From Wikipedia, the free
encyclopedia
Air traffic control (ATC)
is a service provided by ground-based controllers who
direct aircraft on
the ground and through controlledairspace, and can
provide advisory services to aircraft in non-controlled airspace. The primary
purpose of ATC worldwide is to prevent collisions, organize and expedite the
flow of traffic, and provide information and other support for pilots.[1] In
some countries, ATC plays a security or defensive role, or is operated by the
military.
To prevent collisions, ATC enforces traffic
separation rules, which ensure each aircraft maintains a minimum amount of empty space
around it at all times. Many aircraft also have collision
avoidance systems, which provide additional safety by warning pilots
when other aircraft get too close.
In many countries, ATC provides services to
all private, military, and commercial aircraft operating within its airspace.
Depending on the type of flight and the class of airspace, ATC may issue instructions that
pilots are required to obey, or advisories (known as flight information in some countries) that pilots may, at their discretion, disregard.
Generally the pilot in command is the final authority for the safe operation of
the aircraft and may, in an emergency, deviate from ATC instructions to the
extent required to maintain safe operation of their aircraft.
Language
Pursuant to requirements of the International
Civil Aviation Organization (ICAO), ATC operations are conducted
either in the English language or
the language used by the station on the ground.[2] In
practice, the native language for a region is normally used; however, the English language must
be used upon request.[2]
History
In 1921, Croydon Airport, London was
the first airport in the world to introduce air traffic control.[3]
In America, Air Traffic Control developed
three divisions. The first - Air Mail Radio Stations (AMRS) was created in 1922
after World War 1 when the US Post Office began using techniques developed by
the Army to direct and track the movements of reconnaissance aircraft. Over
time the AMRS morphed into Flight Service Stations. Today's Flight Service
Stations do not issue control instructions, but provide pilots with many other
flight related informational services. They do relay control instructions from
ATC in areas where Flight Service is the only facility with radio or phone
coverage. The first Air Traffic Control Tower, regulating arrivals, departures
and surface movement of aircraft at a specific airport, opened in Cleveland in
1930. Approach/Departure Control facilities were created after the invention of
RADAR in the 1950s to monitor and control the busy airspace around larger
airports. The first Air Route Traffic Control Center, which directs the
movement of aircraft between departure and destination was opened in Newark, NJ
in 1935, followed in 1936 by Chicago and Cleveland. [4]
Airport control
The primary method of controlling the
immediate airport environment is visual observation from the aerodrome control
tower (TWR). The tower is a tall, windowed structure located on the airport
grounds. Aerodrome or Tower controllers are responsible for the separation and efficient movement of
aircraft and vehicles operating on the taxiways and runways of the airport
itself, and aircraft in the air near the airport, generally 5 to 10 nautical miles (9 to
18 km) depending on the airport procedures.
Surveillance displays are also available to
controllers at larger airports to assist with controlling air traffic.
Controllers may use a radar system called Secondary
Surveillance Radar for airborne traffic approaching and departing. These displays include a
map of the area, the position of various aircraft, and data tags that include
aircraft identification, speed, altitude, and other information described in
local procedures. In adverse weather conditions the tower controllers may also
use Surface Movement Radar (SMR), Surface Movement Guidance and Control Systems
(SMGCS) or Advanced SMGCS to control traffic on the manoeuvring area (taxiways
and runway).
The areas of responsibility for TWR
controllers fall into three general operational disciplines; Local Control or
Air Control, Ground Control, and Flight Data/Clearance Delivery—other
categories, such as Apron Control or Ground Movement Planner, may exist at extremely busy airports.
While each TWR may have unique airport-specific procedures, such as multiple
teams of controllers ('crews') at major or complex airports with multiple
runways, the following provides a general concept of the delegation of
responsibilities within the TWR environment.
Remote and
Virtual Tower (RVT) is a system based on Air Traffic Controllers being located somewhere
other than at the local airport tower and still able to provide Air Traffic
Control services. Displays for the Air Traffic Controllers may be either
optical live video and/or synthetic images based on surveillance sensor data.
Ground control
Ground Control (sometimes known as Ground
Movement Control) is responsible for the airport "movement" areas, as
well as areas not released to the airlines or other users. This generally
includes all taxiways, inactive runways, holding areas, and some transitional
aprons or intersections where aircraft arrive, having vacated the runway or
departure gate. Exact areas and control responsibilities are clearly defined in
local documents and agreements at each airport. Any aircraft, vehicle, or
person walking or working in these areas is required to have clearance from
Ground Control. This is normally done via VHF/UHF radio, but there may be
special cases where other procedures are used. Aircraft or vehicles without
radios must respond to ATC instructions via aviation light
signals or else be led by vehicles with radios. People working on the airport
surface normally have a communications link through which they can communicate
with Ground Control, commonly either by handheld radio or even cell phone. Ground Control is vital to the
smooth operation of the airport, because this position impacts the sequencing
of departure aircraft, affecting the safety and efficiency of the airport's
operation.
Some busier airports have Surface Movement
Radar (SMR), such as, ASDE-3, AMASS or ASDE-X, designed to display aircraft and
vehicles on the ground. These are used by Ground Control as an additional tool
to control ground traffic, particularly at night or in poor visibility. There
are a wide range of capabilities on these systems as they are being modernized.
Older systems will display a map of the airport and the target. Newer systems
include the capability to display higher quality mapping, radar target, data
blocks, and safety alerts, and to interface with other systems such as digital
flight strips.
Local control or air control
Local Control (known to pilots as
"Tower" or "Tower Control") is responsible for the active
runway surfaces. Local Control clears aircraft for takeoff or landing, ensuring
that prescribed runway separation will exist at all times. If Local Control
detects any unsafe condition, a landing aircraft may be told to "go-around"
and be re-sequenced into the landing pattern by the approach or terminal area
controller.
Within the TWR, a highly disciplined
communications process between Local Control and Ground Control is an absolute
necessity. Ground Control must request and gain approval from Local Control to
cross any active runway with any aircraft or vehicle. Likewise, Local Control
must ensure that Ground Control is aware of any operations that will impact the
taxiways, and work with the approach radar controllers to create
"holes" or "gaps" in the arrival traffic to allow taxiing
traffic to cross runways and to allow departing aircraft to take off.Crew Resource
Management (CRM) procedures are often used to ensure this communication process is
efficient and clear, although this is not as prevalent as CRM for pilots.
Flight data / clearance delivery
Clearance Delivery is the position that
issues route clearances to aircraft, typically before they commence taxiing.
These contain details of the route that the aircraft is expected to fly after
departure. Clearance Delivery or, at busy airports, the Traffic Management
Coordinator (TMC) will, if necessary, coordinate with the en route center and
national command center or flow control to obtain releases for aircraft. Often,
however, such releases are given automatically or are controlled by local
agreements allowing "free-flow" departures. When weather or extremely
high demand for a certain airport or airspace becomes a factor, there may be
ground "stops" (or "slot delays") or re-routes may be
necessary to ensure the system does not get overloaded. The primary
responsibility of Clearance Delivery is to ensure that the aircraft have the
proper route and slot time. This information is also coordinated with the en
route center and Ground Control in order to ensure that the aircraft reaches
the runway in time to meet the slot time provided by the command center. At
some airports, Clearance Delivery also plans aircraft push-backs and engine
starts, in which case it is known as the Ground Movement Planner (GMP): this
position is particularly important at heavily congested airports to prevent
taxiway and apron gridlock.
Flight Data (which is routinely combined with
Clearance Delivery) is the position that is responsible for ensuring that both
controllers and pilots have the most current information: pertinent weather
changes, outages, airport ground delays/ground stops, runway closures, etc.
Flight Data may inform the pilots using a recorded continuous loop on a
specific frequency known as the Automatic
Terminal Information Service (ATIS).
Approach and terminal control
Many airports have a radar control facility
that is associated with the airport. In most countries, this is referred to as Terminal
Control; in the U.S., it is referred to as a TRACON
(Terminal Radar Approach Control). While every airport varies, terminal
controllers usually handle traffic in a 30-to-50-nautical-mile (56 to
93 km) radius from the airport. Where there are many busy airports close
together, one consolidated Terminal Control Center may service all the
airports. The airspace boundaries and altitudes assigned to a Terminal Control
Center, which vary widely from airport to airport, are based on factors such as
traffic flows, neighboring airports and terrain. A large and complex example is
the London Terminal
Control Centre which controls traffic for five main London airports up to 20,000 feet
(6,100 m) and out to 100 nautical miles (190 km).
Terminal controllers are responsible for
providing all ATC services within their airspace. Traffic flow is broadly
divided into departures, arrivals, and overflights. As aircraft move in and out
of the terminal airspace, they are handed off to the next appropriate control
facility (a control tower, an en-route control facility, or a bordering
terminal or approach control). Terminal control is responsible for ensuring that
aircraft are at an appropriate altitude when they are handed off, and that
aircraft arrive at a suitable rate for landing.
Not all airports have a radar approach or
terminal control available. In this case, the en-route center or a neighboring
terminal or approach control may co-ordinate directly with the tower on the
airport and vector inbound aircraft to a position from where they can land
visually. At some of these airports, the tower may provide a non-radar procedural
approach service to arriving aircraft handed over from a radar unit before they are
visual to land. Some units also have a dedicated approach unit which can
provide the procedural
approach service either all the time or for any periods of radar outage for any
reason.
In the U.S., TRACONs are additionally
designated by a three-letter alphanumeric code. For example, the Chicago TRACON
is designated C90.[5]
En route, center, or area control
ATC provides services to aircraft in flight
between airports as well. Pilots fly under one of two sets of rules for
separation: Visual Flight
Rules (VFR) or Instrument
Flight Rules (IFR). Air traffic controllers have different responsibilities to aircraft
operating under the different sets of rules. While IFR flights are under
positive control, in the US VFR pilots can request flight following, which
provides traffic advisory services on a time permitting basis and may also
provide assistance in avoiding areas of weather and flight restrictions. Across
Europe, pilots may request for a "Flight Information Service", which
is similar to flight following. In the UK it is known as a "Traffic
Service".
En-route air traffic controllers issue
clearances and instructions for airborne aircraft, and pilots are required to
comply with these instructions. En-route controllers also provide air traffic
control services to many smaller airports around the country, including
clearance off of the ground and clearance for approach to an airport.
Controllers adhere to a set of separation standards that define the minimum
distance allowed between aircraft. These distances vary depending on the
equipment and procedures used in providing ATC services.
General characteristics
En-route air traffic controllers work in
facilities called Air Traffic Control Centers, each of which is commonly
referred to as a "Center". The United States uses the equivalent term
Air Route Traffic Control Center (ARTCC). Each center is responsible for many
thousands of square miles of airspace (known as a Flight
Information Region) and for the airports within that airspace.
Centers control IFR aircraft from the time they depart from an airport or
terminal area's airspace to the time they arrive at another airport or terminal
area's airspace. Centers may also "pick up" VFR aircraft that are
already airborne and integrate them into the IFR system. These aircraft must,
however, remain VFR until the Center provides a clearance.
Center controllers are responsible for
climbing the aircraft to their requested altitude while, at the same time,
ensuring that the aircraft is properly separated from all other aircraft in the
immediate area. Additionally, the aircraft must be placed in a flow consistent
with the aircraft's route of flight. This effort is complicated by crossing
traffic, severe weather, special missions that require large airspace
allocations, and traffic density. When the aircraft approaches its destination,
the center is responsible for meeting altitude restrictions by specific points,
as well as providing many destination airports with a traffic flow, which
prohibits all of the arrivals being "bunched together". These
"flow restrictions" often begin in the middle of the route, as controllers
will position aircraft landing in the same destination so that when the
aircraft are close to their destination they are sequenced.
As an aircraft reaches the boundary of a
Center's control area it is "handed off" or "handed over"
to the next Area Control Center. In some cases this "hand-off"
process involves a transfer of identification and details between controllers
so that air traffic control services can be provided in a seamless manner; in
other cases local agreements may allow "silent handovers" such that
the receiving center does not require any co-ordination if traffic is presented
in an agreed manner. After the hand-off, the aircraft is given a frequency
change and begins talking to the next controller. This process continues until
the aircraft is handed off to a terminal controller ("approach").
Radar coverage
Since centers control a large airspace area,
they will typically use long range radar that has the capability, at higher
altitudes, to see aircraft within 200 nautical miles (370 km) of the radar
antenna. They may also use TRACON radar
data to control when it provides a better "picture" of the traffic or
when it can fill in a portion of the area not covered by the long range radar.
In the U.S. system, at higher altitudes, over
90% of the U.S. airspace is covered by radar and often by multiple radar
systems; however, coverage may be inconsistent at lower altitudes used by
unpressurized aircraft due to high terrain or distance from radar facilities. A
center may require numerous radar systems to cover the airspace assigned to
them, and may also rely on pilot position reports from aircraft flying below
the floor of radar coverage. This results in a large amount of data being
available to the controller. To address this, automation systems have been
designed that consolidate the radar data for the controller. This consolidation
includes eliminating duplicate radar returns, ensuring the best radar for each
geographical area is providing the data, and displaying the data in an
effective format.
Centers also exercise control over traffic
travelling over the world's ocean areas. These areas are also FIRs.
Because there are no radar systems available for oceanic control, oceanic
controllers provide ATC services using procedural
control. These procedures use aircraft position reports, time,
altitude, distance, and speed to ensure separation. Controllers record
information on flight progress
strips and in specially developed oceanic computer systems as aircraft report
positions. This process requires that aircraft be separated by greater
distances, which reduces the overall capacity for any given route. See for
example the North Atlantic
Track system.
Some Air Navigation Service Providers (e.g.
Airservices Australia, The Federal Aviation Administration, NAV CANADA, etc.) have implemented Automatic
Dependent Surveillance – Broadcast (ADS-B) as part of their surveillance
capability. This new technology reverses the radar concept. Instead of radar
"finding" a target by interrogating the transponder, the ADS-equipped
aircraft sends a position report as determined by the navigation equipment on
board the aircraft. Normally, ADS operates in the "contract" mode
where the aircraft reports a position, automatically or initiated by the pilot,
based on a predetermined time interval. It is also possible for controllers to
request more frequent reports to more quickly establish aircraft position for
specific reasons. However, since the cost for each report is charged by the ADS
service providers to the company operating the aircraft, more frequent reports
are not commonly requested except in emergency situations. ADS is significant
because it can be used where it is not possible to locate the infrastructure
for a radar system (e.g. over water). Computerized radar displays are now being
designed to accept ADS inputs as part of the display. This technology is
currently used in portions of the North Atlantic and the Pacific by a variety
of states who share responsibility for the control of this airspace.
Precision approach
radars are commonly used by military controllers of airforces of several
countries, to assist the Pilot in final phases of landing in places where
Instrument Landing System and other sophisticated air borne equipment are
unavailable to assist the pilots in marginal or near
zero visibility conditions. This procedure is also calledTalkdowns.
A Radar Archive System (RAS) keeps an
electronic record of all radar information, preserving it for a few weeks. This
information can be useful for search and rescue. When an aircraft has
'disappeared' from radar screens, a controller can review the last radar
returns from the aircraft to determine its likely position. For example, see
this crash report.[6] RAS
is also useful to technicians who are maintaining radar systems.
Flight traffic mapping
The mapping of flights in real-time is based
on the air traffic control system. In 1991, data on the location of aircraft
was made available by the Federal Aviation Administration to the airline
industry. The National
Business Aviation Association (NBAA),
the General Aviation Manufacturers Association, the Aircraft Owners &
Pilots Association, the Helicopter Association International, and the National
Air Transportation Association petitioned the FAA to make ASDI information
available on a "need-to-know" basis. Subsequently, NBAAadvocated
the broad-scale dissemination of air traffic data. The Aircraft Situational
Display to Industry (ASDI) system now conveys up-to-date flight
information to the airline industry and the public. Some companies that
distribute ASDI information
are FlightExplorer, FlightView, and FlyteComm. Each company maintains a website
that provides free updated information to the public on flight status.
Stand-alone programs are also available for displaying the geographic location
of airborne IFR (Instrument
Flight Rules) air traffic anywhere in the FAA air traffic system. Positions are
reported for both commercial and general aviation traffic. The programs can
overlay air traffic with a wide selection of maps such as, geo-political
boundaries, air traffic control center boundaries, high altitude jet routes,
satellite cloud and radar imagery.
Problems
Traffic
The day-to-day problems
faced by the air traffic control system are primarily related to the volume of
air traffic demand placed on the system and weather.
Several factors dictate the amount of traffic that can land at an airport in a
given amount of time. Each landing aircraft must touch down, slow, and exit the runway before
the next crosses the approach end of the runway. This process requires at least
one and up to four minutes for each aircraft. Allowing for departures between
arrivals, each runway can thus handle about 30 arrivals per hour. A large
airport with two arrival runways can handle about 60 arrivals per hour in good
weather. Problems begin when airlinesschedule more arrivals into an airport
than can be physically handled, or when delays elsewhere cause groups of
aircraft that would otherwise be separated in time to arrive simultaneously.
Aircraft must then be delayed in the air by holding over
specified locations until they may be safely sequenced to the runway. Up until
the 1990s, holding, which has significant environmental and cost implications,
was a routine occurrence at many airports. Advances in computers now allow the
sequencing of planes hours in advance. Thus, planes may be delayed before they
even take off (by being given a "slot"), or may reduce speed in
flight and proceed more slowly thus significantly reducing the amount of
holding.
Air traffic control
errors occur when the separation (either vertical or horizontal) between
airborne aircraft falls below the minimum prescribed separation set (for the
domestic United States) by the US Federal Aviation Administration. Separation
minimums for terminal control areas (TCAs) around airports are lower than
en-route standards. Errors generally occur during periods following times of
intense activity, when controllers tend to relax and overlook the presence of
traffic and conditions that lead to loss of minimum separation.[7] Paradoxically,
current high precision cruising altitude rules increase the risk of collision
between 10 and 33 times over more sloppy alternatives when air traffic control
errors occur.
Weather
Beyond runway capacity
issues, weather is a major factor in traffic capacity. Rain, ice or snow on
the runway cause landing aircraft to take longer to slow and exit, thus
reducing the safe arrival rate and requiring more space between landing
aircraft. Fog also
requires a decrease in the landing rate. These, in turn, increase airborne
delay for holding aircraft. If more aircraft are scheduled than can be safely
and efficiently held in the air, a ground delay program may be established,
delaying aircraft on the ground before departure due to conditions at the
arrival airport.
In Area Control Centers,
a major weather problem is thunderstorms, which present a variety of
hazards to aircraft. Aircraft will deviate around storms, reducing the capacity
of the en-route system by requiring more space per aircraft, or causing
congestion as many aircraft try to move through a single hole in a line of
thunderstorms. Occasionally weather considerations cause delays to aircraft
prior to their departure as routes are closed by thunderstorms.
Much money has been
spent on creating software to
streamline this process. However, at some ACCs, air traffic controllers still
record data for each flight on strips of paper and personally coordinate their
paths. In newer sites, these flight progress
strips have been replaced by electronic data presented on computer screens. As new
equipment is brought in, more and more sites are upgrading away from paper
flight strips.
Call signs
A prerequisite to safe
air traffic separation is the assignment and use of distinctive call
signs. These are permanently allocated by ICAO on
request usually to scheduled
flights and some air forces for military flights.
They are written callsigns with 3-letter combination like KLM, BAW, VLG
followed by the flight number, like AAL872, VLG1011. As such they appear on
flight plans and ATC radar labels. There are also the audio or Radio-telephony callsigns
used on the radio contact between pilots and Air Traffic Control. These are not
always identical to their written counterparts. An example of an audio callsign
would be "Speedbird 832", instead of the written "BAW832".
This is used to reduce the chance of confusion between ATC and the aircraft. By
default, the callsign for any other flight is the registration
number (tail number) of the aircraft, such as "N12345",
"C-GABC" or "EC-IZD". The short Radio-telephony callsigns
for these tail numbers is the last 3 letters using the NATO phonetic
alphabet (i.e. ABC spoken Alpha-Bravo-Charlie) for C-GABC or the last 3 numbers like
345 spoken as TREE-FORE-FIFE for N12345. In the United States, the prefix may
be an aircraft type, model or manufacturer in place of the first registration
character, for example "N11842" could become "Cessna 842".[8] This
abbreviation is only allowed after communications has been established in each
sector.
The flight number part
is decided by the aircraft operator. In this arrangement, an identical call
sign might well be used for the same scheduled journey each day it is operated,
even if the departure time varies a little across different days of the week.
The call sign of the return flight often differs only by the final digit from
the outbound flight. Generally, airline flight numbers are even if eastbound,
and odd if westbound. In order to reduce the possibility of two callsigns on
one frequency at any time sounding too similar, a number of airlines,
particularly in Europe, have started using alphanumeric callsigns
that are not based on flight numbers. For example DLH23LG, spoken as lufthansa-two-three-lima-golf.
Additionally it is the right of the air traffic controller to change the
'audio' callsign for the period the flight is in his sector if there is a risk
of confusion, usually choosing the tail number instead.
Before around 1980 International
Air Transport Association (IATA) and ICAO were
using the same 2-letter callsigns. Due to the larger number of new airlines
after deregulation ICAOestablished
the 3-letter callsigns as mentioned above. The IATA callsigns
are currently used in aerodromes on the announcement tables but never used any
longer in Air Traffic Control. For example, AA is the IATA callsign
for American Airlines — ATC
equivalent AAL. Other examples include LY/ELY for El
Al, DL/DAL for Delta Air Lines, VY/VLG
forVueling Airlines, etc.
Technology
Many technologies are
used in air traffic control systems. Primary and secondary radar are
used to enhance a controller's situation
awareness within his assigned airspace — all types of aircraft send back primary
echoes of varying sizes to controllers' screens as radar energy is bounced off
their skins, and transponder-equipped aircraft reply to
secondary radar interrogations by giving an ID (Mode A), an altitude (Mode C)
and/or a unique callsign (Mode S). Certain types of weather may also register
on the radar screen.
These inputs, added to
data from other radars, are correlated to build the air situation. Some basic
processing occurs on the radar tracks, such as calculating ground speed and
magnetic headings.
Usually, a Flight Data
Processing System manages all the flight plan related
data, incorporating – in a low or high degree – the information of the track
once the correlation between them (flight plan and track) is established. All
this information is distributed to modern operational
display systems, making it available to controllers.
The FAA has
spent over US$3 billion on software, but a fully automated system is still over
the horizon. In 2002 the UK brought a new area control centre into service at
the London Area
Control Centre, Swanwick, Hampshire, in Hampshire,
relieving a busy suburban centre at West Drayton, Middlesex, north of London Heathrow
Airport. Software from Lockheed-Martin predominates
at the London Area Control Centre. However, the centre was initially troubled
by software and communications problems causing delays and occasional shutdowns.[9]
Some tools are available
in different domains to help the controller further:
·
Flight Data Processing Systems: this is the
system (usually one per Center) that processes all the information related to
the Flight (the Flight Plan), typically in the time horizon from Gate to gate
(airport departure/arrival gates). It uses such processed information to invoke
other Flight Plan related tools (such as e.g. MTCD), and distributes such
processed information to all the stakeholders (Air Traffic Controllers, collateral
Centers, Airports, etc.).
·
Short Term
Conflict Alert (STCA)
that checks possible conflicting trajectories in a time horizon of about 2 or 3
minutes (or even less in approach context – 35 seconds in the French Roissy
& Orly approach centres[10]) and alerts the controller prior to
the loss of separation. The algorithms used may also provide in some systems a
possible vectoring solution, that is, the manner in which to turn, descend, or
climb the aircraft in order to avoid infringing the minimum safety distance or
altitude clearance.
·
Minimum Safe
Altitude Warning (MSAW):
a tool that alerts the controller if an aircraft appears to be flying too low
to the ground or will impact terrain based on its current altitude and heading.
·
System Coordination (SYSCO) to enable
controller to negotiate the release of flights from one sector to another.
·
Area Penetration Warning (APW) to inform a
controller that a flight will penetrate a restricted area.
·
Arrival and Departure Manager to help
sequence the takeoff and landing of aircraft.
·
The Departure
Manager (DMAN): A system aid for the ATC at airports, that
calculates a planned departure flow with the goal to maintain an optimal
throughput at the runway, reduce queuing at holding point and distribute the
information to various stakeholders at the airport (i.e. the airline, ground
handling and Air Traffic Control (ATC)).
·
The Arrival Manager (AMAN): A system aid for
the ATC at airports, that calculates a planned Arrival flow with the goal to
maintain an optimal throughput at the runway, reduce arrival queuing and
distribute the information to various stakeholders.
·
passive Final Approach Spacing Tool (pFAST),
a CTAS tool, provides runway assignment and sequence number advisories to terminal
controllers to improve the arrival rate at congested airports. pFAST was
deployed and operational at five US TRACONs before being cancelled. NASA
research included an Active FAST capability that also provided vector and speed
advisories to implement the runway and sequence advisories.
·
Converging Runway Display Aid (CRDA) enables
Approach controllers to run two final approaches that intersect and make sure
that go arounds are minimized
·
Center TRACON Automation System (CTAS) is a
suite of human centered decision support tools developed by NASA Ames Research
Center. Several of the CTAS tools have been field tested and transitioned to
the FAA for operational evaluation and use. Some of the CTAS tools are: Traffic
Management Advisor (TMA), passive Final Approach Spacing Tool (pFAST),
Collaborative Arrival Planning (CAP), Direct-To (D2), En Route Descent Advisor
(EDA) and Multi Center TMA. The software is running on Linux.[11]
·
Traffic Management Advisor (TMA), a CTAS
tool, is an en route decision support tool that automates time based metering
solutions to provide an upper limit of aircraft to a TRACON from the Center
over a set period of time. Schedules are determined that will not exceed the
specified arrival rate and controllers use the scheduled times to provide the
appropriate delay to arrivals while in the en route domain. This results in an
overall reduction in en route delays and also moves the delays to more
efficient airspace (higher altitudes) than occur if holding near the TRACON
boundary is required to not overload the TRACON controllers. TMA is operational
at most en route air route traffic control centers (ARTCCs) and continues to be
enhanced to address more complex traffic situations (e.g. Adjacent Center
Metering (ACM) and En Route Departure Capability (EDC))
·
MTCD & URET
·
In the US, User Request Evaluation Tool
(URET) takes paper strips out of the equation for En Route controllers at
ARTCCs by providing a display that shows all aircraft that are either in or
currently routed into the sector.
·
In Europe, several MTCD tools are available:
iFACTS (NATS),
VAFORIT (DFS),
New FDPS (MASUAC).
The SESAR[12] Programme
should soon launch new MTCD concepts.
URET
and MTCD provide conflict advisories up to 30 minutes in advance and have a
suite of assistance tools that assist in evaluating resolution options and
pilot requests.
·
Mode S:
provides a data downlink of flight parameters via Secondary Surveillance Radars
allowing radar processing systems and therefore controllers to see various data
on a flight, including airframe unique id (24-bits encoded), indicated airspeed
and flight director selected level, amongst others.
·
CPDLC: Controller
Pilot Data Link Communications —
allows digital messages to be sent between controllers and pilots, avoiding the
need to use radiotelephony. It is especially useful in areas where
difficult-to-use HF radiotelephony
was previously used for communication with aircraft, e.g. oceans. This is
currently in use in various parts of the world including the Atlantic and
Pacific oceans.
·
ADS-B: Automatic Dependent Surveillance
Broadcast — provides a data downlink of various flight parameters to air
traffic control systems via the Transponder (1090 MHz) and reception of
those data by other aircraft in the vicinity. The most important is the
aircraft's latitude, longitude and level: such data can be utilized to create a
radar-like display of aircraft for controllers and thus allows a form of
pseudo-radar control to be done in areas where the installation of radar is
either prohibitive on the grounds of low traffic levels, or technically not
feasible (e.g. oceans). This is currently in use in Australia, Canada and parts
of the Pacific Ocean and Alaska.
A system of electronic
flight strips replacing the old paper strips is being used by several Service
Providers, such as NAV CANADA, MASUAC, DFS, DECEA. E-strips allows controllers
to manage electronic flight data online without Paper Strips, reducing the need
for manual functions, creating new tools and reducing the ATCO's workload. The
firsts electronic flight strips systems were independently and simultaneously
invented and implemented by NAV CANADA and Saipher ATC in 1999. The NAV CANADA
system known as EXCDS[13] and
rebranded in 2011 to NAVCANstrips and Saipher's first generation system known
as SGTC, which is now being updated by its 2nd genreration system, the TATIC
TWR. DECEA in Brazil is the world's largest user of Tower e-strips system,
ranging from very small airports up to the busiest ones, taking the advantage
of real time information and data collection from each of more than 150 sites
for use in ATFM,
Billing and Statistics.
·
Screen Content Recording: Hardware or
software based recording function which is part of most modern Automation
System and that captures the screen content shown to of the ATCO. Such
recordings are used for a later replay together with audio recording for
investigations and post event analysis.[14]
·
Communication Navigation Surveillance / Air
Traffic Management (CNS/ATM)
systems are communications, navigation, and surveillance systems, employing
digital technologies, including satellite systems together with various levels
of automation, applied in support of a seamless global air traffic management
system.[15]
Main article: Air Navigation
Service Provider
·
Brazil – Departamento
de Controle do Espaço Aéreo (ATC/ATM
Authority) and ANAC – Agência
Nacional de Aviação Civil (Civil
Aviation Authority)
Brazil – Departamento
de Controle do Espaço Aéreo (ATC/ATM
Authority) and ANAC – Agência
Nacional de Aviação Civil (Civil
Aviation Authority)
·
Dominican
Republic – Instituto Dominicano
de Aviación Civil (IDAC) "Dominican
Institute of Civil Aviation"
Dominican
Republic – Instituto Dominicano
de Aviación Civil (IDAC) "Dominican
Institute of Civil Aviation"
·
France – Direction Générale de
l'Aviation Civile (DGAC) : Direction des Services
de la Navigation Aérienne (DSNA) (Government
body)
France – Direction Générale de
l'Aviation Civile (DGAC) : Direction des Services
de la Navigation Aérienne (DSNA) (Government
body)
·
Hungary – HungaroControl Magyar
Légiforgalmi Szolgálat Zrt. (HungaroControl
Hungarian Air Navigation Services Pte. Ltd. Co.)
Hungary – HungaroControl Magyar
Légiforgalmi Szolgálat Zrt. (HungaroControl
Hungarian Air Navigation Services Pte. Ltd. Co.)
·
India – Airports
Authority of India (AAI)
(under Ministry of Civil Aviation, Government Of
India and Indian Air Force)
India – Airports
Authority of India (AAI)
(under Ministry of Civil Aviation, Government Of
India and Indian Air Force)
·
Netherlands – Luchtverkeersleiding
Nederland (LVNL) (Dutch ATC) http://www.eurocontrol.nl Eurocontrol (European
area control ATC)
Netherlands – Luchtverkeersleiding
Nederland (LVNL) (Dutch ATC) http://www.eurocontrol.nl Eurocontrol (European
area control ATC)
·
Philippines – Civil
Aviation Authority of the Philippines (CAAP) (under the Philippine
Government)
Philippines – Civil
Aviation Authority of the Philippines (CAAP) (under the Philippine
Government)
·
United Kingdom – National Air
Traffic Services (NATS) (49%
State Owned Public-Private Partnership)
United Kingdom – National Air
Traffic Services (NATS) (49%
State Owned Public-Private Partnership)
Proposed changes
In the United States,
some alterations to traffic control procedures are being examined.
·
The Next
Generation Air Transportation System examines how to overhaul the United
States national airspace system.
·
Free flight is a developing air traffic control
method that uses no centralized control (e.g. air traffic controllers).
Instead, parts of airspace are reserved dynamically and automatically in a
distributed way using computer communication to ensure the required separation
between aircraft.[16]
In Europe, the SESAR[12] (Single European
Sky ATM Research) Programme plans to develop new methods,
technologies, procedures, and systems to accommodate future (2020 and beyond)
air traffic needs.
Many countries have also
privatized or corporatized their air navigation service providers.[17]
Change in regulation in
admittance for possible A.T.C.'s regarding their eye-refraction and correction
thereof by technology has been proposed.
ATC regulations in the United States
FAA Control Tower
Operators (CTO)/Air Traffic
Controllers use FAA Order
7110.65 as the authority for all procedures regarding air traffic. For more
information regarding Air Traffic
Control rules and regulations, refer to the FAA's website.[18]
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