facilities directly related to the aircraft operations, passenger and cargo facilities, maintenance and supply areas, and storage facilities. This report classifies five types of airports.

Carrier airports are those which accommodate aircraft operators certificated by the Federal Aviation Administration to transport persons, property, and mail. Dulles, Friendship and Washington National airports are examples of carrier airports.

General aviation airports are primarily used by persons engaged in personal flying, business flying, and instructional flying. These airports may be either publicly or privately owned. General aviation activities also occur at all the carrier airports in this region, but they are secondary to the main purpose of the carrier airports. General aviation airports, as identified in this report, include only those open for the use of the general public.

A third type of facility identified in this report is the private airport. Private airports are used by general aviation aircraft but are not open to the general public. Private airports may also be either publicly or privately owned: the distinguishing feature is use, not ownership. These airports are usually very small, often do not have paved runways, and have extremely limited equipment.

Military airports are operated primarily for the benefit of the armed forces. They may have functional characteristics similar to carrier airports or general aviation airports, but their purpose is to serve military aviation needs.

A fifth type of airport is the heliport, an area designated and approved to serve helicopters. Most airports can accommodate a helicopter, but a heliport is usually developed exclusively for that purpose.

An operation is the landing or taking-off of an aircraft at an airport. A carrier operation is the taking-off or landing of an aircraft operated under certification by the Federal Aviation Administration to transport persons, property or mail. Local operations are general aviation operations which are performed in sight of the airport tower or in designated practice areas within a twenty-mile radius of the tower. All other general aviation operations are itinerant operations.

The term based aircraft means those aircraft which are stored and maintained at the airport in question. The two main types of aircraft are fixed-wing and rotor. They may be powered by jet engines (jets), piston-driven propellers (props), or by jet-driven propellers (jet-props). New types of aircraft are now under development. The V/STOL craft, or vertical and/or short take-off and landing craft, employ modifications of the traditional wing and power configurations. They are designed to operate from smaller runways than fixed-wing craft and with more efficiency than rotor craft.

CHAPTER II

EXISTING FACILITIES

This chapter presents general information on Metropolitan Washington's carrier and general aviation facilities. More detailed information is available in Appendix II: Facilities Inventory. Figure 2 depicts the location of each of the region's airports. They are shown by type: carrier, general aviation, private, military, and heliport.

Little data are readily available on the region's private airports, military airports, and heliports. This deficiency should be overcome in the next phase of the metropolitan air facilities planning process.

A serious deficiency in the data which are available on carrier and general aviation is that they are not comparable for common time periods. Each year the Federal Aviation Administration (FAA) reports the number of carrier operations at the nation's airports. In this report, the annual Air Traffic Activity Summary, the FAA also reports the number of general aviation operations at the nation's carrier airports. However, there are no comparable data recorded for general aviation airports. Estimates of operations at general aviation airports are made each year but do not represent actual counts. The estimates vary in their reliability, depending on their source and the time of year when they are made. The next phase of COG's air facilities planning process should correct this deficiency. The data on operations and aircraft which are available for the region's general aviation airports are reported in Appendix II: Facilities Inventory. The dates on which the estimates were reported