UAS Airspace Restrictions
The FAA has defined unmanned aircraft, drones, as aircraft. They are therefore subject to Federal Aviation Regulations (FAR). UA are not permitted in Class A airspace without permission. Class A starts at 18,000 feet above sea level. UA are not permitted in Class B airspace without permission and radio contact. Class B is the busiest airports like Kansas City, St. Louis, Mineappolis, Chicago and so forth. There are about 30 Class B airports.
Class C operations require radio contact before entry. Class C includes moderately busy airports such as Des Moines, Omaha, Moline and so forth.
Class D airports require radio operation while in them. These are the smallest towered airports and include Dubuque, Rochester MN, Oshkosh, wI and so forth.
Class E airspace includes airports and other controlled airspace not otherwise listed above. There are no control towers but they are supervised by air traffic control. You can fly in them without talking to people. UAS are restricded from flying very near airports without permission by other rules, but not by airspace restrictions. Some of these rules are 5 miles and 3 miles, depending on the operation and circumstances.
Temporary Flight Restrictions (TFR) are airspace restrictions imposed for short term reasons. These include major sporting events, forest fires,VIP visits and so on. These restrictions should be checked before every flight by referring to a Notice To Airmen (NOTAM). You can get a NOTAM by call FSS or from some online sites, but beware that most online sites are not officieal and if you get busted, it only helps you if you checked with an official site.