3.
Airports With an Operating Control Tower
3.1 Towers have been established to provide for a safe, orderly, and expeditious flow of traffic on and in the vicinity of an airport. When the responsibility has been so delegated, towers also provide for the separation of IFR aircraft in the terminal areas (Approach Control).
3.2 When operating at an airport where traffic control is being exercised by a control tower, pilots are required to maintain two.way radio contact with the tower while operating within the Class B, Class C, and Class D surface area unless the tower authorizes otherwise. Initial callup should be made about 15 miles from the airport. Unless there is a good reason to leave the tower frequency before exiting the Class B, Class C, and Class D surface area, it is a good operating practice to remain on the tower frequency for the purpose of receiving traffic information. In the interest of reducing tower frequency congestion, pilots are reminded that it is not necessary to request permission to leave the tower frequency once outside of Class B, Class C, and Class D surface area. Not all airports with an operating control tower will have Class D airspace. These airports do not have weather reporting which is a requirement for surface.based controlled airspace, previously known as a control zone. The controlled airspace over these airports will normally begin at 700 feet or 1,200 feet above ground
Federal Aviation Administration Twentieth Edition
level and can be determined from the visual aeronautical charts. Pilots are expected to use good operating practices and communicate with the control tower as described in this section.
3.3 When necessary, the tower controller will issue clearances or other information for aircraft to generally follow the desired flight path (traffic pattern) when flying in the Class D airspace, and the proper taxi routes when operating on the ground. If not otherwise authorized or directed by the tower, pilots approach to land in an airplane must circle the airport to the left, and pilots approaching to land in a helicopter must avoid the flow of fixed.wing traffic. However, an appropriate clearance must be received from the tower before landing.
3.4 The following terminology for the various components of a traffic pattern has been adopted as standard for use by control towers and pilots:
3.4.1 Upwind leg. A flight path parallel to the landing runway in the direction of landing.
3.4.2 Crosswind leg. A flight path at right angles to the landing runway off its takeoff end.
3.4.3 Downwind leg. A flight path parallel to the landing runway in the opposite direction of landing.
3.4.4 Base leg. A flight path at right angles to the landing runway off its approach end and extending from the downwind leg to the intersection of the extended runway centerline.
3.4.5 Final approach. A flight path in the direction of landing along the extended runway centerline from the base leg to the runway.
FIG ENR 1.1.1
Components of a Traffic Pattern
NOTE.
FIG ENR 1.1.1 is intended only to illustrate terminology used in identifying various components of a traffic pattern. It should not be used as a reference or guide on how to enter a traffic pattern.
3.5 Many towers are equipped with a tower radar display. The radar uses are intended to enhance the effectiveness and efficiency of the local control, or tower, position. They are not intended to provide radar services or benefits to pilots except as they may accrue through a more efficient tower operation. The four basic uses are:
3.5.1 To determine an aircraft’s exact location. This is accomplished by radar identifying the VFR aircraft through any of the techniques available to a radar position; such as, having the aircraft ident. Once identified, the aircraft’s position and spatial relation-ship to other aircraft can be quickly determined, and standard instructions regarding VFR operation in the aircraft traffic area will be issued. Once initial radar identification of a VFR aircraft has been established and the appropriate instructions have been issued, radar monitoring may be discontinued; the reason being that the local controller’s primary means of surveillance in VFR conditions is usually scanning the airport and local area.
3.5.2 To provide radar traffic advisories. Radar traffic advisories may be provided to the extent that the local controller is able to monitor the radar display. Local control has primary control responsibi-lities to the aircraft operating on the runways which will normally supersede radar monitoring duties.
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