While I will share here many information about airspace and VFR rules, this cannot be used as reference for real flying.
There is 7 different airspaces which use the letters A to G. While you are in flight you will be always in one of the airspaces however 3 of the airspaces basically don’t require anything special for the VFR flights while entering them, the others may need clearance to enter or are actually prohibited for VFR.
A rough comparaison can be found here:
- Class A: is IFR only, and VFR aircraft are not allowed at all
- Class B: VFR allowed and separation handled by ATC
- Class C: VFR allowed and separation from IFR/SVFR (special VFR) to any other handled by ATC, VFR traffic info
- Class D: VFR allowed and separation between IFR/SVFR to IFR/SVFR, traffic info for all
- Class E: No clearance needed for VFR and separation between IFR/SVFR to IFR/SVFR, traffic info where possible
- Class F and G are basically non controlled airspaces
Not all countries use all the airspaces, and its usually written on the back of the paper aviation charts which airspaces are used and how.
What to know as VFR pilot
It’s important for VFR pilots to know which airspace we are in as for a VFR pilot the main difference between class E, F or G are the cloud separation. Beside those airspaces, entering in any other (B, C, D) will require prior approval from the ATC. Therefore knowing where an airspace starts and ends is a must. Airspace infringement is no joke in real life and can end up with high penalties to pay (I found this for the UK: 3400£ fine for airspace infringement).
- Class B: out of the clouds
- Class C-E: 1000 feet vertical and 1500m horizontal (~ 1 nm)
- Class F: (not found maybe like G?)
- Class G: need simply to stay out of the clouds
- Above 10,000ft: 8km (~ 4.5 nm)
- Under 10,000ft: 5km (~ 2.5 nm)
- Special VFR (SVFR): 1500m (~ 0.8 nm)
Note: that SVFR are available only in controlled areas and usually only in B/C
An aircraft must maintain 500ft above the ground and over sparsely populated area (here each countries may have a different definition), and 1000ft over populated areas.
Sadly… there is no clear definition of the “populated areas” which means each countries may have a different definition. Personally I would not fly lower than 1000ft beside for crossing mountain creases.
Airspace in 3D
Airspaces are not just zones placed on the map like countries limit. Airspace do have a vertical structure too. Which means you could have a class C from ground to 3000ft and then a class D from 3000ft to 6000ft and finally a class E above till 10000ft and finally a class D again. Therefore when you plan a route, you must ensure in which airspace you will be at a given altitude on your route.
Airspace and weather
During your planning you should mark down the min. altitude for your different legs and the maximum as well (like flying under controlled airspace). Reason behind this is that you may need to either make some horizontal deviation to avoid low clouds or you may need to sink to go under. In that later case you need to know how low you are allowed to fly. Finally, if you feel turbulences, you may want to fly higher, again it’s extremely important to know how high you are allowed to fly before needing an ATC clearance.
As an example I shall share this: Bern-Belp
This is the official Swiss ICAO chart, you will find the radio frequencies and the different airspaces, of course for non trained people it’s just a huge mess. However if you know how to read it, you can grab the info that just around the LSZB airport you have a class D (CTR) from ground to 5000ft then from 5000ft to FL100 a class D (TMA). Therefore if you want to transit (TRANSIT SOUTH) you should flight 6000ft or above and request a TMA crossing to Bern Approach (127.325)
Why those airspaces?
Airspaces allow high traffic areas like airports to be controlled via the tower or ATC, and low traffic areas to be mostly free. It allows also to have different rules (like cloud separations requirements) or to know when / where you may have IFR support. For VFR pilots, while you think you can simply take your plane and fly, sadly specially in Europe you will have to mind where you will fly, and what are the rules there.