Section 4, Chapter 2 - Area Control Procedures

Question 1

What are the principles of operation for an ACC sector team?

Answer 1

The principles of operation for an ACC sector team include:

• Each controller is responsible for efficiently performing specifically allocated tasks detailed in MATS Part 2.
• Controllers must monitor the actions of other sector team members as much as their primary duties allow.
• Sectors must have a defined prime flight data display for conflict detection, reflecting all clearance instructions and communications.
• Inter-sector coordination requires established criteria that allow the coordinator to use surveillance-derived information for traffic transfer between sectors without referring to the controller, when authorized by the CAA.

Question 2

What are the requirements for coordination between Area Control Centres (ACC) before transferring control of an aircraft?

Answer 2

Coordination between ACCs or sectors must occur before an aircraft penetrates another’s airspace. The transferring controller is responsible for initiating coordination and complying with the accepting controller’s conditions. The process is complete when:

• Notification, negotiation, and agreement occur progressively, step-by-step.
• It is agreed that aircraft can proceed under specified conditions without individual coordination, as detailed in MATS Part 2.
• An estimate message is passed and no objections are raised by the accepting ATC unit. This procedure must be approved by the CAA.

Question 3

What must be done if there are subsequent changes in flight level, routing, or revisions of 3 minutes or more before transferring communication between ACCs?

Answer 3

If there are subsequent changes in flight level, routing, or revisions of 3 minutes or more, the transferring controller must re-coordinate these changes and reach an agreement before the transfer of communication takes place.

Question 4

What must be done if the first reporting point after take-off is in an adjoining area?

Answer 4

If the first reporting point after take-off is in an adjoining area, an approval request must be made to that ACC, and coordination must be achieved before giving clearance to the aircraft. The CAA may waive the requirement for approval requests.

Question 5

Can an ACC provide service to aircraft outside its FIR, and how can transfer points be adjusted?

Answer 5

Normally, an ACC provides service only to aircraft within its own FIR. However, transfer points can be varied by prior arrangement between ACCs to suit traffic arrangements, either permanently or for a particular flight.

Question 6

What data must Approach Control units promptly advise to Area Control regarding IFR flights, and what delegations and modifications can be made?

Answer 6

Approach Control units must promptly advise Area Control of the following data on IFR flights:

• Lowest level at the holding point available for use by Area Control.
• Average time interval between successive approaches.
• Revisions to expected approach times when variations of 5 minutes or more occur.
• Arrival times over the holding point if these vary by 3 minutes or more from the estimate.
• Missed approaches when re-routing is necessary, for coordinated subsequent action.
• Departure times of aircraft.
• All information on overdue aircraft.

This information passing can be delegated from Approach to Aerodrome Control, and any of these items can be removed from routine practice by agreement with Area Control.

Question 7

What instructions can Area Control give regarding the take-off times for departing aircraft, and what must be communicated to aerodrome units?

Answer 7

Area Control may specify a specific time or a time slot during which an aircraft is authorized to take off. Units at aerodromes must be advised of any anticipated delays to departing aircraft along with the reason for the delay.

Question 8

What are the requirements for Area Control when releasing inbound aircraft to Approach Control?

Answer 8

Estimates and Release Messages:

• Estimates on inbound aircraft must be passed to Approach Control at least 15 minutes before the aircraft arrives at the designated approach fix.
• Release messages must be passed in a timely manner and include:
  1. Aircraft identity, type, and SSR code (if applicable).
  2. Point of departure.
  3. Release point.
  4. Estimated time and level at the holding facility, or arrival time and level if after arrival.
  5. Expected approach time.
  6. Contact point.

Controlled Airspace:

• Aircraft released to Approach Control must be within controlled or advisory airspace when the release becomes effective.
• All other aircraft at lower levels must also be released or have procedural separation provided.
• Released aircraft should not be levelled off or climbed above the level at the holding facility without coordination with Area Control.

Release Point:

• Unless approved by the CAA, the release point for aircraft released to Approach Control should be below FL195. If approved, MATS Part 2 must include details of the area and conditions for these procedures.

Approach Sequencing:

• When approach sequencing is in force at aerodromes within Classes A to F airspace, Area Control clears all aircraft to the holding facility with holding instructions and an expected approach time if appropriate.

Class G Airspace:

• Aircraft proceeding to an aerodrome in Class G airspace are cleared to leave controlled or advisory airspace by descent or on an appropriate track, with the acceptance level advised in the release message.

Alternative Holding Facilities:

• Area Control may clear an arriving aircraft to an alternative holding facility or visual holding point after coordinating with Approach Control.

Question 9

What is the “Release Subject Your Discretion” (RSYD) procedure and when is it used?

Answer 9

The RSYD procedure allows outbound clearances that do not provide required separation from inbound or overflying aircraft, under the following conditions:

• The outbound clearance must be qualified with “Release subject your discretion” and include details of the conflicting traffic.
• The release message for the inbound aircraft or full details of the overflying traffic must have already been passed.

RSYD is used to expedite traffic when Approach Control can provide a more efficient resolution of the conflict than Area Control. The approach controller is responsible for ensuring required separation for outbound aircraft and resolving all conflicts or coordinating before transferring the aircraft to Area Control.

Question 10

What is the procedure for issuing departure clearances when two aircraft wish to depart in quick succession?

Answer 10

When two aircraft wish to depart in quick succession, Approach Control may issue departure clearances to Aerodrome Control with a condition, such as a time delay (e.g., “Release subject [callsign] departure plus two minutes”). The Aerodrome Controller is responsible for applying this separation or informing the Approach Controller if it is not possible.

An ACC may also issue two clearances to an Approach Control unit, requesting that aerodrome separation is applied between the aircraft (e.g., “…. release subject [callsign]”). The second aircraft must be separated from the first departure before transfer of control, with separation either constant or increasing. If Approach Control cannot ensure this, they must inform the centre immediately to agree on a new course of action.

Question 11

What is a “radar release” and when might Area Control use it?

Answer 11

A “radar release” is a procedure where Area Control expedites traffic by transferring control of arriving aircraft to Approach Control. The details of this procedure are found in Section 1, Chapter 6.

Question 12

What are the responsibilities of Area Control regarding separation and ATS surveillance services?

Answer 12

• Separation Responsibility: Area Control is responsible for providing separation between aircraft operating in controlled or advisory airspace, based on airspace classification, aircraft flight rules, and ATC clearances.
• ATS Surveillance Services: The area within which ATS surveillance services are provided is determined by equipment coverage and may be further limited to areas defined in MATS Part 2.
• Provision of ATS in Other Airspace: Where authorized, Area Control may provide ATS in airspace normally managed by another control unit, either permanently or on a limited basis, with specific arrangements published in MATS Part 2.

Question 13

How should separation be applied between an aircraft under Radar Control and known traffic outside PSR/SSR cover?

Answer 13

Separation between an aircraft under Radar Control and known traffic outside PSR/SSR cover should be applied as follows:

• Opposite Direction Traffic: Vertical separation must be provided at least 10 NM before the conflicting traffic is expected to enter PSR/SSR cover.
• Same Direction Traffic:
  1. Proceeding into PSR/SSR cover: Vertical separation must be provided until the identified aircraft is at least 10 NM within the point where the conflicting traffic is expected to enter coverage.
  2. Proceeding out of PSR/SSR cover: Vertical or other procedural separation must be established at least 10 NM before the aircraft is expected to leave coverage.

Question 14

What should controllers do if an aircraft reports “abeam” instead of “over” an en-route reporting point?

Answer 14

Controllers must ensure that the aircraft is aware of its correct routing and that separation is not adversely affected. Aircraft should report “over” en-route reporting points as close as possible to the actual time of the event, except when being vectored.

Question 15

When should a pilot make a position report to reduce RTF communication, and when should controllers instruct pilots to make position reports?

Answer 15

Pilots should make a position report:

• On the first transfer of communication from another ACC or sector (containing aircraft identification and flight level only; subsequent reports include position and time).
• On reaching the limit of the ATC clearance.
• When instructed by ATC.

Controllers should instruct pilots to make position reports:

• When the aircraft is outside ATS surveillance system cover.
• Before identification has been achieved.
• As detailed in MATS Part 2.

Question 16

What additional services can ACC units authorized by the CAA provide regarding ILS or radar approaches?

Answer 16

ACC units authorized by the CAA, subject to conditions in the authorization, can provide vectoring and sequencing for ILS or radar approaches, excluding the turn onto final approach, if the unit endorsement of the Area Control Surveillance rating indicates this capability.

Question 17

What information must be provided in flight data for aircraft requiring to cross or join controlled airspace, and what procedures must controllers follow?

Answer 17

For Crossing Flights:

• Aircraft identification and type.
• Position and heading.
• Level and flight conditions.
• Crossing position.
• Requested crossing level and estimate for crossing position.

For Joining Flights:

• Aircraft identification and type.
• Position and heading.
• Level and flight conditions.
• Departure aerodrome.
• Estimated time at entry point.
• Route and point of first intended landing.
• True airspeed.
• Desired level on the route.

Procedures for Controllers:

• Receipt of flight plan data does not constitute clearance; acknowledgment of in-flight information may allow the aircraft to proceed as planned in case of radio failure.
• Aircraft should receive clearance in reply to in-flight requests or be advised to remain outside controlled airspace with instructions on when to expect clearance and a time check.
• Aircraft already cleared to operate at a level within controlled airspace have priority over crossing or joining requests.
• Pilots requesting to cross ATS routes in VMC by day must be handled as IFR flights.
• No clearance is required for aircraft to operate at the lower limit of controlled airspace, but pilots are encouraged to obtain an appropriate ATS from the controlling authority.

Question 18

What are the procedures for military aircraft wishing to join controlled airspace or cross an ATS route within a control area?

Answer 18

• Joining Controlled Airspace: Military aircraft wishing to join controlled airspace and continue as GAT must follow procedures applicable to civil aircraft.
• Crossing ATS Routes:
  1. Military aircraft must obtain a clearance to cross an ATS route or cross under military surveillance control, ensuring separation from traffic without reference to the civil controller.
  2. Requests for crossing clearances can be made to the planner/coordinator or directly to the civil controller. Clearance is granted at the civil controller’s discretion, depending on workload and communication facilities.
• Emergency Procedures: If no crossing clearance can be obtained in an emergency, military aircraft may cross an ATS route at an intermediate 500 ft level (whole thousands plus 500 ft) to provide vertical separation from ATS route cruising levels.

Question 19

What are the procedures for instructing aircraft to hold en-route and handling delays of 20 minutes or more?

Answer 19

Holding En-route:

• Aircraft must always be given an onward clearance time and should never be told holding is indefinite.
• If an accurate calculation cannot be made immediately, provide an arbitrary onward clearance time requiring 10 to 15 minutes of holding, which must be amended to an accurate time before the period elapses.

Delays of 20 Minutes or More:

• Aircraft delayed by 20 minutes or more before commencing an intermediate approach for landing must be given an expected approach time with their clearance to the holding facility.
• If the delay is expected to be less than 20 minutes, no expected approach time should be passed. If the pilot requests the delay, inform them that it is expected to be less than 20 minutes.

Undetermined Delays:

• Procedures for aircraft waiting for approach clearance when the delay cannot be determined are described in Section 1, Chapter 4.

Question 20

What are the responsibilities and actions of the ACC Watch Supervisor when arranging the diversion of aircraft?

Answer 20

Responsibilities of the ACC Watch Supervisor:

• Monitor weather conditions at aerodromes in their area and ensure arriving aircraft have the latest information.
• Anticipate which aerodromes are likely to be most suitable for diversions based on:
  1. Forecast weather conditions from TRENDs/TAFs, consulting with the duty meteorological forecaster if necessary.
  2. Types of aircraft (considering runway length, approach aids, etc.).
• Verify that diversions can be accepted and note any special arrangements required by the diversion aerodrome.

Actions When Diversion is Requested or Considered Expedient:

• Provide the aircraft with a diversion message containing the latest weather information, clearance instructions, radio frequencies, etc.
• Inform the diversion aerodrome with full details of the aircraft, its clearance instructions, etc.
• Notify the original destination aerodrome of the diversion action.

Additional Reference:

• This procedure should be read in conjunction with Section 1, Chapter 8.