regarding airspace classes can be seen directly from SKYbrary.
- Control Zone (CTR): Established around controlled airports. They are established to protect local traffic (usually VFR). Its usual coverage ranges 10-15km horizontally and 1000-5000ft AGL, but it can differ significantly. Therefore, you should take a look at the local AIP to ensure you know where the boundaries are.
- Terminal Area (TMA): Surrounding the CTR, usually ranges vertically from wherever the CTR ends to FL095. Just as the Control Zone, it can vary significantly, so have a look at the AIP.
- Control Area (CTA): Covers a much larger area and is situated above and around TMAs.
In uncontrolled airspace, all aircraft are in charge of their own separation. In order to spot other flights, they can request "traffic information", for which special phraseology is used.
- Traffic Information Zone (TIZ): It can be found around some airports, closest to the ground. In case a pilot requires Emergency Assistance, it is also provided here.
- Traffic Information Area (TIA): Situated above a TIZ, it functions exactly the same way.
Content updated: 15. February 2019.