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AIM

10/12/17

4

−5−7

Surveillance Systems

4

−5−3. Surveillance Radar

a.

Surveillance radars are divided into two general

categories: Airport Surveillance Radar (ASR) and
Air Route Surveillance Radar (ARSR).

1.

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.

2.

ARSR is a long

−range radar system designed

primarily to provide a display of aircraft locations
over large areas.

3.

Center Radar Automated Radar Terminal

Systems (ARTS) Processing (CENRAP) was devel-
oped to provide an alternative to a nonradar
environment at terminal facilities should an ASR fail
or malfunction. CENRAP sends aircraft radar beacon
target information to the ASR terminal facility
equipped with ARTS. Procedures used for the
separation of aircraft may increase under certain
conditions when a facility is utilizing CENRAP
because radar target information updates at a slower
rate than the normal ASR radar. Radar services for
VFR aircraft are also limited during CENRAP
operations because of the additional workload
required to provide services to IFR aircraft.

b.

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.

4

−5−4. Precision Approach Radar (PAR)

a.

PAR is designed for use as a landing aid rather

than an aid for sequencing and spacing aircraft. PAR
equipment may be used as a primary landing aid (See
Chapter 5, Air Traffic Procedures, for additional
information), or it may be used to monitor other types
of approaches. It is designed to display range,
azimuth, and elevation information.

b.

Two antennas are used in the PAR array, one

scanning a vertical plane, and the other scanning

horizontally. Since the range is limited to 10 miles,
azimuth to 20 degrees, and elevation to 7 degrees,
only the final approach area is covered. Each scope is
divided into two parts. The upper half presents
altitude and distance information, and the lower half
presents azimuth and distance.

4

−5−5. Airport Surface Detection

Equipment (ASDE

−X)/Airport Surface

Surveillance Capability (ASSC)

a.

ASDE

−X/ASSC is a multi−sensor surface

surveillance system the FAA is acquiring for airports
in the United States. This system provides high
resolution, short

−range, clutter free surveillance

information about aircraft and vehicles, both moving
and fixed, located on or near the surface of the
airport’s runways and taxiways under all weather and
visibility conditions. The system consists of:

1. A Primary Radar System.

ASDE

−X/

ASSC system coverage includes the airport surface
and the airspace up to 200 feet above the surface.
Typically located on the control tower or other
strategic location on the airport, the Primary Radar
antenna is able to detect and display aircraft that are
not equipped with or have malfunctioning transpond-
ers.

2. Interfaces.

ASDE

−X/ASSC contains an

automation interface for flight identification via all
automation platforms and interfaces with the
terminal radar for position information.

3. Automation.

A Multi

−sensor Data Proces-

sor (MSDP) combines all sensor reports into a single
target which is displayed to the air traffic controller.

4. Air Traffic Control Tower Display.

A high

resolution, color monitor in the control tower cab
provides controllers with a seamless picture of airport
operations on the airport surface.

b.

The combination of data collected from the

multiple sensors ensures that the most accurate
information about aircraft location is received in the
tower, thereby increasing surface safety and
efficiency.