Most of us think AIRPORT, not airport, when we hear the term. We imagine massive sites covering hundreds of acres and filled with hangars, terminals, control towers and parking garages. In reality, many airports don't fit this description. Some are nothing more than a strip of grass, dirt or pavement placed in the middle of a farm or field. These so-called rural airstrips often serve just one or two pilots and don't have any other structures beyond the crude runway itself. Small community airports, on the other hand, may supplement a single airstrip with a few hangars and facilities to train student pilots, although they usually don't have operating control towers.
A regional community airport offers more, including a control tower and an automated weather observation system to provide pilots with real-time weather data. Such a facility usually has multiple Tee hangars -- simple metal enclosures -- and tie-down spots for permanently based or visiting pilots to house or stow their aircraft. A terminal building, with a pilot's lounge, restrooms, vending area and conference rooms, is often available, as is a fuel farm to provide either kerosene-based jet fuel or aviation gasoline (avgas), which is similar to automobile gasoline (mogas) but with some additives to make it perform better in spark-ignited internal combustion engines common in light aircraft. Because of its larger size, a regional community airport can accommodate a wider range of aircraft, from small prop planes to regional jets that seat no more than 20 passengers to larger three-engine jets, such as the Boeing 727, capable of seating up to 189 passengers.
In the U.S., most smaller airports fall into the category of general aviation [source: Airlines for America]. They don't handle military flights or common commercial transport but instead provide facilities and resources for personal flying, business flying, instructional flying and certain commercial flying activities, such as aerial photography and skydiving. Airports that handle passenger planes operated by companies such as Southwest, Delta and United Airlines and cargo planes operated by FedEx, DHL and other similar entities belong to the commercial aviation category. These large facilities are almost always situated near major urban areas, and they can handle national and international flights and support jumbo jets, such as 747s.
The United States boasts one of the world's most extensive aviation systems, with almost 20,000 small, medium and large airports. Nearly 17 percent of these make up the national airport system, which means they are eligible for federal assistance to go toward improvements that increase safety and security or that mitigate environmental impact. The national system includes a network of just over 500 commercial airports, all of which receive public funding and handle at least 2,500 passenger boardings a year [source: Airlines for America]. For the rest of this article, we will focus almost exclusively on these larger, more complex facilities.