¶ Introduction
The indications presented on the ATS surveillance system named radar may
be used to perform the aerodrome, approach and en-route control
service.
At IVAO, the ATS surveillance system is the IVAO ATC software which
simulates a secondary radar.
In this document, all items referred to as "ATS surveillance systems" in
official regulations documentation is translated by the generic word
"radar" as IVAO only provides a secondary radar system.
¶ Radar in the air traffic control service
Direct pilot controller communications shall be established prior to the
provision of radar services.
The number of aircraft simultaneously provided with ATS surveillance
services shall not exceed that which can safely be handled
depending on:
- the structural complexity of the control area and sector capacity
- the functions to be performed within the control area
- the controller workload
- the technical availability of the radar
The radar system can be used in order to help ATC to perform its tasks.
The information provided by the radar and presented on a situation
display may be used to perform the function of air traffic control
service:
- Provide radar services as necessary in order to improve airspace
utilization, reduce delays, provide for direct routings and more
optimum flight profiles, as well as to enhance safety - Provide vectoring to departing aircraft for the purpose of
facilitating an expeditious and efficient departure flow and
expediting climb to cruising level - Provide vectoring to aircraft for the purpose of resolving potential
conflicts - Provide vectoring to arriving aircraft for the purpose of
establishing an expeditious and efficient approach sequence - Provide vectoring to assist pilots in their navigation to or from a
radio navigation aid and/or away from or around areas of adverse
weather - Provide separation and maintain normal traffic flow when an aircraft
experiences communication failure within the area of coverage - Maintain flight path monitoring of air traffic
- When applicable, monitor the progress of air traffic, in order to
provide a procedural control with:- Improved position information regarding aircraft under control
- Supplementary information regarding other traffic
- Information regarding any significant deviations by aircraft
¶ Real life & IVAO differences
In real life, an ATS surveillance system provides:
- Conflict alert (available in IVAO ATC software)
- Minimum safe altitude warning (not available in IVAO ATC software)
- Conflict prediction (partially available in IVAO ATC software with
VERA tool only) - Duplicated SSR code (available in IVAO ATC software)
- Aircraft identification (available in IVAO ATC software)
In IVAO ATC software radar software, today, it is not possible to handle
minimum safe altitude warning and extended conflict prediction like in
the real ATS surveillance systems.
¶ Radar identification procedure
Identification of aircraft consists of:
- Aircraft label on radar shall identify the aircraft : aircraft call
sign or SSR transponder code (A,C,S or ADS-B) and if available
pressure altitude derived level information - Position indication
At IVAO, the radar label is automatically displayed on the IVAO ATC
software radar screen if the transponder code is compatible with a
controlled code. The figure shows an identified aircraft plot.
When the radar is not
displaying an aircraft label, in order to identify an aircraft, ATC can:
- Correlate a particular radar position indication with the
information known - Correlate the position with an aircraft which is known
- Instruct the pilot to execute one or more changes of heading of 30°
or more and correlating the movements of one particular radar
position indication - Correlate the movements of a particular radar position indication
with manoeuvres currently executed by an aircraft having so reported - Change the transponder code and/or use the transponder IDENT
procedure
The separation between aircraft is possible when radar provides:
- SSR transponder is mandatory in the area
- Identification of aircraft is established and maintained
¶ Position report
An aircraft shall be informed of its position under radar surveillance
service in the following circumstances:
- Upon identification (before identification established when
necessary) - When the pilot requests this information
- When the pilot is instructed to resume own navigation after
vectoring if the aircraft had been diverted from a previously
assigned route - Immediately before termination of ATS surveillance service, if the
aircraft is observed to deviate from its intended route
Position information can be one of the following possibilities:
- A well-known geographical position
- Magnetic track and distance to a significant point, an en-route
navigation aid, or an approach aid - Direction and distance from a known position
- Distance to touchdown, if the aircraft is on final approach
- Distance and direction from the centre line of an ATS route
¶ Separation
¶ Vertical separation minima
The vertical separation minimum (VSM) is 300m (1000ft) below FL290 and
600m (2000ft) above FL290.
For the airspace where the reduced vertical separation minimum (RVSM) is
applicable, the separation minimum is 300m (1000ft) below FL410 and 600m
(2000ft) above FL410.
¶ Default horizontal separation minima
The horizontal separation minimum based on radar and/or ADS-B shall be
5NM (9.3km).
In some cases, the horizontal separation may be reduced to 3NM or 2.5NM.
Please consult the "IFR separation using radar" document to read the
information about the application of this reduced separation.
¶ Speed control
A controller may, in order to facilitate sequencing or to reduce the
need for vectoring, request aircraft to adjust their speed in a specific
manner.
¶ Transfer of control
The transfer point, the direction of flight, specified levels, transfer
of communication points and agreed minimum separation between aircraft
have been made the subject of specific instructions or of a specific
letter of agreement between the 2 adjacent ATC units.
When the control of an identified aircraft is to be transferred to a
control sector that will provide the aircraft with procedural
separation, the transferring controller shall ensure that appropriate
procedural separation is established between that aircraft and any
other controlled aircraft before the transfer is affected.
¶ Radar vectoring
Vectoring is the process for an air traffic controller to issue to the
pilot specific headings which enable the aircraft to maintain the
desired track. When vectoring an aircraft, a controller shall comply
with the following points:
- The aircraft shall be vectored along track on which the pilot can
monitor the aircraft position with reference to navigation aids.
This will minimize the amount of navigational assistance required
and alleviate the consequences resulting from air traffic controller
radar failure. - When an aircraft is given its initial vectors diverting it from an
assigned route, the pilot shall be informed what the vector is to
accomplish and the limit of the vector shall be specified
(example: Vectors start at GAKTI intersection for an ILS approach
runway 04) - Aircraft shall not be vectored closer than 2.5NM (4.6km) or a
distance equivalent to 1/2 of the separation minimum if it is
greater than 5NM, next to another aircraft. - Controlled flights shall not be vectored into uncontrolled
airspace except in the case of emergency or in order to
circumnavigate adverse meteorological conditions - The controller shall issue clearances to IFR aircraft such that
the prescribed obstacle clearance will exist at all times until
the pilot will resume own navigation. - Minimum vectoring altitude should be sufficiently high to minimize
activation of aircraft ground proximity warning systems.
¶ Navigation assistance
An identified aircraft observed to deviate significantly from its
intended route or designated holding pattern shall be advised
accordingly. Appropriate action shall also be taken if such deviation is
likely to affect the service of the controller
The pilot of an aircraft requesting navigation assistance from an air
traffic control unit shall state the reason.
An aircraft which has been informed that it is provided with ATS
surveillance service shall be informed immediately when the service is
interrupted or terminated.
Pilots shall be informed by the air traffic controller about adverse
weather, in good time to permit the pilots to decide on an appropriate
course of action to circumnavigate the adverse weather area, if so
desired. When vectoring aircraft for circumnavigating an area of adverse
weather, the controller shall ascertain that the aircraft can be
returned to its intended flight path.
¶ Emergencies
The progress of an aircraft in emergency shall be monitored and whenever
possible plotted on the situation display until the aircraft disappears
from the radar system coverage.
Its position information shall be provided to all air traffic services
units which may be able to give assistance to the aircraft.
¶ Collision hazard
When an identified controlled flight is observed to be on a conflicting
path with an unknown aircraft deemed to constitute a collision hazard,
the pilot of the controlled flight shall, whenever practicable: *be
informed of the unknown aircraft, and if so requested by the controlled
flight or if, in the opinion of the controller, the situation warrants,
a course of avoiding action should be suggested
- be notified when the conflict no longer exists
When an identified IFR flight operating outside controlled airspace is
observed to be on a conflicting path with another aircraft, the pilot
shall:
- be informed as to the need for collision avoidance action to be
initiated. A course of avoiding action should be suggested if the
situation warrants - be notified when the conflict no longer exists
Information regarding traffic on a conflict path shall be given,
whenever practicable, in the following form:
- Relative bearing of the conflicting traffic in terms of the 12-hour
clock - Distance from the conflicting traffic in nautical miles or
kilometres - Direction in which the conflicting traffic appears to be proceeding
- Level and type of aircraft or, if unknown, relative speed of the
conflicting traffic
¶ Aircraft radio transmitter failure
If two-way communication is lost with an aircraft, the controller shall
determine whether or not the aircraft's receiver is functioning by
instructing the aircraft:
- to make a specified manoeuvre and by observing the aircraft's
track, - to operate IDENT or to make SSR code and ADS-B (text communication
for IVAO) changes.
Where it has been established that aircraft's radio receiver is
functioning, continued control can be effected using SSR transponder
code or ADS-B transmission (text communication for IVAO) change or IDENT
transmissions to obtain acknowledgement of clearance issued to the
aircraft.
When a controlled aircraft experiencing complete communication failure
is operating or expected to operate in a controlled airspace, the
controller shall continue to apply adequate separation to all aircraft.
Separation shall be applied between identified aircraft and all
unidentified aircraft observed along the expected route of the aircraft
with the communication failure.
¶ Radar failure
In the event of complete failure of the radar system where voice
communication remains, the controller shall take the necessary action to
establish procedural separation between the aircraft and, if necessary
limit the number of aircraft permitted to enter the area.
As an emergency measure, use of flight levels spaced by half the
applicable vertical separation minimum may be used as a temporary
separation method, if standard procedural separation cannot be provided
immediately.
¶ Use of radar in the approach control service
¶ Radar functions
The indications presented on the radar system may be used to perform the
following additional functions in the provision of approach control
service:
- Provide vectoring of arriving traffic on to final approach
aids - Provide flight path monitoring of parallel ILS approaches and
instruct aircraft to take appropriate action in the event of
possible or actual penetration of the no transgression zone (NTZ) - Provide vectoring of arriving traffic to a point from which a visual
approach can be completed - Provide vectoring of arriving traffic to a point from which a
precision radar approach or a surveillance radar approach can be
made (partially simulated at IVAO due to IVAO ATC software
limitations) - Provide flight path monitoring of other pilot-interpreted
approaches - Provide separation between succeeding departing aircraft
- Provide separation between succeeding arriving aircraft
- Provide separation between a departing aircraft and succeeding
departing aircraft
This last item imposes to ATC not to change the arrival flow due to
departing traffic. Departing aircraft shall not jeopardize the arrival
sequence.
¶ Vectoring procedure
Prior to vectoring for approach, the pilot shall be advised of the
type of approach and the runway to be used. The controller could
advise an aircraft being vectored for an instrument approach of its
position at least once prior to commencement of the final approach.
Aircraft vectored for final approach shall be given a heading or a
series of headings calculated to close with the final approach track:
- The final vector shall enable the aircraft to be established in
level flight on the final approach track prior to intercepting the
specified or nominal descent point or glide path (if an ILS or
radar approach is to be made), and should provide an intercept angle
with the final approach track of 45 degrees or less. - The controller should anticipate the interception manoeuvre and
should provide interception about 30sec minimum before the final
approach fix or point. - Whenever an aircraft is assigned a vector which takes it through the
final approach track, it will be advised accordingly, stating the
reason for the vector. This means that the clearance of the final
approach track is issued with the last vector in the interception of
the final approach track. - An aircraft vectored to intercept a final approach aid (ILS, VOR,
NDB) shall be instructed to report when established on the final
approach track. Clearance for the approach should be issued prior to
when the aircraft reports established. - Vectoring will normally terminate at the time the aircraft leaves
the last assigned heading to intercept the final approach track.
¶ Separation
The controller is responsible for maintaining separation minimum
between succeeding aircraft on the same final approach except that
the responsibility may be transferred to the aerodrome controller in
accordance with procedures defined by your country regulations and your
IVAO division rules, and if the aerodrome controller has a radar system.
¶ Transfer of control
Transfer of control of succeeding aircraft on final approach to the
aerodrome controller shall be done in accordance with procedures
prescribed by your country regulations and your IVAO division rules.
Transfer of communication to the aerodrome controller should be
performed at such a point or time that clearance to land or alternative
instructions can be issued to the aircraft in a timely manner.
This means that transferring an aircraft on short final, or beyond 4NM
from runway threshold is not the right way to perform this transfer.
If there is no procedure, the transfer of control should be done when
the aircraft has intercepted the final approach track but not before
15NM from the runway threshold.
¶ Radar vectoring before a visual approach
The controller may initiate a vectoring of an aircraft for visual
approach and meteorological conditions are such that, with reasonable
assurance, a visual approach and landing can be completed.
Clearance for visual approach shall be issued only after the pilot has
reported the aerodrome or the preceding aircraft in sight, at which time
vectoring will normally be terminated.
¶ Radar approaches
There are two types of radar approaches: Precision (PAR) and
Surveillance (ASR). Controllers conducting radar approach shall be in
possession of information regarding the obstacle clearance
altitude/heights established for the type of approach to be conducted.
(For the IVAO network, each controller shall have charts of their area
of responsibility).
In aviation, approach surveillance radar (ASR or SRA) is a type of
radar instrument approach provided with active assistance from air
traffic control. The only airborne radio equipment required for
radar approaches is a functioning radio transmitter and receiver. The
radar controller vectors the aircraft to align it with the runway
centreline. The controller continues the vectors to keep the aircraft on
course until the pilot can complete the approach and landing by visual
reference to the surface.
As these approaches are specific and used mainly in military airfields,
and as the IVAO ATC software is not fully compatible with them,
we do not develop this subject in this document.
When authorized by country regulations and IVAO division air traffic
control operation rules, radar systems may be used in the provision of
aerodrome control service to perform the following functions:
- Flight path monitoring on final approach
- Flight path monitoring of other aircraft in the vicinity of the
aerodrome - Establishing separation between succeeding departing aircraft
- Providing navigation assistance to VFR flights
Special VFR shall not be vectored unless under special circumstances,
such as emergencies.
Normal VFR should not be vectored unless under special circumstances
(emergencies, assistance requested by pilot) or specific regulations
depending on the airspace class. The controller shall ensure that the
VFR aircraft vectored does not inadvertently enter instrument
meteorological conditions (IMC).
In real life, the use of an ATS surveillance system like radar will
not be detrimental to visual observation of aerodrome traffic.
But at IVAO, the radar simulated by IVAO ATC softwareis today the
primary method to control an aerodrome airfield due to the better
performance provided by this system than the view created by a
flight simulator system which simulates the external visual observation
of the manoeuvring area.
The IVAO ATC software radar can be used as surface movement radar and
the controller uses it to assist with: The IVAO ATC software Radar can
be used as surface movement radar and the controller uses it to assist
with:
- Monitoring of aircraft and vehicles on the manoeuvring area
for compliance with clearance and instructions - Determining that a runway is clear of traffic prior to a
landing or take off - Providing information on the local traffic on or near the
manoeuvring area - Determining the location of aircraft and vehicles on the
manoeuvring area - Providing directional taxi information to aircraft when
requested by the pilot or deemed necessary by the controller
¶ Use of ATS surveillance systems in the flight information service
The radar information may be used to provide identified aircraft with:
- Information regarding any aircraft observed to be on a conflicting
path with the identified aircraft and, suggestions or advices
regarding avoiding actions - Information on the position of significant weather
- Information to assist the aircraft in its navigation when requested
by the pilot or deemed necessary by the controller
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¶
See also
- none
¶
Reference
- ICAO Documentation 4444 - Air Traffic Management - 16th Edition
2016 - Chapter 8.9
¶
Author
- VID 150259 - Author
- VID 435695 - Wiki integration