Surveillance Radar

AIM ¶ 4-5-3 — Surveillance Radar

AIM 4-5-3 explains ASR and ARSR surveillance radar systems used by ATC for terminal and en route traffic control. Key facts for pilot oral exams.

In Plain English

Surveillance radar is the primary tool ATC uses to see where aircraft are. Per AIM 4-5-3, it comes in two flavors:

Airport Surveillance Radar (ASR): Short-range radar covering the area around an airport. Controllers use it to manage terminal area traffic by observing precise aircraft positions on a radarscope. ASR can also serve as an instrument approach aid (think ASR/Surveillance Approaches).
Air Route Surveillance Radar (ARSR): Long-range radar used by ARTCC (Centers) to display aircraft over large geographic areas during the en route phase of flight.

Both types scan 360° in azimuth and present targets on displays located in towers or centers. Controllers use this information either by itself or in combination with other navigation aids to separate and sequence traffic.

Why it matters: knowing the difference helps you understand who's watching you (tower/approach vs Center), why coverage gaps exist at low altitudes far from airports, and why ASR approaches remain a viable backup when other approach aids are unavailable.

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AIM Source Text

FAA AIM ¶ 4-5-3

4-5-3. 4-5-3. Surveillance Radar Surveillance radars are divided into two general categories: Airport Surveillance Radar (ASR) and Air Route Surveillance Radar (ARSR). ASR is designed to provide relatively short-range coverage in the general vicinity of an airport and to serve as an expeditious means of handling terminal area traffic through observation of precise aircraft locations on a radarscope. The ASR can also be used as an instrument approach aid. ARSR is a long-range radar system designed primarily to provide a display of aircraft locations over large areas. Surveillance radars scan through 360 degrees of azimuth and present target information on a radar display located in a tower or center. This information is used independently or in conjunction with other navigational aids in the control of air traffic.

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Oral Exam Questions a DPE Might Ask

Q1What are the two general categories of surveillance radar?

Per AIM 4-5-3, surveillance radars are divided into Airport Surveillance Radar (ASR) and Air Route Surveillance Radar (ARSR).

Q2What is the purpose of ASR versus ARSR?

Per AIM 4-5-3, ASR provides relatively short-range coverage near an airport for handling terminal area traffic and can also be used as an instrument approach aid, while ARSR is a long-range system designed primarily to display aircraft locations over large areas.

Q3How do surveillance radars scan, and how is the information used?

Per AIM 4-5-3, surveillance radars scan through 360 degrees of azimuth and present target information on a radar display in a tower or center, used independently or in conjunction with other navigational aids to control air traffic.

Related Paragraphs in AIM Chapter 4

¶ 4-5-1

Radar Capabilities and Limitations

¶ 4-5-10

ADS-R Rebroadcast

¶ 4-5-2

ATCRBS Secondary Surveillance Radar

¶ 4-5-4

Precision Approach Radar

¶ 4-5-5

ASDE-X/ASSC Surface Surveillance

¶ 4-5-6