How many classes of airspace are there?

There are 7 classes of airspace. The seven classes are: class A, B, C, D, E, F and G.

Class A airspace is the airspace from 18,000 feet mean sea level (MSL) to 600 FL through the continental United States and Alaska.

Class B airspace is defined as the airspace from 10,000 feet surrounding the busiest airports in terms of IFR operations and passengers served.

Class C airspace is defined as the airspace from 4,000 feet surrounding those airports with regular commercial passenger of 100 passengers per flight.

Other classes include class D, class E, class F and class G.