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Their is also E and G. A,B,C,D,and E are classified as controlled airspace while G is uncontrolled.
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What is the difference between A,B,C,D, and E airspace, besides the fact they controlled? Does it have to do with the congestion of the airspace? If it does what differentiates those airspaces from eachother?
The discussion of differences between the different classes of airspace usually consumes at least one hour of ground school, so a comprehensive explanation will not be possible here, but I'll give you a few pointers.
The different classes of airspace represent varying levels of restrictions and control of aircraft. Class A is the most restrictive and most tightly controlled airspace. Class G is the least restrictive and is uncontrolled.
There are differences between the airspaces in the level of separation services provided by ATC, aircraft transponder equipment requirements, VFR weather minima, pilot qualifications, and communications requirements.
Very quickly, Class A is everything from FL180 to FL600. Classes B, C and D are usually associated with airports with varying levels of traffic and Class E (in VERY simple terms)pretty much consumes the rest of the navigable airspace that is not A,B,C or D in the eastern U.S. Class G is usually found at extremely low altitudes in the eastern U.S., and extends higher up in more remote areas out west.
I have not done this topic much justice, but hopefully it's a start.
P.S. As a side note, many countries in the world have the A, B, C, D, E, F, G classification system, however the use of those classes varies widely i.e. just because Class A is everything from FL180 to FL600 in the U.S. does not mean it's the same way in other countries.
Ive never heard of class F in any countries, what is its purpose and altitudes, also what is its cloud clearances, could be useless info for me at this time, but id like to think that one day i might have to deal with it, when im captain on an international flight
Class F is used in the UK for what they call VFR advisory routes. If I recall correctly they are established over remotely populated areas and certain water crossings.
Despite having flown several hundred hours in UK airspace, and a training environment at that... I never used a Class F advisory route. I know they also use Class F in other European airspace, but I cannot remember ever running across it.