Page 11 - InterPilot Vol2 No2
P. 11

air traffic surveillance 11

figure 1: How ADS-B works
figure 1: How ADS-B works
By using a combination of satellites and receivers, ADS-B provides both fight crews and ground control
By using a combination of satellites and receivers, ADS-B provides both flight
personnel with information about the position and velocity of airplanes in the area.
crews and ground control personnel with information about the position and
velocity of airplanes in the area.
global navigation
Satellite System
play traffic both near and far.
Navigation satellites send precise timing
information that allows airplanes equipped
with global navigation satellite system
(GNSS) or GPS receivers to determine their
ADS-B out ADS-B in
own position and velocity. Airplanes Transmitter receiver
equipped with ADS-B Out broadcast precise
position and velocity to ground ADS-B
receivers and to other airplanes via a digital
datalink (1090 megahertz) along with other
data, such as the airplane’s flight number
and emergency status. ADS-B receivers that
are integrated into the ATC systems on the
ground or installed aboard other airplanes
(i.e. ADS-B In) provide users with an accu-
ground Air Traffc ADS-B remote
rate depiction of real-time aviation traffic. control receiver receivers
Unlike conventional radar, ADS-B works at
low altitudes and on the ground so that it
can be used to monitor traffic on the taxi- what ADS-B means
ways and runways of an airport. ADS-B is Automatic Surveillance
Position and velocity information is automatically transmitted Position, velocity, and other airplane information are surveillance
also effective in remote areas where there is periodically (at least once every second) without fight crew or data transmitted.
no radar coverage or where radar coverage operator input. other parameters in the transmission are
preselected and static.
is limited. Broadcast
The information is broadcast to any airplanes or ground station
with an ADS-B receiver. current mode S ATc transponders are
Dependent interrogated and then send a reply.
tHe BenefitS Of ADS-B tO AiRlineS The transmission is dependent on proper operation of on-board
equipment that determines position and velocity and availability of
With appropriate ground and airborne a sending system.
equipage updates and operational Photo courtesy of Boeing Images
procedure readiness, ADS-B may provide
airlines with several benefits, including:
Safety. ADS-B gives the aviation industry
the ability to maintain or improve existing It allows for a much greater margin in accuracy and integrity of the position
safety standards while increasing system which to implement conflict detection and reports but also increases the frequency of
efficiency and capacity. resolution than is available with any other the reports for a better understanding of
ADS-B significantly improves flight crews’ system by providing an effective range of the air traffic environment in the air and on
situational awareness because they know more than 100 nmi with high accuracy. the ground. ADS-B also:
where they are in relation to other airplanes. It clearly and immediately indicates Increases runway capacity with improved
It gives a real-time, common surveillance changes as the conflicting traffic turns, arrival accuracy to the metering fix.
picture to share information quickly if par- accelerates, climbs, or descends. Helps maintain runway approaches using
ticipating airplanes deviate from their ADS-B in applications can provide auto- cockpit display of traffic information in
assigned flight paths. matic traffic call-outs or warnings of immi- marginal visual weather conditions.
It offers more precise and commonly nent runway incursions. Enhances visibility of all airplanes in the
shared traffic information. All participants area to allow more airplanes to use the
have a common operational picture. Capacity. ADS-B can provide a substantial same runway.
It provides more accurate and timely sur- increase in the number of flights the ATC Allows 5 nmi of separation in non-radar
veillance information than radar: ADS-B pro- system can accommodate. More airplanes airspace (NRA) compared to current proce-
vides more frequent updates than radar, can occupy a given airspace simultaneously dural separation, and potentially allows
which rotates once every 6 or 12 seconds if separation standards are reduced, and the reduction of separation from 5 to 3 nmi in
for terminal and en route surveillance, increased precision of ADS-B enables greatly radar airspace.
respectively. reduced separation standards while main-
It displays both airborne and ground traffic. taining safety. ADS-B not only increases the efficiency. ADS-B provides improved 
the safety and technical Journal of ifalPa | InterPilot vol 2 | no 2 | July 2014
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