Federal Aviation Administration
Radar Services

Picture of FAA Radar Services and Procedures

Introduction:

Basic Radar Services Availability:

  • Air Traffic Controllers (ATC) will inform aircraft on initial contact whenever radar outages prevent basic radar services from being issued
    • ATC will apply paragraph 7-1-3, Approach Control Service for Visual Flight Rules (VFR) Arriving Aircraft
  • ATC will provide the service, to the extent possible using an available frequency, if an aircraft desires the service but cannot communicate on the appropriate frequencies
    • Aircraft which do not desire radar service may be fitted into the landing sequence by the tower
    • Coordination of these aircraft must be accomplished with the approach control unless a facility directive/Letter of Agreement (LOA)prescribes otherwise
    • Nonparticipating aircraft must, to the extent possible, will receive the same landing sequence they would have received had they been sequenced by radar vectors
  • Unless the pilot states that the service is not requested, ATC will provide radar sequencing to the primary airport
    • Arriving aircraft are assumed to want radar service unless the pilot states "Negative radar service" or makes a similar comment

Basic Radar Services:

  • Safety alerts
  • Traffic advisories
  • Limited radar vectoring when requested by the pilot
  • Sequencing at locations where procedures have been established for this purpose and/or when covered by an LOA
  • Safety Alerts:

    • A safety alert will be issued to pilots of aircraft controlled by ATC if the controller is aware the aircraft is at an altitude that, in the controller's judgment, places the aircraft in unsafe proximity to terrain, obstructions, or other aircraft
    • This service is contingent upon the capability of the controller to have an awareness of a situation involving unsafe proximity to terrain, obstructions, and uncontrolled aircraft
    • Safety Alerts are mandatory services provided to ALL aircraft
      • Safety alert issuances cannot be mandated, but they can be expected on a reasonable though intermittent basis
        • Stated another way, you cannot expect ATC to see every possible hazard, but when they do, they must say something
      • Once the alert is issued, it is solely the pilot's prerogative to determine what course of action, if any, to take
      • Safety alerts are for use in time-critical situations where aircraft safety is in question
        • Non-critical situations should be handled via normal traffic alert procedures
    • Aircraft systems such as Automatic Dependent Surveillance-Broadcast (ADS-B) may also provide safety alerts
    • There are two types of Safety Alerts:
      • Terrain or Obstruction Alerts
      • Aircraft Conflict Alerts/Mode C Intruder Alert
      • Terrain or Obstruction Alerts:

        • A Terrain/Obstruction Alert is issued when, in the controller's judgment, an aircraft's altitude places it in unsafe proximity to terrain and/or obstructions
        • Issuance is contingent upon the controller's awareness
          • ATC: "Low altitude alert Cessna Three Four Juliet, check your altitude immediately. And if the aircraft is not yet on final approach, the Minimum Vectoring Altitude (Minimum Enroute Altitude/Minimum IFR Altitude/Minimum Obstruction Clearance Altitude) in your area is six thousand"
        • The controller will discontinue alerts if informed by the pilot they're taking action or that the obstruction is in sight
        • Terrain or obstruction alerts are for use in time-critical situations where aircraft safety is in question
        • Minimum Safe Altitude Warning:
          • Designed solely as a controller aid when a tracked mode C equipped aircraft under their control is within potentially unsafe proximity to terrain/obstructions
          • Terminal Automated Radar Terminal System (ARTS) IIIA, Common ARTS (to include ARTS IIIE and ARTS IIE) (CARTS), Micro En Route Automated Radar Tracking System (MEARTS), and Standard Terminal Automation Replacement System (STARS) facilities have an automated function which, if operating, alerts controllers when a tracked Mode C equipped aircraft under their control is below or predicted to be below a predetermined minimum safe altitude
          • The ARTS IIIA, CARTS, MEARTS, and STARS facility will, when Minimum Safe Altitude Warning (MSAW) is operating, provide MSAW monitoring for all aircraft with an operating Mode C altitude encoding transponder as tracked by the system and are:
            • Operating on an Instrument Flight Rules (IFR) flight plan; or
            • Operating VFR and have requested MSAW monitoring
          • Pilots operating VFR may request MSAW monitoring
            • PILOT: "Apache Three Three Papa request MSAW monitoring"
      • Aircraft Conflict Alerts:

        • Controllers will immediately issue an alert to the pilot of an aircraft under their control if they are aware of another aircraft that is not under their control, at an altitude that, in the controller's judgment, places both aircraft in unsafe proximity to each other
        • With the alert, when feasible, the controller will offer the pilot the position of the traffic if time permits and an alternate course(s) of action
        • Any alternate course(s) of action the controller may recommend to the pilot will be predicated only on other traffic being worked by the controller
          • ATC: "American Three, traffic alert, position of traffic, if time permits], advise you turn [right/left] heading [degrees] and/or [climb/descend] to [altitude] immediately"
        • The controller will discontinue alerts if informed by the pilot that they're taking action or the other aircraft is in sight
  • Traffic Advisories:

    • Advisories issued to alert pilots to other known or observed air traffic that may be in such proximity to the position or intended route of flight of their aircraft to warrant their attention
    • Such advisories may be based on:
      • Visual observation
      • Observation of radar identified and nonidentified aircraft targets on an ATC radar display, or
      • Verbal reports from pilots or other facilities
    • Note 1: The word "traffic" followed by additional information, if known, is used to provide such advisories; e.g., "Traffic, 2 o'clock, one zero miles, southbound, eight thousand"
    • Note 2: ATC provides traffic advisory services to the extent possible depending on higher priority duties of the controller or other limitations, e.g., radar limitations, the volume of traffic, frequency congestion, or controller workload. Radar/ nonradar traffic advisories do not relieve the pilot of his/her responsibility to see and avoid other aircraft. There are many times when the controller is not able to give traffic advisories concerning all traffic in the aircraft's proximity; in other words, when a pilot requests or is receiving traffic advisories, he/she should not assume that all traffic will be issued
    • ATC: "Traffic Alert [callsign], turn [left/right] immediately, [climb/descend] and maintain [altitude]"
  • Radar (Vectors) Assistance to VFR Aircraft:

    • Radar equipped ATC facilities provide radar assistance and navigation service (vectors) to VFR aircraft provided the aircraft can communicate with the facility, are within radar coverage, and can be radar identified
    • Vectoring service may be requested by the pilot or with pilot concurrence when suggested by ATC
    • Pilots should clearly understand that radar vectors do not constitute authorization for the pilot to violate Code of Federal Regulations (CFRs). In effect, the assistance provided is on the basis that navigational guidance information issued is advisory and the job of flying the aircraft safely remains with the pilot
    • In many cases, controllers cannot determine if flight into instrument conditions will result from their instructions. To avoid possible hazards resulting from being vectored into IFR conditions, pilots should keep controllers advised of the weather conditions in which they are operating and along the course ahead
    • Radar navigation assistance (vectors) may be initiated by the controller when one of the following conditions exist:
      • The controller suggests the vector, and the pilot concurs
      • A special program has been established and vectoring service has been advertised
      • In the controller's judgment, the vector is necessary for air safety
    • Radar navigation assistance (vectors) and other radar-derived information may be provided in response to pilot requests
    • Many factors, such as limitations of radar, the volume of traffic, communications frequency, congestion, and controller workload, could prevent the controller from providing it. Controllers have complete discretion to provide the service in a particular case. Their decision not to provide the service in a particular case is not subject to question
  • Aircraft Sequencing:

    • Sequencing for VFR aircraft is available at certain terminal locations (see locations listed in the Chart Supplement U.S.). The purpose of the service is to adjust the flow of arriving VFR and IFR aircraft into the traffic pattern safely and to provide radar traffic information to departing VFR aircraft. Pilot participation is urged but is not mandatory. Traffic information is provided on a workload permitting basis. Aircraft sequencing service does not offer standard radar separation between VFR or between VFR and IFR aircraft
      • Pilots of arriving VFR aircraft should initiate radio contact on the publicized frequency with approach control when approximately 25 miles from the airport at which sequencing services are being provided
      • On initial contact by VFR aircraft, approach control will assume that sequencing service is requested
      • After establishing radar contact, the pilot may use pilot navigation to enter the traffic pattern or, depending on traffic conditions; approach control may provide the pilot with routings or vectors necessary for proper sequencing with other participating VFR and IFR traffic en route to the airport
      • When a flight is behind a preceding aircraft and the pilot reports having that aircraft in sight, ATC instructs the pilot to follow the preceding aircraft
        • The ATC instruction to follow the preceding aircraft does not authorize the pilot to comply with any ATC clearance issued to the preceding aircraft
      • If other "nonparticipating" or "local" aircraft are in the traffic pattern, the tower will issue a landing sequence
      • If an arriving aircraft does not want radar service, the pilot should state "negative radar service" or make a similar comment on initial contact with approach control
      • Approach control will issue wind and runway, except when the pilot states "have numbers" or this information is contained in the Automatic Terminal Information Service (ATIS) broadcast and the pilot reports receiving the current ATIS information
        • Traffic information is provided on a workload permitting basis
        • Approach control will specify the time or place the pilot is to contact the tower on local control frequency for further landing information
      • Radar service is automatically terminated when an arriving VFR aircraft receiving radar services to a tower-controlled airport is instructed to change to tower or advisory frequency. (See FAA Order JO 7110.65, Air Traffic Control, Paragraph 5-1-13, Radar Service Termination)
      • Pilots of departing VFR aircraft are encouraged to request radar traffic information by notifying ground control, or where applicable, clearance delivery, on initial contact with their request and proposed direction of flight
        • Pilot: Xray ground control, November One Eight Six, Cessna One Seventy Two, ready to taxi, VFR southbound at 2,500, have information bravo and request radar traffic information"
        • Note the tower will advise when to contact departure control following takeoff
      • Pilots of aircraft transiting the area and in radar contact/communication with approach control will receive traffic information on a controller workload permitting basis
        • Pilots of such aircraft should give their position, altitude, aircraft call sign, aircraft type, radar beacon code (if transponder equipped), destination, and/or route of flight

Air Route Traffic Control Center (ARTCC):

  • In air traffic control, an Area Control Center (ACC), also known as a Center
  • Is a facility responsible for controlling instrument flight rules aircraft en route in a particular volume of airspace (a Flight Information Region) at high altitudes between airport approaches and departures

Terminal Radar Approach Control (TRACON):

  • The TRACON is generally within the vicinity of an airport
  • Typically, the TRACON controls aircraft approaching and departing between 5 and 50 miles of the airport
  • Radar equipment allows an air traffic controller to "see" the aircraft even at that distance
  • Terminal Radar Services for VFR Aircraft:

    • Terminal Radar Service Area (TSRA) Service (Radar Sequencing and Separation Service):
      • Specific terminal locations implement this service as advertised in the Chart Supplement U.S. This service aims to provide separation between all participating VFR aircraft and all IFR aircraft operating within the airspace defined as the TSRA. Pilot participation is urged but is not mandatory
      • If any aircraft does not want the service, the pilot should state "negative TSRA service" or make a similar comment, on initial contact with approach control or ground control, as appropriate
      • TRSAs are depicted on sectional aeronautical charts and listed in the Chart Supplement U.S.
      • While operating within a TRSA, pilots are provided TRSA service and separation as prescribed in this paragraph. Separation and sequencing of VFR aircraft suspend in a radar outage as this service depends on radar. The pilot will be advised that the service is unavailable and issued wind, runway information, and the time or place to contact the tower. Traffic information will be provided on a workload permitting basis
      • When prevailing conditions permit, visual separation is applied as follows:
        • When a VFR flight is behind a preceding aircraft and the pilot reports having that aircraft in sight, the pilot will be instructed by ATC to follow the preceding aircraft. Radar service will be continued to the runway. The ATC instruction to follow the preceding aircraft does not authorize the pilot to comply with any ATC clearance issued to the preceding aircraft
        • If other "nonparticipating" or "local" aircraft are in the traffic pattern, the tower will issue a landing sequence
        • Departing VFR aircraft may be asked if they can visually follow a preceding departure out of the TRSA. The pilot will be instructed to follow the other aircraft provided that the pilot can maintain visual contact with that aircraft
      • VFR aircraft will be separated from VFR/IFR aircraft by one of the following:
        • 500 feet vertical separation
        • Visual separation
        • Target resolution (a process to ensure that correlated radar targets do not touch)
      • Participating pilots operating VFR in a TRSA:
        • Must maintain an altitude when assigned by ATC unless the altitude assignment is to maintain at or below a specified altitude. ATC may assign altitudes for separation that do not conform to 14 CFR Section 91.159. When the pilot can maintain separation without an assigned altitude or when leaving the TRSA, the instruction will broadcast, "resume appropriate VFR altitudes." Pilots must then return to an altitude that conforms to 14 CFR Section 91.159 as soon as practicable
        • When not assigned an altitude, the pilot should coordinate with ATC before any altitude change
      • Within the TRSA, traffic information on observed but unidentified targets will, to the extent possible, be provided to all IFR and participating VFR aircraft. The pilot will be vectored upon request to avoid the observed traffic, provided the aircraft to be vectored is within the airspace under the jurisdiction of the controller
      • Departing aircraft should inform ATC of their intended destination and/or route of flight and proposed cruising altitude
      • ATC will normally advise participating VFR aircraft when leaving the geographical limits of the TRSA. Radar service is not automatically terminated with this advisory unless specifically stated by the controller
    • Class C Service: This service provides, in addition to basic radar service, approved separation between IFR and VFR aircraft, and sequencing of VFR arrivals to the primary airport
    • Class B Service: This service provides, in addition to basic radar service, approved separation of aircraft based on IFR, VFR, and/or weight, and sequencing of VFR arrivals to the primary airport(s)
    • ATC services for VFR aircraft participating in terminal radar services are dependent on ATC radar. Services for VFR aircraft are not available during periods of a radar outage and are limited during Center Radar Presentation (CENRAP) operations. The pilot will be advised when VFR services are limited or not available
      • NOTE-Class B and Class C airspace are areas of regulated airspace. The absence of ATC radar does not negate the requirement of an ATC clearance to enter Class B airspace or two-way radio contact with ATC to enter Class C airspace

Radar Traffic Information Service (Flight Following):

  • Radar Traffic Information Service, more commonly known as flight following, is an air traffic control service that provides pilots with advisories of any observed radar target along the route of flight which may be hazardous
  • Issuance of traffic information is intended to alert the pilot to the traffic, to be on the lookout for it, and thereby be in a better position to take appropriate action should the need arise
  • Radar ATC facilities normally display and monitor both primary and secondary radar as well as ADS-B, although the primary source may differ based on airspace
    • The monitoring of these sources allow controllers to issue traffic information of known targets based on proximity along a pilot's flight path
  • Service Availability:

    • Traffic information is routinely provided to all aircraft operating on IFR flight plans except when the pilot declines the service or the pilot is operating within Class A airspace
      • Traffic information may be provided to VFR flights (regardless of a filed flight plan) when requested
    • Many factors, such as limitations of the radar, the volume of traffic, controller workload, and communications frequency congestion, could prevent the controller from providing this service
    • Controllers possess complete discretion for determining whether they can provide or continue to provide this service based on workload
      • The controller's reason against providing or continuing to provide the service in a particular case is not subject to question, nor does it need to be communicated to the pilot
  • Requesting Flight Following:

    • Flight following may be requested by ATC as early as when contacting clearance delivery or ground control
      • "[Agency], [Callsign], ready to taxi, request flight following to [Location/Working Area]"
    • If operating out of an uncontrolled airfield, or already airborne, you may contact the controlling agency (approach/center) airborne
    • To request flight following, first provide an initial call to the Air Traffic Control Center servicing your area of operation
      • "[Agency], [Callsign], with request"
    • ATC will respond when able to receive the pilot's request
      • "[Callsign], [Agency], say request"
    • Be sure to provide ATC a location (so they know where you are) and your intentions, such as a destination or working area (so they know your route)
      • "[Callsign], [Location], request flight following to [Destination]"
    • With an understanding of your request, ATC will acknowledge they see you and give you instructions so they can appropriately track your flight
      • "[Callsign], radar contact [Location], [Altimeter Setting], squawk [Code], [Restrictions]"
    • Now that you're being monitored, enter the squawk code and acknowledge any calls from ATC
    • When complete, request to cancel flight following
      • "[Agency], [Callsign], cancel flight following"
    • ATC will cancel your squawk code and stop providing radar services
      • "[Callsign] radar services terminated, squawk VFR"
  • Issuance of Traffic Information:

    • Induced Error in Position of Traffic
      Induced Error in Position of Traffic
    • Induced Error in Position of Traffic
      Induced Error in Position of Traffic
    • Traffic information will include the following concerning a target that may constitute traffic for an aircraft that is:
      • Radar Identified:

        • Azimuth from the aircraft in terms of the 12-hour clock, or
        • When rapidly maneuvering civil test or military aircraft prevents accurate traffic issuance, ATC reports the direction from an aircraft's position in the eight cardinal compass points (N, NE, E, SE, S SW, W, NW). This method must be terminated at the pilot's request
        • The distance from the aircraft in nautical miles;
        • The direction in which the target is proceeding; and
        • Type of aircraft and altitude if known
        • Example: Traffic 10 o'clock, 3 miles, west-bound (type aircraft and altitude, if known, of the observed traffic). The altitude may be known through Mode C, but not verified with the pilot for accuracy. (To be valid for separation purposes by ATC, the accuracy of Mode C readouts must be verified. This is usually accomplished upon initial entry into the radar system by comparing the readout to pilot stated altitude or the field elevation in the case of continuous readout being received from an aircraft on the airport.) When necessary to issue traffic advisories containing unverified altitude information, the controller will issue the indicated altitude of the aircraft. Upon receipt of traffic information, the pilot may request a vector (heading) to avoid such traffic. The vector will be provided to the extent possible
      • Not Radar Identified:

        • The distance and direction to or from a fix;
        • The direction in which the target is proceeding; and
        • Type of aircraft and altitude if known
        • Example: Traffic 8 miles south of the airport northeast bound (type aircraft and altitude if known)
    • Traffic information is given based on aircraft track (what controllers can see) not aircraft heading:
      • Example: In [Figure 1], traffic information would be issued to the pilot of aircraft "A" as 12 o'clock. The actual position of the traffic as seen by the pilot of aircraft "A" would be 2 o'clock. Traffic information issued to aircraft "B" would also be given as 12 o'clock, but in this case, the pilot of "B" would see the traffic at 10 o'clock
      • Example: In [Figure 2], traffic information would be issued to the pilot of aircraft "C" as 2 o'clock. The actual position of the traffic as seen by the pilot of aircraft "C" would be 3 o'clock. Traffic information issued to aircraft "D" would be at an 11 o'clock position. Since it is not necessary for the pilot of aircraft "D" to apply wind correction (crab) to remain on track, the actual position of the traffic issued would be correct. Since the radar controller can only observe aircraft track (course) on the radar display, traffic advisories are issued accordingly, and pilots should give due consideration to this fact when looking for reported traffic
      • Induced Error in Position of Traffic
        Induced Error in Position of Traffic
      • Induced Error in Position of Traffic
        Induced Error in Position of Traffic
  • Flight Following Considerations:

    • Flight Following does not relieve the pilot of the responsibility for continual vigilance to see and avoid other aircraft
    • ATC can also provide other services while in contact with pilots, such as weather or obstruction avoidance
    • Not that surveillance radar used by ATC does not provide altitude information unless the aircraft is Mode C equipped and the radar facility is capable of displaying altitude information
    • If an outage occurs, pilots in contact with the affected ATC facility are normally advised, and service limitations may be imposed
      • "primary radar out of service; traffic advisories available on transponder or ADS-B aircraft only"
    • When receiving VFR radar advisory service, pilots should monitor the assigned frequency at all times
      • Monitoring precludes controllers' concern for radio failure or emergency assistance to aircraft under the controller's jurisdiction
    • VFR radar advisory service does not include vectors away from conflicting traffic unless requested by the pilot
    • When advisory service is no longer desired, advise the controller before changing frequencies and then change your transponder code to 1200, if applicable
    • Pilots should also inform the controller when changing VFR cruising altitude and may be explicitly requested to do so
    • Except in programs where radar service is automatically terminated, the controller will advise the aircraft when radar service is terminated
    • Traffic information is routinely provided to all aircraft operating on IFR flight plans except when the pilot declines the service or the pilot is operating within Class A airspace
    • Traffic information may be provided to flights not operating on IFR flight plans when requested by pilots of such flights
    • Advantages include clearance through certain airspace, such as restricted areas when they're not active
    • Participation by VFR pilots in formal programs implemented at certain terminal locations constitutes a pilot request
      • This also applies to participating pilots at those locations where arriving VFR flights are encouraged to make their first contact with the tower on the approach control frequency

Radar Service Responsibilities:

  • Radar Service Pilot Responsibilities:

    • These services do not relieve the pilot of their responsibilities to see and avoid other traffic operating in basic VFR weather conditions, to adjust their operations and flight path as necessary to preclude serious wake turbulence encounters, to maintain appropriate terrain and obstruction compliance with an assigned route, heading and/or altitude is likely to compromise pilot responsibility respecting terrain and obstruction clearance, vortex exposure, and weather minimums
    • Approach control should so be advised and a revised clearance or instruction obtained

FAA Radar Services Knowledge Quiz:

Conclusion:

  • Note that VFR flight following does not come with filing or opening a VFR flight plan, and neither does VFR flight following need to connect to a flight plan
    • If filing a flight plan, however, consider adding a note saying "request flight following" to notify ATC ahead of time of your intent
  • Request flight following even when you don't think you need or, or perhaps even when you don't have a destination
  • Although a contract service under the purview of the Federal Aviation Administration, Automated Flight Service Stations exist as reach back for routine services such as weather and filing flight plans
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