Traffic Pattern Operations

Introduction:

  • The traffic pattern is the standardized flow of aircraft in the terminal area
  • This standard flow allows for predictability in an otherwise extremely dangerous environment
  • The traffic pattern is the ultimate goal which began with the rectangular course with many hazards

 

 

Towered Airports:

  • When operating at an airport where traffic control is exercised by a tower, two-way communication is required, unless otherwise authorized
    • 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 areas, 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 areas
  • When operating at uncontrolled fields, keep to normal towered procedures to remain predictable
  • Not all airports with an operating control tower will have Class D airspace and thus 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′ or 1,200′ AGL (see Class Echo Airspace) and can be determined from the visual aeronautical charts
    • Pilots are expected to use good operating practices and communicate with the control tower same as above
  • When necessary, the tower controller will issue clearances or other information for aircraft to generally follow the desired flight path (traffic patterns) when flying in Class B, Class C, and Class D surface areas and the proper taxi routes when operating on the ground
    • Thus, if not otherwise authorized or directed by the tower, pilots of fixed-wing aircraft approaching to land must circle the airport to the left
    • Pilots approaching to land in a helicopter must avoid the flow of fixed-wing traffic
    • In all instances, an appropriate clearance must be received from the tower before landing
  • Many towers will have radar display
  • 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 uses are:
    • Determining an aircraft’s exact location:
      • Accomplished by radar identifying the VFR aircraft through any of the techniques available to a radar position, such as having the aircraft squawk ident
      • Once identified, the aircraft’s position and spatial relationship to other aircraft can be quickly determined, and standard instructions regarding VFR operation in Class B, Class C, and Class D surface areas 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 visually scanning the airport and local area
    • 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 responsibilities to the aircraft operating on the runways, which will normally supersede radar monitoring duties
    • Provide direction or suggested heading:
      • The local controller may provide pilots flying VFR with generalized instructions which will facilitate operations; e.g., “Procedure southwest-bound, enter a right downwind runway three zero,” or provide a suggested heading to establish radar identification or as an advisory aid to navigation; “Suggested heading two two zero, for radar identification
      • In both cases, the instructions are advisory aids to the pilot flying VFR and are not radar vectors which gives pilots complete discretion regarding acceptance of the suggestions as they have sole responsibility for seeing and avoiding other aircraft
      • Pilots have complete discretion regarding acceptance of the suggested headings or directions and have sole responsibility for seeing and avoiding other aircraft
    • To provide information and instructions:
      • In an example of this situation, the local controller would use the radar to advise a pilot on an extended downwind when to turn base leg

 

NOTE:
The above tower radar applications are intended to augment the standard functions of the local control position. There is no controller requirement to maintain constant radar identification. In fact, such a requirement could compromise the local controller’s ability to visually scan the airport and local area to meet FAA responsibilities to the aircraft operating on the runways and within the Class B, Class C, and Class D surface areas. Normally, pilots will not be advised of being in radar contact since that continued status cannot be guaranteed and since the purpose of the radar identification is not to establish a link for the provision of radar services
 

NOTE:
A few of the radar equipped towers are authorized to use the radar to ensure separation between aircraft in specific situations, while still others may function as limited radar approach controls. The various radar uses are strictly a function of FAA operational need. The facilities may be indistinguishable to pilots since they are all referred to as tower and no publication lists the degree of radar use. Therefore, when in communication with a tower controller who may have radar available, do not assume that constant radar monitoring and complete ATC radar services are being provided
 

Traffic Pattern Arrival:

  • These procedures develop the ability to stay safely and efficiently arrive at an uncontrolled airport, or after arrival, utilize the traffic pattern
  • ATC will provide instructions for controlled airspace but the following is a general procedure
  • Procedure:
    • Complete the descent checklist
    • At least 10 NM from the airport, attempt to determine the active runway
    • If the runway in use cannot be determined:
      • Over fly the airport at 500-1,000′ above traffic pattern altitude to observe traffic, wind direction indications, etc. to determine a runway to use
    • At least 2 NM from the runway, enter the traffic pattern at traffic pattern altitude on a 45° entry to the downwind, maintaining a none-half mile distance from the runway on the downwind leg
    • Complete the appropriate approach and landing procedure
    • Maintain pattern altitude until abeam approach end of the landing runway on the downwind leg
    • Complete turn to final at least 1/4 mile from the runway

 

Traffic Advisory Practices at Airports Without Operating Control Towers:

  • Airport Operations Without Operating Control Tower:
  • Communicating on a Common Frequency:

 

Summary of Recommended Communication Procedures
Figure 1: Summary of Recommended Communication Procedures

 

Visual Indicators at Airports Without an Operating Control Tower:

  • At those airports without an operating control tower, a segmented circle visual indicator system, if installed, is designed to provide traffic pattern information
  • The segmented circle system consists of the following components:
    • The segmented circle: Located in a position affording maximum visibility to pilots in the air and on the ground and providing a centralized location for other elements of the system
    • The wind direction indicator: A wind cone, wind sock, or wind tee installed near the operational runway to indicate wind direction. The large end of the wind cone/wind sock points into the wind as does the large end (cross bar) of the wind tee. In lieu of a tetrahedron and where a wind sock or wind cone is collocated with a wind tee, the wind tee may be manually aligned with the runway in use to indicate landing direction. These signaling devices may be located in the center of the segmented circle and may be lighted for night use. Pilots are cautioned against using a tetrahedron to indicate wind direction
    • The landing direction indicator: A tetrahedron is installed when conditions at the airport warrant its use. It may be used to indicate the direction of landings and takeoffs. A tetrahedron may be located at the center of a segmented circle and may be lighted for night operations. The small end of the tetrahedron points in the direction of landing. Pilots are cautioned against using a tetrahedron for any purpose other than as an indicator of landing direction. Further, pilots should use extreme caution when making runway selection by use of a tetrahedron in very light or calm wind conditions as the tetrahedron may not be aligned with the designated calm-wind runway. At airports with control towers, the tetrahedron should only be referenced when the control tower is not in operation. Tower instructions supersede tetrahedron indications
    • Landing strip indicators: Installed in pairs as shown in the segmented circle diagram and used to show the alignment of landing strips
    • Traffic pattern indicators: Arranged in pairs in conjunction with landing strip indicators and used to indicate the direction of turns when there is a variation from the normal left traffic pattern. (If there is no segmented circle installed at the airport, traffic pattern indicators may be installed on or near the end of the runway)
  • Preparatory to landing at an airport without a control tower, or when the control tower is not in operation, pilots should concern themselves with the indicator for the approach end of the runway to be used. When approaching for landing, all turns must be made to the left unless a traffic pattern indicator indicates that turns should be made to the right. If the pilot will mentally enlarge the indicator for the runway to be used, the base and final approach legs of the traffic pattern to be flown immediately become apparent. Similar treatment of the indicator at the departure end of the runway will clearly indicate the direction of turn after takeoff
  • When two or more aircraft are approaching an airport for the purpose of landing, the pilot of the aircraft at the lower altitude has the right-of-way over the pilot of the aircraft at the higher altitude. However, the pilot operating at the lower altitude should not take advantage of another aircraft, which is on final approach to land, by cutting in front of, or overtaking that aircraf

 

Unexpected Maneuvers in the Airport Traffic Pattern:

  • There have been several incidents in the vicinity of controlled airports that were caused primarily by aircraft executing unexpected maneuvers
  • Controllers establish the sequence of arriving and departing aircraft by requiring them to adjust flight as necessary to achieve proper spacing
  • These adjustments can only be based on observed traffic, accurate pilot reports, and anticipated aircraft maneuvers
  • Pilots are expected to cooperate so as to preclude disrupting traffic flows or creating conflicting patterns
  • The pilot-in-command of an aircraft is directly responsible for and is the final authority as to the operation of the aircraft
  • On occasion it may be necessary for pilots to maneuver their aircraft to maintain spacing with the traffic they have been sequenced to follow
  • The controller can anticipate minor maneuvering such as shallow “S” turns
  • The controller cannot, however, anticipate a major maneuver such as a 360° turn
  • If a pilot makes a 360° turn after obtaining a landing sequence, the result is usually a gap in the landing interval and, more importantly, it causes a chain reaction which may result in a conflict with following traffic and an interruption of the sequence established by the tower or approach controller
  • Should a pilot decide to make maneuvering turns to maintain spacing behind a preceding aircraft, the pilot should always advise the controller if at all possible
  • Except when requested by the controller or in emergency situations, a 360 degree turn should never be executed in the traffic pattern or when receiving radar service without first advising the controller

 

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