3/21/24 

AIM 

NOTE

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All aircraft should comply with 14 CFR §91.119(c) “

…

aircraft may not be operated closer than 500 feet to any person, 

vessel, vehicle, or structure.” 

(2) 

To avoid interference Non

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Transponder/Non

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ADS

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B Out equipped aircraft should avoid flight 

within 1.0 NM horizontally, at all altitudes, from the wind turbine farms. 

(3) 

Because detection loss near and above wind turbine farms for search

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only targets causes dropped 

tracks, erroneous tracks, and can result in loss of separation, it is imperative that Non

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Transponder/Non

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ADS

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B 

Out equipped aircraft operate at the proper VFR altitudes per hemispheric rule and utilize see

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and

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avoid 

techniques. 

(4) 

Pilots should be aware that air traffic controllers cannot provide separation from 

Non

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Transponder/Non

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ADS

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B Out equipped aircraft in the vicinity of wind turbine farms. See

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and

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avoid is 

the pilot’s responsibility, as these non

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equipped aircraft may not appear on radar and will not appear on the 

Traffic Information Services

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Broadcast (TIS

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B). 

(h) 

The controller’s ability to advise a pilot flying on instruments or in visual conditions of the aircraft’s 

proximity to another aircraft will be limited if the unknown aircraft is not observed on radar, if no flight plan 

information is available, or if the volume of traffic and workload prevent issuing traffic information. The 

controller’s first priority is given to establishing vertical, lateral, or longitudinal separation between aircraft 

flying IFR under the control of ATC. 

c. 

FAA radar units operate continuously at the locations shown in the Chart Supplement, and their services 

are available to all pilots, both civil and military. Contact the associated FAA control tower or ARTCC on any 

frequency guarded for initial instructions, or in an emergency, any FAA facility for information on the nearest 

radar service. 

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2.  Air Traffic Control Radar Beacon System (ATCRBS) 

a. 

The ATCRBS, sometimes referred to as secondary surveillance radar, consists of three main components: 

1.  Interrogator. 

Primary radar relies on a signal being transmitted from the radar antenna site and for this 

signal to be reflected or “bounced back” from an object (such as an aircraft). This reflected signal is then 

displayed as a “target” on the controller’s radarscope. In the ATCRBS, the Interrogator, a ground based radar 

beacon transmitter

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receiver, scans in synchronism with the primary radar and transmits discrete radio signals 

which repetitiously request all transponders, on the mode being used, to reply. The replies received are then 

mixed with the primary returns and both are displayed on the same radarscope. 

2.  Transponder. 

This airborne radar beacon transmitter

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receiver automatically receives the signals from 

the interrogator and selectively replies with a specific pulse group (code) only to those interrogations being 

received on the mode to which it is set. These replies are independent of, and much stronger than a primary radar 

return. 

3.  Radarscope. 

The radarscope used by the controller displays returns from both the primary radar system 

and the ATCRBS. These returns, called targets, are what the controller refers to in the control and separation of 

traffic. 

b. 

The job of identifying and maintaining identification of primary radar targets is a long and tedious task for 

the controller. Some of the advantages of ATCRBS over primary radar are: 

1. 

Reinforcement of radar targets. 

2. 

Rapid target identification. 

3. 

Unique display of selected codes. 

c. 

A part of the ATCRBS ground equipment is the decoder. This equipment enables a controller to assign 

discrete transponder codes to each aircraft under his/her control. Normally only one code will be assigned for 

Surveillance Systems 

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